CN108984867A - Based on the GF-4 and MODIS the Method for Retrieving Evapotranspiration combined and system - Google Patents
Based on the GF-4 and MODIS the Method for Retrieving Evapotranspiration combined and system Download PDFInfo
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Abstract
The present invention provides a kind of the Method for Retrieving Evapotranspiration combined based on GF-4 and MODIS and systems, by obtaining the GF-4 data and MODIS data of target area, and obtain earth's surface key parameter according to GF-4 data and MODIS data inversion；Based on earth's surface key parameter, the Heat Flux Exchange data between uniform earth's surface and atmosphere are obtained using Land surface energy budget model SEBAL；It based on Heat Flux Exchange data, is decomposed using energy balance model TSEB, obtains Vegetation canopy Heat Flux Exchange data and soil heat flux exchange data；It is calculated according to Vegetation canopy Heat Flux Exchange data and soil heat flux exchange data, obtains instantaneous evapotranspiration amount；Instantaneous evapotranspiration amount is subjected to time day spatial scaling, obtains the day evapotranspiration amount of target area.Present invention combination GF-4 data and MODIS data can obtain high-precision ET result by merging the Multiple Source Sensor data of different spatial resolutions with inverting.
Description
Technical field
The present invention relates to evapotranspiration inversion technique fields, are evapotranspired more particularly, to a kind of based on what GF-4 and MODIS was combined
Send out remote sensing inversion method and system.
Background technique
Evapotranspiration (evapotranspiration, ET) is the important link and earth's surface of Water Cycle in Earth-atmospheric system
The component of estimation is most difficult in energy circulation, water circulation and carbon cycle.In arid, semiarid zone, it is raw that evapotranspiration amount accounts for farmland
80% or more of total water consumption in state system, therefore, quantitatively calculate evapotranspiration amount for embodiment agricultural hydrology circulating analog, refer to
Agriculture water management is led to be of great significance.It is especially bigger in the more complicated and broken irrigated area effect of pattern of farming.
The development of remote sensing technology makes it possible that the quick, accurate of area crops evapotranspiration, large area are estimated, that it changes
The theory of traditional single-point earth observation becomes the effective way for simulating a wide range of Crop evapotranspiration hair now.With earth observation skill
The fast development of art, obtainable remotely-sensed data source is more and more, and existing embodiment is still generally confined to based on single-sensor
The inverting of data progress ET.But by cloud, rain, mist/haze, different sensors parameter and spatial resolution, revisiting period, image capturing
When the uncertain factors such as complicated earth surface influence, single-sensor in the entire life process of crop obtainable data compared with
Less, space-time expending is poor, its ET inversion result is caused also to deposit in terms of Regional suitability apart from precision agriculture monitoring businessization
In larger gap.
Summary of the invention
In view of this, the purpose of the present invention is to provide the Method for Retrieving Evapotranspiration based on GF-4 and MODIS combination
And system can obtain high-precision ET result by merging the Multiple Source Sensor data of different spatial resolutions with inverting.
In a first aspect, the embodiment of the invention provides a kind of evapotranspiration remote-sensing inversion sides combined based on GF-4 and MODIS
Method, comprising:
The GF-4 data and MODIS data of target area are obtained, and anti-according to the GF-4 data and the MODIS data
It drills to obtain earth's surface key parameter；
Based on the earth's surface key parameter, obtained between uniform earth's surface and atmosphere using Land surface energy budget model SEBAL
Heat Flux Exchange data；
It based on the Heat Flux Exchange data, is decomposed using energy balance model TSEB, it is logical to obtain Vegetation canopy heat
Amount exchange data and soil heat flux exchange data；
It is calculated, is obtained according to the Vegetation canopy Heat Flux Exchange data and soil heat flux exchange data
Instantaneous evapotranspiration amount；
The instantaneous evapotranspiration amount is subjected to time day spatial scaling, obtains the day evapotranspiration amount of the target area.
With reference to first aspect, the embodiment of the invention provides the first possible embodiments of first aspect, wherein institute
State the step of earth's surface key parameter is obtained according to the GF-4 data and the MODIS data inversion, comprising:
Leaf area index inverting is carried out according to the GF-4 data, obtains leaf area index；
Surface temperature, normalized differential vegetation index, surface albedo and earth's surface ratio are obtained according to the MODIS data inversion
Radiance.
The possible embodiment of with reference to first aspect the first, the embodiment of the invention provides second of first aspect
Possible embodiment, wherein it is described to carry out leaf area index inverting according to the GF-4 data, obtain the step of leaf area index
Suddenly, comprising:
Based on the GF-4 data, leaf area index is carried out using LUT Method using PROSAIL radiative transfer model
Inverting obtains the leaf area index.
With reference to first aspect, the embodiment of the invention provides the third possible embodiments of first aspect, wherein institute
It states and is calculated according to the Vegetation canopy Heat Flux Exchange data and soil heat flux exchange data, instantaneously steamed
The step of emission, comprising:
Obtain the initial value of Vegetation canopy latent heat flux；
According to energy balance rule to the Vegetation canopy Heat Flux Exchange data, the soil heat flux exchange data with
And the initial value is iterated calculating, obtains instantaneous evapotranspiration amount；
The third possible embodiment with reference to first aspect, the embodiment of the invention provides the 4th kind of first aspect
Possible embodiment, wherein it is described obtain Vegetation canopy latent heat flux initial value the step of, comprising:
Based on the Vegetation canopy Heat Flux Exchange data, the vegetation is calculated according to Priestley-Taylor formula and is preced with
The initial value of layer latent heat flux.
The possible embodiment of with reference to first aspect the first, the embodiment of the invention provides the 5th kind of first aspect
Possible embodiment, wherein it is described to be based on the earth's surface key parameter, it is obtained using Land surface energy budget model SEBAL
The step of Heat Flux Exchange data between even earth's surface and atmosphere, comprising:
Based on the earth's surface key parameter, using the Land surface energy budget model SEBAL obtain surface net radiation flux,
Sensible Heating Flux and soil heat flux.
The 5th kind of possible embodiment with reference to first aspect, the embodiment of the invention provides the 6th kind of first aspect
Possible embodiment, wherein it is described to be based on the Heat Flux Exchange data, it is decomposed using energy balance model TSEB
Step includes:
The surface net radiation flux is decomposed into soil net radiation flux and Vegetation canopy net radiation flux；And it will
The Sensible Heating Flux is decomposed into soil Sensible Heating Flux and Vegetation canopy Sensible Heating Flux.
The 5th kind of possible embodiment with reference to first aspect, the embodiment of the invention provides the 7th kind of first aspect
Possible embodiment, wherein it is described to be based on the earth's surface key parameter, felt using Land surface energy budget model SEBAL
The step of heat flux, comprising:
Aerodynamic resistance is carried out based on the surface temperature, and using the Land surface energy budget model SEBAL
Iterative calculation, obtains the Sensible Heating Flux.
