Transmission of solar radiation through clouds on melting glaciers: a comparison of parameterizations and their impact on melt modelling

AbstractWe explore the robustness and transferability of parameterizations of cloud radiative forcing used in glacier melt models at two sites in the Swiss Alps. We also look at the rationale behind some of the most commonly used approaches, and explore the relationship between cloud transmittance and several standard meteorological variables. The 2 m air-temperature diurnal range is the best predictor of variations in cloud transmittance. However, linear and exponential parameterizations can only explain 30–50% of the observed variance in computed cloud transmittance factors. We examine the impact of modelled cloud transmittance factors on both solar radiation and ablation rates computed with an enhanced temperature-index model. The melt model performance decreases when modelled radiation is used, the reduction being due to an underestimation of incoming solar radiation on clear-sky days. The model works well under overcast conditions. We also seek alternatives to the use of in situ ground data. However, outputs from an atmospheric model (2.2 km horizontal resolution) do not seem to provide an alternative to the parameterizations of cloud radiative forcing based on observations of air temperature at glacier automatic weather stations. Conversely, the correct definition of overcast conditions is important.

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The impact of heat on human physical work capacity; Part III: the impact of solar radiation varies with air temperature, humidity, and clothing coverage.

10.1101/2021.07.01.449782 ◽

2021 ◽

Author(s):

Josh Foster ◽

James W Smallcombe ◽

Simon G Hodder ◽

Andreas D Flouris ◽

Lars Nybo ◽

...

Keyword(s):

Solar Radiation ◽

Air Temperature ◽

Work Productivity ◽

Work Capacity ◽

Physical Work ◽

Physical Work Capacity ◽

Adult Males ◽

Cumulative Energy ◽

Heat Effects ◽

The Impact

It is well-known that heat impacts human labour/physical work capacity (PWC), but systematic evaluations of solar radiation (SOLAR) effects and the interaction with air temperature and humidity levels and clothing are lacking, as most lab-studies are conducted in semi-nude subjects without radiation or only in a single climatic condition. Due to the high relevance of SOLAR in various occupations, this study quantified how SOLAR interacts with clothing and other primary environmental factors (air temperature/humidity) of importance to determine PWC in the heat. The data allowed the development of a SOLAR correction factor for predicting PWC in major outdoor industries. Fourteen young adult males (7 wearing a standardised work coverall (0.9 Clo), 7 with shorts and trainers (0.3 Clo) walked for 1-hour at a fixed heart rate of 130 b∙min-1, in seven combinations of air temperature (25 to 45 Celsius) and relative humidity (20 or 80%), with and without SOLAR (800 W/m2 from solar lamps). Cumulative energy expenditure in the heat, relative to the work achieved in a cool reference condition, was used to determine PWC%. Skin temperature was the primary determinant of PWC in the heat. In dry climates with exposed skin (0.3 Clo), SOLAR caused PWC to decrease exponentially with rising air temperature, whereas work coveralls (0.9 Clo) negated this effect. In humid conditions, the SOLAR-induced reduction in PWC was consistent and linear across all levels of air temperature, and clothing conditions. WBGT and UTCI based prediction equations of PWC represented SOLAR correctly. For heat indices not intrinsically accounting for SOLAR, correction factors are provided enabling forecasting of heat effects on work productivity.

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Parametrization of Models and Use of Estimated Global Solar Radiation Data in the Irrigated Rice Yield Simulation

Revista Brasileira de Meteorologia ◽

10.1590/0102-7786332003 ◽

2018 ◽

Vol 33 (2) ◽

pp. 238-246

Author(s):

João Rodrigo de Castro ◽

Santiago Vianna Cuadra ◽

Luciana Barros Pinto ◽

João Marcelo Hoffmann de Souza ◽

Marcos Paulo dos Santos ◽

...

