RU2531050C2 - Method of determining spectral streams of solar radiation taking into account effects of absorption and scattering of radiation by aerosols and clouds at earth surface level - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: invention relates to atmospheric physics and can be used for meteorological purposes. The method uses data on coordinates of an estimation point, date and time of estimation to calculate extra-atmospheric spectral streams of solar radiation, the ozone absorption section, coefficients of attenuation of solar radiation as a result of scattering by gases and optical mass of the atmosphere. Data on the value of surface pressure, air humidity, total content of ozone at the level of the earth's surface, overall amount of clouds and average size of cloud and aerosol particles are used to determine coefficients of haze and coefficients of attenuation of solar radiation by atmospheric aerosol and clouds. Spectral streams of solar radiation are then calculated taking into accounts effects of absorption and scattering of radiation by aerosol and clouds.

EFFECT: high accuracy of estimating spectral streams of solar radiation for a geographic point.

Description

The invention relates to the field of monitoring, in particular to monitoring changes in weather, climate and chemical composition of the atmosphere, the environmental situation in the region.

A known method for assessing the spatial variability of solar radiation fluxes and meteorological parameters associated with solar radiation (US Pat. No. 6,748,327 B1) is used to assess the geographical variability of solar-dependent meteorological parameters based on measurements at meteorological stations. The method includes a statistical analysis of regional data, calculation of average climatic characteristics and deviations from them, the construction of empirical models of variability of average values and deviations. This method allows us to evaluate the similar characteristics of solar radiation and the associated meteorological characteristics in areas that do not have measurements based on correlation relationships from data at individual stations.

However, this method does not allow to evaluate the actual values of solar radiation fluxes at a geographical point of research interest, based on actual data on meteorological characteristics that affect the attenuation of solar radiation, such as air concentration, temperature, ozone content and atmospheric transparency. In addition, the analogue allows you to statistically evaluate the integral, i.e. independent of the spectrum of solar radiation, the characteristics of radiation fluxes and does not allow taking into account the spectral differences in the attenuation of solar radiation.

In the aforementioned analogue, geographic correlation relationships are used to solve this problem, allowing for taking into account geographical variability, but not taking into account the actual weather condition at the point of interest.

A known method for calculating solar radiation fluxes taking into account molecular scattering (JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 97, NO.DY, PAGES 7593-7601, MAY 20, 1992) consists in calculating direct and diffuse solar radiation fluxes to calculate atmospheric photodissociation rates gases. This method allows you to take into account the scattering of radiation by atmospheric gases at different heights of the atmosphere.

However, this method does not allow scattering and attenuation by atmospheric aerosol and clouds to be taken into account and is focused on calculating solar radiation fluxes in the stratosphere, i.e. above layers of cloudiness and aerosol pollution, and does not allow the calculation of the spectral flux of solar radiation at ground level.

The technical result is to increase the accuracy of the estimation of the spectral fluxes of solar radiation for a geographical point and their localization by taking into account data on the meteorological situation, total ozone and transparency of the atmosphere.

The fluxes of solar radiation at the level of the earth's surface determine the heating of the soil, the irradiation of biological organisms, affect the heating of the atmosphere, atmospheric circulation and are a key factor in the comfortable living of the population. Accurate estimates of solar radiation fluxes are essential for a numerical weather forecast, selection of energy consumption modes, and environmental assessment. The magnitude of the fluxes of solar radiation at the level of the earth's surface is determined by its weakening when passing through the atmosphere, in particular, by the content of absorbed gases and, primarily, molecular oxygen and ozone, molecular scattering, attenuation by clouds and aerosol.

, координаты точки оценки (φ - широта точки оценки), дату и время оценки.To solve this problem, the surface pressure (p), air humidity, total ozone at the surface level (S _O3 ), total cloudiness score N _h , and the average size of cloud and aerosol particles are taken as initial data

, coordinates of the evaluation point (φ is the latitude of the evaluation point), date and time of the evaluation.

Next, F _λ is determined _{, ∞} is the extra-atmospheric spectral flux of solar radiation, where λ is the wavelength in the spectrum of the Sun, which is set from 290 to 700 nm in increments of 5 nm. For each value of the wavelength, F _{λ, ∞ is} determined from the actinometric reference book. Also for the same wavelengths from the Chemical Kinetics and Photochemical Data for Use in Atmospheric Studies, NASA, JPL Evaluation 15, JPL Publication 06-02, Pasadena, California, 2006, there is σ _{λ, O3} is the ozone absorption cross section at wavelength λ .

After that, k _{λ is} calculated _{, scat} is the attenuation coefficient of solar radiation as a result of scattering by gases for the same wavelengths, using the formula:

Standard surface pressure p ₀ = 1025 mb.

After that, the turbidity coefficient β is determined for the same wavelengths as the ratio of the attenuation coefficient for the current atmosphere to the attenuation coefficient for an ideal atmosphere that does not contain clouds and aerosols. Depending on the degree of air pollution, the turbidity factor is taken equal to 3 or 4.

Next, the attenuation coefficient of solar radiation by atmospheric aerosol and clouds k _{λ, cloud} for the above wavelengths is determined by the formula:

.

.

, где

- средний размер облачных и аэрозольных частиц.The coefficient n depends on the size of the cloud and aerosol particles and is determined by the formula

where

- the average size of cloud and aerosol particles.

After that, the optical mass of the atmosphere m _{θ is} calculated.

The optical mass of the atmosphere m _θ is a value that shows how many times the path of the sun's beam in the atmosphere increases at the zenith angle θ compared to the zenith angle.

The zenith angle of the Sun θ varies depending on the rotation of the Earth around the Sun and the rotation of the Earth around its axis.

Throughout the year, the Earth describes an elliptical orbit around the Sun. To the observer on Earth, on the contrary, it seems that the Sun moves along the arch of heaven and describes the path called the ecliptic throughout the year. The ecliptic plane makes an angle of 23 ° 27 '(about 23 and a half degrees) with the plane of the earth's equator. In addition, the Earth still rotates around its axis, as a result of which the zenith angle depends on the hour angle.

Thus, taking into account changes in the declination of the Sun, the latitude of the observer and time relative to true noon, the zenith angle, taking into account spherical geometry, is determined by the formula:

.

.

The declination of the Earth’s orbit δ, depending on the date of the estimate and the time of the true noon t _p in seconds, is determined by the actinometric reference book.

Given the sphericity of the Earth and the atmosphere, the optical mass t @ is calculated by the formula:

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.

Next, the spectral flux of solar radiation is directly determined taking into account the effects of absorption and scattering of radiation by aerosols and clouds with a wavelength of λ (for all wavelengths with lengths from 290 to 700 nm in increments of 5 nm) at the earth's surface F _{λ, surƒ} according to the formula:

.

.

Claims (1)

A method for determining the spectral fluxes of solar radiation, taking into account the effects of absorption and scattering of radiation by aerosols and clouds at the level of the earth's surface, which consists in calculating the extra-atmospheric spectral fluxes of solar radiation, ozone absorption cross sections, attenuation coefficients based on the coordinates of the assessment point, date and time of the assessment solar radiation as a result of scattering by gases, the optical mass of the atmosphere, characterized in that according to the data on the surface pressure, air humidity, the total ozone and at the level of the earth's surface, the total cloudiness score, the average size of cloud and aerosol particles are determined by the turbidity coefficients and attenuation coefficients of solar radiation by atmospheric aerosol and clouds and according to the formula

The spectral fluxes of solar radiation are determined taking into account the effects of absorption and scattering of radiation by aerosols and clouds.