Second aspect, the embodiment of the present invention also provide a kind of evapotranspiration remote-sensing inversion system combined based on GF-4 and MODIS
System, comprising:
Data acquisition module, for obtaining the GF-4 data and MODIS data of target area, and according to the GF-4 data
Earth's surface key parameter is obtained with the MODIS data inversion；
SEBAL model computation module utilizes Land surface energy budget model SEBAL for being based on the earth's surface key parameter
Obtain the Heat Flux Exchange data between uniform earth's surface and atmosphere；
TSEB model decomposition module is carried out for being based on the Heat Flux Exchange data using energy balance model TSEB
It decomposes, obtains Vegetation canopy Heat Flux Exchange data and soil heat flux exchange data；
TSEB model computation module, for according to the Vegetation canopy Heat Flux Exchange data and the soil heat flux
Exchange data are calculated, and instantaneous evapotranspiration amount is obtained；
Conversion module obtains the target area for the instantaneous evapotranspiration amount to be carried out time day spatial scaling
Day evapotranspiration amount.
In conjunction with second aspect, the embodiment of the invention provides the first possible embodiments of second aspect, wherein institute
Stating data acquisition module includes:
First inverting unit obtains leaf area index for carrying out leaf area index inverting according to the GF-4 data；
Second inverting unit, for according to the MODIS data inversion obtain surface temperature, normalized differential vegetation index,
Table albedo and Land surface emissivity.
The embodiment of the present invention bring it is following the utility model has the advantages that
The embodiment of the invention provides a kind of the Method for Retrieving Evapotranspiration combined based on GF-4 and MODIS and system,
By obtaining the GF-4 data and MODIS data of target area, and earth's surface is obtained according to GF-4 data and MODIS data inversion and is closed
Bond parameter；Based on earth's surface key parameter, the heat flux between uniform earth's surface and atmosphere is obtained using Land surface energy budget model SEBAL
Exchange data；It based on Heat Flux Exchange data, is decomposed using energy balance model TSEB, obtains the friendship of Vegetation canopy heat flux
Change data and soil heat flux exchange data；According to Vegetation canopy Heat Flux Exchange data and soil heat flux exchange data into
Row calculates, and obtains instantaneous evapotranspiration amount；Instantaneous evapotranspiration amount is subjected to time day spatial scaling, is evapotranspired the day for obtaining target area
Hair amount.It can be with inverting by merging the Multiple Source Sensor data of different spatial resolutions in conjunction with GF-4 data and MODIS data
Obtain high-precision ET result.
Other features and advantages of the present invention will illustrate in the following description, also, partly become from specification
It obtains it is clear that understand through the implementation of the invention.The objectives and other advantages of the invention are in specification, claims
And specifically noted structure is achieved and obtained in attached drawing.
To enable the above objects, features and advantages of the present invention to be clearer and more comprehensible, preferred embodiment is cited below particularly, and cooperate
Appended attached drawing, is described in detail below.
Detailed description of the invention
It, below will be to specific in order to illustrate more clearly of the specific embodiment of the invention or technical solution in the prior art
Embodiment or attached drawing needed to be used in the description of the prior art be briefly described, it should be apparent that, it is described below
Attached drawing is some embodiments of the present invention, for those of ordinary skill in the art, before not making the creative labor
It puts, is also possible to obtain other drawings based on these drawings.
Fig. 1 is the Method for Retrieving Evapotranspiration flow chart provided in an embodiment of the present invention combined based on GF-4 and MODIS；
Fig. 2 be another embodiment of the present invention provides the Method for Retrieving Evapotranspiration stream combined based on GF-4 and MODIS
Cheng Tu；
Fig. 3 is the evapotranspiration remote-sensing inversion system schematic provided in an embodiment of the present invention combined based on GF-4 and MODIS；
Fig. 4 is electronic equipment schematic diagram provided in an embodiment of the present invention.
Icon: 10- data acquisition module；20-SEBAL model computation module；30-TSEB model decomposition module；40-TSEB
Model computation module；50- conversion module；1000- electronic equipment；500- processor；501- memory；502- bus；503- is logical
Believe interface.
Specific embodiment
In order to make the object, technical scheme and advantages of the embodiment of the invention clearer, below in conjunction with attached drawing to the present invention
Technical solution be clearly and completely described, it is clear that described embodiments are some of the embodiments of the present invention, rather than
Whole embodiments.Based on the embodiments of the present invention, those of ordinary skill in the art are not making creative work premise
Under every other embodiment obtained, shall fall within the protection scope of the present invention.
Currently, existing remote-sensing inversion embodiment is still generally confined to carry out the inverting of ET based on single-sensor data.But
It is uncertain by complicated earth surface when cloud, rain, mist/haze, different sensors parameter and spatial resolution, revisiting period, image capturing etc.
Sexual factor influences, and single-sensor obtainable data in the entire life process of crop are less, space-time expending is poor, make
At its ET inversion result, apart from precision agriculture monitoring business, there is also larger gaps in terms of Regional suitability.Based on this, originally
A kind of the Method for Retrieving Evapotranspiration and system based on GF-4 and MODIS combination that inventive embodiments provide, by merging not
The Multiple Source Sensor data of isospace resolution ratio can obtain high-precision ET result with inverting.
For convenient for understanding the present embodiment, first to one kind disclosed in the embodiment of the present invention be based on GF-4 and
The Method for Retrieving Evapotranspiration that MODIS is combined describes in detail.
High score four (GF-4) satellites are geostationary orbit remote sensing satellites, and it is red to be equipped with 50 meters/medium wave of a visible light
Outer 400 meters of resolution ratio stares camera greater than 400 kilometers of breadth, is imaged using the face battle array mode of staring, has visible light, mostly light
Spectrum and infrared imaging ability.
The full name of MODIS is Moderate Imaging Spectroradiomete (moderate-resolution imaging
Spectroradiometer), be an important sensor being mounted on Terra and Aqua satellite, uniquely will on satellite
Real-time observed data is directly broadcasted by x wave band to the whole world, and can freely receive the spaceborne instrument of data and use without compensation.
During earth observation, it is per second can obtain simultaneously 11 megabits from atmosphere, ocean and land surface information, it is daily or every
A global observation data can be obtained within 2nd.
Fig. 1 shows the Method for Retrieving Evapotranspiration stream provided in an embodiment of the present invention combined based on GF-4 and MODIS
Cheng Tu.
As shown in Figure 1, a kind of the Method for Retrieving Evapotranspiration combined based on GF-4 and MODIS is present embodiments provided,
It can be applied to the evapotranspiration remote-sensing inversion of area crops, comprising the following steps:
Step S101 obtains the GF-4 data and MODIS data of target area, and according to GF-4 data and MODIS data
Inverting obtains earth's surface key parameter；
Specifically, GF-4 data include the GF-4 satellite image of target area, available Reflectivity for Growing Season, MODIS number
According to including reflectivity product MOD09A1 and temperature emissivity product MOD11A2, available another kind Reflectivity for Growing Season and earth's surface
Temperature.
