scholarly journals Estimation of Aerosol-Corrected Surface Solar Irradiance at Local Incidence Angle over Different Physiographic Subdivisions of India and Adjoining Areas Using MODIS and SRTM Data

2020 ◽  
Vol 37 (2) ◽  
pp. 161-175 ◽  
Author(s):  
Libeesh Lukose ◽  
Dibyendu Dutta
Keyword(s):  
Solar Irradiance ◽  
Incidence Angle ◽  
Surface Radiation ◽  
Radiation Budget ◽  
Transmission Factor ◽  
Radiation Data ◽  
Surface Irradiance ◽  
Dewpoint Temperature ◽  
Moderate Resolution ◽  
Moderate Resolution Imaging Spectroradiometer

AbstractSurface solar irradiance is considered as an important component of the surface radiation budget and constitutes one of the essential climate variables. In the present study, clear-sky instantaneous solar irradiance was estimated over 15 physiographic regions of India during January. Dewpoint temperature profiles were extracted from Moderate Resolution Imaging Spectroradiometer (MODIS) instrument onboard the Aqua satellite to calculate actual vapor pressure following Clausius–Clapeyron equation, which was further used in the Zillman parameterization for solar irradiance. The effect of terrain slope and aspect on direct radiation was taken into account by modifying the parameterized incoming shortwave flux by introducing the local incidence angle. A significant positive correlation was found between terrain-corrected MODIS irradiance and measured radiation data but the RMSE was very high (187 W m−2). Further, the effect of aerosol extinction was introduced by multiplying the terrain-corrected flux by a transmission factor obtained from satellite-derived aerosol optical depth and Ångström exponent. Due to the inclusion of the aerosol transmittance, the correlation was significantly improved (R2 = 0.84) and RMSE was reduced (31 W m−2). Further the effect of surface orientation on surface irradiance was evaluated on six hilly subdivisions. A large variation in the flux (135 to 161 W m−2) was noticed among different aspect classes. The variability was highest in the Eastern Himalayas subdivision (>250 W m−2) and was a minimum in the Eastern Hills subdivision (<28 W m−2). In absence of ground radiation data in hills, Modern-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2), was used for validation of model output but it performed poorly and got saturated at higher surface irradiance values.

scholarly journals Satellite-Based Estimation of Temporally Resolved Dust Radiative Forcing in Snow Cover

2016 ◽  
Vol 17 (7) ◽  
pp. 1999-2011 ◽  
Author(s):  
Steven D. Miller ◽  
Fang Wang ◽  
Ann B. Burgess ◽  
S. McKenzie Skiles ◽  
Matthew Rogers ◽  
...  
Keyword(s):  
Solar Irradiance ◽  
Radiative Forcing ◽  
Hydrological Cycle ◽  
Clear Sky ◽  
Operational Management ◽  
Moderate Resolution ◽  
Resolution Imaging ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Sky Conditions

Abstract Runoff from mountain snowpack is an important freshwater supply for many parts of the world. The deposition of aeolian dust on snow decreases snow albedo and increases the absorption of solar irradiance. This absorption accelerates melting, impacting the regional hydrological cycle in terms of timing and magnitude of runoff. The Moderate Resolution Imaging Spectroradiometer (MODIS) Dust Radiative Forcing in Snow (MODDRFS) satellite product allows estimation of the instantaneous (at time of satellite overpass) surface radiative forcing caused by dust. While such snapshots are useful, energy balance modeling requires temporally resolved radiative forcing to represent energy fluxes to the snowpack, as modulated primarily by varying cloud cover. Here, the instantaneous MODDRFS estimate is used as a tie point to calculate temporally resolved surface radiative forcing. Dust radiative forcing scenarios were considered for 1) clear-sky conditions and 2) all-sky conditions using satellite-based cloud observations. Comparisons against in situ stations in the Rocky Mountains show that accounting for the temporally resolved all-sky solar irradiance via satellite retrievals yields a more representative time series of dust radiative effects compared to the clear-sky assumption. The modeled impact of dust on enhanced snowmelt was found to be significant, accounting for nearly 50% of the total melt at the more contaminated station sites. The algorithm is applicable to regional basins worldwide, bearing relevance to both climate process research and the operational management of water resources.

scholarly journals Meteorological Conditions and Cloud Effects on Surface Radiation Balance Near Helheim Glacier and Jakobshavn Isbræ (Greenland) Using Ground-Based Observations

