Topographic Effects on the Surface Radiation Balance in and around Arizona’s Meteor Crater

2010 ◽  
Vol 49 (6) ◽  
pp. 1114-1128 ◽  
Author(s):  
Sebastian W. Hoch ◽  
C. David Whiteman
Keyword(s):  
Longwave Radiation ◽  
Diffuse Radiation ◽  
Temperature Inversion ◽  
Surface Radiation ◽  
Shortwave Radiation ◽  
Western Slope ◽  
Radiation Balance ◽  
Topographic Effects ◽  
Crater Floor ◽  
A Site

Abstract The individual components of the slope-parallel surface radiation balance were measured in and around Arizona’s Meteor Crater to investigate the effects of topography on the radiation balance. The crater basin has a diameter of 1.2 km and a depth of 170 m. The observations cover the crater floor, the crater rim, four sites on the inner sidewalls on an east–west transect, and two sites outside the crater. Interpretation of the role of topography on radiation differences among the sites on a representative clear day is facilitated by the unique symmetric crater topography. The shortwave radiation balance was affected by the topographic effects of terrain exposure, terrain shading, and terrain reflections, and by surface albedo variations. Terrain exposure caused a site on the steeper upper eastern sidewall of the crater to receive 6% more daily integrated shortwave energy than a site on the lower part of the same slope. Terrain shading had a larger effect on the lower slopes than on the upper slopes. At the lower western slope site the daily total was reduced by 6%. Measurements indicate a diffuse radiation enhancement due to sidewall reflections. The longwave radiation balance was affected by counterradiation from the crater sidewalls and by reduced emissions due to the formation of a nighttime temperature inversion. The total nighttime longwave energy loss at the crater floor was 72% of the loss observed at the crater rim.

scholarly journals An Evaluation of Surface Atmospheric Changes over the Arctic Ocean for 2000–09 Using Recent Reanalyses

2015 ◽  
Vol 19 (2) ◽  
pp. 1-18 ◽  
Author(s):  
Ayan H. Chaudhuri ◽  
Rui M. Ponte
Keyword(s):  
Arctic Ocean ◽  
Extreme Event ◽  
Longwave Radiation ◽  
Remotely Sensed ◽  
Surface Radiation ◽  
Shortwave Radiation ◽  
The Arctic ◽  
Near Surface ◽  
The Arctic Ocean ◽  
Ice Retreat

Abstract The authors examine five recent reanalysis products [NCEP Climate Forecast System Reanalysis (CFSR), Modern-Era Retrospective Analysis for Research and Applications (MERRA), Japanese 25-year Reanalysis Project (JRA-25), Interim ECMWF Re-Analysis (ERA-Interim), and Arctic System Reanalysis (ASR)] for 1) trends in near-surface radiation fluxes, air temperature, and humidity, which are important indicators of changes within the Arctic Ocean and also influence sea ice and ocean conditions, and 2) fidelity of these atmospheric fields and effects for an extreme event: namely, the 2007 ice retreat. An analysis of trends over the Arctic for the past decade (2000–09) shows that reanalysis solutions have large spreads, particularly for downwelling shortwave radiation. In many cases, the differences in significant trends between the five reanalysis products are comparable to the estimated trend within a particular product. These discrepancies make it difficult to establish a consensus on likely changes occurring in the Arctic solely based on results from reanalyses fields. Regarding the 2007 ice retreat event, comparisons with remotely sensed estimates of downwelling radiation observations against these reanalysis products present an ambiguity. Remotely sensed observations from a study cited herewith suggest a large increase in downwelling summertime shortwave radiation and decrease in downwelling summertime longwave radiation from 2006 and 2007. On the contrary, the reanalysis products show only small gains in summertime shortwave radiation, if any; however, all the products show increases in downwelling longwave radiation. Thus, agreement within reanalysis fields needs to be further checked against observations to assess possible biases common to all products.

scholarly journals Estimation of Net Radiation using satellite based data inputs

2014 ◽  
Vol XL-8 ◽  
pp. 307-313 ◽  
Author(s):  
S. V. S. Sai Krishna ◽  
P. Manavalan ◽  
P. V. N. Rao
Keyword(s):  
Outgoing Longwave Radiation ◽  
Surface Air Temperature ◽  
Longwave Radiation ◽  
Surface Radiation ◽  
Shortwave Radiation ◽  
Net Radiation ◽  
Clear Sky ◽  
Statistical Measures ◽  
Indian Land ◽  
Radiation Fluxes

