scholarly journals Long-Term Changes in Solar Shortwave Irradiance Due to Different Atmospheric Factors According to Measurements and Reconstruction Model in Northern Eurasia

2020 ◽  
Vol 4 (1) ◽  
pp. 5
Author(s):  
Elena Volpert ◽  
Natalia Chubarova
Keyword(s):  
Optical Thickness ◽  
Cloud Amount ◽  
Shortwave Radiation ◽  
Northern Eurasia ◽  
Factors Affecting ◽  
Meteorological Observatory ◽  
Cloud Optical Thickness ◽  
Reconstruction Model ◽  
Good Agreement

The temporal variability of solar shortwave radiation (SSR) has been assessed over northern Eurasia (40°–80° N; 10° W–180° E) by using an SSR reconstruction model since the middle of the 20th century. The reconstruction model estimates the year-to-year SSR variability as a sum of variations in SSR due to changes in aerosol, effective cloud amount and cloud optical thickness, which are the most effective factors affecting SSR. The retrievals of year-to-year SSR variations according to different factors were tested against long-term measurements in the Moscow State University Meteorological Observatory from 1968–2016. The reconstructed changes show a good agreement with measurements with determination factor R2 = 0.8. The analysis of SSR trends since 1979 has detected a significant growth of 2.5% per decade, which may be explained by its increase due to the change in cloud amount (+2.4% per decade) and aerosol optical thickness (+0.4% per decade). The trend due to cloud optical thickness was statistically insignificant. Using the SSR reconstruction model, we obtained the long-term SSR variability due to different factors for the territory of northern Eurasia. The increasing SSR trends have been detected on most sites since 1979. The long-term SSR variability over northern Eurasia is effectively explained by changes in cloud amount and, in addition, by changes in aerosol loading over the polluted regions. The retrievals of the SSR variations showed a good agreement with the changes in global radiance measurements from the World Radiation Data Center (WRDC) archive. The work was supported by RFBR grant number 18-05-00700.

LONG-TERM CHANGES IN SOLAR RADIATION IN NORTHERN EURASIA DURING THE WARM SEASON ACCORDING TO MEASUREMENTS AND RECONSTRUCTION MODEL

2021 ◽  
pp. 21-37
Author(s):  
E.V. VOL'PERT ◽  
◽  
N.E. CHUBAROVA ◽  
Keyword(s):  
Solar Radiation ◽  
Warm Season ◽  
Temporal Variations ◽  
Coefficient Of Determination ◽  
Northern Eurasia ◽  
State University ◽  
Surface Solar Radiation ◽  
Meteorological Observatory ◽  
Reconstruction Model

A reconstruction model of surface solar radiation (SR) is developed. The results of reconstructing the interannual SR variability for the period of 1968-2016 are tested against the observations at MSU (Lomonosov Moscow State University) Meteorological Observatory for the warm season (May-September), the comparison showed a good agreement (the coefficient of determination R2 = 0.8). The analysis of temporal variations in SR over Northern Eurasia (40-80 N; 10 W-180 E) due to various factors revealed that in most cases there has been a trend toward an SR increase since 1979. In addition, it is demonstrated that the long-term SR variability over Northern Eurasia was effectively explained by variations in the cloud transmission of Sr, except for the polluted regions of Siberia and China and several stations in Northern Europe, where the aerosol factor dominates in some cases.

scholarly journals Estimating cloud optical thickness and associated surface UV irradiance from SEVIRI by implementing a semi-analytical cloud retrieval algorithm

2012 ◽  
Vol 12 (17) ◽  
pp. 7961-7975 ◽  
Author(s):  
P. Pandey ◽  
K. De Ridder ◽  
D. Gillotay ◽  
N. P. M. van Lipzig
Keyword(s):  
Optical Thickness ◽  
Correlation Coefficients ◽  
Retrieval Algorithm ◽  
Satellite Mission ◽  
Spectral Bands ◽  
Uv Irradiance ◽  
Intercomparison Exercises ◽  
Cloud Optical Thickness ◽  
Mean Square Difference ◽  
Good Agreement