2021 ◽  
Vol 8 ◽  
Author(s):  
G. Djoumna ◽  
S. H. Mernild ◽  
D. M. Holland
Keyword(s):  
Short Wave ◽  
Surface Radiation ◽  
Radiation Budget ◽  
Wave Radiation ◽  
Short Wave Radiation ◽  
Radiative Fluxes ◽  
Radiation Data ◽  
Long Wave ◽  
Transmittance Factor ◽  
Cloud Metrics

The surface radiation budget is an essential component of the total energy exchange between the atmosphere and the Earth’s surface. Measurements of radiative fluxes near/on ice surfaces are sparse in the polar regions, including on the Greenland Ice Sheet (GrIS), and the effects of cloud on radiative fluxes are still poorly studied. In this work, we assess the impacts of cloud on radiative fluxes using two metrics: the longwave-equivalent cloudiness, derived from long-wave radiation measurements, and the cloud transmittance factor, obtained from short-wave radiation data. The metrics are applied to radiation data from two automatic weather stations located over the bare ground near the ice front of Helheim (HG, 66.3290°N, 38.1460°W) and Jakobshavn Isbræ(JI, 69.2220°N, 49.8150°W) on the GrIS. Comparisons of meteorological parameters, surface radiation fluxes, and cloud metrics show significant differences between the two sites. The cloud transmittance factor is higher at HG than at JI, and the incoming short-wave radiation in the summer at HG is about 50.0 W m−2 larger than at JI. Cloud metrics derived at the two sites reveal partly cloudy conditions were frequent (42 and 65% of the period at HG and JI) with a high dependency on the wind direction. The total cloud radiative effect (CREnet) generally increases during melt season at the two stations due to long-wave CRE enhancement by cloud fraction. CREnet decreases from May to June and increases afterward, due to the strengthened short-wave CRE. The annually averaged CREnet were 3.0 ± 7.4 W m−2 and 1.9±15.1 W m−2 at JI and HG. CREnet estimated from AWS indicates that clouds cool the JI and HG during melt season at different rates.

scholarly journals Uncertainty in Satellite-Derived Surface Irradiances and Challenges in Producing Surface Radiation Budget Climate Data Record

2020 ◽  
Vol 12 (12) ◽  
pp. 1950
Author(s):  
Seiji Kato ◽  
David A. Rutan ◽  
Fred G. Rose ◽  
Thomas E. Caldwell ◽  
Seung-Hee Ham ◽  
...  
Keyword(s):  
Sensible Heat Flux ◽  
Radiant Energy ◽  
Energy System ◽  
Surface Radiation ◽  
Radiation Budget ◽  
Climate Data ◽  
Surface Irradiance ◽  
Uncertainty Estimates ◽  
The Difference ◽  
Global Mean

The Clouds and the Earth’s Radiant Energy System (CERES) Energy Balanced and Filled (EBAF) Edition 4.1 data product provides global surface irradiances. Uncertainties in the global and regional monthly and annual mean all-sky net shortwave, longwave, and shortwave plus longwave (total) irradiances are estimated using ground-based observations. Error covariance is derived from surface irradiance sensitivity to surface, atmospheric, cloud and aerosol property perturbations. Uncertainties in global annual mean net shortwave, longwave, and total irradiances at the surface are, respectively, 5.7 Wm−2, 6.7 Wm−2, and 9.7 Wm−2. In addition, the uncertainty in surface downward irradiance monthly anomalies and their trends are estimated based on the difference derived from EBAF surface irradiances and observations. The uncertainty in the decadal trend suggests that when differences of decadal global mean downward shortwave and longwave irradiances are, respectively, greater than 0.45 Wm−2 and 0.52 Wm−2, the difference is larger than 1σ uncertainties. However, surface irradiance observation sites are located predominately over tropical oceans and the northern hemisphere mid-latitude. As a consequence, the effect of a discontinuity introduced by using multiple geostationary satellites in deriving cloud properties is likely to be excluded from these trend and decadal change uncertainty estimates. Nevertheless, the monthly anomaly timeseries of radiative cooling in the atmosphere (multiplied by −1) agrees reasonably well with the anomaly time series of diabatic heating derived from global mean precipitation and sensible heat flux with a correlation coefficient of 0.46.

scholarly journals A Supplementary Clear-Sky Snow and Ice Recognition Technique for CERES Level 2 Products