Daily net surface radiation fluxes are estimated for Indian land mass at spatial grid intervals of 0.1 degree. Two approaches are employed to obtain daily net radiation for four sample days viz., November 19, 2013, December 16, 2013, January 8, 2014 and March 20, 2014. Both the approaches compute net shortwave and net longwave fluxes, separately and sum them up to obtain net radiation. The first approach computes net shortwave radiation using daily insolation product of Kalpana VHRR and 15 days time composited broadband albedo product of Oceansat OCM2. The net outgoing longwave radiation is computed using Stefan Boltzmann equation corrected for humidity and cloudiness. In the second approach, instantaneous clear-sky net-shortwave radiation is estimated using computed clear-sky incoming shortwave radiation and the gridded MODIS 16-day time composited albedo product. The net longwave radiation is obtained by estimating outgoing and incoming longwave radiation fluxes, independently. In this, MODIS derived surface emissivity and skin temperature parameters are used for estimating outgoing longwave radiation component. In both the approaches, surface air temperature data required for estimation of net longwave radiation fluxes are extracted from India Meteorological Department’s (IMD) Automatic Weather Station (AWS) records. Estimates by the two different approaches are evaluated by comparing daily net radiation fluxes with CERES based estimates corresponding to the sample days, through statistical measures. The estimated all sky daily net radiation using the first approach compared well with CERES SYN1deg daily average net radiation with r<sup>2</sup> values of the order of 0.7 and RMS errors of the order of 8&ndash;16 w/m<sup>2</sup>.

scholarly journals Trends in surface radiation and cloud radiative effect at four Swiss sites for the 1996–2015 period

2019 ◽  
Vol 19 (20) ◽  
pp. 13227-13241 ◽  
Author(s):  
Stephan Nyeki ◽  
Stefan Wacker ◽  
Christine Aebi ◽  
Julian Gröbner ◽  
Giovanni Martucci ◽  
...  
Keyword(s):  
Longwave Radiation ◽  
Ground Temperature ◽  
Surface Radiation ◽  
Specific Humidity ◽  
Shortwave Radiation ◽  
Radiative Effect ◽  
Cloud Properties ◽  
Cloud Radiative Effect ◽  
Downward Longwave Radiation ◽  
Integrated Water Vapour

Abstract. The trends of meteorological parameters and surface downward shortwave radiation (DSR) and downward longwave radiation (DLR) were analysed at four stations (between 370 and 3580 m a.s.l.) in Switzerland for the 1996–2015 period. Ground temperature, specific humidity, and atmospheric integrated water vapour (IWV) trends were positive during all-sky and cloud-free conditions. All-sky DSR and DLR trends were in the ranges of 0.6–4.3 W m−2 decade−1 and 0.9–4.3 W m−2 decade−1, respectively, while corresponding cloud-free trends were −2.9–3.3 W m−2 decade−1 and 2.9–5.4 W m−2 decade−1. Most trends were significant at the 90 % and 95 % confidence levels. The cloud radiative effect (CRE) was determined using radiative-transfer calculations for cloud-free DSR and an empirical scheme for cloud-free DLR. The CRE decreased in magnitude by 0.9–3.1 W m−2 decade−1 (only one trend significant at 90 % confidence level), which implies a change in macrophysical and/or microphysical cloud properties. Between 10 % and 70 % of the increase in DLR is explained by factors other than ground temperature and IWV. A more detailed, long-term quantification of cloud changes is crucial and will be possible in the future, as cloud cameras have been measuring reliably at two of the four stations since 2013.

Topographic effects on longwave and shortwave surface radiation in a kilometre-scale regional climate model

2020 ◽  
Author(s):  
Christian Steger ◽  
Jesus Vergara-Temprado ◽  
Nikolina Ban ◽  
Christoph Schär
Keyword(s):  
Snow Cover ◽  
Surface Radiation ◽  
Shortwave Radiation ◽  
View Factor ◽  
Topographic Effects ◽  
Radiation Correction ◽  
Correction Scheme ◽  
Weather And Climate ◽  
The Impact ◽  
Topographic Parameters

