CN106202982A - A kind of method and device estimating oasis farmland clear sky solar radiation - Google Patents

Abstract

The present invention relates to a kind of method and device estimating oasis farmland clear sky solar radiation, wherein, method comprises determining that surface albedo and Reflectivity for Growing Season；Utilize Thermal infrared bands to determine surface temperature, based in the reference surface in the range of oasis farmland, assert that surface temperature is equal with air themperature；Utilize ground measured data, it is thus achieved that descending shortwave radiation and descending long-wave radiation；Utilize the ratio between the ratio between the parameter determination net radiation flux of above-mentioned acquisition, average daily net radiation and instant cleaning liquid radiation, net radiation on daytime and instant cleaning liquid radiation and moment t₂Instant cleaning liquid radiation with satellite pass by time moment t₁Instant cleaning liquid radiation between ratio；The ratio between ratio, net radiation on daytime and instant cleaning liquid radiation between radiating according to net radiation flux, average daily net radiation and instant cleaning liquid and moment t₂Instant cleaning liquid radiation with satellite pass by time moment t₁Instant cleaning liquid radiation between ratio determine average daily net radiation, net radiation on daytime and any time point net radiation.

Description

A kind of method and device estimating oasis farmland clear sky solar radiation

Technical field

The present invention relates to solar radiation technical field, particularly to a kind of method estimating oasis farmland clear sky solar radiation And device.

Background technology

The shortwave radiation sent from the sun does not all arrive at earth's surface, wherein has quite a few through propagation in atmosphere During, reflected by the different molecular in cloud layer, air and aerosol particle, scatter or absorb.Steam in air and low The components such as cloud and earth's surface start upwards to launch long-wave radiation after absorbing solar radiation.

Surface net radiation (Rn) is input quantity and the summation of output of the long and short wave radiation in earth's surface, represents surface energy The balance absorb, reflecting and scattering.It is as thermal source, it is provided that earth's surface, the heating or lower the temperature and evaporate of bottom-layer, rising Heat dissipation, directly influences the mankind and the temperature environment in biological existence space, humidity environment and luminous environment.The space-time of surface net radiation The regularity of distribution is surface layer air and the immediate cause of topsoil soils variations in temperature, is determining that agricultural Characteristics of micrometeorology, farmland are steamed Dissipate, the formation of plant growth and development process, Biomass with the aspect such as to add up significant, the particularly estimation of field evapotranspiration In essential.As the main energy sources of driving air motion, surface net radiation controls to enter the Sensible Heating Flux of air And latent heat flux, heat and moisture condition that earth's surface is different can form different ecosystems.But, surface net radiation data are subject to Restriction to technology and funds is difficult to directly monitor, even if can be monitored by meteorological site, but is also typically only capable to generation The region that table is less, does not represents the Spatial Variation in region.Therefore, their research is concentrated on region by many researcheres Surface net radiation is estimated by yardstick.In order to enable the distribution of surface net radiation to be carried out space mapping, in conjunction with remote sensing image number According to being necessary with earth's surface, atmosphere data.Mainly by the reflectance obtained from satellite data, emissivity and earth's surface temperature Degrees of data is modeled.Instant cleaning liquid radiation can calculate according to below equation:

Rn_i=Rs_↓i(1-α)+εRl_↓i-εσT_si ⁴ (1)

Wherein, Rs_↓Being descending shortwave radiation, unit is Wm^-2, α is surface albedo (α=Rs_↑/Rs_↓, Rs_↑It is up short Wave radiation), ε is earth's surface emissivity, Rl_↓Being descending long-wave radiation, unit is Wm^-2, σ is Stefan-Boltzmann constant, unit For Wm^-2K^-4, T_sFor surface temperature, unit is K.At above-mentioned formula, all subscripts i represent momentary time values.Generally, α, ε and T_s Can be obtained by the method for satellite data, and Rs_↓And Rl_↓Can be measured by earth's surface or model and estimate.

If formula (1) is feasible, then surface net radiation is carried out the drawing of accurate region and there has also been probability.But, These results can only reflect instantaneous result when satellite passes by, and oasis farming application (such as estimation evapotranspiration) is it is generally required to average daily Net radiation (Rn_d) or net radiation on daytime (Rn_D), the two is also commonly referred to as net radiation round the clock.In this sense, it is possible to calculate day All net radiation (Rn_d) and net radiation on daytime (Rn_D), the model of net radiation the most round the clock and method are the most few.

First, average daily net radiation can be obtained according to following formula:

${\mathrm{Rn}}_d=C_d{\mathrm{Rn}}_i={\[\frac{{\mathrm{Rn}}_d}{{\mathrm{Rn}}_i}\]}_{local}{\mathrm{Rn}}_i---\left(2\right)$

Wherein, C_dIt is average daily net radiation Rn_dRn is radiated with instant cleaning liquid_iBetween ratio, can from ground obtain net radiation Data are calculated.C_dValue over time, date or the change of website latitude and change, but unrelated with vegetation pattern, the most right A value determined can be regarded as every width image.As it is shown in figure 1, for utilizing satellite data to calculate average daily net radiation Rn_dSimulation drawing.From figure 1 it appears that during estimating net radiation every day, although C_dConstant, but Rn_dAnd Rn_iOften Value in individual pixel is entirely different, and owing to conventional weather station lacks net radiation data, the application of this method is by the biggest limit System.Therefore, scholar is had to also been proposed some estimations C_dMethod.

Seguin and Itier (1983) analyzes the summer day C of fine day_dExcursion.Data from 3 years are divided In analysis, it is contemplated that instantaneous value at noon (during the 12:00 sun), they think C_dValue be 0.30 ± 0.03.By extensively after this value Apply in many research, but use during have ignored region and seasonal characteristic.For not obtaining at noon in summer The instantaneous value taken, C_dRatio be accomplished by recalculating.

In order to be able to draw annual Rn_dFigure, Rivas and Carmona (2013) proposes the method using linear equation.From The net radiation measurement data result that in March, 2007 and 2009, December obtained at Tan Dier (37 ° of 19'S, 59 ° of 05'W) between 3 years Analyze, it was demonstrated that the ratio of net radiation flux became with the time, it is believed that C_d=0.43-54/Rn_i, wherein Rn_iFrom satellite data Estimate instant cleaning liquid radiation.Meanwhile, Sobrino etc. (2007) use and are positioned at Iberia Peninsula (39 ° of 21'S, 0 ° of 19'W) ell Buddhist nun The net radiation flux data that Nuo Sale area weather station records, it was found that C_dRatio and the day radiation value of different time in year Between relation, it is proposed that a quadratic polynomial equation calculates C_dValue.