Abstract. In this paper, we describe the implementation of the Semi-Analytical Cloud Retrieval Algorithm (SACURA), to obtain scaled cloud optical thickness (SCOT) from satellite imagery acquired with the SEVIRI instrument and surface UV irradiance levels. In estimation of SCOT particular care is given to the proper specification of the background (i.e. cloud-free) spectral albedo and the retrieval of the cloud water phase from reflectance ratios in SEVIRI's 0.6 μm and 1.6 μm spectral bands. The SACURA scheme is then applied to daytime SEVIRI imagery over Europe, for the month of June 2006, at 15-min time increments. The resulting SCOT fields are compared with values obtained by the CloudSat experimental satellite mission, yielding a negligible bias, correlation coefficients ranging from 0.51 to 0.78, and a root mean square difference of 1 to 2 SCOT increments. These findings compare favourably to results from similar intercomparison exercises reported in the literature. Based on the retrieved SCOT from SEVIRI and radiative transfer modelling approach, simple parameterisations are proposed to estimate the surface UV-A and UV-B irradiance. The validation of the modelled UV-A and UV-B irradiance against the measurements over two Belgian stations, Redu and Ostend, indicate good agreement with the high correlation, index of agreement and low bias. The SCOT fields estimated by implementing SACURA on imagery from geostationary satellite are reliable and its impact on surface UV irradiance levels is well produced.

scholarly journals Long-term variability of aerosol optical thickness in Eastern Europe over 2001–2014 according to the measurements at the Moscow MSU MO AERONET site with additional cloud and NO<sub>2</sub> correction

2015 ◽  
Vol 8 (7) ◽  
pp. 7843-7878
Author(s):  
N. Y. Chubarova ◽  
A. A. Poliukhov ◽  
I. D. Gorlova
Keyword(s):  
Optical Thickness ◽  
Aerosol Optical Thickness ◽  
Quality Data ◽  
Emission Rates ◽  
State University ◽  
Data Control ◽  
Uv Irradiance ◽  
Meteorological Observatory ◽  
Moscow State University

Abstract. The aerosol properties of the atmosphere were obtained within the framework of the AERONET program at the Moscow State University Meteorological Observatory (Moscow MSU MO) over 2001–2014 period. The quality data control has revealed the necessity of their additional cloud and NO2 correction. The application of cloud correction according to hourly visual cloud observations provides a decrease in average aerosol optical thickness (AOT) at 500 nm of up to 0.03 compared with the standard dataset. We also show that the additional NO2 correction of the AERONET data is needed in large megalopolis, like Moscow, with 12 million residents and the NOx emission rates of about 100 kt yr−1. According to the developed method we estimated monthly mean NO2 content, which provides an additional decrease of 0.01 for AOT at 340 nm, and of about 0.015 – for AOT at 380 and 440 nm. The ratios of NO2 optical thickness to AOT at 380 and 440 nm are about 5–6 % in summer and reach 15–20 % in winter when both factors have similar effects on UV irradiance. Seasonal cycle of AOT at 500 nm is characterized by a noticeable summer and spring maxima, and minimum in winter conditions, changing from 0.08 in December and January up to 0.3 in August. The application of the additional cloud correction removes a local AOT maximum in February, and lowered the December artificial high AOT values. The pronounced negative AOT trends of about −1–5 % yr−1 have been obtained for most months, which could be attributed to the negative trends in emissions (E) of different aerosol precursors of about 116 Gg yr−2 in ESOx, 78 Gg yr−2 in ENMVOC, and 272 Gg yr−2 in ECO over European territory of Russia. No influence of natural factors on temporal AOT variations has been revealed.

scholarly journals UV variability in Moscow according to long-term UV measurements and reconstruction model

2008 ◽  
Vol 8 (12) ◽  
pp. 3025-3031 ◽  
Author(s):  
N. Y. Chubarova
Keyword(s):  
Seasonal Variations ◽  
Total Ozone ◽  
Cloud Amount ◽  
Point Of View ◽  
Atmospheric Parameters ◽  
Aerosol Loading ◽  
Uv Irradiance ◽  
The Impact ◽  
Reconstruction Model