Keyword(s):

Solar Radiation ◽

Air Temperature ◽

Rice Yield ◽

Simulation Models ◽

Global Solar Radiation ◽

Empirical Models ◽

Potential Yield ◽

Irrigated Rice ◽

Radiation Data ◽

The Impact

Abstract The objective of this study was to evaluate the use of estimated global solar radiation data in the simulations of potential yield of irrigated rice. Global solar radiation was estimated by four empirical models, based on air temperature, and a meteorological satellite derivated. The empirical models were calibrated and validated for 10 sites, representative of the six rice regions of the State of Rio Grande do Sul - Brazil. To evaluate the impact of the radiation estimates on irrigated rice yield simulations, the CERES-Rice model, calibrated for four cultivars, was used. The estimates of global solar radiation of the empirical models based on the air temperature showed deviations, from the observed values, of 20 to 30% and the estimated by satellite deviations of more than 30%. The global solar radiation data estimated by the Hargreaves and Samani, Donatelli and Campbell and derived satellite (PowerNasa) type air temperature-based empirical models can be used as input data in simulation models of crop growth, development and productivity of irrigated rice.

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Transmission of Solar Radiation by Clouds over Snow and Ice Surfaces. Part II: Cloud Optical Depth and Shortwave Radiative Forcing from Pyranometer Measurements in the Southern Ocean

Journal of Climate ◽

10.1175/jcli3562.1 ◽

2005 ◽

Vol 18 (22) ◽

pp. 4637-4648 ◽

Cited By ~ 17

Author(s):

Melanie F. Fitzpatrick ◽

Stephen G. Warren

Keyword(s):

Solar Radiation ◽

Southern Ocean ◽

Sea Ice ◽

Optical Depth ◽

Radiative Forcing ◽

Surface Albedo ◽

Cloud Droplet ◽

Frequency Distributions ◽

Cloud Optical Depth ◽

Cloud Radiative Forcing

Abstract Downward solar irradiance at the sea surface, measured on several voyages of an icebreaker in the Southern Ocean, is used to infer transmittance of solar radiation by clouds. Together with surface albedo estimated from coincident hourly sea ice reports, instantaneous cloud radiative forcing and effective cloud optical depth are obtained. Values of “raw cloud transmittance” (trc), the ratio of downward irradiance under cloud to downward irradiance measured under clear sky, vary from 0.1 to 1.0. Over sea ice, few values of trc were observed between 0.8 and 1.0, possibly due to the threshold nature of the aerosol-to-cloud-droplet transition. This sparsely populated region of transmittances is referred to as the Köhler gap. The instantaneous downward shortwave cloud radiative forcing is computed, as well as the time-averaged net forcing. The net forcing at a solar zenith angle of 60° is typically −250 W m−2 over open ocean, but only half this value over sea ice because of the higher surface albedo and less frequent occurrence of clouds. “Effective” optical depths τ (for a radiatively equivalent horizontally homogeneous cloud) are classified by season and surface type. The frequency distributions of τ are well fitted by decaying exponentials, giving a characteristic optical depth of 15 at 47°S, increasing to 24 in the region of maximum cloud cover at 58°S, and decreasing to 11 at 67°S near the coast of Antarctica.

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Quantifying the impact of heat on human physical work capacity; part III: the impact of solar radiation varies with air temperature, humidity, and clothing coverage

International Journal of Biometeorology ◽

10.1007/s00484-021-02205-x ◽

2021 ◽

Author(s):

Josh Foster ◽

James W. Smallcombe ◽

Simon Hodder ◽

Ollie Jay ◽

Andreas D. Flouris ◽

...

Keyword(s):