In evapotranspiration calculating, the parameter of remote-sensing inversion specifically includes that surface temperature, is that earth's surface-atmosphere interface reaches heat
Amount balance as a result, determining the size of earth's surface long-wave radiation energy；Surface albedo determines the big of surface effective energy
It is small；Land surface emissivity is the most basic parameter of Surface Temperature Retrieval；Vegetation index is that the distribution of remote sensing monitoring surface vegetation is planted
By the instruction parameter of cover degree.The earth's surface key parameter of the present embodiment further includes leaf area index, refer to the plant leaf blade gross area with
The ratio of land area.The density of it and vegetation, structure (single layer or cladding), trees biological characteristics (branch angle, leaf it is raw
Angle, shade tolerance etc.) and environmental condition (illumination, moisture, soil nutrient status) it is related, be to indicate vegetation using luminous energy situation and hat
One overall target of layer structure.
Further, the step of earth's surface key parameter being obtained according to GF-4 data and MODIS data inversion in step S101,
Include: to carry out leaf area index inverting according to GF-4 data, obtains leaf area index；Earth's surface is obtained according to MODIS data inversion
Temperature, normalized differential vegetation index, surface albedo and Land surface emissivity.
(1) vegetation index
Vegetation index is the numerical value for having indicative significance to vegetation cover degree, biomass and growth vigor etc., is remote sensing prison
One of geodetic table plant growth and the method for distribution.It passes through the linearly or nonlinearly group to near-infrared and red spectral band reflectivity
It closes, does not need other auxiliary informations, to eliminate the influence of soil spectrum in image, realize the expression to plant information state.Return
One change vegetation index (NDVI) be vegetation growth state and vegetation coverage best indicator, can eliminate part and too
Positive elevation angle, moonscope angle, atmospheric conditions, cloud/shade, landform and the influence in relation to irradiation level condition variation etc..
The data that the present embodiment uses are the MODIS data productions that NASA NASA received and passed through that processing obtains
Product (HDF format).For MODIS image, NDVI is near infrared band (the 1st wave band) and red spectral band (the 2nd wave band)
The difference α of numerical value2-α1With the sum of the two wave band numerical value α1+α2Ratio.Such as formula (1):
For the main covering of land surface, snow, cloud, water have in red spectral band than near infrared band higher anti-
The effect of penetrating, therefore its NDVI value is negative value, naked rock has similar reflex in two wave bands, thus its NDVI value is bordering on 0, is having
In the case where vegetative coverage, NDVI is positive value, and is increased with the increase of vegetation coverage.
Vegetation coverage is normally defined the ratio between planimetric area and sample gross area of phytobiocoenose totality greenery.It
It is the important controlling elements for influencing surface vegetation transpiration and soil water evaporation loss process, is Vegetation canopy shape, vegetation sky
Between distribution, leaf inclination angle and overlapping be formed by parameter, it is unrelated with the spectral signature of vegetation, but using remote sensing inverting plant
When coating cover degree, mainly estimated by vegetation index, especially by formula (2):
In formula, NDVI is vegetation index, and NDVIv and NDVIs are dense vegetative coverage and complete exposed soil pixel respectively
NDVI value.For MODIS data, NDVIv=0.9, NDVIs=0.15 are usually taken.Therefore, as NDVI > NDVIv=0.9, fv
=1, it indicates that the pixel is the area of a dense vegetative coverage, does not see exposed soil surface；Otherwise, as NDVI < NDVIs
When=0.15, fv=0 indicates that the pixel is a completely exposed area, without any vegetative coverage.
(2) surface albedo
Surface albedo (Albedo) is earth's surface different type object reflected solar radiation energy and is incident on the object
The ratio of total solar energy.Earth's surface different underlying surface is characterized to the albedo of solar radiation, decides point of the energy between ground-gas
Proportion is to influence one of Surface Energy Budget balance and most important parameters of ecological process.Albedo is with change in time and space
And change, change under normal circumstances relatively slowly, but its value in the case where climatic environment is mutated (sandstorm, snowstorm etc.)
Variation is obvious.Surface albedo is influenced by the factors such as spatial distribution of underlying surface situation, solar zenith angle, incident radiation, benefit
With atmospheric radiation transmission, using analogy method to nine kinds of multiband satellites, including AVHHR, Landsat TM/ETM+,
MODIS, ASTER etc. are established in relation to seeking broadband equation group, and precision about can reach 0.02, and the present embodiment can use beam
Broadband albedo algorithm, such as formula are calculated using the narrow-band reflectivity of MODIS data along what (2000) such as woodss proposed
(3):
The α of α=0.1601+0.291α2+0.243α3+0.116α4+0.112α5+0.081ε7-0.0015 (3)
Wherein, α is broadband surface albedo, α1,2,3,4,5,7Each wave band of correspondence respectively after Atmospheric Correction
Reflectivity.
(3) Land surface emissivity
Land surface emissivity (ε), also known as earth's surface emissivity are object and black matrix in synthermal, giving off under co-wavelength
The ratio for degree of penetrating is a nondimensional amount, and the value of ε is between 0~1.Emissivity is the outside electromagnetic radiation of earth's surface object
The ability of wave, it by the component of earth's surface object, surface state, temperature, object radiation can wavelength, observation angle and other objects
Rationality matter (dielectric constant, water content etc.) has substantial connection.Embodiment show Land surface emissivity there are 0.01 error,
The estimation error that will lead to surface temperature reaches 1-2 DEG C.Therefore, estimation Land surface emissivity is to the inverting of surface temperature to closing weight
It wants.
Although the surface infrastructure of earth surface different zones is complicated, from the point of view of satellite picture dot scale, it is divided into 3 substantially
Type: water body, cities and towns and natural surface.Cities and towns picture dot generally accounted in image ratio is little.And on the contrary, natural surface is usual
It is maximum to account for image picture dot ratio, is emphasis in need of consideration in Surface Temperature Retrieval.Valor thinks that earth's surface can simply be regarded as
It is formed mixed by vegetation integral shroud and exposed soil by different proportion.Therefore the present embodiment, according to the different tributes of earth's surface emissivity
It offers, establishes the estimation formula of the Land surface emissivity of MODIS image, such as formula (4):
εi=fvRvεiv+(1-fv)Rsεis+dε (4)
Wherein, εiIt is the Land surface emissivity of the i-th wave band of MODIS image (i=31,32)；εivAnd εisRespectively represent vegetation
With exposed soil in the surface radiation rate of the i-th wave band, ε is generally taken31v=0.98672, ε32v=0.98990, ε31s=0.96767, ε32s
=0.97790；fvIt is vegetation coverage；dεIt is heat radiation interaction correction, is interacted by the heat radiation between vegetation and exposed soil
Cause；RvAnd RsIt is the radiation ratio of vegetation and exposed soil respectively, is defined as formula (5) and formula (6):
Rv=Bv(Tv)/B(T) (5)
Rs=Bs(Ts)/B(T) (6)
In formula, Bv(Tv) and Bs(Ts) be respectively vegetation and exposed soil in mixed pixel caloradiance, be mixed pixel
Caloradiance.