On the other hand, some research worker are thought and are had only to the data considering daytime as evaporation, the movable master such as rising Want driving force.Rn_DCan obtain according to equation below:

${\mathrm{Rn}}_D=C_D{\mathrm{Rn}}_i={\[\frac{{\mathrm{Rn}}_D}{{\mathrm{Rn}}_i}\]}_{local}{\mathrm{Rn}}_i---\left(3\right)$

Wherein, C_DIt is the ratio between net radiation on daytime and instant cleaning liquid radiation.Samani etc. (2005) suppose the phase by day Between receive net radiation be directly proportional to shortwave solar radiation, proposition C_DIt it is the ratio of descending shortwave radiation annual average and instantaneous value Value.He employ 2007 New Mexico (32 ° of 36'N, 106 ° of 41'W) observation data demonstrate his hypothesis.Wherein, wink Time radiation value Selecting time be point in the morning 11 mountain standard time.In some cases, due to instantaneous value and daily mean temperature Between difference, cause having over-evaluated Rn_DValue, therefore, it has to build new formula to estimate Rn_DValue.

Additionally, Bisht et al. (2005) proposes a sinusoidal model to estimate average daily net radiation and net radiation round the clock.Just The advantage of string model has only to Satellite Observations (Terra-MODIS) exactly and rebuilds clear sky day-night change model, and utilizes Ground data is verified, this is a good method.But, net radiation round the clock that inverting obtains and average daily net radiation all by Over-evaluating, all there is obvious error in all of result.

In a word, when net radiation cannot be measured, existing model is all passed by by oasis farmland zone position, date and satellite The restriction of time, is difficult to meet existing various demand.Therefore exigence has one to utilize satellite data to estimate oasis The universal model of farmland net radiation, and utilize the fast inversion of this model realization net radiation.

Summary of the invention

The main purpose of the embodiment of the present invention is to propose a kind of method estimating oasis farmland clear sky solar radiation and dress Putting, the technical program estimates the new model of net radiation round the clock by ground survey data and satellite data, builds region net radiation The generic physical model of estimation, thus meet existing various demand.

For achieving the above object, the invention provides a kind of method estimating oasis farmland clear sky solar radiation, including:

Based on the reference surface in the range of oasis farmland, utilize visible ray and near infrared band, determine the earth's surface reflection of light Rate α_refWith Reflectivity for Growing Season ε_ref；

Thermal infrared bands is utilized to determine surface temperature T_s, based in the reference surface in the range of oasis farmland, assert Surface temperature T_sWith air themperature T_aEqual, it is thus achieved that daytime air themperature T_ad, moment t₂Air themperatureWhen satellite passes by Moment t₁Air themperatureAnd air themperature T of the instantaneous moment i that satellite is when passing by_ai；

Utilize ground measured data, it is thus achieved that daytime descending shortwave radiation Rs_↓d, descending long-wave radiation on daytime Rl_↓d, moment t₂'s Descending shortwave radiationMoment t when satellite passes by₁Descending shortwave radiationMoment t₂Descending long-wave radiationMoment t when satellite passes by₁Descending long-wave radiationThe descending shortwave radiation of instantaneous moment i when satellite passes by Rs_↓i, the descending long-wave radiation Rl of satellite instantaneous moment i when passing by_↓i；

Utilize described surface albedo α_ref, described earth's surface emissivity ε_ref, descending shortwave radiation Rs on described daytime_↓d, described Descending long-wave radiation on daytime Rl_↓d, air themperature T on described daytime_ad, described moment t₂Air themperatureWhen described satellite passes by Moment t₁Air themperatureAir themperature T of instantaneous moment i when described satellite passes by_ai, described satellite is when passing by The descending shortwave radiation Rs of instantaneous moment i_↓i, moment t₂Descending shortwave radiationInstantaneous moment i's when satellite passes by Descending shortwave radiationMoment t₂Descending long-wave radiationMoment t when satellite passes by₁Descending long-wave radiation Determine net radiation flux Rn_i, average daily net radiation and instant cleaning liquid radiation between ratio C_d, net radiation on daytime and instant cleaning liquid radiate it Between ratio C_DAnd moment t₂Instant cleaning liquid radiation with satellite pass by time moment t₁Instant cleaning liquid radiation between ratio

According to net radiation flux Rn_i, average daily net radiation and instant cleaning liquid radiation between ratio C_d, net radiation on daytime and instantaneous Ratio C between net radiation_DAnd moment t₂Instant cleaning liquid radiation with satellite pass by time moment t₁Instant cleaning liquid radiation between RatioDetermine average daily net radiation Rn_d, net radiation on daytime Rn_DAnd any time point net radiation

Preferably, described average daily net radiation Rn_dExpression formula be:

${\mathrm{Rn}}_d=\[\frac{(1-{\mathrm{\α}}_{ref}){\mathrm{Rs}}_{\↓d}+{\mathrm{\ϵ}}_{ref}({\mathrm{Rl}}_{\↓d}-{{\mathrm{\σT}}_a^4}_d)}{(1-{\mathrm{\α}}_{ref}){\mathrm{Rs}}_{\↓i}+{\mathrm{\ϵ}}_{ref}({\mathrm{Rl}}_{\↓i}-{{\mathrm{\σT}}_a^4}_i)}\]{\mathrm{Rn}}_i$

In formula, σ is Stefan-Boltzmann constant, and unit is Wm^-2K^-4；Net radiation flux Rn_iExpression formula be:

Rn_i=Rs_↓i(1-α_ref)+ε_refRl_↓i-ε_refσT_ai ⁴。

Preferably, described net radiation on daytime Rn_DExpression formula be:

${\mathrm{Rn}}_D=\[\frac{(1-{\mathrm{\α}}_{ref}){\mathrm{Rs}}_{\↓d}+{\mathrm{\ϵ}}_{ref}({\mathrm{Rl}}_{\↓d}-{{\mathrm{\σT}}_a^4}_d)(N/24)}{(1-{\mathrm{\α}}_{ref}){\mathrm{Rs}}_{\↓i}+{\mathrm{\ϵ}}_{ref}({\mathrm{Rl}}_{\↓i}-{{\mathrm{\σT}}_a^4}_i)}\]{\mathrm{Rn}}_i$

In formula, σ is Stefan-Boltzmann constant, and unit is Wm^-2K^-4；N is sunshine-duration or the maximum of duration on daytime Value,Wherein, ω_sBeing radian sunset hour angle, φ is latitude, and δ is solar declination；DOY is the some day in 1 year；Net radiation flux Rn_iExpression formula be:

Rn_i=Rs_↓i(1-α_ref)+ε_refRl_↓i-ε_refσT_ai ⁴。

Preferably, described any time point net radiationExpression formula be:

In formula, σ is Stefan-Boltzmann constant, and unit is Wm^-2K^-4；t₁The net radiation in momentLed to by net radiation Amount Rn_iDetermine, net radiation flux Rn_iExpression formula be: Rn_i=Rs_↓i(1-α_ref)+ε_refRl_↓i-ε_refσT_ai ⁴；By net radiation flux Rn_iExpression formula in i take t₁Time be t₁The net radiation in moment

Accordingly, for achieving the above object, the invention provides a kind of device estimating oasis farmland clear sky solar radiation, Including:

Surface albedo and Reflectivity for Growing Season determine unit, are used for based on the reference surface in the range of oasis farmland, Utilize visible ray and near infrared band, determine surface albedo α_refWith Reflectivity for Growing Season ε_ref；