Heat Stress ◽

Solar Radiation ◽

Air Temperature ◽

Work Capacity ◽

Stress Index ◽

Physical Work ◽

Physical Work Capacity ◽

Heat Effects ◽

Heat Stress Index ◽

The Impact

AbstractHeat stress decreases human physical work capacity (PWC), but the extent to which solar radiation (SOLAR) compounds this response is not well understood. This study empirically quantified how SOLAR impacts PWC in the heat, considering wide, but controlled, variations in air temperature, humidity, and clothing coverage. We also provide correction equations so PWC can be quantified outdoors using heat stress indices that do not ordinarily account for SOLAR (including the Heat Stress Index, Humidex, and Wet-Bulb Temperature). Fourteen young adult males (7 donning a work coverall, 7 with shorts and trainers) walked for 1 h at a fixed heart rate of 130 beats∙min−1, in seven combinations of air temperature (25 to 45°C) and relative humidity (20 or 80%), with and without SOLAR (800 W/m2 from solar lamps). Cumulative energy expenditure in the heat, relative to the work achieved in a cool reference condition, was used to determine PWC%. Skin temperature was the primary determinant of PWC in the heat. In dry climates with exposed skin (0.3 Clo), SOLAR caused PWC to decrease exponentially with rising air temperature, whereas work coveralls (0.9 Clo) negated this effect. In humid conditions, the SOLAR-induced reduction in PWC was consistent and linear across all levels of air temperature and clothing conditions. Wet-Bulb Globe Temperature and the Universal Thermal Climate Index represented SOLAR correctly and did not require a correction factor. For the Heat Stress Index, Humidex, and Wet-Bulb Temperature, correction factors are provided enabling forecasting of heat effects on work productivity.

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Effects of model resolution on entrainment (inversion heights), cloud-radiation interactions, and cloud radiative forcing

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-8-20399-2008 ◽

2008 ◽

Vol 8 (6) ◽

pp. 20399-20425 ◽

Cited By ~ 5

Author(s):

H. Guo ◽

Y. Liu ◽

P. H. Daum ◽

X. Zeng ◽

X. Li ◽

...

Keyword(s):

Liquid Water ◽

Radiative Forcing ◽

Horizontal Resolution ◽

Vertical Resolution ◽

Model Resolution ◽

Liquid Water Path ◽

Cloud Liquid Water ◽

Cloud Radiative Forcing ◽

Water Path ◽

Cloud Liquid Water Path

Abstract. We undertook three-dimensional numerical studies of a marine stratus deck under a strong inversion using an interactive shortwave- and longwave-radiation module. A suite of sensitivity tests were conducted to address the effects of model resolution on entrainment (inversion heights), cloud-radiation interactions, and cloud radiative-forcings by varying model horizontal resolution only, varying vertical resolution only, and varying horizontal- and vertical-resolution simultaneously but with a fixed aspect ratio of 2.5. Our results showed that entrainment (inversion height) is more sensitive to vertical- than to horizontal-resolution. A vertical resolution finer than 40 m can simulate spatial- and temporal-variations in the inversion height well. The inversion height decreases with increasing vertical resolution, but tends to increase with increasing horizontal resolution. Cloud liquid water path doubles after refining both the vertical- and horizontal-resolution by a factor of four. This doubling is associated with a positive feedback between cloud water and cloud top radiative cooling, which amplifies small differences initiated by changes in the model resolution. The magnitude of the cloud radiative-forcing tends to increase with increasing model resolution, mainly attributable to the increase in the cloud liquid water path. Shortwave radiative forcing is dominant, and more sensitive to model resolution than the longwave counterpart.

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The Impact of Milankovitch Solar Radiation Variations on Sea-Ice and Air Temperature in a Coupled Energy-Balance Climate-Sea-Ice Model

Annals of Glaciology ◽

10.3189/s0260305500008454 ◽

1990 ◽

Vol 14 ◽

pp. 144-147 ◽

Cited By ~ 1

Author(s):

Tamara Shapiro Ledley

Keyword(s):

Solar Radiation ◽

Sea Ice ◽

Air Temperature ◽

Energy Transport ◽

Model Simulation ◽

Surface Air Temperature ◽

Ice Thickness ◽

Sea Ice Thickness ◽

The Mean ◽

The Impact

The sensitivity of thermodynamically-varying sea-ice and surface air temperature to variations in solar radiation on the 104 to 105 time scales is examined in this study. Model simulation results show the mean annual sea-ice thickness is very sensitive to the magnitude of midsummer solar radiation. During periods of high midsummer solar radiation between 115 ka B.P. and the present the sea ice is thinner, producing larger summer time leads and longer periods of open ocean. This has an effect on the mean annual sea-ice thickness, but not on the mean annual air temperature. However, the changes in sea ice are accompanied by similar variations in the summer surface air temperature, which are the result of the variations in the solar radiation and meridional energy transport.