It is shown by simulating calculated result, RvAnd RsDepend primarily on temperature change and vegetation coverage, and vegetation coverage
Influence it is bigger, therefore, establish Rv, Rs and fvRelationship estimated.Such as formula (7) and formula (8):
Rv=0.92762+0.07033fv (7)
Rs=0.99782+0.08362fv (8)
Finally to heat radiation interaction correction term dεIt is estimated, due to dεReach when vegetation respectively accounts for half with exposed soil
Therefore maximum value can be estimated according to following empirical equation:
Work as fv=0 or fvWhen=1, dεMinimum, dε=0；
As 0 < fvWhen < 0.5, dε=0.003796fv；
As 0.5 < fvWhen < 1, dε=0.003796 (1-fv)；
Work as fvWhen=0.5, dεMaximum, dε=0.001898；
The ε being calculated with above-mentioned formulaiIf more than εiv, then ε is takeni；If εiLess than εis, then ε is takeni=εi。
Further, it can use PROSAIL radiative transfer model according to the progress leaf area index inverting of GF-4 data to adopt
Leaf area index inverting is carried out with LUT Method, obtains leaf area index.
The physical model of leaf area index (leaf area index, LAI) inverting is more, but is mostly limited by Finite Number
The input parameter of amount.PROSAIL radiative transfer model is simulated with it to Vegetation canopy spectral reflectivity and LAI, vegetation physiology are raw
The stability and robustness for changing parameter estimation become using more one of model, have obtained extensive verifying and application.
PROSAIL model is coupled to form by canopy reflectance model SAIL and blade optical property model PROSPECT.
PROSPECT model is the radiative transfer model from leaf scale simulation direction blade hemispherical reflectivity and transmission.PROSPECT is base
It is improved in the flat plate model of Allen etc., optical characteristics of the fresh blade from 400nm-2500nm can be characterized.Model it is defeated
Entering parameter includes blade construction parameter (N), the content (Cab) of chlorophyll a+b, equivalent water thickness (Cw), dry matter content (Cm)
Deng.SAIL model is vegetation as turbid media, it is assumed that blade azimuth angle is evenly distributed, and considers that arbitrary angle, canopy are two-way
Reflectivity describes the radiative transfer model of two tropism reflectivity of Vegetation canopy as a function of observation angle.SAIL is most
It is early to be used to simulate one of model of canopy reflectance spectrum, with progressions model it is contemplated that the influence of hot spot-effect.SAIL model master
The input parameter wanted has LAI, average Leaf inclination (ALIA), hot spot parameters (hot), skylight scattering ratio (skyl), soil lightness
Parameter, Soil Background reflectivity, solar zenith angle, view zenith angle, relative bearing, leaf reflectance and transmissivity.Coupling
PROSAIL model afterwards can come using the PROSPECT leaf reflectance simulated and transmissivity as the input parameter of SAIL
Simulated visible light-near infrared spectrum direction canopy reflectance spectrum.
PROSAIL mode input parameter area and distribution such as table 1.The input ranges of all parameters and distribution with reference to
Previous embodiment.Chlorophyll content, biomass, equivalent water thickness and average Leaf inclination are according to measured data.Skylight scattering
It is very smaller than due to being influenced on canopy reflectance spectrum, according to previous embodiment, it can be set as 0.1.Spectral reflectance spectrum according to
The value of field observation is averaged.Solar zenith angle, view zenith angle, relative bearing can be straight directly from image header file
It connects to obtain.
1 PROSAIL mode input parameter area of table and distribution
LUT Method (LUT) is to solve the problems, such as that model inversion is most simple, effective method.Overcome Iteration Optimization
Caused by the low problem of computational efficiency, also overcome and be not easy problem analysis caused by Artificial Neural Network secret operation, fit
Together in the inverting of LAI.According to the input parameter area of model, embodiment carries out stochastical sampling to parameter first；Then in conjunction with distant
The information such as zenith angle, the azimuth of sense image capturing, which are all input in PROSAIL model, carries out simulation narrow-band reflectivity；It utilizes
Broad-band reflective rate of the spectral response functions simulation different sensors of different sensors data in visible light, near infrared band；
Generate the look-up table that leaf area index is constituted from different broad-band reflective rates.Wherein broad-band reflective rate can use following formula
(9) it calculates:
In formula, ρ s (λ) be simulation sensor broad-band reflective rate, λ min and λ max be respectively band wavelength it is upper,
Lower bound.ρ s (λ i) is the reflectivity of the i-th wave band of narrow-band, and φ (λ i) is the spectral response functions of the i-th wave band of narrow-band.
To keep look-up table more representative, accurate enough, the size rank of look-up table should be sufficiently large.Therefore, look-up table
Size rank be set as 200,000.In order to avoid observation error or the different spectrum of jljl, foreign matter are asked with ill-posed inversion caused by spectrum
Topic, refutation strategy application minimize root-mean-square error cost function method.When cost function value is smaller, modeling reflectance value
It is closer with remotely-sensed data actual reflectance, then when cost function value is minimum or it is smaller when corresponding simulation LAI value recognized
To be inversion result.The cost function that embodiment is chosen is opposite root-mean-square error, referring to formula (10):
Wherein, m is wave band number.
Under the conditions of PROSAIL modeling reflectivity and Remote Sensing Reflectance cost function are the smallest, corresponding input parameter
One group of solution.But due to the imperfection of observation error and model, the result of obtained solution not necessarily optimal solution, may not also
Uniquely.To overcome this problem, embodiment is combined according to the value of opposite root-mean-square error by spread parameter from small to large, and selection is looked into
The opposite root-mean-square error of the minimum of 10% look-up table number in table is looked for be worth the mean value of corresponding inverted parameters combination as finally
LAI estimation result.
Step S102 is based on earth's surface key parameter, utilizes Land surface energy budget model SEBAL (Surface energy
Balance algorithm for land, SEBAL) obtain the Heat Flux Exchange data between uniform earth's surface and atmosphere；
Further, step S102 is included: and is obtained based on earth's surface key parameter using Land surface energy budget model SEBAL
Surface net radiation flux, Sensible Heating Flux and soil heat flux.
Specifically, the process for the associated flux sought based on SEBAL model is as follows:
Using remote sensing come the evapotranspiration amount of estimation area, basic thought is to ignore plant photosynthesis energy consumption and water
Square upward energy input, establishes different Evapotranspiration by Using Remote Sensing, such as SEBAL, earth's surface energy based on energy-balance equation
Balance system SEBS (Surface energy balance system, SEBS) model etc. is measured, they make full use of remote sensing anti-
The Land Surface Parameters drilled carry out the Remote sensing inverting in region in conjunction with a small amount of conventional meteorological data, and different Remote Sensing Models is to gas
It is different as the characteristics of element and embodiment object, make it have different practicability and inversion accuracy.Energy-balance equation can
It is expressed as formula (11):
Rn=H+G+ λ ET (11)
In formula, RnFor surface net radiation flux (W/m2), it is the energy summation that earth's surface receives；H is the sense of earth's surface and atmosphere
Heat flux (also referred to as Sensible Heating Flux) (W/m2)；G is the soil heat flux (W/m of earth's surface2), i.e. heat flux between underlying surface and soil
Exchange heats up for underlying surface earth's surface；λ ET is latent heat flux (W/m2), i.e., the heat exchange of steam between underlying surface and atmosphere, wherein
λ is the latent heat of vaporization of water, and ET is evapotranspiration.As long as therefore obtaining Rn, G, H value, so that it may find out λ ET value, and then ask calculating
Evapotranspiration amount ET.
