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The global energy balance from a surface perspective
Abstract and Figures
In the framework of the global energy balance, the radiative energy exchanges between Sun, Earth and space are now accurately quantified from new satellite missions. Much less is known about the magnitude of the energy flows within the climate system and at the Earth surface, which cannot be directly measured by satellites. In addition to satellite observations, here we make extensive use of the growing number of surface observations to constrain the global energy balance not only from space,but also from the surface. We combine these observations with the latest modeling efforts performed for the 5th IPCC assessment report to infer best estimates for the global mean surface radiative components. Our analyses favor global mean downward surface solar and thermal radiation values near 185 and 342 Wm-2, respectively, which are most compatible with surface observations. Combined with an estimated surface absorbed solar radiation and thermal emission of 161 and 397 Wm-2, respectively, this leaves 106 Wm-2 of surface net radiation available globally for distribution amongst the non-radiative surface energy balance components. The climate models overestimate the downward solar and underestimate the downward thermal radiation, thereby simulating nevertheless an adequate global mean surface net radiation by error compensation. This also suggests that, globally, the simulated surface sensible and latent heat fluxes, around 20 and 85 Wm-2 on average, state realistic values. The findings of this study are compiled into a new global energy balance diagram, which may be able to reconcile currently disputed inconsistenciesbetween energy and water cycle estimates.
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Data
January 2013
... A "Model democracy" multi-model ensembles approach is often adopted, giving equal weight to each model, which makes it difficult to distinguish between the performances of different models [34][35][36][37][38] . Some studies use simple linear regression with observational results to obtain optimal estimates, which, while intuitive, makes it hard to assess the uncertainty of these estimates 39,40 . Although it is straightforward to define a "model performance index", demonstrating its relevance and usefulness for predictive accuracy presents a more complex challenge 41 .The Reliability Ensemble Averaging (REA) method has been employed to enhance the credibility of subcontinental-scale climate change projections. ...
... By incorporating observational constraints, the BMA method mitigates the impact of these systematic errors, resulting in lower EEI data. Besides, Research by Wild et al. indicates that CMIP5 models significantly overestimate downward shortwave radiation and underestimate upward longwave radiation compared to surface observations ( Figure S3), and our study shows that CMIP6 models still exhibit the same issues 39 . After being constrained by observational data, the downward shortwave radiation decreased to 186 Wm -2 , and the upward longwave radiation increased to 401 Wm -2 , which are similar to the results of the latest IPCC AR6 report 54 . ...
... However, models still face many challenges in simulating most of the components of the surface energy budget 46 . Apart from the surface shortwave solar radiation, other components still rely heavily on very sparse terrestrial in situ observational networks for constraint 24,39,49 . Although our EEI estimate and those based on the total energy estimate of the ocean, land, atmosphere, and surface are highly consistent in terms of trend changes, there are still certain differences in absolute values (Figs. ...
Tracking the energy balance of the Earth system is a key method for studying the contribution of human activities to climate change. However, accurately estimating the surface energy balance has long been a challenge, primarily due to uncertainties that dwarf the energy flux changes induced and a lack of precise observational data at the surface. We have employed the Bayesian Model Averaging (BMA) method, integrating it with recent developments in surface solar radiation observational data, to refine the ensemble of CMIP6 model outputs. This has resulted in an enhanced estimation of Surface Earth System Energy Imbalance (EEI) changes since the late 19th century. Our findings show that CMIP6 model outputs, constrained by this observational data, reflect changes in energy imbalance consistent with observations in Ocean Heat Content (OHC), offering a narrower uncertainty range at the 95% confidence level than previous estimates. Observing the EEI series, dominated by changes due to external forcing, we note a relative stability (0.22 Wm⁻²) over the past half-century, but with a intensification (reaching 0.80 Wm⁻²) in the mid to late 1990s, indicating an escalation in the adverse impacts of global warming and climate change, which provides another independent confirmation of what recent studies have shown.
