The solar radiative processes that contribute to Earth's surface and atmospheric energy budgets are strongly dependent on wavelength. For example, snow and water vapor become more absorptive as incident radiation shifts from visible (VIS) to near-infrared (NIR) wavelengths. Some earth system models (ESMs) aggregate solar radiation into just two bands (VIS and NIR) partitioned at 0.7 μm for transmission between the atmospheric and surface components. In the widely used radiative transfer model RRTMG_SW this partition is near the center of the overlap spectral band spanning 0.625–0.778 μm, whose flux is often approximated as being evenly divided between the VIS and NIR surface bands. Using a hyperspectral radiative transfer model, we show that the fractional downwelling surface flux within the overlap band is usually distributed about 55.5%:44.5% VIS:NIR. This improved approximation shifts as much as 4.27 W m −2 from the NIR to the VIS band, leading to an instantaneous decrease in surface absorption of up to 0.91 W m −2 over snow-covered surfaces. Century-long fully coupled ESM simulations show surface absorption over snow decreases by over 1.6 W m −2 . The coupled response in sea ice regions amplifies the initial forcing ten-fold, and increases seasonal sea ice area by up to 4.9%. These results highlight the importance of accurately representing the spectral distribution of solar radiation in the cryosphere.

We explore the implications of indicating the biosphere's self-organization by the trend over time of the net entropic flow from the Earth's surface, the actual physical boundary of virtually all biotic mass. This flow, derived from the radiative surface entropy budget, is approximately inversely related to the surface temperature when the solar incident flux remains constant. In the geophysiological ('gaian') interpretation, biospheric self-organization has increased with the progressive colonization of the continents and evolutionary developments in the land biota, as a result of surface cooling arising from biotic enhancement of weathering. The key site for this self-organization is at the interface between land and atmosphere, the soil, where carbon is sequestered by its reaction (as carbonic and organic acids) with calcium magnesium silicates. Along with disequilibrium (steady-state) levels of carbon dioxide in the atmosphere, the occurrence of differentiated soil is the critical material evidence for biospheric self-organization, whether it be geophysiological or geochemical (ie., purely result of inorganic reactions). The computed equilibrium levels of carbon dioxide and corresponding equilibrium temperatures in the past are dramatically different from the steady-state levels. With future solar luminosity increase, the biospheric capacity for climatic regulation will decrease, leading to the ending of self-organization some two billion years from now. The Earth's surfa

It varies according to the place and time. Tropical regions get the most insolation, it gradually decreases towards the poles. Insolation happens more in summers and less in winters. The major factors which influence the amount of insolation received are: - Solar constant - The angle of incidence of the sun’s rays - Duration of the day - Earth distance from Sun - Transparency of the atmosphere Solar Constant At the top of the earth’s atmosphere, received insolation is expressed as the solar constant. It receives at the top of the atmospheric surface (thermopause) on a perpendicular plane to the solar beam. The average insolation received at the thermopause i.e.1368Wm2 (Watt per squaremetre) energy(solar constant) is in the form of short wave. Thus, it is termed as solar constant for that mean distance from the sun. These solar constant is varying over 1 Wm2 by periodic disturbances and explosions in the solar surface basically related to sun spot. Sun spots are dark and cooler areas visible on the sun’s surface. The recent researches have shown that more and more energy is released when the sunspots are in large number.

A windowless rare-gas ionization chamber has been developed to measure the absolute value of the solar extreme UV flux in the 50-575-A region. Successful results were obtained on a solar-pointing sounding rocket. The ionization chamber, operated in total absorption, is an inherently stable absolute detector of ionizing UV radiation and was designed to be independent of effects from secondary ionization and gas effusion. The net error of the measurement is + or - 7.3 percent, which is primarily due to residual outgassing in the instrument, other errors such as multiple ionization, photoelectron collection, and extrapolation to the zero atmospheric optical depth being small in comparison. For the day of the flight, Aug. 10, 1982, the solar irradiance (50-575 A), normalized to unit solar distance, was found to be 5.71 + or - 0.42 x 10 to the 10th photons per sq cm sec.