Surface net radiation flux is surface energy, substance conveying is formed with the motive power and weather exchanged and transformation
Main foundation.Surface net radiation flux can be expressed as the difference of the income and expenditure of earth's surface shortwave and long-wave radiation, can be according to spoke
It penetrates equilibrium equation emanated energy is subtracted by projectile energy and acquire, such as formula (12):
Rn=(1- α) Rs↓+(RL↓-RL↑)-(1-ε)RL↓ (12)
In formula, Rs↓For the solar shortwave radiation W/m for being incident on earth's surface2, RL↓For the long _ wave radiation W/ for being incident to earth's surface
m2, RL↑For the long-wave radiation W/m for reflexing to atmosphere2, α is surface albedo, and ε is Land surface emissivity, in which:
RL↓=1.08 (- ln τ)0.265σTa 4
RL↑=ε σ Ts 4
In formula, GscIt is solar constant (1367)；τ is atmospheric transmittance；θ is solar zenith angle；Dr is with astronomical unit's table
The solar distance shown, σ are that Stefan-Boltzmann constant (takes 5.67 × 10-8)；T0It is the celsius temperature scale of near surface temperature；
TaFor the thermodynamic temperature value of air themperature；TsFor the surface temperature of inverting；J is that satellite image obtains the date in solar calendar
Arrange serial number.
Soil heat flux refers to by conduction and is stored in the energy in soil and vegetation, it is to soil evaporation, earth's surface
Energy exchange has an impact, smaller relative to net radiation, latent heat and Sensible Heating Flux, but an important component.Soil Thermal
Flux is generally difficult to be utilized remote sensing and directly acquires, but can according to surface temperature, net radiation flux, surface albedo and
The empirical statistics relationship of normalized differential vegetation index carries out estimation and seeks, and in calculating process, SEBAL model and TSEB model have
The respective estimation formula established using the above parameter, wherein carrying out the calculating of soil heat flux solution using SEBAL model
Formula is (13):
Wherein, c11It indicates influence of the satellite transit time to G, correction appropriate is carried out according to satellite transit time, is passed by
Time c when before 12 points of the local time11Take 0.9；Transit time takes 1.0 between 12 points to 14 points of the local time；At 14 points
1.1 are taken between to 16 points.
Further, it is based on earth's surface key parameter, obtains the step of Sensible Heating Flux using Land surface energy budget model SEBAL
Suddenly, comprising: it is based on surface temperature, and calculating is iterated to aerodynamic resistance using Land surface energy budget model SEBAL,
Obtain Sensible Heating Flux.
Specifically, Sensible Heating Flux, also known as sensible heat flux are the heat exchanges of turbulence form between underlying surface and atmosphere, mainly
Underlying surface is acted on and lost energy by energy conduction and atmosphere convection.The calculating of Sensible Heating Flux is considerably complicated, by land use,
The many factors such as soil texture and composition, vegetative coverage, landform influence, and are generally estimated by following formula (14):
In formula, ρ is atmospheric density (Kg/m3)；CpAir specific heat for normal atmosphere pressure (usually takes 1004J/kg
℃)；rahFor aerodynamic resistance (s/m), wind profile theoretical calculation can be used；Tr is aerodynamics temperature (K), and Ta is big
Gas mean effort temperature.
By formula (14) it is found that Sensible Heating Flux and aerodynamic resistance, temperature gradient are closely related, and utilize remote sensing
Method is difficult directly to measure aerodynamics temperature and impedance.To acquire temperature gradient, SEBAL model introduce two it is extreme
" anchor point " (doing, wet point) is used as boundary condition, and utilizing the Sensible Heating Flux of " wet point " is approximately zero, and evapotranspiration reaches maximum；And
The evapotranspiration of " doing " is approximately zero, and Sensible Heating Flux reaches maximum it is assumed that carrying out the calculating of temperature gradient.It is steady due to atmosphere
Qualitative to influence obviously on aerodynamic resistance, to eliminate buoyancy effect caused by earth's surface heat, SEBAL model introduces Monin-
Obukhov is theoretical, by complicated loop iteration process, obtains stablizing the ginseng such as antitripic wind, dynamics impedance under atmospheric conditions
Number, and rahSensible Heating Flux is needed again in correction course, therefore can solve to obtain stable Sensible Heating Flux H using alternative manner.
In Sensible Heating Flux calculating, the quality that dry and wet point is chosen directly affects final Sensible Heating Flux precision, utilizes temperature-
The space characteristics relationship of vegetation index (Ts-VI) can carry out the fast selecting of dry and wet point, it is considered that moisture supply abundance, vegetation
Riotous growth, temperature be very low, pixel in potential evapotranspiration level, can be the good region being completely covered of vegetation growth or
Open water body is that wet (cold) puts optimal candidate regions；And the idle farmland or saline and alkaline of the drying of opposite not vegetative coverage
Ground, temperature is very high, and evapotranspiration is almost 0 pixel, is the best candidate area for doing (" Hot ").And note that in the process of selection
In, it avoids choosing extreme picture dot, because temperature gradient is built upon on the basis of natural vegetation in SEBAL model, if selection pole
" puppet is dry for shade or cloud in low temperature picture dot etc. " pseudo- cold spot picture dot " or the city cement floor for selecting excessive temperature picture dot etc.
Point picture dot ", then necessarily cause estimation error.
In the loop iteration of Sensible Heating Flux calculates, need to calculate power roughness, wind friction velocity, aerodynamics first
Impedance；It is then assumed that temperature gradient dT and TsBetween there are linear relationships, such as formula (15):
DT=aTs+b (15)
Then, according to do, wet point temperature gradient and TsNumerical value, seek linear dimensions a and b, such as formula (16) and
Formula (17), and then acquire the distribution of each picture dot temperature gradient of entire image.
After calculating acquires parameter a and b, available temperature gradient dT, Sensible Heating Flux H can be sought by bringing formula (18) into:
But in practical situations, influence of the air stability to aerodynamic resistance is obvious, for the buoyancy for eliminating atmosphere
The Monin-Obukhov theory of similarity is incorporated herein, the calculation formula such as (19) of Monin-Obukhov length in effect:
Wherein, u*It is wind friction velocity (m/s), k is von karman constant 0.41, and g is acceleration of gravity (9.81m/s2)。L
For Monin-Obukhov length, it determines the stability state of atmosphere, if L is greater than 0, indicates that air is stable；If L is less than
0, then air is unstable；If L is equal to 0, the buoyancy effect for being not required to consider atmosphere is represented.
If L > 0, correction term ψm(200m)、ψm(0.1m)、ψm(2m)It is calculated respectively according to following formula:
The correction term ψ if L < 0m(200m)、ψm(0.1m)、ψm(2m)It is calculated respectively according to following formula:
Wherein:
If L=0, ψm=0, ψh=0.Bring correction value into U*And rahCorrection formula (20) and formula (21) in, again
Calculate new u*And rah:
Wherein, Zom is momentum surface roughness, utilizes the u newly calculated*And rah, according to formula (18) and formula (19) weight
It is new to calculate H and L, it constantly iterates to calculate, until rah(r can be taken until stabilizationahAmplitude of variation is lower than 3% or less).