... Most of the thermal radiative exchange from the Earth's surface takes place via the atmosphere, primarily water vapour and greenhouse gases, with a relatively small fraction escaping directly from the Earth's surface into outer space 56 , as illustrated schematically in Fig. 6c. One characteristic of the thermoradiative diode is that the emission is relatively narrow (compare Fig. 2a), offering the possibility of restricting radiative exchange through a narrow atmospheric absorption window to the radiatively cold conditions in space. ...
Satellite products provide the best way to monitor the solar radiation reaching the Earth's surface on a global scale. However, their capability to monitor solar radiation trends needs to be constantly evaluated. This depends on their temporal stability and the accurate representation of all processes driving solar radiation. This study evaluates these aspects by comparing and cross-comparing different solar radiation products (ERA5, CAMS-RAD 4.6, SARAH-3, CLARA-A3, CERES-EBAF 4.2) against in-situ measurements over Europe. All products show a moderate positive bias over Europe but strong differences in their root mean squared deviation (RMSD) related to their different cloud transmittance models. Geostationary-based products (SARAH-3, CAMS-RAD 4.6) provide the smallest RMSD closely followed by CLARA-A3, whereas ERA5 shows a large RMSD due to random errors in cloud transmittance. All products show an increase in surface solar radiation, or brightening, over the last 40 years over Europe, but the magnitude of the trends and their spatiotemporal variability differ between products. Despite finding temporal inhomogeneities in some products, the different trends are mostly due to different aerosol modeling approaches implemented by each product. Both SARAH-3 (+2.3 W∕m 2 ∕decade, 2001-22) and CERES-EBAF 4.2 (+2.2 W∕m 2 ∕decade, 2001-22) provide the most consistent trends compared to in-situ data, showing that after stabilizing in the late 2000s, brightening is particularly recovering in Western Europe. In-situ measurements show a reduction of aerosol optical depth from 2001 to 2022 that has been accentuated in the last 10 years, particularly in Western Europe. This would be consistent with the hypothesis that brightening recovery is driven by an aerosol reduction, though other analyses suggest that clouds also play a role in this recovery. More work is needed to understand the contribution of aerosols to solar radiation trends and the exact aerosol effects represented by each solar radiation product.
Many fundamental concepts of synoptic-scale extratropical dynamics are based on the quasi-geostrophic equations of a dry atmosphere. This “dry dynamics” provides the essential understanding of, for example, the formation of extratropical cyclones and the propagation of Rossby waves and makes potential vorticity (PV) a materially conserved quantity. Classically, for extratropical weather systems, the importance of so-called “diabatic effects”, e.g. surface fluxes, phase changes of water in clouds, and radiation, has been regarded as secondary compared to the dry dynamical processes. As outlined in this review article, research during recent decades has modified this view of the role of diabatic processes. A combination of complementary research approaches revealed that the nonlinear dynamics of extratropical cyclones and upper-tropospheric Rossby waves is affected – in some cases strongly – by diabatic processes. Despite the violation of material PV conservation in the presence of diabatic processes, the concept of PV has been of utmost importance to identify and quantify the role of diabatic processes and to integrate their effects into the classical understanding based on dry dynamics. This review first summarises the theoretical concepts of diabatic PV modification, moist PV, and slantwise moist convection and provides a concise overview of early research on diabatic effects until the late 1970s. Two poorly predicted high-impact cyclones affecting eastern North America then triggered an impressive diversity of efforts to investigate the role of diabatic processes in rapid cyclone intensification in the last 2 decades of the 20th century. These research activities, including the development of sophisticated diagnostics, growing applications of the Lagrangian perspective, real-case and idealised numerical experiments, and dedicated field experiments, are reviewed in detail. This historical perspective provides insight about how societal relevance, international collaboration, technical development, and creative science contributed to establishing this important theme of dynamical meteorology. The second part of the review then more selectively outlines important achievements in the last 2 decades in our understanding of how diabatic effects, in particular those related to cloud microphysics, affect the structure, dynamics, and predictability of different types of extratropical cyclones and their mesoscale substructures, upper-tropospheric blocks, Rossby waves, and interactions. A novel aspect is the relevance of research on diabatic processes for climate change research. The review closes by highlighting important implications of investigating diabatic processes in extratropical weather systems for the broader field of weather and climate dynamics and its fundamentals and representation in numerical models.
