Global distribution of Earth's surface shortwave radiation budget

Journal of Climate, 1999

Climatological averages of surface radiation budget parameters, namely, the shortwave and longwave surface radiative fluxes, have been derived for each month of the year on a global scale. These climatological averages were derived from an 8-yr (96 month) time series of monthly average fluxes. The monthly averages were computed using fast radiation parameterizations and satellite data from the International Satellite Cloud Climatology Project and the Earth Radiation Budget Experiment. Results are presented as time series of hemispheric and global averages and as geographical distributions and time-latitude cross sections of climatological averages. The spatial/temporal variabilities of the results were found to be clearly related to the corresponding variabilities of meteorological and other inputs to the parameterizations. Numerous comparisons of the present results were made with available surface measurements for the purpose of validation. In most cases, the differences were found to be within the uncertainties of the measurements. In some cases, where they were large, the differences were attributable to identifiable deficiencies in the meteorological inputs and/or the surface measurements. However, large differences remained unexplained in a few cases. Anomalies of shortwave and longwave surface fluxes during the 1986/87 El Niño-Southern Oscillation episode show a strong relationship with corresponding top-of-atmosphere anomalies derived from an independent data source. Comparisons with results from several general circulation models showed large differences, but, in most cases, these were attributable to well-recognized deficiencies in model simulations. Global annual average downward and net shortwave fluxes were found to be about 185 and 161 W m Ϫ2 , respectively. These values are 10-20 W m Ϫ2 lower than those obtained from the general circulation models, but they are in good agreement with other satellite-derived estimates. Global annual average downward and net longwave fluxes were found to be about 348 and Ϫ48 W m Ϫ2 , respectively, which are about 10-15 W m Ϫ2 higher than corresponding values from general circulation models. Atmospheric shortwave absorption derived from the present results is 10-15 W m Ϫ2 larger than from the general circulation models, but it is in good agreement with another estimate based on satellite data.

Atmospheric Chemistry and Physics, 2004

The mean monthly shortwave (SW) radiation budget at the top of atmosphere (TOA) was computed on 2.5 • longitude-latitude resolution for the 14-year period from 1984 to 1997, using a radiative transfer model with long-term climatological data from the International Satellite Cloud Climatology Project (ISCCP-D2) supplemented by data from 5 the National Centers for Environmental Prediction -National Center for Atmospheric Research (NCEP-NCAR) Global Reanalysis project, and other global data bases such as TIROS Operational Vertical Sounder (TOVS) and Global Aerosol Data Set (GADS). The model radiative fluxes at TOA were validated against Earth Radiation Budget Experiment (ERBE) S4 scanner satellite data (1985)(1986)(1987)(1988)(1989)). The model is able to predict 10 the seasonal and geographical variation of SW TOA fluxes. On a mean annual and global basis, the model is in very good agreement with ERBE, overestimating the outgoing SW radiation at TOA (OSR) by 0.93 Wm −2 (or by 0.92%), within the ERBE uncertainties. At pixel level, the OSR differences between model and ERBE are mostly within ±10 Wm −2 , with ±5 Wm −2 over extended regions, while there exist some geographic 15 areas with differences of up to 40 Wm −2 , associated with uncertainties in cloud properties and surface albedo. The 14-year average model results give a planetary albedo equal to 29.6% and a TOA OSR flux of 101.2 Wm −2 . A significant linearly decreasing trend in OSR and planetary albedo was found, equal to 2.3 Wm −2 and 0.6% over the 14-year period (from January 1984 to December 1997), indicating an increasing solar 20 planetary warming. This planetary SW radiative heating occurs in the tropical and subtropical areas (20 • S-20 • N), with clouds being the most likely cause. The computed global mean OSR anomaly ranges within ±4 Wm −2 , with signals from El Niño and La Niña events or Pinatubo eruption, whereas significant negative OSR anomalies, starting from year 1992, are also detected. Abstract Introduction Conclusions References Tables Figures Back Close Full Screen / Esc Print Version Interactive Discussion © EGU 2004 25