Step S103 is based on Heat Flux Exchange data, utilizes energy balance model TSEB (Two-source energy
Balance, TSEB) it is decomposed, obtain Vegetation canopy Heat Flux Exchange data and soil heat flux exchange data；
Further, step S103 includes: that surface net radiation flux is decomposed into soil net radiation flux and Vegetation canopy
Net radiation flux；And Sensible Heating Flux is decomposed into soil Sensible Heating Flux and Vegetation canopy Sensible Heating Flux.
Step S104 is calculated according to Vegetation canopy Heat Flux Exchange data and soil heat flux exchange data, is obtained
To instantaneous evapotranspiration amount；
Further, as shown in Fig. 2, step S104 includes:
Step S1041 obtains the initial value of Vegetation canopy latent heat flux；
Specifically, Vegetation canopy Heat Flux Exchange data are based on, vegetation hat is calculated according to Priestley-Taylor formula
The initial value of layer latent heat flux；
Step S1042 exchanges data to Vegetation canopy Heat Flux Exchange data, soil heat flux according to energy balance rule
And initial value is iterated calculating, obtains instantaneous evapotranspiration amount.
Specifically, the process for the associated flux sought based on TSEB model is as follows:
Though TSEB model and the same all based on energy-balance equation with single-layer model, obviously not with single-layer model
Together, in TSEB model, earth's surface is no longer single, the uniform underlying surface in single-layer model, but is carried out to soil and vegetation
It decomposes, is based respectively on respective energy-balance equation and is solved, such as formula (22):
Rns=Hs+LETs+G
Rnc=Hc+LETc (22)
In formula, RnsAnd RncRespectively soil net radiation flux and Vegetation canopy net radiation flux；Hs and Hc is respectively soil
Sensible Heating Flux and Vegetation canopy Sensible Heating Flux；LETsAnd LETcRespectively soil latent heat flux and Vegetation canopy latent heat flux.
And for RnsAnd RncCalculating, can be estimated according to solar elevation and leaf area index, experience in TSEB model
Vegetation canopy net radiation flux is calculated, then seeks soil net radiation flux by the difference of total net radiation and Vegetation canopy net radiation, such as
Formula (23):
Rns=Rn-Rnc (23)
Wherein, LAI is leaf area index, and θ is solar zenith angle, k be canopy attenuation coefficient.
In the calculating process of soil heat flux, it is all root that SEBAL and TSEB model, which has respective empirical estimating formula,
According to the relationship of soil flux and net radiation, estimation formula is established, since the calculating of soil heat flux in SEBAL model is having vegetation
Estimation precision is higher when covering, relatively accurate using the empirical estimating of TSEB when vegetative coverage rareness, even exposed soil, public
Formula are as follows: G=0.15Rn。
Priestley-Taylor formula can be evaluated whether the situation of evapotranspiring of wet saturation underlying surface, in TSEB model, root
The initial calculation value that Vegetation canopy latent heat flux is calculated according to Priestley-Taylor formula, such as formula (24):
In formula, αPTFor Priestley-Taylor constant (taking 1.26), fGIt is the portion that greenery area accounts for total leaf area index
Point；Δ is slope of the saturation vapour pressure-temperature curve at Vegetation canopy temperature, and S is wet and dry bulb constant (taking 66.0).
In series connection bilayer model, vegetation and two layers of soil coupling, so that the air themperature at mixing height is equal to sky
Aerodynamics temperature, the value of entire Sensible Heating Flux are the sum of soil Sensible Heating Flux and vegetation Sensible Heating Flux, and SEBAL model is calculated
Obtained Sensible Heating Flux H is decomposed into the Sensible Heating Flux Hc of soil Sensible Heating Flux Hs and Vegetation canopy, such as formula (25):
H=Hc+Hs (25)
To sum up, it is known that the Sensible Heating Flux and latent heat flux of decomposition are unknown numbers, remaining is calculated by SEBAL model as
Know number, available using interative computation:
Hc=Rnc-LETc
Hs=H-Hc
LETs=Rns-G-Hs
According to practical situation, estimate that the picture dot of the latent heat flux of soil and vegetation all should be nonnegative value, so according to
It is calculating as a result, set the picture dot that all soil latent heat fluxs are negative as 0, then be iterated calculating:
Hs=Rns-G-LETs=Rns-G
Hc=H-Hs
LETc=Rnc-Hc
Stop calculating when vegetation latent heat flux picture dot is nonnegative value, otherwise continue to calculate, it is known that all soil and
Stopping when vegetation latent heat flux picture dot is nonnegative value, so that the latent heat flux value of instantaneous soil and vegetation is respectively obtained, two
The sum of person is final latent heat flux.
Instantaneous evapotranspiration amount is carried out time day spatial scaling, obtains the day evapotranspiration amount of target area by step S105.
Specifically, can only to represent the satellite ground that moment inverting obtains of passing by using the Surface Heat Flux Over of remote sensing appraising instantaneous
Value, and the fields such as the hydrology, ecology, weather are at least day scale to the embodiment of Surface Heat Flux Over in time scale, there are also more
Therefore the long moon, year scale need the expansion that time scale is carried out to the result for estimation of evapotranspiring in practical applications.
When fine, the diurnal variation curve of each component of the balance of solar radiation on the regions such as farmland and evapotranspiration amount is in just
String variation, and there is also sine relations for the diurnal variation of corresponding solar radiation flux density.Therefore, inquired by instantaneous evapotranspiration rate
The calculation formula that day evapotranspires can be expressed as (26):
In formula, NENumber when for day evapotranspiration, one hour after practical sunrise, before sunset, can be with since evapotranspiration is few
Ignore, therefore actual NEIt can be subtracted 2 hours and be obtained with sunshine time；T is to be counted from sunrise to satellite to obtain remotely-sensed data
The time interval at moment；Due to only obtaining daily sunshine time from weather station, without exact sunrise moment, the present embodiment root
It passes by according to sunshine time and satellite and carries out empirical estimating constantly, such as formula (27):
SIN function method it is only necessary to know that sunshine time and sunrise time can obtain the same day daily evapotranspiration, method
Simplicity, therefore the present embodiment carries out daily evapotranspiration expansion using SIN function method.
Single layer SEBAL model clear physics conception requires less, in Surface radiometric temperature and aerodynamics meteorological data
Loop iteration operation is utilized in temperature conversion, avoids artificial experience bring error；Connecting, also physical concept is clear for TSEB model
It is clear, separate soil, two turbulent flow source of Vegetation canopy, the evapotranspiration amount in available difference earth's surface source.The present embodiment is by two moulds
Type coupling, seeks the Heat Flux Exchange between uniform earth's surface and atmosphere using SEBAL model, then considers the internal junction of uniform earth's surface
Structure is decomposed into soil and Vegetation canopy heat flux using the total heat flux sought.
The present embodiment had not only solved the problems, such as that transpiration and soil evaporation cannot be distinguished in single layer SEBAL model, but also avoided
The complicated solving of soil impedance in series connection TSEB model, and so that the TSEB is inherited the robustness of SEBAL model, it is anti-to be suitable for ET
It drills.The present embodiment based on SEBAL and TSEB coupling ET quantitative inversion model, realize No. four GF-4 of domestic high score for the first time and defend
The area crops ET inverting that star and MODIS product combine, compared with the ET inversion result of simple MODIS product, precision is obtained
It is apparent to improve.