&lt;p&gt;Weather and climate in alpine areas are strongly modulated by complex topography. Besides its influence on atmospheric flow and thermodynamics (such as orographic precipitation and foehn winds), topography also affects incoming surface radiation in various ways. Direct shortwave radiation might be blocked due to shading effects from neighbouring terrain. Diffuse shortwave radiation can be altered by a reduced sky view factor and reflectance of radiation from surrounding terrain. Similar, the net longwave radiation is affected by emissions from neighbouring terrain.&lt;/p&gt;&lt;p&gt;Radiation in virtually all state-of-the-art weather and climate models is only computed in the vertical direction using the column approximation, and the above-mentioned effects are usually not represented. Still, a few models consider topographic effects by correcting incoming radiation fluxes based on topographic parameters like slope aspect and angle, elevation of horizon, and sky view factor. The Consortium for Small-scale Modeling (COSMO) model includes such a scheme, which is currently only used in the Numerical Weather Prediction mode of the model.&lt;/p&gt;&lt;p&gt;In this study, we apply the surface radiation correction scheme in the climate mode of COSMO. To study its impacts in detail, we force COSMO&amp;#8217;s land-surface model (TERRA) offline with output from a COSMO simulation, which was run without radiation correction at a horizontal resolution of 2.2 km and for a domain covering the Alps. A useful proxy to study the impact of the correction scheme is snow cover duration (SCD), because snow cover length is, amongst other factors, strongly controlled by incoming surface radiation that drives ablation. A comparison of SCD simulated by COSMO with satellite-derived snow cover data (MODIS and AVHRR) reveals a distinctive bias, where SCD is overestimated for south-facing grid cells and underestimated for north-facing cells. Applying the radiation correction in the offline TERRA simulation shows only a moderate reduction of the bias. One reason for this minor improvement is the fact that the topographic parameters are computed from a smoothed digital elevation model (DEM) &amp;#8211; thus the impact of the radiation correction scheme is damped. If topographic parameters are computed from unsmoothed DEM, biases in SCD are further reduced. Currently, further sensitivity experiments are conducted to investigate the effect of computing the topographic parameters from a sub-grid DEM and to assess the energy conservation of the radiation correction scheme.&lt;/p&gt;

Surface Radiation Characteristics of the Ali Area, Northern Tibetan Plateau

2021 ◽  
Author(s):  
Ge Wang ◽  
Lin Han
Keyword(s):  
Tibetan Plateau ◽  
Longwave Radiation ◽  
Early Summer ◽  
Surface Radiation ◽  
Radiation Budget ◽  
Shortwave Radiation ◽  
Radiative Energy ◽  
Net Radiation ◽  
Daily Average ◽  
Northern Tibetan Plateau

&lt;p&gt;This study analyses the diurnal seasonal mean and the seasonal and annual variation in the radiation budget at the Ali Meteorological Bureau observation station in the northern Tibetan Plateau for 2019. The results indicate that the daily average variation in incidental shortwave and reflected radiation across all seasons in the Ali area had typical unimodal symmetry. The average daily variation in incidental shortwave radiation was in phase with reflected radiation, but the amplitude of the incidental shortwave radiation was greater than that of reflected radiation. The daily amplitude, daily average, and monthly average upwelling longwave radiation were greater than those for downwelling radiation, and the diurnal cycle of downwelling atmospheric radiation lagged behind that of upwelling longwave radiation. The daily amplitude of surface net radiation in winter in the Ali area was less than in other seasons, as expected, and the seasonal transformation had a great impact on the net radiation for this region. The net radiative energy at the surface was highest in late spring and early summer, which played a decisive role in the formation of terrestrial and atmospheric heating.&lt;/p&gt;

scholarly journals Evaluation of Surface Radiative Fluxes over the Tropical Oceans in AMIP Simulations

Atmosphere ◽  
2019 ◽  
Vol 10 (10) ◽  
pp. 606 ◽  
Author(s):  
Xin Zhou ◽  
Pallav Ray ◽  
Kristine Boykin ◽  
Bradford S. Barrett ◽  
Pang-Chi Hsu
Keyword(s):  
Longwave Radiation ◽  
Atmospheric Model ◽  
Surface Radiation ◽  
Shortwave Radiation ◽  
Systematic Bias ◽  
Model Ensemble ◽  
Low Level ◽  
Tropical Oceans ◽  
Ensemble Mean ◽  
Better Than