A dynamic, coupled thermal reservoir description of the Earth's atmospheric energy transfer processes is presented. Solar heat is stored and released by four coupled reservoirs, the land, the oceans and the upper and lower troposphere. In addition to the temperature, there are three other important parameters need to be considered. The first is the thermal gradient, the second is the interaction length and the third is the time delay or phase shift between the incident flux and reservoir thermal response. The Earth's climate is stabilized by the heat stored in these thermal reservoirs, particularly the oceans and the lower troposphere up to 2 km. Almost all of the downward long wave infrared (LWIR) flux reaching the surface originates in the lower troposphere. The dominant energy transfer process within the troposphere is moist convection. At night, the lower troposphere acts as a thermal blanket that slows the surface cooling. The upper troposphere cools continuously by LWIR emission to space. A change in temperature requires a change in the heat stored in the reservoir that has to be calculated using the heat capacity and the time dependent flux balance. The LWIR flux cannot be separated and used to define a change in ‘average surface temperature’ using blackbody theory.

Concentrating solar power plants, specifically central receiver type systems and their heliostat field, are struggling with negative reputation in the USA, due to perceived underperformance and reliability issues. This is in part due to a lack of standards for performance assessment as well as overly simplified techno-economical models. A better understanding of influences and losses along the solar radiation path from the sun, across the solar collector to the receiver, increases the fidelity of heliostat efficiency assessment as well as solar field performance predictions. Such data are currently scarce and require a complete set of metrology capabilities to evaluate direct solar irradiance, sun shape, atmospheric attenuation, reflectance, collector shape, slope errors and total beam dispersion. In preparation for establishing a 3rd party metrology platform in collaboration with Sandia National Labs, NLR conducted a scoping study on available metrology. We present an extensive overview of techniques and commercial systems for each category. Our work includes an analysis to increase understanding of strengths and limitations of the many techniques used for surface shape and slope measurement. This applies to a controlled, indoor or outdoor laboratory environment assessing a single heliostat.

Solar radiation and cutaneous melanoma. Exposure to solar radiation has been widely implicated in the dramatic rise in the incidence of cutaneous melanoma throughout the world. The association may be more complex than originally suspected, involving such factors as sunspot-activity cycles and changes in the ozone layer affecting ultraviolet flux at the earth's surface. The evidence for these relationships is examined. Published in Hospital practice (Office ed.) (1982)

Medically important solar ultraviolet A. Radiation measurements. Results from a 6-year study of solar ultraviolet A (UVA) radiation measurements at the equatorial location of Penang (5 degrees N) are presented. On clear days, the diurnal flux reaches a very high dosage of about 3.0 x 10(-2) KWHM-2 around midday. The average daily total flux is in the range of 1.6 x 10(-1) KWHM-2 and does not change much seasonally. The high 83% cloud cover only reduces the incoming flux to about half. The radiation flux represents a lower limit of the incident UVA radiation applicable to much of the equatorial/tropical region. Published in International journal of dermatology (1988)

Solar cycles and malignant melanoma. There has been a sixfold increase in the incidence of malignant melanoma in the State of Connecticut during the past forty years. Superimposed on a steady incidence rise are cycles of markedly increased incidence rates which follow periods of maximum sunspot activity. We propose that the effect of sunspot cycles on human melanoma occurrence is mediated by modulation of stratospheric ozone and thus indirectly affects UV flux at the earth's surface. This hypothesis would predict a time lag in melanoma incidence cycles, relative to sunspot activity, with increasing distance from polar caps. This appears to be the case. The increase in melanoma incidence related to a given reduction in ozone depletion in this hypothesis, is in great excess of existing models relating anthropogenic ozone depletion and skin cancer. Published in Medical hypotheses (1979)

Ocular hazards arising from depletion of the natural atmospheric ozone layer: a review. The processes contributing to the maintenance of the natural, atmospheric, ozone layer, which screens the earth's surface from solar ultraviolet radiation at wavelengths below 300 nm, are described. The possible adverse effects of man-made chemicals such as chlorofluorocarbons (CFCs) on this layer are outlined. Consideration of the flux of ultraviolet light reaching the earth's surface as a function of the ozone concentration and other factors allows the effect of ozone changes on ocular health to be evaluated. It is concluded that the changes of the order of a few per cent that are predicted by current models of the atmosphere, and which are comparable with natural fluctuations in ozone, would have relatively little effect on the incidence of solar keratitis at the cornea. Larger changes, in the order of 50%, would be expected to have a significant effect. There might also be an increase in the incidence of brunescent cataract. Ozone changes would have a negligible effect on the amounts of solar radiation reaching the retina.