Surface temperature and air themperature determine unit, are used for utilizing Thermal infrared bands to determine surface temperature T_s, based on oasis In reference surface in the range of farmland, assert surface temperature T_sWith air themperature T_aEqual, it is thus achieved that daytime air themperature T_ad、 Moment t₂Air themperatureMoment t when satellite passes by₁Air themperatureThe sky of instantaneous moment i when satellite passes by Temperature T_aiAnd surface temperature T of the instantaneous moment i that satellite is when passing by_si；

Shortwave radiation and long-wave radiation determine unit, are used for utilizing ground measured data, it is thus achieved that daytime descending shortwave radiation Rs_↓d, descending long-wave radiation on daytime Rl_↓d, moment t₂Descending shortwave radiationMoment t when satellite passes by₁Descending shortwave RadiationMoment t₂Descending long-wave radiationMoment t when satellite passes by₁Descending long-wave radiationSatellite mistake The descending shortwave radiation Rs of instantaneous moment i during border_↓i, the descending long-wave radiation Rl of satellite instantaneous moment i when passing by_↓i；

Computing unit, is used for utilizing described surface albedo α_ref, described earth's surface emissivity ε_ref, descending shortwave on described daytime Radiation Rs_↓d, descending long-wave radiation on described daytime Rl_↓d, air themperature T on described daytime_ad, described moment t₂Air themperature Moment t when described satellite passes by₁Air themperatureAir themperature T of instantaneous moment i when described satellite passes by_ai, institute State the descending shortwave radiation Rs of instantaneous moment i when satellite passes by_↓i, moment t₂Descending shortwave radiationWhen satellite passes by The descending shortwave radiation of instantaneous moment iMoment t₂Descending long-wave radiationMoment t when satellite passes by₁Under Row long-wave radiationDetermine net radiation flux Rn_i, average daily net radiation and instant cleaning liquid radiation between ratio C_d, net radiation on daytime And the ratio C between instant cleaning liquid radiation_DAnd moment t₂Instant cleaning liquid radiation with satellite pass by time moment t₁Instant cleaning liquid radiation Between ratio

Radiation determines unit, for according to net radiation flux Rn_i, average daily net radiation and instant cleaning liquid radiation between ratio C_d、 Ratio C between net radiation on daytime and instant cleaning liquid radiation_DAnd moment t₂Instant cleaning liquid radiation with satellite pass by time moment t₁'s Ratio between instant cleaning liquid radiationDetermine average daily net radiation Rn_d, net radiation on daytime Rn_DAnd any time point net radiation

Preferably, described radiation determines the average daily net radiation Rn that unit determines_dExpression formula be:

${\mathrm{Rn}}_d=\[\frac{(1-{\mathrm{\α}}_{ref}){\mathrm{Rs}}_{\↓d}+{\mathrm{\ϵ}}_{ref}({\mathrm{Rl}}_{\↓d}-{{\mathrm{\σT}}_a^4}_d)}{(1-{\mathrm{\α}}_{ref}){\mathrm{Rs}}_{\↓i}+{\mathrm{\ϵ}}_{ref}({\mathrm{Rl}}_{\↓i}-{{\mathrm{\σT}}_a^4}_i)}\]{\mathrm{Rn}}_i$

In formula, σ is Stefan-Boltzmann constant, and unit is Wm^-2K^-4；Net radiation flux Rn_iExpression formula be: Rn_i= Rs_↓i(1-α_ref)+ε_refRl_↓i-ε_refσT_ai ⁴。

Preferably, described radiation determines net radiation on the daytime Rn that unit determines_DExpression formula be:

${\mathrm{Rn}}_D=\[\frac{(1-{\mathrm{\α}}_{ref}){\mathrm{Rs}}_{\↓d}+{\mathrm{\ϵ}}_{ref}({\mathrm{Rl}}_{\↓d}-{{\mathrm{\σT}}_a^4}_d)(N/24)}{(1-{\mathrm{\α}}_{ref}){\mathrm{Rs}}_{\↓i}+{\mathrm{\ϵ}}_{ref}({\mathrm{Rl}}_{\↓i}-{{\mathrm{\σT}}_a^4}_i)}\]{\mathrm{Rn}}_i$

In formula, σ is Stefan-Boltzmann constant, and unit is Wm^-2K^-4；N is sunshine-duration or the maximum of duration on daytime Value,Wherein, ω_sBeing radian sunset hour angle, φ is latitude, and δ is solar declination；DOY is the some day in 1 year；Net radiation flux Rn_iExpression formula be: Rn_i=Rs_↓i (1-α_ref)+ε_refRl_↓i-ε_refσT_ai ⁴。

Preferably, described radiation determines any time point net radiation that unit determinesExpression formula be:

${\mathrm{Rn}}_{t_2}={\mathrm{Rn}}_{t_1}\[\frac{(1-{\mathrm{\α}}_{ref}){\mathrm{Rs}}_{\↓t_2}+{\mathrm{\ϵ}}_{ref}({\mathrm{Rl}}_{\↓t_2}-{{\mathrm{\σT}}_a^4}_{t_2})}{(1-{\mathrm{\α}}_{ref}){\mathrm{Rs}}_{\↓t_1}+{\mathrm{\ϵ}}_{ref}({\mathrm{Rl}}_{\↓t_1}-{{\mathrm{\σT}}_a^4}_{t_1})}\]$

In formula, σ is Stefan-Boltzmann constant, and unit is Wm^-2K^-4；t₁The net radiation in momentLed to by net radiation Amount Rn_iDetermine, net radiation flux Rn_iExpression formula be: Rn_i=Rs_↓i(1-α_ref)+ε_refRl_↓i-ε_refσT_ai ⁴；By net radiation flux Rn_iExpression formula in i take t₁Time be t₁The net radiation in moment

Technique scheme has the advantages that

The technical program employs the image obtained from TM sensor (Landsat 7) and auxiliary meteorological data is estimated Sun net radiation, this is most important to the application of oasis farmland Evapotranspiration by Using, and the method is not limited to latitude, date, or satellite Transit time.Therefore, as long as by the visible ray of satellite image, infrared and Thermal infrared bands obtains instant cleaning liquid radiation, the present invention The model proposed just be can apply to over, present or future.

Accompanying drawing explanation

In order to be illustrated more clearly that the embodiment of the present invention or technical scheme of the prior art, below will be to embodiment or existing In having technology to describe, the required accompanying drawing used is briefly described, it should be apparent that, the accompanying drawing in describing below is only this Some embodiments of invention, for those of ordinary skill in the art, on the premise of not paying creative work, it is also possible to Other accompanying drawing is obtained according to these accompanying drawings.

Fig. 1 calculates average daily net radiation Rn for utilizing satellite data_dSimulation drawing；

Fig. 2 is a kind of method flow diagram estimating oasis farmland clear sky solar radiation that the present invention proposes；

Fig. 3 is the ratio C between average daily net radiation and instant cleaning liquid radiation_dEvaluation method schematic diagram；

Fig. 4 is a kind of device block diagram estimating oasis farmland clear sky solar radiation that the present invention proposes；

Fig. 5 is the test block schematic diagram of the present embodiment.

Detailed description of the invention

Below in conjunction with the accompanying drawing in the embodiment of the present invention, the technical scheme in the embodiment of the present invention is carried out clear, complete Describe, it is clear that described embodiment is only a part of embodiment of the present invention rather than whole embodiments wholely.Based on Embodiment in the present invention, it is every other that those of ordinary skill in the art are obtained under not making creative work premise Embodiment, broadly falls into the scope of protection of the invention.

