CN104180907A - Sea surface temperature cooperative inversion method based on near-infrared high spectrum and thermal infrared single-channel image - Google Patents

Abstract

The invention discloses a sea surface temperature cooperative inversion method based on a near-infrared high spectrum and a thermal infrared single-channel image, which is characterized in that the sea surface temperature cooperative inversion method comprises the following steps: S1, performing cloud detection on thermal infrared data; S2, performing atmosphere steam content inversion on high-spectrum data; S3, calculating an atmosphere transmittance and an effective average temperature; and S4, calculating the sea surface temperature. The atmosphere steam content is a main factor which affects infrared seam temperature inversion precision. Currently, a method of utilizing thermal infrared split-window technology or introducing meteorological observation auxiliary data for correcting atmosphere steam effect is widely used. The invention provides a novel method of utilizing near-infrared steam absorption peak high-spectrum data for acquiring the atmosphere steam content, thereby performing thermal infrared image sea surface temperature inversion and correcting the atmosphere effect. The method can effectively settle a problem that synchronous atmosphere steam content data is in shortage in sea surface temperature inversion by a thermal infrared single-channel image.

Description

A kind of sea surface temperature based on the high spectrum of near infrared and thermal infrared single channel image is worked in coordination with inversion method

Technical field

The present invention relates to application of satellitic remote sensing technical field, particularly relate to a kind of sea surface temperature inversion method.

Background technology

Steam is that near infrared is to the topmost Atmospheric Absorption gas of thermal infrared spectral coverage, also be the main source of single channel thermal infrared remote sensing load sea surface temperature inversion error, the existing single channel thermal infrared warm inverting in sea utilizes the acquisition Water Vapor Content information of meteorological stations observational data or numerical weather prediction model, due to Dao Ji weather station, off-lying sea marine site quantity rareness, and the steam product space resolution of numerical model output is also difficult to and the satellite time match that passes by far below Novel hot infrared remote sensing load, the forecast frequency, therefore cause the reduction of sea surface temperature inversion accuracy.

Summary of the invention

In order to overcome above-mentioned the deficiencies in the prior art, the invention provides the collaborative inversion method of a kind of sea surface temperature based on the high spectrum of near infrared and thermal infrared single channel image.

The technical problem to be solved in the present invention is the collaborative inversion method of a kind of sea surface temperature based on the high spectrum of near infrared and thermal infrared single channel image, the high spectrum simultaneously carrying for my army novel space borne imagery scouting platform and the work of thermal infrared remote sensing load data inverting sea-surface temperature (SST), improve sea surface temperature quantitative inversion precision.

The technical solution adopted in the present invention is:

Passing threshold method is carried out cloud detection to Detection Using Thermal Infrared Channel remote sensing image, only comprised the input image of clear sky pixel, utilize the high-spectrum remote-sensing device water vapor absorption passage observation data of carrying with platform with infrared remote sensor to extract Water Vapor Content, and then utilize approximation relation to estimate atmospheric transmittance and effective Zenith Distance temperature of Detection Using Thermal Infrared Channel, finally carry out sea surface temperature quantitative inversion by the funtcional relationship between Detection Using Thermal Infrared Channel brightness temperature and above-mentioned each parameter.

Compared with prior art, the invention has the beneficial effects as follows: the Water Vapor Content information of utilizing the high spectrum load of the near infrared carrying with platform with thermal infrared load to extract, on observation time, mate completely with infrared data, in observation angle and space covering, also gap is very little, the space-time matching error having existed while therefore effectively having avoided prior art to utilize meteorological stations observation and numerical model forecast to obtain steam information.

Brief description of the drawings

Fig. 1 is the process flow diagram of the collaborative inverting of sea surface temperature based on the high spectrum of near infrared and thermal infrared single channel image.

Embodiment

Below in conjunction with accompanying drawing, the present invention is further described.

Following examples are used for illustrating the present invention, but are not used for limiting the scope of the invention.

(1) cloud detection

Utilize threshold method to carry out cloud detection to input infrared image.At open ocean surface, when brightness temperature corresponding to certain pixel is during lower than a certain thresholding, think that pixel is under non-clear sky condition.Choosing of this thresholding is relevant with the factor such as longitude and latitude, weather conditions in cloud monitoring marine site.

(2) Retrieval of Vapor Content of Atmosphere

The radiation intensity difference that the strong absorption of steam closing on and weak absorption bands receive, mainly by Water Vapor Content control, therefore can adopt continuous wave band interpolation calculation Water Vapor Content:

R＝L(λ _a)/[c ₁L(λ ₁)+c ₂L(λ ₂)]

c ₁＝(λ ₂-λ _a)/(λ ₂-λ ₁) (1)

c ₂＝(λ ₁-λ _a)/(λ ₂-λ ₁)

Wherein, R is continuous interpolation band ratio, and L is wave band radiance, λ _a, λ ₁and λ ₂the weak absorption bands of 2 steam that is respectively the strong absorption bands of steam and be close to before and after it, as 943nm, 865nm and 1013nm.

Because remote sensor observation angle may exist non-substar Vertical Observation, the therefore Water Vapor Content w of oblique journey ^*and the funtcional relationship between continuous interpolation band ratio R is:

$\sqrt{w^{*}}=a_1\×\ln R+a_2---\left(2\right)$

Wherein, a ₁and a ₂for undetermined coefficient, its size is relevant with wave band response function with the steam wave band position of choosing, can be by atmosphere radiation transmission mode analog computations such as MODTRAN.

The tiltedly Water Vapor Content w of journey ^*can be converted to the total moisture content w of vertical direction atmosphere by following formula:

w＝w ^*/(1/cosθ _s+1/cosθ _v) (3)

Wherein, θ _sand θ _vbe respectively solar zenith angle and moonscope zenith angle.

