Solar radiation and the global energy budget

Abstract Idealized climate modeling studies often choose to neglect spatiotemporal variations in solar radiation, but doing so comes with an important decision about how to average solar radiation in space and time. Since both clear-sky and cloud albedo are increasing functions of the solar zenith angle, one can choose an absorption-weighted zenith angle that reproduces the spatial- or time-mean absorbed solar radiation. Calculations are performed for a pure scattering atmosphere and with a more detailed radiative transfer model and show that the absorption-weighted zenith angle is usually between the daytime-weighted and insolation-weighted zenith angles but much closer to the insolation-weighted zenith angle in most cases, especially if clouds are responsible for much of the shortwave reflection. Use of daytime-average zenith angle may lead to a high bias in planetary albedo of approximately 3%, equivalent to a deficit in shortwave absorption of approximately 10 W m−2 in the global energy budget (comparable to the radiative forcing of a roughly sixfold change in CO2 concentration). Other studies that have used general circulation models with spatially constant insolation have underestimated the global-mean zenith angle, with a consequent low bias in planetary albedo of approximately 2%–6% or a surplus in shortwave absorption of approximately 7–20 W m−2 in the global energy budget.

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Solar radiation and the global energy budget

Atmosphere, Weather and Climate ◽

10.4324/9780203871027-8 ◽

2009 ◽

pp. 56-93

Keyword(s):

Solar Radiation ◽

Energy Budget ◽

Global Energy ◽

Global Energy Budget

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A model for the surface brightness of a turbulent, low Mach number jet. II - The global energy budget and radiative losses

The Astrophysical Journal ◽

10.1086/163836 ◽

1986 ◽

Vol 300 ◽

pp. 591 ◽

Cited By ~ 35

Author(s):

G. V. Bicknell

Keyword(s):

Mach Number ◽

Energy Budget ◽

Surface Brightness ◽

Global Energy ◽

Low Mach Number ◽

Radiative Losses ◽

Global Energy Budget

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Quantifying Climate Forcings and Feedbacks over the Last Millennium in the CMIP5–PMIP3 Models*

Journal of Climate ◽

10.1175/jcli-d-15-0063.1 ◽

2016 ◽

Vol 29 (3) ◽

pp. 1161-1178 ◽

Cited By ~ 38

Author(s):

A. R. Atwood ◽

E. Wu ◽

D. M. W. Frierson ◽

D. S. Battisti ◽

J. P. Sachs

Keyword(s):

Energy Budget ◽

Climate Model ◽

Ice Age ◽

Lapse Rate ◽

Last Millennium ◽

Climate Feedbacks ◽

Global Energy ◽

Radiative Forcings ◽

Global Cooling ◽

Global Energy Budget

Abstract The role of radiative forcings and climate feedbacks on global cooling over the last millennium is quantified in the CMIP5–PMIP3 transient climate model simulations. Changes in the global energy budget over the last millennium are decomposed into contributions from radiative forcings and climate feedbacks through the use of the approximate partial radiative perturbation method and radiative kernels. Global cooling occurs circa 1200–1850 CE in the multimodel ensemble mean with pronounced minima corresponding with volcanically active periods that are outside the range of natural variability. Analysis of the global energy budget during the last millennium indicates that Little Ice Age (LIA; 1600–1850 CE) cooling is largely driven by volcanic forcing (comprising an average of 65% of the total forcing among models), while contributions due to changes in land use (13%), greenhouse gas concentrations (12%), and insolation (10%) are substantially lower. The combination of these forcings directly contributes to 47% of the global cooling during the LIA, while the remainder of the cooling arises from the sum of the climate feedbacks. The dominant positive feedback is the water vapor feedback, which contributes 29% of the global cooling. Additional positive feedbacks include the surface albedo feedback (which contributes 7% of the global cooling and arises owing to high-latitude sea ice expansion and increased snow cover) and the lapse rate feedback (which contributes an additional 7% of the global cooling and arises owing to greater cooling near the surface than aloft in the middle and high latitudes).

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Poleward Atmospheric Energy Transports and Their Variability as Evaluated from ECMWF Reanalysis Data

Journal of Climate ◽

10.1175/jcli-d-11-00202.1 ◽

2012 ◽

Vol 25 (2) ◽

pp. 734-752 ◽

Cited By ~ 47

Author(s):

Michael Mayer ◽

Leopold Haimberger

Keyword(s):

Energy Budget ◽

Energy Transport ◽

Southern Oscillation ◽

Forecast Model ◽

Reanalysis Data ◽

Energy Budgets ◽

Global Energy ◽

Weather Forecasts ◽

Short Period ◽

Global Energy Budget

Abstract The vertically integrated global energy budget is evaluated with a direct and an indirect method (both corrected for mass inconsistencies of the forecast model), mainly using the European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis Interim (ERA-Interim) data. A new estimate for the net poleward total energy transport is given. Comparison to satellite-derived radiation data proves that ERA-Interim is better suited for investigation of interannual variations of the global energy budget than available satellite data since these either cover a relatively short period of time or are too inhomogeneous in time. While much improved compared to the 40-yr ECMWF Re-Analysis (ERA-40), regionally averaged energy budgets of ERA-Interim show that strong anomalies of forecasted vertical fluxes tend to be partly compensated by unrealistically large forecasted energy storage rates. Discrepancies between observed and forecasted monthly mean tendencies can be taken as rough measure for the uncertainties involved in the ERA-Interim energy budget. El Niño–Southern Oscillation (ENSO) is shown to have large impact on regional energy budgets, but strong compensation occurs between the western and eastern Pacific, leading to only small net variations of the total poleward energy transports (similar magnitude as the uncertainty of the computations). However, Hovmöller longitude–time plots of tropical energy exports show relatively strong slowly eastward-moving poleward transport anomalies in connection with ENSO. Verification of these findings using independent estimates still needs to be done.

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