The performance of 20 models from the Atmospheric Model Intercomparison Project (AMIP) was evaluated concerning surface radiation over the tropical oceans (30° S–30° N) from 1979 to 2000. The model ensemble mean of the net surface shortwave radiation (QSW) was underestimated compared to the International Satellite Cloud Climatology Project (ISCCP) data by 4 W m−2. On the other hand, net longwave radiation (QLW) was overestimated by 4 W m−2, leading to an underestimation of the net surface radiation (Qrad) by 8 W m−2. The most prominent bias in the Qrad appears to be over regions of low-level clouds in the off-equatorial eastern Pacific, eastern Atlantic, and the south-eastern Indian Ocean. The root means squared error of QLW was larger than that of QSW in 17 out of 20 AMIP models. Overestimation of the total cloud cover and atmospheric humidity contributed to the underestimation of Qrad. In general, models with higher horizontal resolutions performed slightly better than those with coarser horizontal resolutions, although some systematic bias persists in all models and in all seasons, in particular, in regions of low-level clouds for QLW, and high-level clouds for QSW. The ensemble mean performed better than most models, but two high-resolution models (GFDL-HIRAM-C180 and GFDL-HIRAM-C360) outperform the model ensemble.

scholarly journals A grid-based model of backwasting of supraglacial ice cliffs on debris-covered glaciers

2016 ◽  
Vol 57 (71) ◽  
pp. 199-211 ◽  
Author(s):  
Pascal Buri ◽  
Francesca Pellicciotti ◽  
Jakob F. Steiner ◽  
Evan S. Miles ◽  
Walter W. Immerzeel
Keyword(s):  
Longwave Radiation ◽  
Diffuse Radiation ◽  
Shortwave Radiation ◽  
High Mass ◽  
Mass Losses ◽  
Scale Models ◽  
Hindu Kush ◽  
Constant Slope ◽  
Grid Based ◽  
Measurement Period

AbstractIce cliffs might be partly responsible for the high mass losses of debris-covered glaciers in the Hindu Kush-Karakoram-Himalaya region. The few existing models of cliff backwasting are point-scale models applied at few locations or assume cliffs to be planes with constant slope and aspect, a major simplification given the complex surfaces of most cliffs. We develop the first grid-based model of cliff backwasting for two cliffs on debris-covered Lirung Glacier, Nepal. The model includes an improved representation of shortwave and longwave radiation, and their interplay with the glacier topography. Shortwave radiation varies considerably across the two cliffs, mostly due to direct radiation. Diffuse radiation is the major shortwave component, as the direct component is strongly reduced by the cliffs’ aspect and slope through self-shading. Incoming longwave radiation is higher than the total incoming shortwave flux, due to radiation emitted by the surrounding terrain, which is 25% of the incoming flux. Melt is highly variable in space, suggesting that simple models provide inaccurate estimates of total melt volumes. Although only representing 0.09% of the glacier tongue area, the total melt at the two cliffs over the measurement period is 2313 and 8282 m3, 1.23% of the total melt simulated by a glacio-hydrological model for the glacier’s tongue.

scholarly journals Revising short and longwave radiation archives in view of possible revisions of the WSG and WISG reference scales: Methods and implications

2017 ◽  
Author(s):  
Stephan Nyeki ◽  
Stefan Wacker ◽  
Julian Gröbner ◽  
Wolfgang Finsterle ◽  
Martin Wild
Keyword(s):  
Time Series ◽  
Longwave Radiation ◽  
Surface Radiation ◽  
Shortwave Radiation ◽  
Standard Group ◽  
Water Vapour Content ◽  
Data Archives ◽  
Downward Longwave Radiation ◽  
Integrated Water Vapour ◽  
A Minor

Abstract. A large number of radiometers are traceable to the World Standard Group (WSG) for shortwave radiation and the interim World Infra-red Standard Group (WISG) for longwave radiation, hosted by the Physikalisch Meteorologisches Observatorium Davos/World Radiation Centre (PMOD/WRC, Davos, Switzerland). The WSG and WISG have recently been found to over- and underestimate radiation values, respectively (Fehlmann et al., 2012; Gröbner et al., 2014), although research is still ongoing. In view of a possible revision of the reference scales of both standard groups, this study discusses the methods involved, and the implications on existing archives of radiation time-series, such as the Baseline Surface Radiation Network (BSRN). Based on PMOD/WRC calibration archives and BSRN data archives, the downward longwave radiation (DLR) time-series over the 2006–2015 periods were analysed at four stations (polar and mid-latitude locations). DLR was found to increase by up to 3.5 and 5.4 W m−2, respectively, after applying a WISG reference scale correction and a minor correction for the dependence of pyrgeometer sensitivity on atmospheric integrated water vapour content. Similar increases in DLR may be expected at other BSRN stations. Based on our analysis, a number of recommendations are made for future studies.