Objective: This study investigates how the researchers approached the theme the climate change impacts on photovoltaic production (PVP) from the perspective of simulations using climate models. Methodology: A comprehensive literature review was conducted to establish correlations between future PV production and climate change susceptibility on regional and global scales. Keywords related to the theme were used in the Web of Science database. Inclusion criteria selected only complete, free, English scientific articles related to the research theme, published between 1965 and 2023. Results and analysis: As a result, it generated a sample consisted of 58 articles on the impact of climate change on photovoltaic production, with 14 included in the final quantitative synthesis. A wide range of results was presented, stemming from both climate change models and models assessing the influence of weather-related factors on PV production. Patterns in the impacts of climate change on photovoltaic production were observed, and the main climate models used to estimate PVP were recognized, grouped, and discussed. Key databases, commonly used simulation periods, and equations linking meteorological variables to PVP were identified and examined. Conclusion: Numerous publications have emerged on the impacts of climate change on PVP, focusing on empirical equations that relate meteorological variables, cell temperature, and cell efficiency. Most studies adopted a forecast period until the end of the 21st century. The majority of the studies focused on Europe and Asia, with little research on impacts of climate changes on PVP in South and Central America.
The temperature that the Earth's surface would have without the greenhouse effect, with an atmosphere completely transparent to infrared radiation, or even without an atmosphere at all, is generally estimated at-18°C. The greenhouse effect is estimated to induce a warming of 33°C to justify the surface temperature of +15°C. To explain this discrepancy, we examine, with the ideal gas law, to which the Earth's atmosphere obeys its normal conditions of pressure and temperature, the role that the adiabatic compression of the atmospheric mass subjected to gravity can play. The dimensional analysis of the ideal gas law demonstrates that compression of the atmosphere produces energy, which can be calculated in Joules. The temperature of the atmosphere near the Earth's surface is influenced by both its invariable atmospheric mass, solar irradiation and the greenhouse effect. This calls into question the commonly established Earth's energy budgets which consider almost exclusively radiative effects, and which deduce a back radiation attributed to the greenhouse effect which is abnormally high.
Stellar evolution theory predicts that the Sun was fainter in the past, which can pose difficulties for understanding Earth’s climate history. One proposed solution to this Faint Young Sun problem is a more luminous Sun in the past. In this paper, we address the robustness of the solar luminosity history using the YREC code to compute solar models including rotation, magnetized winds, and the associated mass loss. We present detailed solar models, including their evolutionary history, which are in excellent agreement with solar observables. Consistent with prior standard models, we infer a high solar metal content. We provide predicted X-ray luminosities and rotation histories for usage in climate reconstructions and activity studies. We find that the Sun’s luminosity deviates from the standard solar model trajectory by at most 0.5% during the Archean (corresponding to a radiative forcing of 0.849 W m−2). The total mass loss experienced by solar models is modest because of strong feedback between mass and angular momentum loss. We find a maximum mass loss of 1.35 × 10−3M⊙ since birth, at or below the level predicted by empirical estimates. The associated maximum luminosity increase falls well short of the level necessary to solve the FYS problem. We present compilations of paleotemperature and CO2 reconstructions. 1-D ‘inverse’ climate models demonstrate a mismatch between the solar constant needed to reach high temperatures (e.g. 60-80 ○C) and the narrow range of plausible solar luminosities determined in this study. Maintaining a temperate Earth, however, is plausible given these conditions.
