scholarly journals Predicting Downward Longwave Radiation for Various Land Use in All-Sky Condition: Northeast Florida

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Chi-Han Cheng ◽  
Fidelia Nnadi
Keyword(s):  
Land Use ◽  
Cloud Cover ◽  
Water Vapor Pressure ◽  
Longwave Radiation ◽  
Heat Fluxes ◽  
Surface Radiation ◽  
Radiation Budget ◽  
Seasonal Effects ◽  
Land Use Patterns ◽  
Downward Longwave Radiation

Accurate estimate of the surface longwave radiation is important for the surface radiation budget, which in turn controls evaporation and sensible heat fluxes. Regional land use changes can impact local weather conditions; for example, heterogeneous land use patterns and temporal changes in atmospheric circulation patterns would affect air temperature and water vapor pressure, which are more commonly used as inputs in existing models for estimating downward longwave radiation (LWd). In this study, first, we analyzed the cloud cover and land use covers impacts onLWd. Next,LWdon all-sky conditions were developed by using the existing land use-adapted model and cloud cover data from the region of Saint Johns River Water Management District (SJRWMD), FL. The results show that factors, such as, seasonal effects, cloud cover, and land use, are of importance in the estimation ofLWdand they cannot be ignored when developing a model forLWdprediction. The all-sky land use-adapted model with all factors taken into account performs better than other existing models statistically. The results of the statistical analyses indicated that the BIAS, RMSE, MAE, and PMRE are −0.18 Wm−2, 10.81 Wm−2, 8.00 Wm−2, and 2.30%; −2.61 Wm−2, 14.45 Wm−2, 10.64 Wm−2, and 3.19%; −0.07 Wm−2, 10.53 Wm−2, 8.03 Wm−2, and 2.27%; and −0.62 Wm−2, 13.97 Wm−2, 9.76 Wm−2, and 2.87% for urban, rangeland, agricultural, and wetland areas, respectively.

scholarly journals Evaluation of the Surface Radiation Budget in the Atmospheric Component of the Hadley Centre Global Environmental Model (HadGEM1)

2008 ◽  
Vol 21 (18) ◽  
pp. 4723-4748 ◽  
Author(s):  
A. Bodas-Salcedo ◽  
M. A. Ringer ◽  
A. Jones
Keyword(s):  
Land Surface ◽  
Surface Albedo ◽  
Longwave Radiation ◽  
Surface Radiation ◽  
Radiation Budget ◽  
Surface Radiation Budget ◽  
Global Environmental ◽  
Downward Longwave Radiation ◽  
Global Dimming ◽  
Hadley Centre

Abstract The partitioning of the earth radiation budget (ERB) between its atmosphere and surface components is of crucial interest in climate studies as it has a significant role in the oceanic and atmospheric general circulation. An analysis of the present-day climate simulation of the surface radiation budget in the atmospheric component of the new Hadley Centre Global Environmental Model version 1 (HadGEM1) is presented, and the simulations are assessed by comparing the results with fluxes derived from satellite data from the International Satellite Cloud Climatology Project (ISCCP) and ground measurements from the Baseline Surface Radiation Network (BSRN). Comparisons against radiative fluxes from satellite and ground observations show that the model tends to overestimate the surface incoming solar radiation (Ss,d). The model simulates Ss,d very well over the polar regions. Consistency in the comparisons against BSRN and ISCCP-FD suggests that the ISCCP-FD database is a good test for the performance of the surface downwelling solar radiation in climate model simulations. Overall, the simulation of downward longwave radiation is closer to observations than its shortwave counterpart. The model underestimates the downward longwave radiation with respect to BSRN measurements by 6.0 W m−2. Comparisons of land surface albedo from the model and estimates from the Moderate Resolution Imaging Spectroradiometer (MODIS) show that HadGEM1 overestimates the land surface albedo over deserts and over midlatitude landmasses in the Northern Hemisphere in January. Analysis of the seasonal cycle of the land surface albedo in different regions shows that the amplitude and phase of the seasonal cycle are not well represented in the model, although a more extensive validation needs to be carried out. Two decades of coupled model simulations of the twentieth-century climate are used to look into the model’s simulation of global dimming/brightening. The model results are in line with the conclusions of the studies that suggest that global dimming is far from being a uniform phenomenon across the globe.