One skilled in the art will appreciate that embodiments of the present invention can be implemented as a kind of system, device, equipment, method Or computer program.Therefore, the disclosure can be to be implemented as following form, it may be assumed that hardware, completely software completely (including firmware, resident software, microcode etc.), or the form that hardware and software combines.

According to the embodiment of the present invention, it is proposed that a kind of method and device estimating oasis farmland clear sky solar radiation.

In this article, it is to be understood that in involved term:

1, solar radiation: the sun the most outwards transmits energy, claims solar radiation (solar Radiation), electromagnetic wave and particle flux that the sun launches are referred to cosmic space.The energy that solar radiation is transmitted, claims the sun Radiation energy.Solar radiant energy claims solar radiation spectrum by the distribution of wavelength.

2, ground net radiation: by the shortwave radiation on ground and long-wave radiation after the income balances the expenditure, the clean receipts on earth's surface Enter or the amount of radiation of net disbursement is exactly ground net radiation (also referred to as surface radiation balance).

3, shortwave radiation: wavelength is shorter than the electromagnetic radiation of 3 μm.

4, long-wave radiation: the energy of atmospheric emission is concentrated mainly on the radiation in 4 μm-120 μ m wavelength range.

5, directly radiation: from the radiation not being scattered and reflecting in radiation source direction.

Additionally, any number of elements in accompanying drawing is used to example and unrestricted, and any name is only used for distinguishing, And not there is any limitation.

Principle and spirit below with reference to some representative embodiments of the present invention, in detail the explaination present invention.

As in figure 2 it is shown, a kind of method flow diagram estimating oasis farmland clear sky solar radiation proposed for the present invention.Bag Include:

Step 201): based on the reference surface in the range of oasis farmland, utilize visible ray and near infrared band, determine Surface albedo α_refWith Reflectivity for Growing Season ε_ref；

Computational methods after the surface albedo α use integration of the technical program:

α=0.356 ρ_1S+0.130ρ_3S+0.373ρ_4S+0.085ρ_5S+0.072ρ_7S (17)

Wherein, ρ_λSIt it is the Reflectivity for Growing Season of λ wave band.The visible ray used and the image of infrared band employ dark matter picture The atmospheric correction method of unit is corrected.Therefore, Reflectivity for Growing Season use equation below:

${\mathrm{\ρ}}_{\mathrm{\λ}S}=\frac{\mathrm{\π}(L_{\mathrm{\λ}SAT}-L_{\mathrm{\λ}P})}{{\mathrm{\τ}}_{\mathrm{\λ}v}(E_{\mathrm{\λ}0}{d}^{-2}{\mathrm{cos\θ}}_Z{\mathrm{\τ}}_{\mathrm{\λ}Z}+E_{\mathrm{\λ}down})}---\left(18\right)$

Wherein, L_λSATIt is satellite retrieval data (Wm^-2sr^-1μm^-1), L_λPIt is journey radiation data (Wm^-2sr^-1μm^-1), E_λ0It is The outer solar irradiation degrees of data (Wm of air^-2μm^-1), d is solar distance, θ_ZIt is solar zenith angle, τ_λvIt is target and sensor orientation Atmospheric transmissivity data, τ_λZIt is the atmospheric transmissivity at direction of illumination, E_λdownIt is descending diffusing radiation data (Wm^-2μm^-1)。

The technical program passes through vegetation coverage P_vAnd by soil and vegetation emissivity component ε_sAnd ε_vEstimate earth's surface Emissivity.

ε=ε_vP_v+ε_s(1-P_v)(1-1.74P_v)+1.7372P_v(1-P_v) (19)

Wherein, according to the research of Rubio, Caselles, and Badenas (1997) et al., ε_v=0.985, ε_s= 0.960.Vegetation coverage P_vCalculated by below equation:

$P_v={\left(\frac{NDVI-{\mathrm{NDVI}}_{min}}{{\mathrm{NDVI}}_{max}-{\mathrm{NDVI}}_{min}}\right)}^2---\left(20\right)$

Wherein, NDVI_maxAnd NDVI_minCorrespond to vegetation region and the NDVI value without vegetation region.The calculating of NDVI employs the 4th Wave band (0.630 0.680 μm) and the 5th wave band (0.845 0.885 μm) are calculated.

Step 202): utilize Thermal infrared bands to determine surface temperature T_s, based on the reference table in the range of oasis farmland In face, assert surface temperature T_sWith air themperature T_aEqual, it is thus achieved that daytime air themperature T_ad, moment t₂Air themperatureDefend Moment t when star passes by₁Air themperatureAnd air themperature T of the instantaneous moment i that satellite is when passing by_ai；

Surface temperature T_sUse radiation transfer equation calculates:

$B\left(T\right)=\[\left(\frac{(L_{6SAT}-L_{atm}^{\↑})}{\mathrm{\τ}}\right)-(1-\mathrm{\ϵ})L_{atm}^{\↑}\]{\mathrm{\ϵ}}^{-1}---\left(21\right)$

Wherein, B (T) (Wm^-2sr^-1μm^-1) it is T_s(K) Planck equation,It is that air is observed The up sky radiation in direction,Be descending sky irradiance be big divided by π (assuming that lambertian), τ Gas absorbance.These atmospheric parameters are calculated by MODTRAN4.0 code respectively.

Step 203): utilize ground measured data, it is thus achieved that daytime descending shortwave radiation Rs_↓d, descending long-wave radiation on daytime Rl_↓d, moment t₂Descending shortwave radiationMoment t when satellite passes by₁Descending shortwave radiationMoment t₂Descending Long-wave radiationMoment t when satellite passes by₁Descending long-wave radiationInstantaneous moment i's when satellite passes by is descending Shortwave radiation Rs_↓i, the descending long-wave radiation Rl of satellite instantaneous moment i when passing by_↓i；

Step 204): utilize described surface albedo α_ref, described earth's surface emissivity ε_ref, descending shortwave radiation on described daytime Rs_↓d, descending long-wave radiation on described daytime Rl_↓d, air themperature T on described daytime_ad, described moment t₂Air themperatureDescribed Moment t when satellite passes by₁Air themperatureAir themperature T of instantaneous moment i when described satellite passes by_aiDefend described in, The descending shortwave radiation Rs of instantaneous moment i when star passes by_↓i, moment t₂Descending shortwave radiationWink when satellite passes by Time moment i descending shortwave radiationMoment t₂Descending long-wave radiationMoment t when satellite passes by₁Descending length Wave radiationDetermine net radiation flux Rn_i, average daily net radiation and instant cleaning liquid radiation between ratio C_d, net radiation on daytime and wink Time net radiation between ratio C_DAnd moment t₂Instant cleaning liquid radiation with satellite pass by time moment t₁Instant cleaning liquid radiation between Ratio