Abstract. Long-term measurements of erythemally weighted UV irradiance (Qer) have been analyzed for the 1999–2006 period as well as UV variability according to a reconstruction model since 1968. The estimates of different atmospheric parameters effects, including NO2 content, on Qer have been obtained on seasonal and interannual scales. It has been shown that NO2 content in conditions of large megalopolis provides average Qer decrease of about 1.5–2%. The seasonal variations of the observed UV indices are discussed from the point of view of the impact on health. Using the reconstruction model we showed a distinct growth in Qer since 1980 due to changes in total ozone (+2.5% per decade), effective cloud amount transmission (+2.1% per decade) and aerosol loading (+1.1% per decade). However, there is no change in Qer over the longer 1968–2006 period due to significant decrease in effective cloud amount transmission (−11% per decade) in 1968–1980.

scholarly journals UV variability in Moscow according to long-term UV measurements and reconstruction model

2008 ◽  
Vol 8 (1) ◽  
pp. 893-906 ◽  
Author(s):  
N. Y. Chubarova
Keyword(s):  
Seasonal Variations ◽  
Total Ozone ◽  
Cloud Amount ◽  
Point Of View ◽  
Atmospheric Parameters ◽  
Aerosol Loading ◽  
Uv Irradiance ◽  
The Impact ◽  
Reconstruction Model

Abstract. Long-term measurements of erythemally weighted UV irradiance (Qer) have been analyzed for the 1999–2006 period as well as UV variability according to reconstruction model since 1968. The estimates of different atmospheric parameters effects, including NO2 content, on Qer) have been obtained on seasonal and interannual scales. It has been shown that NO2 content in conditions of large megalopolis provides average Qer decrease of about 1.5–2%. The seasonal variations of the observed UV indices are discussed from the point of view of the impact on health. Using the reconstruction model we showed a distinct growth in Qer since 1980 due to decrease in total ozone (+2.5% per decade), effective cloud amount transmission (+2.1% per decade) and aerosol loading (+1.1% per decade). However, there is no changes in Qer over larger 1968–2006 period due to significant decrease in effective cloud amount transmission (−11% per decade) in 1968–1980.

scholarly journals A long-term time series of global and diffuse photosynthetically active radiation in the Mediterranean: interannual variability and cloud effects

2017 ◽  
Author(s):  
Pamela Trisolino ◽  
Alcide di Sarra ◽  
Fabrizio Anello ◽  
Carlo Bommarito ◽  
Tatiana Di Iorio ◽  
...  
Keyword(s):  
Optical Thickness ◽  
Annual Cycle ◽  
Cloud Fraction ◽  
Radiative Effect ◽  
Diffuse Component ◽  
Active Radiation ◽  
Cloud Radiative Effect ◽  
Cloud Optical Thickness ◽  
Cloud Top Pressure