2013 ◽  
Vol 30 (3) ◽  
pp. 557-568 ◽  
Author(s):  
Alexander Radkevich ◽  
Konstantin Khlopenkov ◽  
David Rutan ◽  
Seiji Kato
Keyword(s):  
Confidence Intervals ◽  
Radiant Energy ◽  
Energy System ◽  
Radiation Budget ◽  
Data Series ◽  
Clear Sky ◽  
Multiple Thresholds ◽  
Moderate Resolution ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Snow And Ice

Abstract Identification of clear-sky snow and ice is an important step in the production of cryosphere radiation budget products, which are used in the derivation of long-term data series for climate research. In this paper, a new method of clear-sky snow/ice identification for Moderate Resolution Imaging Spectroradiometer (MODIS) is presented. The algorithm’s goal is to enhance the identification of snow and ice within the Clouds and the Earth’s Radiant Energy System (CERES) data after application of the standard CERES scene identification scheme. The input of the algorithm uses spectral radiances from five MODIS bands and surface skin temperature available in the CERES Single Scanner Footprint (SSF) product. The algorithm produces a cryosphere rating from an aggregated test: a higher rating corresponds to a more certain identification of the clear-sky snow/ice-covered scene. Empirical analysis of regions of interest representing distinctive targets such as snow, ice, ice and water clouds, open waters, and snow-free land selected from a number of MODIS images shows that the cryosphere rating of snow/ice targets falls into 95% confidence intervals lying above the same confidence intervals of all other targets. This enables recognition of clear-sky cryosphere by using a single threshold applied to the rating, which makes this technique different from traditional branching techniques based on multiple thresholds. Limited tests show that the established threshold clearly separates the cryosphere rating values computed for the cryosphere from those computed for noncryosphere scenes, whereas individual tests applied consequently cannot reliably identify the cryosphere for complex scenes.

Intercomparison of Surface broadband Albedo products from MODIS, CGLS over Northeast Asia

2020 ◽  
Author(s):  
Noh-Hun Seong ◽  
Sungwon Choi ◽  
Donghyun Jin ◽  
Daeseong Jung ◽  
Kyung-soo Han
Keyword(s):  
Northeast Asia ◽  
Radiation Budget ◽  
Data Sets ◽  
Land Type ◽  
Comparison Results ◽  
Moderate Resolution ◽  
Resolution Imaging ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Land Types

&lt;p&gt;Surface broadband albedo&amp;#160;is one of the climate variables that understand Earth&amp;#8217;s radiation budget. Currently, the polar-orbit satellite-derived surface broadband albedo products are retrieved by several organizations. As there are many kinds, it is necessary to identify the characteristics of each products. In this study, we were to compare representative products for long-term that the albedo products based on polar-obit satellite such as moderate resolution imaging spectroradiometer (MODIS) and the Copernicus Global Land Service (CGLS). We studied the Northeast Asia region where the land type remains unchanged from 2000 to 2018. The overall trend of the two products was similar. However, differences occurred depending on the land types and season. The relatively high value of MODIS albedo was calculated in winter because it was sensitive to the snow. In other seasons, the CGLS albedo was higher than the MODIS albedo. The MODIS albedo was calculated higher than CGLS albedo for all land types except forest. The comparison results showed that caution should be given before operational use of the albedo data sets in these regions.&lt;/p&gt;

scholarly journals A Comparison of MODIS-Derived Cloud Fraction with Surface Observations at Five SURFRAD Sites

2015 ◽  
Vol 54 (5) ◽  
pp. 1009-1020 ◽  
Author(s):  
Ning An ◽  
Kaicun Wang
Keyword(s):  
Solar Radiation ◽  
Correlation Coefficients ◽  
Cloud Fraction ◽  
Surface Radiation ◽  
Convective Clouds ◽  
Solar Radiation Incident ◽  
Surface Data ◽  
Moderate Resolution ◽  
Resolution Imaging ◽  
Moderate Resolution Imaging Spectroradiometer

AbstractClouds determine the amount of solar radiation incident to the surface. Accurately quantifying cloud fraction is of great importance but is difficult to accomplish. Satellite and surface cloud observations have different fields of view (FOVs); the lack of conformity of different FOVs may cause large discrepancies when comparing satellite- and surface-derived cloud fractions. From the viewpoint of surface-incident solar radiation, this paper compares Moderate Resolution Imaging Spectroradiometer (MODIS) level-2 cloud-fraction data with three surface cloud-fraction datasets at five Surface Radiation Network (SURFRAD) sites. The correlation coefficients between MODIS and the surface cloud fractions are in the 0.80–0.91 range and vary at different SURFRAD sites. In a number of cases, MODIS observations show a large cloud-fraction bias when compared with surface data. The variances between MODIS and the surface cloud-fraction datasets are more apparent when small convective or broken clouds exist in the FOVs. The magnitude of the discrepancy between MODIS and surface-derived cloud fractions depends on the satellite’s view zenith angle (VZA). On average, relative to surface cloud-fraction data, MODIS observes a larger cloud fraction at VZA > 40° and a smaller cloud fraction at VZA < 20°. When comparing long-term MODIS averages with surface datasets, Aqua MODIS observes a higher annual mean cloud fraction, likely because convective clouds are better developed in the afternoon when Aqua is observing.