Step 205): according to net radiation flux Rn_i, average daily net radiation and instant cleaning liquid radiation between ratio C_d, clean spoke on daytime Penetrate the ratio C between instant cleaning liquid radiation_DAnd moment t₂Instant cleaning liquid radiation with satellite pass by time moment t₁Instant cleaning liquid spoke Ratio between penetratingDetermine average daily net radiation Rn_d, net radiation on daytime Rn_DAnd any time point net radiation

For technique scheme, it is assumed that in specific region, α, ε and T can be passed through_SThe Rn obtained builds Spatial variability model.Assume in the range of oasis farmland, have a known surface, hereinafter referred to as reference surface (reference surface), Have the following characteristics that

(1) surface albedo value is known, it is believed that α=α_ref；

(2) this earth's surface emissivity value is known, it is believed that ε=ε_ref；

(3) this reference surface has high soil moisture, it is possible to assume T_sClose to air themperature T_a。

For average daily net radiation Rn_d, according to formula (2), C for satellite data_dRatio may be considered individual fixing Value, therefore formula (2) can be rewritten as:

$C_d={\[\frac{{\mathrm{Rn}}_d}{{\mathrm{Rn}}_i}\]}_{local}={\[\frac{{\mathrm{Rn}}_d}{{\mathrm{Rn}}_i}\]}_1={\[\frac{{\mathrm{Rn}}_d}{{\mathrm{Rn}}_i}\]}_2=...={\[\frac{{\mathrm{Rn}}_d}{{\mathrm{Rn}}_i}\]}_n---\left(4\right)$

Wherein, subscript 1,2 ..., n is ground mulching type (Cotton Gossypii, Semen Tritici aestivi, Semen Maydis, sand different in oasis farmland district Ground etc.).Although from this, it will be seen that Rn_d1≠Rn_d1≠…≠Rn_dnAnd Rn_i1≠Rn_i2≠…≠Rn_in, but C_dRatio is still protected Hold constant.

Therefore formula (4) can be further rewritten as:

$C_d={\[\frac{{\mathrm{Rn}}_d}{{\mathrm{Rn}}_i}\]}_{local}=\[\frac{(1-\mathrm{\α}){\mathrm{Rs}}_{\↓d}+{\mathrm{\ϵRl}}_{\↓d}-{{\mathrm{\ϵ\σT}}_s^4}_d}{(1-\mathrm{\α}){\mathrm{Rs}}_{\↓i}+{\mathrm{\ϵRl}}_{\↓i}-{{\mathrm{\ϵ\σT}}_s^4}_i}\]---\left(5\right)$

According to assumed above, C_dCan also be further rewritten as:

$C_d=\[\frac{(1-{\mathrm{\α}}_{ref}){\mathrm{Rs}}_{\↓d}+{\mathrm{\ϵ}}_{ref}({\mathrm{Rl}}_{\↓d}-{{\mathrm{\σT}}_a^4}_d)}{(1-{\mathrm{\α}}_{ref}){\mathrm{Rs}}_{\↓i}+{\mathrm{\ϵ}}_{ref}({\mathrm{Rl}}_{\↓i}-{{\mathrm{\σT}}_a^4}_i)}\]={\[\frac{{\mathrm{Rn}}_d}{{\mathrm{Rn}}_i}\]}_{ref}---\left(6\right)$

Wherein, α_refAnd ε_refCan be obtained by experiment.Fig. 3 is to consider an imaginary datum level also in oasis farmland region Utilize the schematic diagram of the hypothesized model that ground meteorological data proposed.Atmospheric temperature and solar radiation are measured by conventional weather station, And descending long-wave radiation is the most measured can only be modeled.

Finally, Rn_dValue can be calculated by below equation:

${\mathrm{Rn}}_d=C_d{\mathrm{Rn}}_i={\[\frac{{\mathrm{Rn}}_d}{{\mathrm{Rn}}_i}\]}_{ref}{\mathrm{Rn}}_i---\left(7\right)$

For net radiation on daytime Rn_D, according to formula (7), propose one and be used for estimating Rn_DImproved model:

${\mathrm{Rn}}_D=C_D{\mathrm{Rn}}_i={\[\frac{{\mathrm{Rn}}_D}{{\mathrm{Rn}}_i}\]}_{ref}{\mathrm{Rn}}_i---\left(8\right)$

Equation below is used to estimate net radiation on the daytime Rn of reference surface_Dref:

${\mathrm{Rn}}_{Dref}=(1-{\mathrm{\α}}_{ref}){\mathrm{Rs}}_{\↓d}+{\mathrm{\ϵ}}_{ref}({\mathrm{Rl}}_{\↓d}-{{\mathrm{\σT}}_a^4}_d)\[N/24\]---\left(9\right)$

Wherein, N is sunshine-duration or the maximum of duration on daytime.N/24 is so that the negative value quilt of clean long-wave radiation at night Ignore.Only time section Rn_iFor on the occasion of estimating Rn_D, therefore, it can be calculated by equation below:

$N=\frac{24}{\mathrm{\π}}{\mathrm{\ω}}_s=\frac{24}{\mathrm{\π}}\[arccos(-tg\mathrm{\φ}tg\mathrm{\δ})\]---\left(10\right)$

Wherein, ω_sBeing radian sunset hour angle, φ is latitude, and δ is solar declination:

$\mathrm{\δ}=0.409sen(\frac{2\mathrm{\π}DOY}{365}-1.39)---\left(11\right)$

Wherein, the some day of (1-365) during DOY is 1 year.Finally, in conjunction with formula (8) and (9), Rn_DCan be by as follows Formula calculates:

$\begin{array}{c}{\mathrm{Rn}}_D={\mathrm{Rn}}_i{C}_D={\mathrm{Rn}}_i{\[\frac{{\mathrm{Rn}}_D}{{\mathrm{Rn}}_i}\]}_{ref}=...\\ ={\mathrm{Rn}}_i\[\frac{(1-{\mathrm{\α}}_{ref}){\mathrm{Rs}}_{\↓d}+{\mathrm{\ϵ}}_{ref}({\mathrm{Rl}}_{\↓d}-{{\mathrm{\σT}}_a^4}_d)\[N/24\]}{(1-{\mathrm{\α}}_{ref}){\mathrm{Rs}}_{\↓i}+{\mathrm{\ϵ}}_{ref}({\mathrm{Rl}}_{\↓i}-{{\mathrm{\σT}}_a^4}_i)}\]\end{array}---\left(12\right)$

For any time point net radiationIn view of the difference of satellite transit time, formula (2) can be written as:

${\mathrm{Rn}}_d=C_{d,i}{\mathrm{Rn}}_i=C_{d,t_1}{\mathrm{Rn}}_{t_1}=C_{d,t_2}{\mathrm{Rn}}_{t_2}=...=C_{d,t_m}{\mathrm{Rn}}_{t_m}---\left(13\right)$

Wherein, i=t₁,t₂,...,t_mRepresent (the mainly daytime) of some day the most in the same time, the most just can be from two T the most in the same time₁And t₂Net radiation be worth to instant cleaning liquid radiation value:

${\mathrm{Rn}}_{t_2}={\mathrm{Rn}}_{t_1}\frac{C_{d,t_1}}{C_{d,t_2}}---\left(14\right)$

Therefore, if it is considered that the transit time t of satellite₁(the Rn data on regional scale can be provided), it is possible to T is estimated according to formula (14)₂The Rn value of time.