Developing an algorithm to consider sub-grid topographic effects on surface radiation in a kilometre-scale regional climate model

2021 ◽  
Author(s):  
Christian Steger ◽  
Christoph Schär
Keyword(s):  
High Resolution ◽  
Regional Climate Model ◽  
Climate Model ◽  
Regional Climate ◽  
Longwave Radiation ◽  
Surface Radiation ◽  
Shortwave Radiation ◽  
View Factor ◽  
Radiation Correction ◽  
Sky View Factor

&lt;p&gt;In mountainous regions, atmospheric and surface conditions (like snow coverage) are strongly modulated by complex terrain. One relevant process is the topographic effect on incoming/outgoing surface short- and longwave radiation by surrounding terrain. Radiation in weather and climate models is typically represented by the two-stream approximation, which only allows for vertical radiation exchange and thus no lateral interaction with terrain. In reality, surface radiation can be modulated through various processes: the direct-beam part of the incoming shortwave radiation depends on local surface inclination and on shading from the neighbouring terrain. Incoming diffuse shortwave radiation is modified by partial sky-obstruction and terrain reflection. Outgoing longwave radiation is reduced by interception from neighbouring terrain.&lt;/p&gt;&lt;p&gt;In this study, we develop a parameterisation which considers the above-mentioned processes on a sub-grid scale, and implement the scheme in the Regional Climate Model COSMO (Consortium for Small-scale Modeling). On the grid scale, such a parameterisation is already available and has been applied in the numerical weather prediction mode of COSMO. Applying this parameterisation in the climate mode of COSMO has revealed that biases like the over-/underestimation of snow cover duration at south-/north-facing slopes can be improved. However, the associated radiation correction appears to be too weak because only terrain effects on the resolved scales are considered. We therefore parameterise these effects on a sub-grid scale.&lt;/p&gt;&lt;p&gt;The (current) surface radiation correction scheme requires consideration of topographic parameters like the elevation of the horizon and the sky-view factor. The computation of these parameters on the sub-grid scale is very expensive, because non-local information of a large high-resolution Digital Elevation Model (DEM) needs to be processed. We developed a new algorithm, which allows for horizon computations from a high-resolution DEM in a fast and flexible way. We furthermore found that existing sky-view factor algorithms might yield inaccurate results for locations with very steep terrain and subsequently developed an improved method. Output of these new algorithms will be used for the new sub-grid radiation parameterisation scheme.&lt;/p&gt;

scholarly journals Measurements of Cloud Radiative Effect across the Southern Ocean (43° S–79° S, 63° E–158° W)

Atmosphere ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 949
Author(s):  
Haoran Wang ◽  
Andrew R. Klekociuk ◽  
W. John R. French ◽  
Simon P. Alexander ◽  
Tom A. Warner
Keyword(s):  
Southern Ocean ◽  
Radiation Effect ◽  
Longwave Radiation ◽  
Surface Radiation ◽  
Radiation Environment ◽  
Shortwave Radiation ◽  
Radiative Effect ◽  
Weather Forecasts ◽  
Cloud Radiative Effect ◽  
Radiation Sensors

The surface radiation environment over the Southern Ocean within the region bound by 42.8° S to 78.7° S and 62.6° E to 157.7° W is summarised for three austral summers. This is done using ship-based measurements with the combination of downwelling radiation sensors and a cloud imager. We focus on characterising the cloud radiative effect (CRE) under a variety of conditions, comparing observations in the open ocean with those in the sea ice zone. For comparison with our observed data, we obtained surface data from the European Centre for Medium-Range Weather Forecasts fifth reanalysis (ERA5). We found that the daily average cloud fraction was slightly lower in ERA5 compared with the observations (0.71 and 0.75, respectively). ERA5 also showed positive biases in the shortwave radiation effect and a negative bias in the longwave radiation effect. The observed mean surface CRE of −164 ± 100 Wm−2 was more negative than the mean surface CRE for ERA5 of −101 W m−2.

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