scholarly journals Development and validation of a snow albedo algorithm for the MODIS instrument

2002 ◽  
Vol 34 ◽  
pp. 45-52 ◽  
Author(s):  
Andrew G. Klein ◽  
Julienne Stroeve
Keyword(s):  
Atmospheric Correction ◽  
Anisotropic Scattering ◽  
Daily Basis ◽  
Surface Radiation ◽  
Radiation Budget ◽  
Cloud Detection ◽  
Snow Albedo ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Using Data

AbstractA prototype snow albedo algorithm has been developed for the Moderate Resolution Imaging Spectroradiometer (MODIS). It complements existing MODIS products by providing albedo measurements for areas mapped as snow on a global daily basis by MODIS. Cloud detection and atmospheric correction are accomplished using existing MODIS products. Models of the bidirectional reflectance of snow created using a discrete-ordinate radiative transfer (DISORT) model are used to correct for anisotropic scattering effects over non-forested surfaces. Initial algorithm validation is undertaken through comparisons with broadband albedo measurements made at the U.S. National Oceanic and Atmospheric Administration (NOAA) Surface Radiation Budget Network (SURFRAD) site in Fort Peck, MT. In situ SURFRAD albedo measurements are compared to daily MODIS snow albedo retrievals for the period 21–26 November 2000 created from five narrow-to-broadband albedo conversion schemes. The prototype MODIS algorithm produces reasonable broadband albedo estimates. Maximum daily differences between the five MODIS broadband albedo retrievals and in situ albedo are 15%. Daily differences between the best MODIS broadband estimate and the measured SURFRAD albedo are 1–8%. However, no single conversion scheme consistently provides the closest albedo estimate. Further validation and algorithm development using data from North America and Greenland is ongoing.

scholarly journals Geostationary Enhanced Temporal Interpolation for CERES Flux Products

2013 ◽  
Vol 30 (6) ◽  
pp. 1072-1090 ◽  
Author(s):  
David R. Doelling ◽  
Norman G. Loeb ◽  
Dennis F. Keyes ◽  
Michele L. Nordeen ◽  
Daniel Morstad ◽  
...  
Keyword(s):  
Global Climate ◽  
Radiant Energy ◽  
Energy System ◽  
Radiation Budget ◽  
Cloud Properties ◽  
Marine Stratus ◽  
Temporal Interpolation ◽  
Moderate Resolution ◽  
Moderate Resolution Imaging Spectroradiometer ◽  
Observation Times

Abstract The Clouds and the Earth’s Radiant Energy System (CERES) instruments on board the Terra and Aqua spacecraft continue to provide an unprecedented global climate record of the earth’s top-of-atmosphere (TOA) energy budget since March 2000. A critical step in determining accurate daily averaged flux involves estimating the flux between CERES Terra or Aqua overpass times. CERES employs the CERES-only (CO) and the CERES geostationary (CG) temporal interpolation methods. The CO method assumes that the cloud properties at the time of the CERES observation remain constant and that it only accounts for changes in albedo with solar zenith angle and diurnal land heating, by assuming a shape for unresolved changes in the diurnal cycle. The CG method enhances the CERES data by explicitly accounting for changes in cloud and radiation between CERES observation times using 3-hourly imager data from five geostationary (GEO) satellites. To maintain calibration traceability, GEO radiances are calibrated against Moderate Resolution Imaging Spectroradiometer (MODIS) and the derived GEO fluxes are normalized to the CERES measurements. While the regional (1° latitude × 1° longitude) monthly-mean difference between the CG and CO methods can exceed 25 W m−2 over marine stratus and land convection, these regional biases nearly cancel in the global mean. The regional monthly CG shortwave (SW) and longwave (LW) flux uncertainty is reduced by 20%, whereas the daily uncertainty is reduced by 50% and 20%, respectively, over the CO method, based on comparisons with 15-min Geostationary Earth Radiation Budget (GERB) data.

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