Improving observations of ocean heat content show that Earth is absorbing more energy from the sun than it is radiating to space as heat, even during the recent solar minimum. The inferred planetary energy imbalance, 0.59 ± 0.15 W m−2 during the 6-year period 2005–2010, confirms the dominant role of the human-made greenhouse effect in driving global climate change. Observed surface temperature change and ocean heat gain together constrain the net climate forcing and ocean mixing rates. We conclude that most climate models mix heat too efficiently into the deep ocean and as a result underestimate the negative forcing by human-made aerosols. Aerosol climate forcing today is inferred to be −1.6 ± 0.3 W m−2, implying substantial aerosol indirect climate forcing via cloud changes. Continued failure to quantify the specific origins of this large forcing is untenable, as knowledge of changing aerosol effects is needed to understand future climate change. We conclude that recent slowdown of ocean heat uptake was caused by a delayed rebound effect from Mount Pinatubo aerosols and a deep prolonged solar minimum. Observed sea level rise during the Argo float era is readily accounted for by ice melt and ocean thermal expansion, but the ascendency of ice melt leads us to anticipate acceleration of the rate of sea level rise this decade.
Humanity is potentially vulnerable to global temperature change, as discussed in the Intergovernmental Panel on Climate Change (IPCC, 2001, 2007) reports and by innumerable authors. Although climate change is driven by many climate forcing agents and the climate system also exhibits unforced (chaotic) variability, it is now widely agreed that the strong global warming trend of recent decades is caused predominantly by human-made changes of atmospheric composition (IPCC, 2007).
The basic physics underlying this global warming, the greenhouse effect, is simple. An increase of gases such as CO2 makes the atmosphere more opaque at infrared wavelengths. This added opacity causes the planet's heat radiation to space to arise from higher, colder levels in the atmosphere, thus reducing emission of heat energy to space. The temporary imbalance between the energy absorbed from the sun and heat emission to space, causes the planet to warm until planetary energy balance is restored.
The planetary energy imbalance caused by a change of atmospheric composition defines a climate forcing. Climate sensitivity, the eventual global temperature change per unit forcing, is known with good accuracy from Earth's paleoclimate history. However, two fundamental uncertainties limit our ability to predict global temperature change on decadal time scales.
First, although climate forcing by human-made greenhouse gases (GHGs) is known accurately, climate forcing caused by changing human-made aerosols is practically unmeasured. Aerosols are fine particles suspended in the air, such as dust, sulfates, and black soot (Ramanathan et al., 2001). Aerosol climate forcing is complex, because aerosols both reflect solar radiation to space (a cooling effect) and absorb solar radiation (a warming effect). In addition, atmospheric aerosols can alter cloud cover and cloud properties. Therefore, precise composition-specific measurements of aerosols and their effects on clouds are needed to assess the aerosol role in climate change.
Second, the rate at which Earth's surface temperature approaches a new equilibrium in response to a climate forcing depends on how efficiently heat perturbations are mixed into the deeper ocean. Ocean mixing is complex and not necessarily simulated well by climate models. Empirical data on ocean heat uptake are improving rapidly, but still suffer limitations.
We summarize current understanding of this basic physics of global warming and note observations needed to narrow uncertainties. Appropriate measurements can quantify the major factors driving climate change, reveal how much additional global warming is already in the pipeline, and help define the reduction of climate forcing needed to stabilize climate.
Cloud Fraction (CF) is the dominant modulator of radiative fluxes. In this study, we evaluate CF simulated in the IPCC AR4 GCMs against ARM ground measurements, with a focus on the vertical structure, total amount of cloud and its effect on cloud shortwave transmissivity. Our intercomparisons of three CF or sky-cover related datasets reveal that the relative differences are usually less than 10 % (5 %) for multi-year monthly (annual) mean values, while daily differences are quite significant. The results also show that the model-observation and inter-model deviations have similar magnitudes for the total CF (TCF) and the normalized cloud effect, and these deviations are twice as large as the deviations in surface downward solar radiation and cloud transmissivity. This implies that other cloud properties, such as cloud optical depth and height, have a similar magnitude of disparity to TCF among the GCMs, and suggests that the better agreement among the GCMs in solar radiative fluxes is the result of compensating errors in cloud vertical structure, cloud optical depth and cloud fraction. The internal variability of CF simulated in ensemble runs with the same model is very minimal. Similar deviation patterns between inter-model and model-measurement comparisons suggest that the climate models tend to generate larger biases against observations for those variables with larger inter-model deviation.