In conjunction with formula (8) and formula (14), can obtain:

${\mathrm{Rn}}_{t_2}={\mathrm{Rn}}_{t_1}\frac{C_{d,t_1}}{C_{d,t_2}}={\mathrm{Rn}}_{t_1}\frac{{\[\frac{{\mathrm{Rn}}_d}{{\mathrm{Rn}}_{t_1}}\]}_{ref}}{{\[\frac{{\mathrm{Rn}}_d}{{\mathrm{Rn}}_{t_2}}\]}_{ref}}---\left(15\right)$

Finally, the time point t of reference surface is determined according to formula (1)₁Instant cleaning liquid radiation and the time point t of reference surface₂ Instant cleaning liquid radiation, estimationFormula can be written as:

$\begin{array}{c}{\mathrm{Rn}}_{t_2}={\mathrm{Rn}}_{t_1}\[\frac{{\mathrm{Rn}}_{t_2,ref}}{{\mathrm{Rn}}_{t_1,ref}}\]={\mathrm{Rn}}_{t_1}{C}_{t_2,t_1}=\\ ={\mathrm{Rn}}_{t_1}\[\frac{(1-{\mathrm{\α}}_{ref}){\mathrm{Rs}}_{\↓t_2}+{\mathrm{\ϵ}}_{ref}({\mathrm{Rl}}_{\↓t_2}-{{\mathrm{\σT}}_a^4}_{t_2})}{(1-{\mathrm{\α}}_{ref}){\mathrm{Rs}}_{\↓t_1}+{\mathrm{\ϵ}}_{ref}({\mathrm{Rl}}_{\↓t_1}-{{\mathrm{\σT}}_a^4}_{t_1})}\]\end{array}---\left(16\right)$

Wherein,For time point t₂Instant cleaning liquid radiation with satellite pass by time moment t₁Corresponding instant cleaning liquid radiation Ratio.Therefore, use formula (16) that random time point net radiation can be obtained.

As shown in Figure 4, a kind of device block diagram estimating oasis farmland clear sky solar radiation proposed for the present invention.Including:

Surface albedo and Reflectivity for Growing Season determine unit 401, for based on the reference table in the range of oasis farmland Face, utilizes visible ray and near infrared band, determines surface albedo α_refWith Reflectivity for Growing Season ε_ref；

Surface temperature and air themperature determine unit 402, are used for utilizing Thermal infrared bands to determine surface temperature T_s, based on green In reference surface in the range of farmland, continent, assert surface temperature T_sWith air themperature T_aEqual, it is thus achieved that daytime air themperature T_ad, moment t₂Air themperatureMoment t when satellite passes by₁Air themperatureAnd the instantaneous moment that satellite is when passing by Air themperature T of i_ai；

Shortwave radiation and long-wave radiation determine unit 403, are used for utilizing ground measured data, it is thus achieved that daytime descending shortwave spoke Penetrate Rs_↓d, descending long-wave radiation on daytime Rl_↓d, moment t₂Descending shortwave radiationMoment t when satellite passes by₁Descending short Wave radiationMoment t₂Descending long-wave radiationMoment t when satellite passes by₁Descending long-wave radiationSatellite The descending shortwave radiation Rs of instantaneous moment i when passing by_↓i, the descending long-wave radiation Rl of satellite instantaneous moment i when passing by_↓i；

Computing unit 404, is used for utilizing described surface albedo α_ref, described earth's surface emissivity ε_ref, described daytime descending Shortwave radiation Rs_↓d, descending long-wave radiation on described daytime Rl_↓d, air themperature T on described daytime_ad, described moment t₂Air themperatureMoment t when described satellite passes by₁Air themperatureAir themperature T of instantaneous moment i when described satellite passes by_ai、 The descending shortwave radiation Rs of instantaneous moment i when described satellite passes by_↓i, moment t₂Descending shortwave radiationSatellite passes by Time the descending shortwave radiation of instantaneous moment iMoment t₂Descending long-wave radiationMoment t when satellite passes by₁'s Descending long-wave radiationDetermine net radiation flux Rn_i, average daily net radiation and instant cleaning liquid radiation between ratio C_d, clean spoke on daytime Penetrate the ratio C between instant cleaning liquid radiation_DAnd moment t₂Instant cleaning liquid radiation with satellite pass by time moment t₁Instant cleaning liquid spoke Ratio between penetrating

Radiation determines unit 405, for according to net radiation flux Rn_i, average daily net radiation and instant cleaning liquid radiation between ratio Value C_d, net radiation on daytime and instant cleaning liquid radiation between ratio C_DAnd moment t₂Instant cleaning liquid radiation with satellite pass by time time Carve t₁Instant cleaning liquid radiation between ratioDetermine average daily net radiation Rn_d, net radiation on daytime Rn_DAnd any time point is clean Radiation

Embodiment

● test block overview

As it is shown in figure 5, be the test block schematic diagram of the present embodiment.Test block is Manas river, Typical Oases district, Xinjiang Territory, is positioned at Xinjiang Tianshan northern foot, In The Southern Part of Jungger Basin, and administrative region includes Shihezi, Shawan County and Manas County, and It is distributed in the Production and Construction Corps of Xinjiang the 8th teacher and the agriculture and animal husbandry group field of the 6th teacher in two borders of the county.43 ° 27 '-45 ° 21 ' of geographical position N, 85 ° of 01 '-86 ° of 32 ' E, the basin gross area about 2.1 × 104km², physical features is northwestwards tilted by the southeast, the highest 5242m of height above sea level, Minimum 256m, landform slope is divided into mountain region, pediment plain and desert three Macro Landform class area from south to north.Genus inland, basin is done Drought-hit area, summer, sweltering heat was dried, and winter, cold was windy, average annual temperature 6.8 DEG C, annual precipitation 110-200mm.From east orientation west in basin It is respectively the tower Xihe River, Manasi river, Ning Jiahe, Jin Gouhe and Ba Yin ditch river, all rises in Northern Piedmont of Tianshan Mountains Yi Lianha Bill Ga Shan Arteries and veins, flows into the Junggar Basin, wherein Manasi river total length 324km from south to north, water yield maximum, flow process in the Ye Shi Junggar Basin The longest continental river.

● ground station data

Experiment is that the different location in the range of the kilometer radius of distance Shihezi 50 is carried out.Section 1 is tested at stone river The cotton field of sub-university's experimental teaching of agronomy field is carried out, and Section 2 experiment is carried out in the weather station, desert of 150.Experiment uses net radiation Component, the measured result of air themperature/relative humidity, downlink and uplink shortwave (0.3-2.8 μm) and long wave (4.5-42 μm) spoke Penetrate use CNR-4 net radiation meter (CNR 4Net Radiometer, Kipp&Zonen) to be measured, air themperature/relative humidity CS215-L probe (Campbell Scientific) is used to measure.All the sensors is separately mounted to the most about 2 The position of rice, and by CR10X data logger (Campbell Scientific), the average data record of every 15 minutes is existed For subsequent treatment in the memory module of processor.The time that the time of ground experiment acquisition data passes by with satellite keeps consistent, But in order to avoid some unpredictable interference, on the previous day that satellite passes by, the same day with carry out data acquisition the most respectively, To guarantee authentic and valid ground data.