(3) atmospheric transmittance and effective Zenith Distance temperature computation

There is following approximation relation in atmospheric transmittance τ and Water Vapor Content w:

τ=0.974290-0.08007w (temperature >=30 DEG C)

τ=0.982007-0.09611w (30 DEG C of temperature <) (4)

Effectively Zenith Distance temperature can be estimated with following formula:

$T_a=\frac{1}{w}{\&Integral;}_0^{z}1000T_z{\mathrm{\&rho;}}_{\mathrm{vz}}{d}_z---\left(5\right)$

In formula, w is the moisture content in atmosphere; T _zfor apart from sea level height being the atmospheric temperature (K) that z (km) locates, with height pass be T _z=T-6.5z; ρ _vzfor apart from earth's surface height being the unit volume moisture content (kg/m that z (km) locates ³), with the rule that is highly index decreased, calculate the moisture content ρ of differing heights z according to moisture content _vz

ρ _vz＝ρ _vexp(-z) (6)

In formula, ρ _vfor sea table moisture content, can be calculated by following formula:

${\mathrm{\&rho;}}_v=\frac{e}{R_{v}T}---\left(7\right)$

In formula, e is vapour pressure; T is sea table temperature; R _vfor steam gas law constant, value 461.495J/ (kgK).Vapour pressure e is obtained by following formula:

e＝e _sR _H (8)

In formula, R _hfor relative humidity, e _sfor saturation vapour pressure is obtained by following formula:

$e_s=611\exp \left[\frac{a(T-273.15)}{T-b}\right]---\left(9\right)$

In formula, a=17.67, b=29.65.

(4) sea surface temperature calculates

Between the bright temperature that sea surface temperature and thermal infrared remote sensing load are obtained, relation can be expressed as:

T _s＝{A(1-C-D)+[B(1-C-D)+C+D]T _sensor-DT _a)/C (10)

In formula, T _sfor sea surface temperature; T _sensorthe bright temperature of Detection Using Thermal Infrared Channel of obtaining for infrared remote sensor; T _afor effective Zenith Distance temperature; A, B is dimensionless constant, is respectively 67.355,0.458; C=ε τ, ε is emissivity of sea water (desirable approximate value 0.985), τ is atmospheric transmittance; D=(1-τ) [1+ (1-ε) τ].

Utilize atmospheric transmittance and the effective Zenith Distance temperature that the high spectrum of near infrared calculates to be updated to (10) formula by aforementioned, can calculate sea surface temperature.

Claims (5)

1. the collaborative inversion method of the sea surface temperature based on the high spectrum of near infrared and thermal infrared single channel image, is characterized in that, the collaborative inversion method of described sea surface temperature comprises the following steps:

S1: Thermal Infrared Data cloud detection;

S2: high-spectral data Retrieval of Vapor Content of Atmosphere;

S3: atmospheric transmittance and effectively medial temperature calculating;

S4: sea surface temperature calculates.

2. the collaborative inversion method of the sea surface temperature based on the high spectrum of near infrared and thermal infrared single channel image as claimed in claim 1, is characterized in that in described S1, the cloud detection of single channel Thermal Infrared Data adopts threshold method to carry out.

3. the collaborative inversion method of the sea surface temperature based on the high spectrum of near infrared and thermal infrared single channel image as claimed in claim 1, is characterized in that in described S2, high-spectral data Retrieval of Vapor Content of Atmosphere comprises:

S21: utilize the continuous interpolation band ratio of wave band interpolation calculation, computing formula is:

R＝L(λ _a)/[c ₁L(λ ₁)+c ₂L(λ ₂)]

c ₁＝(λ ₂-λ _a)/(λ ₂-λ ₁) (1)

c ₂＝(λ ₁-λ _a)/(λ ₂-λ ₁)

Wherein, R is continuous interpolation band ratio, and L is wave band radiance, λ _a, λ ₁and λ ₂the weak absorption bands of 2 steam that is respectively the strong absorption bands of steam and be close to before and after it, as 943nm, 865nm and 1013nm.

S22: utilize continuous interpolation band ratio R to calculate oblique journey Water Vapor Content w ^*' computing formula is:

Wherein, a ₁and a ₂for undetermined coefficient, its size is relevant with wave band response function with the steam wave band position of choosing, can be by atmosphere radiation transmission mode analog computations such as MODTRAN.

S23: by oblique journey Water Vapor Content w ^*' be converted to the total moisture content W of vertical direction atmosphere:

w＝w ^*/(1/cosθ _s+1/cosθ _v) (3)

Wherein, θ _sand θ _vbe respectively solar zenith angle and moonscope zenith angle.

4. the collaborative inversion method of the sea surface temperature based on the high spectrum of near infrared and thermal infrared single channel image as claimed in claim 1, is characterized in that described S3 comprises:

S31: calculate atmospheric transmittance τ by Water Vapor Content w;

S32: calculate effective Zenith Distance temperature by Water Vapor Content w.

5. the collaborative inversion method of the sea surface temperature based on the high spectrum of near infrared and thermal infrared single channel image as claimed in claim 1, is characterized in that described sea temperature computing formula is:

T _s＝{A(1-C-D)+[B(1-C-D)+C+D]T _sensor-DT _a}/C (4)

In formula, T _sfor sea surface temperature; T _sensorthe bright temperature of Detection Using Thermal Infrared Channel of obtaining for infrared remote sensor; T _afor effective Zenith Distance temperature; A, B is dimensionless constant, is respectively 67.355,0.458; C=ε τ, ε is emissivity of sea water (desirable approximate value 0.985), τ is atmospheric transmittance; D=(1-τ) [1+ (1-ε) τ].