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Modeling In-Vehicle VOCs Distribution from Cabin Interior Surfaces under Solar Radiation

Sustainability ◽

10.3390/su12145526 ◽

2020 ◽

Vol 12 (14) ◽

pp. 5526

Author(s):

Zheming Tong ◽

Hao Liu

Keyword(s):

Solar Radiation ◽

Thermal Environment ◽

Critical Role ◽

Model Performance ◽

Strong Temperature Dependence ◽

Emission Model ◽

Thermal Buoyancy ◽

Cabin Environment ◽

The Impact ◽

Vocs Emission

In-vehicle air pollution has become a public health priority worldwide, especially for volatile organic compounds (VOCs) emitted from the vehicle interiors. Although existing literature shows VOCs emission is temperature-dependent, the impact of solar radiation on VOCs distribution in enclosed cabin space is not well understood. Here we made an early effort to investigate the VOCs levels in vehicle microenvironments using numerical modeling. We evaluated the model performance using a number of turbulence and radiation model combinations to predict heat transfer coupled with natural convection, heat conduction and radiation with a laboratory airship. The Shear–Stress Transport (SST) k-ω model, Surface-to-surface (S2S) model and solar load model were employed to investigate the thermal environment of a closed automobile cabin under solar radiation in the summer. A VOCs emission model was employed to simulate the spatial distribution of VOCs. Our finding shows that solar radiation plays a critical role in determining the temperature distribution in the cabin, which can increase by 30 °C for directly exposed cabin surfaces and 10 °C for shaded ones, respectively. Ignoring the thermal radiation reduced the accuracy of temperature and airflow prediction. Due to the strong temperature dependence, the hotter interiors such as the dashboard and rear board released more VOCs per unit time and area. A VOC plume rose from the interior sources as a result of the thermal buoyancy flow. A total of 19 mg of VOCs was released from the interiors within two simulated hours from 10:00 am to noon. The findings, such as modeled spatial distributions of VOCs, provide a key reference to automakers, who are paying increasing attention to cabin environment and the health of drivers and passengers.

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The Impact of Milankovitch Solar Radiation Variations on Sea-Ice and Air Temperature in a Coupled Energy-Balance Climate-Sea-Ice Model

Annals of Glaciology ◽

10.1017/s0260305500008454 ◽

1990 ◽

Vol 14 ◽

pp. 144-147 ◽

Cited By ~ 5

Author(s):

Tamara Shapiro Ledley

Keyword(s):

Solar Radiation ◽

Sea Ice ◽

Air Temperature ◽

Energy Transport ◽

Model Simulation ◽

Surface Air Temperature ◽

Ice Thickness ◽

Sea Ice Thickness ◽

The Mean ◽

The Impact

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Changes in snow storages and their impact on occurrence and extremity of runoff caused by rain-on-snow events

10.5194/egusphere-egu2020-13431 ◽

2020 ◽

Author(s):

Ondrej Hotovy ◽

Michal Jenicek

Keyword(s):