● remotely-sensed data

Experiment employs cloudless LandSat7 data (table 1) in 2010, and image is at visible light wave range and near infrared band Spatial resolution be 30m, the spatial resolution of Thermal infrared bands is 60m, and final image forms through 6 scape image joints.

Table 1 Landsat7 satellite sensor parameter list

Wave band	Wave-length coverage (μm)	Ground resolution
			1	0.45～0.515	30 meters
2	0.525～0.605	30 meters
			3	0.63～0.690	30 meters
4	0.75～0.90	30 meters
			5	1.55～1.75	30 meters
6	10.40～12.50	60 meters
			7	2.09～2.35	30 meters
8	0.52～0.90	15 meters

2. interpretation of result

In order to assess the precision of the method sum of use, it is right to have carried out with measured value after end value being extracted from figure Ratio.The results are shown in Table 2.Result shows that the surface albedo precision obtained by application formula is higher, Rn_i、Rn_dWith Rn_DThe prediction of value Precision is the highest, produces a desired effect.

Table 2 Rn_i、Rn_dWith Rn_DPredictive value contrasts with measured value

By statistical method it can also be seen that predictive value and measured value coincide very much, PRMSE is ± 3%, and BIAS connects It is bordering on zero (table 3), shows that this model is ideal.

Table 3 statistical parameter table

Remote sensing image	BIAS(Wm-2)	RMSE(Wm-2)	PRMSE (%)
				30/08/2010	4	±10	±3

3. conclusion

The predictive value that the model that the technical program is set up obtains with measured value relatively, meets various actual demand. And the technical program employs the image obtained from TM sensor (Landsat 7) and auxiliary meteorological data to estimate the sun Net radiation, this is most important to the application of oasis farmland Evapotranspiration by Using, and the method is not limited to latitude, date, or satellite and passes by Time.

Above detailed description of the invention, has been carried out the most specifically the purpose of the present invention, technical scheme and beneficial effect Bright, be it should be understood that the detailed description of the invention that these are only the present invention, the protection model being not intended to limit the present invention Enclose, all within the spirit and principles in the present invention, any modification, equivalent substitution and improvement etc. done, should be included in the present invention Protection domain within.

Claims (8)

1. the method estimating oasis farmland clear sky solar radiation, it is characterised in that including:

Based on the reference surface in the range of oasis farmland, utilize visible ray and near infrared band, determine surface albedo α_ref With Reflectivity for Growing Season ε_ref；

Thermal infrared bands is utilized to determine surface temperature T_s, based in the reference surface in the range of oasis farmland, assert earth's surface temperature Degree T_sWith air themperature T_aEqual, it is thus achieved that daytime air themperature T_ad, moment t₂Air themperatureMoment t when satellite passes by₁ Air themperatureAnd air themperature T of the instantaneous moment i that satellite is when passing by_ai；

Utilize ground measured data, it is thus achieved that daytime descending shortwave radiation Rs_↓d, descending long-wave radiation on daytime Rl_↓d, moment t₂Descending Shortwave radiationMoment t when satellite passes by₁Descending shortwave radiationMoment t₂Descending long-wave radiationDefend Moment t when star passes by₁Descending long-wave radiationThe descending shortwave radiation Rs of instantaneous moment i when satellite passes by_↓i, defend The descending long-wave radiation Rl of instantaneous moment i when star passes by_↓i；

Utilize described surface albedo α_ref, described earth's surface emissivity ε_ref, descending shortwave radiation Rs on described daytime_↓d, described daytime Descending long-wave radiation Rl_↓d, air themperature T on described daytime_ad, described moment t₂Air themperatureWhen described satellite passes by time Carve t₁Air themperatureAir themperature T of instantaneous moment i when described satellite passes by_ai, instantaneous when passing by of described satellite The descending shortwave radiation Rs of moment i_↓i, moment t₂Descending shortwave radiationInstantaneous moment i's when satellite passes by is descending Shortwave radiationMoment t₂Descending long-wave radiationMoment t when satellite passes by₁Descending long-wave radiationDetermine Net radiation flux Rn_i, average daily net radiation and instant cleaning liquid radiation between ratio C_d, net radiation on daytime and instant cleaning liquid radiation between Ratio C_DAnd moment t₂Instant cleaning liquid radiation with satellite pass by time moment t₁Instant cleaning liquid radiation between ratio

According to net radiation flux Rn_i, average daily net radiation and instant cleaning liquid radiation between ratio C_d, net radiation on daytime and instant cleaning liquid spoke Ratio C between penetrating_DAnd moment t₂Instant cleaning liquid radiation with satellite pass by time moment t₁Instant cleaning liquid radiation between ratioDetermine average daily net radiation Rn_d, net radiation on daytime Rn_DAnd any time point net radiation

2. the method for claim 1, it is characterised in that described average daily net radiation Rn_dExpression formula be:

${\mathrm{Rn}}_d=\[\frac{(1-{\mathrm{\α}}_{ref}){\mathrm{Rs}}_{\↓d}+{\mathrm{\ϵ}}_{ref}({\mathrm{Rl}}_{\↓d}-{{\mathrm{\σT}}_a^4}_d)}{(1-{\mathrm{\α}}_{ref}){\mathrm{Rs}}_{\↓i}+{\mathrm{\ϵ}}_{ref}({\mathrm{Rl}}_{\↓i}-{{\mathrm{\σT}}_a^4}_i)}\]{\mathrm{Rn}}_i$

In formula, σ is Stefan-Boltzmann constant, and unit is Wm^-2K^-4；Net radiation flux Rn_iExpression formula be: Rn_i=Rs_↓i (1-α_ref)+ε_refRl_↓i-ε_refσT_ai ⁴。

3. the method for claim 1, it is characterised in that described net radiation on daytime Rn_DExpression formula be:

${\mathrm{Rn}}_D=\[\frac{(1-{\mathrm{\α}}_{ref}){\mathrm{Rs}}_{\↓d}+{\mathrm{\ϵ}}_{ref}({\mathrm{Rl}}_{\↓d}-{{\mathrm{\σT}}_a^4}_d)(N/24)}{(1-{\mathrm{\α}}_{ref}){\mathrm{Rs}}_{\↓i}+{\mathrm{\ϵ}}_{ref}({\mathrm{Rl}}_{\↓i}-{{\mathrm{\σT}}_a^4}_i)}\]{\mathrm{Rn}}_i$

In formula, σ is Stefan-Boltzmann constant, and unit is Wm^-2K^-4；N is sunshine-duration or the maximum of duration on daytime,Wherein, ω_sBeing radian sunset hour angle, φ is latitude, and δ is solar declination；DOY is the some day in 1 year；Net radiation flux Rn_iExpression formula be: Rn_i=Rs_↓i (1-α_ref)+ε_refRl_↓i-ε_refσT_ai ⁴。

4. the method for claim 1, it is characterised in that described any time point net radiationExpression formula be:

${\mathrm{Rn}}_{t_2}={\mathrm{Rn}}_{t_1}\[\frac{\left(1-{\mathrm{\α}}_{ref}\right){\mathrm{Rs}}_{\↓t_2}+{\mathrm{\ϵ}}_{ref}\left({\mathrm{Rl}}_{\↓t_2}-{{\mathrm{\σT}}_a^4}_{t_2}\right)}{\left(1-{\mathrm{\α}}_{ref}\right){\mathrm{Rs}}_{\↓t_1}+{\mathrm{\ϵ}}_{ref}\left({\mathrm{Rl}}_{\↓t_1}-{{\mathrm{\σT}}_a^4}_{t_1}\right)}\]$

In formula, σ is Stefan-Boltzmann constant, and unit is Wm^-2K^-4；t₁The net radiation in momentPass through net radiation flux Rn_iDetermine, net radiation flux Rn_iExpression formula be: Rn_i=Rs_↓i(1-α_ref)+ε_refRl_↓i-ε_refσT_ai ⁴；By net radiation flux Rn_i Expression formula in i take t₁Time be t₁The net radiation in moment

5. the device estimating oasis farmland clear sky solar radiation, it is characterised in that including:

Surface albedo and Reflectivity for Growing Season determine unit, for based on the reference surface in the range of oasis farmland, utilize Visible ray and near infrared band, determine surface albedo α_refWith Reflectivity for Growing Season ε_ref；

Surface temperature and air themperature determine unit, are used for utilizing Thermal infrared bands to determine surface temperature T_s, based on oasis farmland model Enclose in interior reference surface, assert surface temperature T_sWith air themperature T_aEqual, it is thus achieved that daytime air themperature T_ad, moment t₂ Air themperatureMoment t when satellite passes by₁Air themperatureAnd the Air Temperature of the instantaneous moment i that satellite is when passing by Degree T_ai；

Shortwave radiation and long-wave radiation determine unit, are used for utilizing ground measured data, it is thus achieved that daytime descending shortwave radiation Rs_↓d、 Descending long-wave radiation on daytime Rl_↓d, moment t₂Descending shortwave radiationMoment t when satellite passes by₁Descending shortwave radiationMoment t₂Descending long-wave radiationMoment t when satellite passes by₁Descending long-wave radiationWhen satellite passes by The descending shortwave radiation Rs of instantaneous moment i_↓i, the descending long-wave radiation Rl of satellite instantaneous moment i when passing by_↓i；

Computing unit, is used for utilizing described surface albedo α_ref, described earth's surface emissivity ε_ref, descending shortwave radiation on described daytime Rs_↓d, descending long-wave radiation on described daytime Rl_↓d, air themperature T on described daytime_ad, described moment t₂Air themperatureDescribed Moment t when satellite passes by₁Air themperatureAir themperature T of instantaneous moment i when described satellite passes by_aiDefend described in, The descending shortwave radiation Rs of instantaneous moment i when star passes by_↓i, the descending shortwave radiation of moment t2Wink when satellite passes by Time moment i descending shortwave radiationMoment t₂Descending long-wave radiationMoment t when satellite passes by₁Descending length Wave radiationDetermine net radiation flux Rn_i, average daily net radiation and instant cleaning liquid radiation between ratio C_d, net radiation on daytime and wink Time net radiation between ratio C_DAnd moment t₂Instant cleaning liquid radiation with satellite pass by time moment t₁Instant cleaning liquid radiation between Ratio

Radiation determines unit, for according to net radiation flux Rn_i, average daily net radiation and instant cleaning liquid radiation between ratio C_d, daytime Ratio C between net radiation and instant cleaning liquid radiation_DAnd moment t₂Instant cleaning liquid radiation with satellite pass by time moment t₁Instantaneous Ratio between net radiationDetermine average daily net radiation Rn_d, net radiation on daytime Rn_DAnd any time point net radiation

6. device as claimed in claim 5, it is characterised in that described radiation determines the average daily net radiation Rn that unit determines_dTable Reaching formula is:

${\mathrm{Rn}}_d=\[\frac{(1-{\mathrm{\α}}_{ref}){\mathrm{Rs}}_{\↓d}+{\mathrm{\ϵ}}_{ref}({\mathrm{Rl}}_{\↓d}-{{\mathrm{\σT}}_a^4}_d)}{(1-{\mathrm{\α}}_{ref}){\mathrm{Rs}}_{\↓i}+{\mathrm{\ϵ}}_{ref}({\mathrm{Rl}}_{\↓i}-{{\mathrm{\σT}}_a^4}_i)}\]{\mathrm{Rn}}_i$

In formula, σ is Stefan-Boltzmann constant, and unit is Wm^-2K^-4；Net radiation flux Rn_iExpression formula be: Rn_i=Rs_↓i (1-α_ref)+ε_refRl_↓i-ε_refσT_ai ⁴。

7. device as claimed in claim 5, it is characterised in that described radiation determines net radiation on the daytime Rn that unit determines_DTable Reaching formula is:

${\mathrm{Rn}}_D=\[\frac{(1-{\mathrm{\α}}_{ref}){\mathrm{Rs}}_{\↓d}+{\mathrm{\ϵ}}_{ref}({\mathrm{Rl}}_{\↓d}-{{\mathrm{\σT}}_a^4}_d)(N/24)}{(1-{\mathrm{\α}}_{ref}){\mathrm{Rs}}_{\↓i}+{\mathrm{\ϵ}}_{ref}({\mathrm{Rl}}_{\↓i}-{{\mathrm{\σT}}_a^4}_i)}\]{\mathrm{Rn}}_i$

In formula, σ is Stefan-Boltzmann constant, and unit is Wm^-2K^-4；N is sunshine-duration or the maximum of duration on daytime,Wherein, ω_sBeing radian sunset hour angle, φ is latitude, and δ is solar declination；DOY is the some day in 1 year；Net radiation flux Rn_iExpression formula be: Rn_i=Rs_↓i (1-α_ref)+ε_refRl_↓i-ε_refσT_ai ⁴。

8. device as claimed in claim 5, it is characterised in that described radiation determines any time point net radiation that unit determinesExpression formula be:

${\mathrm{Rn}}_{t_2}={\mathrm{Rn}}_{t_1}\[\frac{\left(1-{\mathrm{\α}}_{ref}\right){\mathrm{Rs}}_{\↓t_2}+{\mathrm{\ϵ}}_{ref}\left({\mathrm{Rl}}_{\↓t_2}-{{\mathrm{\σT}}_a^4}_{t_2}\right)}{\left(1-{\mathrm{\α}}_{ref}\right){\mathrm{Rs}}_{\↓t_1}+{\mathrm{\ϵ}}_{ref}\left({\mathrm{Rl}}_{\↓t_1}-{{\mathrm{\σT}}_a^4}_{t_1}\right)}\]$

In formula, σ is Stefan-Boltzmann constant, and unit is Wm^-2K^-4；t₁The net radiation in momentPass through net radiation flux Rn_iDetermine, net radiation flux Rn_iExpression formula be: Rn_i=Rs_↓i(1-α_ref)+ε_refRl_↓i-ε_refσT_ai ⁴；By net radiation flux Rn_i Expression formula in i take t₁Time be t₁The net radiation in moment