Accurate representation of urban properties and processes at higher resolutions in global modeling systems is essential for advancing urban climate science and informing effective resilience strategies. However, the prescription of coarse global-scale urban properties in most state-of-the-art Earth system models is limiting their potential for capturing these climate signals as they advance toward kilometer-scale simulation capabilities. To bridge this gap in inadequate urban property representation and to advance urban-resolving Earth system modeling, this work integrates the newly-developed global 1 km-resolution facet-level urban surface property dataset, U-Surf, into the Community Earth System Model (CESM). These CESM simulations are validated against satellite measurements, ground-based urban weather stations, flux tower observations, and reanalysis data. Results demonstrate that the enhanced urban properties allow improved simulations of urban meteorology and surface energy fluxes compared to the default coarse-resolution categorical urban canopy parameters. Spatial scaling analysis reveals climate-dependent information loss during resolution aggregation, as well as substantial scale-dependent variations in urban surface energy flux representation. These findings have critical implications for coupled Earth system modeling when including the effect of land-atmosphere interaction. This work establishes a foundation for future urban-resolving kilometer-scale ESM developme

Thermal infrared-based remote sensing of surface energy fluxes has traditionally relied on high spatial resolution satellite data with revisit frequencies on the order of weeks. In this study, we evaluate a biophysics-based analytical surface energy balance model for predicting latent energy ( LE ) and sensible heat ( H ) fluxes using proximal sensing observations. The Surface Temperature Initiated Closure (STIC1.2) model has been extensively validated across a wide range of spatial and temporal scales using various satellite-derived thermal infrared data sets. Here we extend this validation by applying STIC at sub-hourly temporal resolution over multiple growing seasons for four distinct agricultural systems. We further develop and evaluate novel STIC variants that incorporate machine learning (ML) techniques to eliminate the need for surface energy balance observations, specifically net radiation and soil heat flux, thereby enhancing model applicability in data-sparse settings. The integration of a ML component to estimate surface available energy is shown to have strong predictive performance for both LE (R 2 = 0.81–0.94) and H (R 2 = 0.46–0.72) across all agricultural systems examined here, demonstrating the potential of hybrid biophysical-machine learning approaches for surface energy balance modeling with minimal data requirements. This study concludes with a novel application of explainable machine learning (exML) to diagnose sources of model error. This exML framework

Altered surface albedo due to land-cover conversions and management is a significant driver of global climate change. Albedo can be directly measured at ground stations, and remote sensing data can be used to scale-up albedo values to regional and global levels. Some previous studies have retrieved fine-resolution (10–30 m) instantaneous albedo and coarse-resolution (500–1000 m) daily mean albedo from remote sensing data, but they all required the input of Moderate Resolution Imaging Spectroradiometer (MODIS) albedo information at 500-m resolution, and none have assembled both instantaneous and daily albedo based exclusively on fine-resolution satellite data. Here, to address this issue, we compiled 387 instantaneous and 346 daily albedo records using field net radiometer measurements from the bioenergy croplands at the W. K. Kellogg Biological Station in southwest Michigan. We then connected these albedo records with a suite of variables derived from harmonized Landsat and Sentinel-2 data through two machine learning algorithms (random forest regression and extreme gradient boosting) to retrieve clear-sky instantaneous and daily shortwave broadband albedo. The performance statistics indicate reasonable accuracy of model results [root-mean-square error (RMSE)] around or below 0.03 except for snow-covered surfaces), suggesting that the retrieval of both instantaneous and daily albedo based exclusively on fine-resolution satellite data is promising. To facilitate the use of fin