Atmospheric Chemistry and Physics, 2013

Measured upwelling radiances from Nimbus-7 SBUV (Solar Backscatter Ultraviolet) and seven NOAA SBUV/2 instruments have been used to calculate the 340 nm Lambertian equivalent reflectivity (LER) of the Earth from 1979 to 2011 after applying a common calibration. The 340 nm LER is highly correlated with cloud and aerosol cover because of the low surface reflectivity of the land and oceans (typically 2 to 6 RU, reflectivity units, where 1 RU = 0.01 = 1.0 %) relative to the much higher reflectivity of clouds plus nonabsorbing aerosols (typically 10 to 90 RU). Because of the nearly constant seasonal and longterm 340 nm surface reflectivity in areas without snow and ice, the 340 nm LER can be used to estimate changes in cloud plus aerosol amount associated with seasonal and interannual variability and decadal climate change. The annual motion of the Intertropical Convergence Zone (ITCZ), episodic El Niño Southern Oscillation (ENSO), and latitudedependent seasonal cycles are apparent in the LER time series. LER trend estimates from 5 • zonal average and from 2 • × 5 • , latitude × longitude, time series show that there has been a global net decrease in 340 nm cloud plus aerosol reflectivity. The decrease in cos 2 (latitude) weighted average LER from 60 • S to 60 • N is 0.79 ± 0.03 RU over 33 yr, corresponding to a 3.6 ± 0.2 % decrease in LER. Applying a 3.6 % cloud reflectivity perturbation to the shortwave energy balance partitioning given by Trenberth et al. (2009) corresponds to an increase of 2.7 W m −2 of solar energy reaching the Earth's surface and an increase of 1.4 % or 2.3 W m −2 absorbed by the surface, which is partially offset by increased longwave cooling to space. Most of the decreases in LER occur over land, with the largest decreases occurring over the US (−0.97 RU decade −1), Brazil (−0.9 RU decade −1), and central Europe (−1.35 RU decade −1). There are reflectivity increases near the west coast of Peru and Chile (0.8 ± 0.1 RU decade −1), over parts of India, China, and Indochina, and almost no change over Australia. The largest Pacific Ocean change is −2 ± 0.1 RU decade −1 over the central equatorial region associated with ENSO. There has been little observed change in LER over central Greenland, but there has been a significant decrease over a portion of the west coast of Greenland. Similar significant decreases in LER are observed over a portion of the coast of Antarctica for longitudes −160 • to −60 • and 80 • to 150 • .

2000

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Journal of Climate, 2008

The partitioning of the earth radiation budget (ERB) between its atmosphere and surface components is of crucial interest in climate studies as it has a significant role in the oceanic and atmospheric general circulation. An analysis of the present-day climate simulation of the surface radiation budget in the atmospheric component of the new Hadley Centre Global Environmental Model version 1 (HadGEM1) is presented, and the simulations are assessed by comparing the results with fluxes derived from satellite data from the International Satellite Cloud Climatology Project (ISCCP) and ground measurements from the Baseline Surface Radiation Network (BSRN).

Journal of Climate, 1998

An updated evaluation of the surface radiation budget in climate models (1994–96 versions; seven datasets available, with and without aerosols) and in two new satellite-based global datasets (with aerosols) is presented. All nine datasets capture the broad mean monthly zonal variations in the flux components and in the net radiation, with maximum differences of some 100 W m−2 occurring in the downwelling fluxes at specific latitudes. Using long-term surface observations, both from land stations and the Pacific warm pool (with typical uncertainties in the annual values varying between ±5 and 20 W m−2), excess net radiation (RN) and downwelling shortwave flux density (So↓) are found in all datasets, consistent with results from earlier studies [for global land, excesses of 15%–20% (12 W m−2) in RN and about 12% (20 W m−2) in So↓]. For the nine datasets combined, the spread in annual fluxes is significant: for RN, it is 15 (50) W m−2 over global land (Pacific warm pool) in an observed ...

2008

This paper presents the annual and seasonal averaged earth atmosphere radiation budgets derived from the most complete set of satellite observations available in late 1979. The budgets are derived from a composite of 48 monthly mean radiation budget maps. The annual, global average emitted infrared flux is 234 W.m -2, planetary albedo is 0.30 and the net flux is zero within measurement uncertainty. The influence of continentality is apparent in the geographic distribution of the radiation budget, particularly planetary albedo. The net flux distributions display distinct regions of zonal asymetry particularly within those regions (latitudes) associated with the maximum solar insolation. The globally averaged net flux displays an annual cycle which is mainly attributed to the annual cycle imposed by external forcings associated with regular variation of the solar declination throughout the year. A study of the geographical distribution of the total variability of the net flux reveals ...

Geophysical Research Letters, 2014

2007

Diurnal variation in albedo and infrared radiation from Nimbus 3 and ESSA 7 for April fitted with TIROS 4 profiles 21 Northern hemisphere monthly zonal index from 35N to 55N on a 700 mb surface (solid curve); mean monthly zonal index based upon a 9 year average (dashed curve) 24 14 Northern hemisphere zonal kinetic energy in the mixed space-time domain for the layer 850 mb to 200 mb from 20N to 90N (solid curve); mean monthly zonal kinetic energy based on a 9 year average (dashed curve). .. 15 Northern hemisphere eddy kinetic energy in the mixed space-time domain for the later 850 mb to 200 mb from 20N to 90N (solid curve); mean monthly eddy kinetic energy based on a 9 year average (dashed curve). .. . 37 l6a Correlation coefficients of interannual variations with the general circulation parameters leading (-months) and lagging (+months) the net radiation gradient.. .. 40 l6b Correlation coefficients of interannual variations with the general circulation parameters leading (-months) and lagging (+months) the net radiation gradient. .