Air Temperature ◽

Snow Water Equivalent ◽

Hydrological Cycle ◽

Winter Season ◽

Model Performance ◽

Catchment Scale ◽

The Future ◽

Snow Water ◽

The Impact ◽

Catchment Runoff

Seasonal snowpack significantly influences the catchment runoff and thus represents an important input for the hydrological cycle. Changes in the precipitation distribution and intensity, as well as a shift from snowfall to rain is expected in the future due to climate changes. As a result, rain-on-snow events, which are considered to be one of the main causes of floods in winter and spring, may occur more frequently.The objective of this study is 1) to evaluate the frequency, inter-annual variability and extremity of rain-on-snow events in the past based on existing measurements and 2) to simulate the effect of predicted increase in air temperature on the occurrence of rain-on-snow events in the future. We selected 59 near-natural mountain catchments in Czechia with significant snow influence on runoff and with available long-time series (>35 years) of daily hydrological and meteorological variables. A semi-distributed conceptual model, HBV-light, was used to simulate the individual components of the water cycle at a catchment scale. The model was calibrated for each of study catchments by using 100 calibration trials which resulted in respective number of optimized parameter sets. The model performance was evaluated against observed runoff and snow water equivalent. Rain-on-snow events definition by threshold values for air temperature, snow depth, rain intensity and snow water equivalent decrease allowed us to analyze inter-annual variations and trends in rain-on-snow events during the study period 1980-2014 and to explain the role of different catchment attributes.The preliminary results show that a significant change of rain-on-snow events related to increasing air temperature is not clearly evident. Since both air temperature and elevation seem to be an important rain-on-snow drivers, there is an increasing rain-on-snow events occurrence during winter season due to a decrease in snowfall fraction. In contrast, a decrease in total number of events was observed due to the shortening of the period with existing snow cover on the ground. Modelling approach also opened further questions related to model structure and parameterization, specifically how individual model procedures and parameters represent the real natural processes. To understand potential model artefacts might be important when using HBV or similar bucket-type models for impact studies, such as modelling the impact of climate change on catchment runoff.

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Modelled and observed changes in aerosols and surface solar radiation over Europe between 1960 and 2009

Atmospheric Chemistry and Physics ◽

10.5194/acp-15-9477-2015 ◽

2015 ◽

Vol 15 (16) ◽

pp. 9477-9500 ◽

Cited By ~ 41

Author(s):

S. T. Turnock ◽

D. V. Spracklen ◽

K. S. Carslaw ◽

G. W. Mann ◽

M. T. Woodhouse ◽

...

Keyword(s):

Solar Radiation ◽

Radiative Forcing ◽

Climate Model ◽

Suspended Particle ◽

Sulfate Aerosol ◽

Anthropogenic Aerosols ◽

Surface Solar Radiation ◽

Aerosol Mass ◽

The Impact ◽

Aerosol Radiative

Abstract. Substantial changes in anthropogenic aerosols and precursor gas emissions have occurred over recent decades due to the implementation of air pollution control legislation and economic growth. The response of atmospheric aerosols to these changes and the impact on climate are poorly constrained, particularly in studies using detailed aerosol chemistry–climate models. Here we compare the HadGEM3-UKCA (Hadley Centre Global Environment Model-United Kingdom Chemistry and Aerosols) coupled chemistry–climate model for the period 1960–2009 against extensive ground-based observations of sulfate aerosol mass (1978–2009), total suspended particle matter (SPM, 1978–1998), PM10 (1997–2009), aerosol optical depth (AOD, 2000–2009), aerosol size distributions (2008–2009) and surface solar radiation (SSR, 1960–2009) over Europe. The model underestimates observed sulfate aerosol mass (normalised mean bias factor (NMBF) = −0.4), SPM (NMBF = −0.9), PM10 (NMBF = −0.2), aerosol number concentrations (N30 NMBF = −0.85; N50 NMBF = −0.65; and N100 NMBF = −0.96) and AOD (NMBF = −0.01) but slightly overpredicts SSR (NMBF = 0.02). Trends in aerosol over the observational period are well simulated by the model, with observed (simulated) changes in sulfate of −68 % (−78 %), SPM of −42 % (−20 %), PM10 of −9 % (−8 %) and AOD of −11 % (−14 %). Discrepancies in the magnitude of simulated aerosol mass do not affect the ability of the model to reproduce the observed SSR trends. The positive change in observed European SSR (5 %) during 1990–2009 ("brightening") is better reproduced by the model when aerosol radiative effects (ARE) are included (3 %), compared to simulations where ARE are excluded (0.2 %). The simulated top-of-the-atmosphere aerosol radiative forcing over Europe under all-sky conditions increased by > 3.0 W m−2 during the period 1970–2009 in response to changes in anthropogenic emissions and aerosol concentrations.

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