As shown in figure 3, a kind of evapotranspiration remote-sensing inversion system combined based on GF-4 and MODIS is present embodiments provided,
Including data acquisition module 10, SEBAL model computation module 20, TSEB model decomposition module 30, TSEB model computation module 40
And conversion module 50:
Data acquisition module 10, for obtaining the GF-4 data and MODIS data of target area, and according to GF-4 data and
MODIS data inversion obtains earth's surface key parameter；
SEBAL model computation module 20 is obtained for being based on earth's surface key parameter using Land surface energy budget model SEBAL
To the Heat Flux Exchange data between uniform earth's surface and atmosphere；
TSEB model decomposition module 30 is divided for being based on Heat Flux Exchange data using energy balance model TSEB
Solution obtains Vegetation canopy Heat Flux Exchange data and soil heat flux exchange data；
TSEB model computation module 40, for exchanging number according to Vegetation canopy Heat Flux Exchange data and soil heat flux
According to being calculated, instantaneous evapotranspiration amount is obtained；
Conversion module 50 evapotranspires the day for obtaining target area for instantaneous evapotranspiration amount to be carried out time day spatial scaling
Hair amount.
Further, data acquisition module 10 includes the first inverting unit and the second inverting unit:
First inverting unit obtains leaf area index for carrying out leaf area index inverting according to GF-4 data；
Second inverting unit, it is anti-for obtaining surface temperature, normalized differential vegetation index, earth's surface according to MODIS data inversion
According to rate and Land surface emissivity.
The evapotranspiration remote-sensing inversion system provided in an embodiment of the present invention combined based on GF-4 and MODIS, with above-mentioned implementation
The Method for Retrieving Evapotranspiration technical characteristic having the same combined based on GF-4 and MODIS that example provides, so can also solve
Certainly identical technical problem reaches identical technical effect.
The embodiment of the present invention also provides a kind of electronic equipment, including memory, processor, and being stored in memory can locate
The computer program that runs on reason device, processor realized when executing computer program it is provided by the above embodiment based on GF-4 and
The step of the Method for Retrieving Evapotranspiration that MODIS is combined.
The embodiment of the present invention also provides a kind of computer readable storage medium, and meter is stored on computer readable storage medium
Calculation machine program executes the evapotranspiration combined based on GF-4 and MODIS of above-described embodiment when computer program is run by processor
The step of remote sensing inversion method.
Referring to fig. 4, the embodiment of the present invention also provides a kind of electronic equipment 1000, comprising: processor 500, memory 501,
Bus 502 and communication interface 503, processor 500, communication interface 503 and memory 501 are connected by bus 502；Memory
501 for storing program；Processor 500 is used to call the program being stored in memory 501 by bus 502, executes above-mentioned
The Method for Retrieving Evapotranspiration of embodiment combined based on GF-4 and MODIS.
Wherein, memory 501 may include high-speed random access memory (RAM, Random Access Memory),
It may further include non-labile memory (non-volatile memory), for example, at least a magnetic disk storage.By extremely
A few communication interface 503 (can be wired or wireless) is realized logical between the system network element and at least one other network element
Letter connection, can be used internet, wide area network, local network, Metropolitan Area Network (MAN) etc..
Bus 502 can be isa bus, pci bus or eisa bus etc..The bus can be divided into address bus, number
According to bus, control bus etc..Only to be indicated with a four-headed arrow in Fig. 4, it is not intended that an only bus convenient for indicating
Or a type of bus.
Wherein, memory 501 is for storing program, and processor 500 executes described program after receiving and executing instruction,
Method performed by the device that the stream process that aforementioned any embodiment of the embodiment of the present invention discloses defines can be applied to processor
In 500, or realized by processor 500.
Processor 500 may be a kind of IC chip, the processing capacity with signal.It is above-mentioned during realization
Each step of method can be completed by the integrated logic circuit of the hardware in processor 500 or the instruction of software form.On
The processor 500 stated can be general processor, including central processing unit (Central Processing Unit, abbreviation
CPU), network processing unit (Network Processor, abbreviation NP) etc.；It can also be digital signal processor (Digital
Signal Processing, abbreviation DSP), specific integrated circuit (Application Specific Integrated
Circuit, abbreviation ASIC), ready-made programmable gate array (Field-Programmable Gate Array, abbreviation FPGA) or
Person other programmable logic device, discrete gate or transistor logic, discrete hardware components.It may be implemented or execute sheet
Disclosed each method, step and logic diagram in inventive embodiments.General processor can be microprocessor or the processing
Device is also possible to any conventional processor etc..The step of method in conjunction with disclosed in the embodiment of the present invention, can be embodied directly in
Hardware decoding processor executes completion, or in decoding processor hardware and software module combination execute completion.Software mould
Block can be located at random access memory, flash memory, read-only memory, programmable read only memory or electrically erasable programmable storage
In the storage medium of this fields such as device, register maturation.The storage medium is located at memory 501, and processor 500 reads memory
Information in 501, in conjunction with the step of its hardware completion above method.
The calculating based on the GF-4 and MODIS the Method for Retrieving Evapotranspiration combined is carried out provided by the embodiment of the present invention
Machine program product, the computer readable storage medium including storing the executable non-volatile program code of processor are described
The instruction that program code includes can be used for executing previous methods method as described in the examples, and specific implementation can be found in method and implement
Example, details are not described herein.
It is apparent to those skilled in the art that for convenience and simplicity of description, the system of foregoing description,
The specific work process of device and unit, can refer to corresponding processes in the foregoing method embodiment, and details are not described herein.
In several embodiments provided herein, it should be understood that disclosed systems, devices and methods, it can be with
It realizes by another way.The apparatus embodiments described above are merely exemplary, for example, the division of the unit,
Only a kind of logical function partition, there may be another division manner in actual implementation, in another example, multiple units or components can
To combine or be desirably integrated into another system, or some features can be ignored or not executed.Another point, it is shown or beg for
The mutual coupling, direct-coupling or communication connection of opinion can be through some communication interfaces, device or unit it is indirect
Coupling or communication connection can be electrical property, mechanical or other forms.
The unit as illustrated by the separation member may or may not be physically separated, aobvious as unit
The component shown may or may not be physical unit, it can and it is in one place, or may be distributed over multiple
In network unit.It can select some or all of unit therein according to the actual needs to realize the mesh of this embodiment scheme
's.
It, can also be in addition, the functional units in various embodiments of the present invention may be integrated into one processing unit
It is that each unit physically exists alone, can also be integrated in one unit with two or more units.
It, can be with if the function is realized in the form of SFU software functional unit and when sold or used as an independent product
It is stored in the executable non-volatile computer-readable storage medium of a processor.Based on this understanding, of the invention
Technical solution substantially the part of the part that contributes to existing technology or the technical solution can be with software in other words
The form of product embodies, which is stored in a storage medium, including some instructions use so that
One computer equipment (can be personal computer, server or the network equipment etc.) executes each embodiment institute of the present invention
State all or part of the steps of method.And storage medium above-mentioned includes: USB flash disk, mobile hard disk, read-only memory (ROM, Read-
Only Memory), random access memory (RAM, Random Access Memory), magnetic or disk etc. are various can be with
Store the medium of program code.