Differences are found in GCM performance over the three ARM sites: Southern Great Plains (SGP), Manus, Papua New Guinea and North Slope of Alaska (NSA). The GCMs perform better at SGP than at the other two sites in simulating the seasonal variation and probability distribution of TCF. However, the models remarkably underpredict the TCF and cloud transmissivity is less susceptible to the change of TCF than observed. Much larger inter-model deviation and model bias are found over NSA than the other sites, suggesting that the Arctic region continues to challenge cloud simulations in climate models. In the tropics, most of the GCMs tend to underpredict CF and fail to capture the seasonal variation of CF at middle and low levels. The high altitude CF is much larger in the GCMs than the observations and the inter-model variability of CF also reaches a maximum at high levels in the tropics, indicating difficulties in the representation of ice cloud associated with convection in the models.
The integrity of the Baseline Surface Radiation Network (BSRN) radiation monthly averages are assessed by investigating the impact on monthly means due to the frequency of data gaps caused by missing or discarded high time resolution data. The monthly statistics, especially means, are considered to be important and useful values for climate research, model performance evaluations and for assessing the quality of satellite (time- and space-averaged) data products. The study investigates the spread in different algorithms that have been applied for the computation of monthly means from 1-min values.
The paper reveals that the computation of monthly means from 1-min observations distinctly depends on the method utilized to account for the missing data. The intra-method difference generally increases with an increasing fraction of missing data. We found that a substantial fraction of the radiation fluxes observed at BSRN sites is either missing or flagged as questionable. The percentage of missing data is 4.4%, 13.0%, and 6.5% for global radiation, direct shortwave radiation, and downwelling longwave radiation, respectively. Most flagged data in the shortwave are due to nighttime instrumental noise and can reasonably be set to zero after correcting for thermal offsets in the daytime data. The study demonstrates that the handling of flagged data clearly impacts on monthly mean estimates obtained with different methods. We showed that the spread of monthly shortwave fluxes is generally clearly higher than for downwelling longwave radiation.
Overall, BSRN observations provide sufficient accuracy and completeness for reliable estimates of monthly mean values. However, the value of future data could be further increased by reducing the frequency of data gaps and the number of outliers. It is shown that two independent methods for accounting for the diurnal and seasonal variations in the missing data permit consistent monthly means to within less than one Wm−2 in most cases. The authors suggest using a standardized method for the computation of monthly means which addresses diurnal variations in the missing data in order to avoid a mismatch of future published monthly mean radiation fluxes from BSRN.
Clouds and the Earth's Radiant Energy System (CERES) is an investigation to examine the role of cloud/radiation feedback in the Earth's climate system. The CERES broadband scanning radiometers are an improved version of the Earth Radiation Budget Experiment (ERBE) radiometers. The CERES instruments will fly on several National Aeronautics and Space Administration Earth Observing System (EOS) satellites starting in 1998 and extending over at least 15 years. The CERES science investigations will provide data to extend the ERBE climate record of top-of-atmosphere shortwave (SW) and longwave (LW) radiative fluxes. CERES will also combine simultaneous cloud property data derived using EOS narrowband imagers to provide a consistent set of cloud/radiation data, including SW and LW radiative fluxes at the surface and at several selected levels within the atmosphere. CERES data are expected to provide top-of-atmosphere radiative fluxes with a factor of 2 to 3 less error than the ERBE data. Estimates of radiative fluxes at the surface and especially within the atmosphere will be a much greater challenge but should also show significant improvements over current capabilities.
Energy balance on the earth's surface is reevaluated based mainly on the
instrumentally measured fluxes. The basic data source for the present
work is the Global Energy Balance Archive (GEBA), WCP-Water Project A7.
The present article explains the content of the GEBA and presents the
first results of the reevaluation, which are centred around radiation.