Abstract. Measurements of global and diffuse photosynthetically active radiation (PAR) have been carried out on the island of Lampedusa, in the central Mediterranean Sea, since 2002. PAR is derived from observations made with multi filter rotating shadowband radiometers (MFRSRs) by comparison with a freshly calibrated PAR sensor and by relying on the on-site Langley plots. In this way, a long-term calibrated record covering the period 2002–2016 is obtained and is presented in this work. The monthly mean global PAR peaks in June, with about 160 W m−2, while the diffuse PAR reaches 60 W m−2 in some cases in spring or summer. The global PAR displays a clear annual cycle with a semi amplitude of about 52 W m−2. The diffuse PAR annual cycle has a semi amplitude of about 12 W m−2 (about 23 % of the annual mean value). The diffuse PAR is about 39 % of the global, with a marked seasonal variation, between about 25–30 % in winter and about 50 % in summer. A simple method to retrieve the cloud-free PAR global and diffuse irradiances in days characterized by partly cloudy conditions has been implemented and applied to the dataset. This method allows to retrieve the cloud-free evolution of PAR, and to calculate the cloud radiative effect. CRE, for downwelling PAR. The cloud-free monthly mean global PAR reaches 175 W m−2 in summer, and the diffuse PAR about 40 W m−2. The annual semi amplitudes are similar for all-sky and cloud-free data. The diffuse PAR for the cloud-free cases is about 24 % of the global. The cloud radiative effect, CRE, on global and diffuse PAR is calculated as the difference between all-sky and cloud-free measurements. The average CRE is about −14.7 W m−2 for the global, and +8.1 W m−2 for the diffuse PAR. The smallest CRE is observed in July, due to the high cloud-free conditions frequency. Maxima (negative for the global, and positive for the diffuse component) occur in March–April and in October, due to the combination of elevated PAR irradiances and high occurrence of cloudy conditions. Largest monthly mean values of CRE are at about −31 W m−2 for the global (April 2007), and +18 W m−2 for the diffuse component (April 2010). Summer clouds appear to be characterized by a low frequency of occurrence, low altitude, and low optical thickness, possibly linked to the peculiar marine boundary layer structure. These properties also contribute to produce small radiative effects on PAR in summer. The cloud radiative effect has been de-seasonalized to remove the influence of annual irradiance variations. The monthly mean normalized CRE for global PAR shows a statistically significant high correlation with monthly cloud fraction, cloud top pressure, and cloud optical thickness, as determined from satellite MODIS observations. The normalized CRE for diffuse PAR show lower correlations, although still statistically significant, with cloud fraction and cloud top pressure, while displays a limited correlation with cloud optical thickness. Cloud fraction seems to be the most relevant parameter driving the cloud radiative effects. Normalized CRE data have been de-seasonalized and related with variations of the de-seasonalized PAR. A statistically significant correlation is found between the de-seasonalized PAR and the de-seasonalized normalized CRE. This correlation is seasonally dependent, and suggests that about 77 % of the global PAR interannual variability may be ascribed to clouds variability in winter.

scholarly journals Estimating cloud optical thickness and associated surface UV irradiance from SEVIRI by implementing a semi-analytical cloud retrieval algorithm

2012 ◽  
Vol 12 (1) ◽  
pp. 691-721 ◽  
Author(s):  
P. Pandey ◽  
K. De Ridder ◽  
D. Gillotay ◽  
N. P. M. van Lipzig
Keyword(s):  
Optical Thickness ◽  
Correlation Coefficients ◽  
Retrieval Algorithm ◽  
Satellite Mission ◽  
Spectral Bands ◽  
Uv Irradiance ◽  
Intercomparison Exercises ◽  
Cloud Optical Thickness ◽  
Mean Square Difference ◽  
Good Agreement

Abstract. In this paper, we describe the implementation of the Semi-Analytical Cloud Retrieval Algorithm (SACURA), to obtain scaled cloud optical thickness (SCOT) from satellite imagery acquired with the SEVIRI instrument and surface UV irradiance levels. In estimation of SCOT particular care is given to the proper specification of the background (i.e., cloud-free) spectral albedo and the retrieval of the cloud water phase from reflectance ratios in SEVIRI's 0.6 μm and 1.6 μm spectral bands. The SACURA scheme is then applied to daytime SEVIRI imagery over Europe, for the month of June 2006, at 15-min time increments. The resulting SCOT fields are compared with values obtained by the CloudSat experimental satellite mission, yielding a negligible bias, correlation coefficients ranging from 0.51 to 0.78, and a root mean square difference of 1 to 2 SCOT increments. These findings compare favourably to results from similar intercomparison exercises reported in the literature. Based on the retrieved SCOT from SEVIRI and radiative transfer modelling approach, simple parameterisations are proposed to estimate the surface UV-A and UV-B irradiance. The validation of the modelled UV-A and UV-B irradiance against the measurements over two Belgian stations, Redu and Ostend, indicate good agreement with the high correlation, index of agreement and low bias. The SCOT fields estimated by implementing SACURA on imagery from geostationary satellite are reliable and its impact on surface UV irradiance levels is well produced.

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