Finally, it should be noted that embodiment described above, only a specific embodiment of the invention, to illustrate the present invention
Technical solution, rather than its limitations, scope of protection of the present invention is not limited thereto, although with reference to the foregoing embodiments to this hair
It is bright to be described in detail, those skilled in the art should understand that: anyone skilled in the art
In the technical scope disclosed by the present invention, it can still modify to technical solution documented by previous embodiment or can be light
It is readily conceivable that variation or equivalent replacement of some of the technical features；And these modifications, variation or replacement, do not make
The essence of corresponding technical solution is detached from the spirit and scope of technical solution of the embodiment of the present invention, should all cover in protection of the invention
Within the scope of.Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (10)
1. a kind of the Method for Retrieving Evapotranspiration combined based on GF-4 and MODIS characterized by comprising
The GF-4 data and MODIS data of target area are obtained, and are obtained according to the GF-4 data and the MODIS data inversion
To earth's surface key parameter；
Based on the earth's surface key parameter, it is logical that the heat between uniform earth's surface and atmosphere is obtained using Land surface energy budget model SEBAL
Amount exchange data；
It based on the Heat Flux Exchange data, is decomposed using energy balance model TSEB, obtains the friendship of Vegetation canopy heat flux
Change data and soil heat flux exchange data；
It is calculated, is obtained instantaneous according to the Vegetation canopy Heat Flux Exchange data and soil heat flux exchange data
Evapotranspiration amount；
The instantaneous evapotranspiration amount is subjected to time day spatial scaling, obtains the day evapotranspiration amount of the target area.
2. the method according to claim 1, wherein described according to the GF-4 data and the MODIS data
Inverting obtains the step of earth's surface key parameter, comprising:
Leaf area index inverting is carried out according to the GF-4 data, obtains leaf area index；
Surface temperature, normalized differential vegetation index, surface albedo and earth's surface are obtained than radiation according to the MODIS data inversion
Rate.
3. according to the method described in claim 2, it is characterized in that, described anti-according to GF-4 data progress leaf area index
The step of drilling, obtaining leaf area index, comprising:
Based on the GF-4 data, leaf area index inverting is carried out using LUT Method using PROSAIL radiative transfer model,
Obtain the leaf area index.
4. the method according to claim 1, wherein it is described according to the Vegetation canopy Heat Flux Exchange data with
And the soil heat flux exchanges the step of data are calculated, obtain instantaneous evapotranspiration amount, comprising:
Obtain the initial value of Vegetation canopy latent heat flux；
According to energy balance rule to the Vegetation canopy Heat Flux Exchange data, soil heat flux exchange data and institute
It states initial value and is iterated calculating, obtain instantaneous evapotranspiration amount.
5. according to the method described in claim 4, it is characterized in that, the step of the initial value for obtaining Vegetation canopy latent heat flux
Suddenly, comprising:
Based on the Vegetation canopy Heat Flux Exchange data, it is latent that the Vegetation canopy is calculated according to Priestley-Taylor formula
The initial value of heat flux.
6. according to the method described in claim 2, it is characterized in that, it is described be based on the earth's surface key parameter, utilize earth's surface energy
The step of amount balance model SEBAL obtains the Heat Flux Exchange data between uniform earth's surface and atmosphere, comprising:
Based on the earth's surface key parameter, surface net radiation flux, sensible heat are obtained using the Land surface energy budget model SEBAL
Flux and soil heat flux.
7. according to the method described in claim 6, it is characterized in that, it is described be based on the Heat Flux Exchange data, utilize energy
The step of balance model TSEB is decomposed include:
The surface net radiation flux is decomposed into soil net radiation flux and Vegetation canopy net radiation flux；
And
The Sensible Heating Flux is decomposed into soil Sensible Heating Flux and Vegetation canopy Sensible Heating Flux.
8. according to the method described in claim 6, it is characterized in that, it is described be based on the earth's surface key parameter, utilize earth's surface energy
The step of amount balance model SEBAL obtains Sensible Heating Flux, comprising:
Aerodynamic resistance is iterated based on the surface temperature, and using the Land surface energy budget model SEBAL
It calculates, obtains the Sensible Heating Flux.
9. a kind of evapotranspiration remote-sensing inversion system combined based on GF-4 and MODIS characterized by comprising
Data acquisition module, for obtaining the GF-4 data and MODIS data of target area, and according to the GF-4 data and institute
It states MODIS data inversion and obtains earth's surface key parameter；
SEBAL model computation module is obtained for being based on the earth's surface key parameter using Land surface energy budget model SEBAL
Heat Flux Exchange data between uniform earth's surface and atmosphere；
TSEB model decomposition module, for being decomposed using energy balance model TSEB based on the Heat Flux Exchange data,
Obtain Vegetation canopy Heat Flux Exchange data and soil heat flux exchange data；
TSEB model computation module, for being exchanged according to the Vegetation canopy Heat Flux Exchange data and the soil heat flux
Data are calculated, and instantaneous evapotranspiration amount is obtained；
Conversion module, for the instantaneous evapotranspiration amount to be carried out time day spatial scaling, the day for obtaining the target area steams
Emission.
10. system according to claim 9, which is characterized in that the data acquisition module includes:
First inverting unit obtains leaf area index for carrying out leaf area index inverting according to the GF-4 data；
Second inverting unit, it is anti-for obtaining surface temperature, normalized differential vegetation index, earth's surface according to the MODIS data inversion
According to rate and Land surface emissivity.
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| CN111999251A (en) * | 2020-08-14 | 2020-11-27 | 中国水利水电科学研究院 | Remote sensing model method for regional vegetation transpiration and soil evaporation inversion based on thermal infrared remote sensing |
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| CN110400014A (en) * | 2019-07-23 | 2019-11-01 | 华东师范大学 | A kind of coastal cities multi-source flood method for numerical simulation based on GIS grid operation |
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| CN111999251A (en) * | 2020-08-14 | 2020-11-27 | 中国水利水电科学研究院 | Remote sensing model method for regional vegetation transpiration and soil evaporation inversion based on thermal infrared remote sensing |
| CN111999251B (en) * | 2020-08-14 | 2021-03-23 | 中国水利水电科学研究院 | Remote sensing model method for regional vegetation transpiration and soil evaporation inversion based on thermal infrared remote sensing |
| CN112991247A (en) * | 2021-03-04 | 2021-06-18 | 河南省气象科学研究所 | Winter wheat evapotranspiration remote sensing inversion and crop model assimilation method |
| CN113742636A (en) * | 2021-06-29 | 2021-12-03 | 西安理工大学 | Basin actual evaporation capacity estimation method based on meteorological observation data and vegetation index |
| CN113742636B (en) * | 2021-06-29 | 2024-04-19 | 西安理工大学 | River basin actual evaporation capacity estimation method based on meteorological observation data and vegetation index |
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