Regional and global distributions of global radiation, surface albedo
and absorbed shortwave radiation are investigated and their latitudinal
distributions and global means are calculated. The annual mean of global
radiation for the earth is about 50% of the extraterrestrial solar
radiation. The Northern Hemisphere receives slightly more global
radiation than the Southern Hemisphere. The globally averaged global
radiation reaches a maximum and minimum in December and June,
respectively. The monthly albedo of the earth's surface is evaluated for
the land surfaces taking the snow cover into account, for the open water
surface taking solar altitude and cloud amount into account and for the
sea ice covered surface taking ice concentration and seasonal albedo
change of the ice floe into account. The global mean earth's surface
albedo is 0.16. The new value for the global mean absorbed shortwave
radiation is 142 Wm-2 or 42% of the extraterrestrial solar
radiation. The annual mean absorbed shortwave radiation is the same for
both hemispheres. The global mean absorbed shortwave radiation reaches
the maximum and minimum in December and June, respectively.
The problems of underestimation of longwave measurement by the
conventional installation method for pyrradiometers and pyrgeometers are
discussed and the degree of the underestimation of the longwave incoming
radiation is estimated at 10 to 15 Wm-2. This puts the annual
mean net radiation for the earth's surface at 102 Wm-2 or 30
% of the extraatmospheric solar radiation.
[1] Solar radiation budgets from 20 general circulation models (GCMs) participating in the second phase of the Atmospheric Model Intercomparison Project (AMIPII) are analyzed. The models largely differ in their global mean radiation budgets, particularly at the surface. Compared to a comprehensive data set of 760 worldwide-distributed surface stations from the Global Energy Balance Archive, the models tend to overestimate the land surface insolation by 9 Wm−2 on average. The biases in the net solar fluxes at the top of atmosphere are generally smaller. This suggests that the excessive surface insolation in the GCMs is rather related to inaccurate partitioning of solar absorption between surface and atmosphere than to excessive absorption by the planet as a whole. This applies also to 13 state-of-the-art GCMs participating in IPCC AR4. Uncertainties in the solar absorption by the atmospheric constituents are thus still significant in current GCMs and contribute to the large discrepancies amongst the GCM radiation budgets and their biases compared to surface observations.
Climate change is governed by changes to the global energy balance. At the top of the atmosphere, this balance is monitored globally by satellite sensors that provide measurements of energy flowing to and from Earth. By contrast, observations at the surface are limited mostly to land areas. As a result, the global balance of energy fluxes within the atmosphere or at Earth's surface cannot be derived directly from measured fluxes, and is therefore uncertain. This lack of precise knowledge of surface energy fluxes profoundly affects our ability to understand how Earth's climate responds to increasing concentrations of greenhouse gases. In light of compilations of up-to-date surface and satellite data, the surface energy balance needs to be revised. Specifically, the longwave radiation received at the surface is estimated to be significantly larger, by between 10 and 17 Wm−2, than earlier model-based estimates. Moreover, the latest satellite observations of global precipitation indicate that more precipitation is generated than previously thought. This additional precipitation is sustained by more energy leaving the surface by evaporation — that is, in the form of latent heat flux — and thereby offsets much of the increase in longwave flux to the surface.
Differences between observed and LOWTRAN7-computed downward longwave irradiances were examined at each of four globally diverse locations for an entire year at each site. The final results are restricted to times determined to be completely or nearly cloud-free. The irradiances from 367 such times range from 60 to 435 W m−2, and results indicate that the modeled irradiances and those measured directly using a pyrgeometer agree to within 5 W m−2 at individual sites and to within lm than 0.2 W m−2 when averaged over all four sites, neglecting any site-specific biases. The standard deviations and standard errors associated with these results are roughly 10 and 1 W m−2, respectively. An unbiased estimate of the agreement between the model and observations results in a mean difference of 0.62 W m−2 with standard deviation of 5 W m−2 but an even larger 95% confidence interval because of the small sample size. The comparison variance can be logically ascribed to a number of different sources, including ...
Evidence is presented that the excess surface net radiation calculated in general circulation models at continental surfaces is mostly due to excess incoming shortwave fluxes. Based on long-term observations from 22 worldwide inland stations and results from four general circulation models, the overestimate in models of 20% (11 W m-2) in net radiation on an annual basis compares with 6% (9 W m-2) for shortwave fluxes for the same 22 locations, or 9% (18 W m-2) for a larger set of 93 stations (71 having shortwave fluxes only). For annual fluxes, these differences appear to be significant. -Author