scholarly journals Estimation of Long-Term Surface Downward Longwave Radiation over the Global Land from 2000 to 2018

2021 ◽  
Vol 13 (9) ◽  
pp. 1848
Author(s):  
Chunjie Feng ◽  
Xiaotong Zhang ◽  
Yu Wei ◽  
Weiyu Zhang ◽  
Ning Hou ◽  
...  
Keyword(s):  
Water Vapor ◽  
Spatial Resolution ◽  
Land Surface ◽  
Longwave Radiation ◽  
Surface Radiation ◽  
Radiation Budget ◽  
Mean Bias Error ◽  
Downward Longwave Radiation ◽  
Global Land

It is of great importance for climate change studies to construct a worldwide, long-term surface downward longwave radiation (Ld, 4–100 μm) dataset. Although a number of global Ld datasets are available, their low accuracies and coarse spatial resolutions limit their applications. This study generated a daily Ld dataset with a 5-km spatial resolution over the global land surface from 2000 to 2018 using atmospheric parameters, which include 2-m air temperature (Ta), relative humidity (RH) at 1000 hPa, total column water vapor (TCWV), surface downward shortwave radiation (Sd), and elevation, based on the gradient boosting regression tree (GBRT) method. The generated Ld dataset was evaluated using ground measurements collected from AmeriFlux, AsiaFlux, baseline surface radiation network (BSRN), surface radiation budget network (SURFRAD), and FLUXNET networks. The validation results showed that the root mean square error (RMSE), mean bias error (MBE), and correlation coefficient (R) values of the generated daily Ld dataset were 17.78 W m−2, 0.99 W m−2, and 0.96 (p < 0.01). Comparisons with other global land surface radiation products indicated that the generated Ld dataset performed better than the clouds and earth’s radiant energy system synoptic (CERES-SYN) edition 4.1 dataset and ERA5 reanalysis product at the selected sites. In addition, the analysis of the spatiotemporal characteristics for the generated Ld dataset showed an increasing trend of 1.8 W m−2 per decade (p < 0.01) from 2003 to 2018, which was closely related to Ta and water vapor pressure. In general, the generated Ld dataset has a higher spatial resolution and accuracy, which can contribute to perfect the existing radiation products.

scholarly journals The surface energy budget in the Antarctic summer sea-ice pack

2001 ◽  
Vol 33 ◽  
pp. 275-279 ◽  
Author(s):  
Gerd Wendler ◽  
Anthony P. Worby
Keyword(s):  
Sea Ice ◽  
Cloud Cover ◽  
Global Radiation ◽  
Longwave Radiation ◽  
Surface Energy Budget ◽  
Surface Radiation ◽  
Radiation Budget ◽  
Shortwave Radiation ◽  
Mean Values ◽  
Fractional Cloud

AbstractThe surface radiation budget was continuously measured in the sea-ice zone between 140° E (Terre Adélie) and 180° (McMurdo Sound) close to mid-summer, when the sea ice is disintegrating. These measurements were carried out during a cruise of the USCGC Polar Sea from Hobart, Tasmania, to McMurdo station, Antarctica, in 1998/99. Some of the findings are: the solar radiation is the major atmospheric energy source for the melting of ice. The sun was above the horizon for 24 h for most of the cruise. Due to a high amount of fractional cloudiness, the global radiation was somewhat reduced when compared to areas with lesser cloud cover Mean noon values were around 400 W m−2, while at midnight a value of 30 W m−2 was measured. Daily mean values of the net shortwave radiation varied widely, a function of the reflectivity of the surface, which is strongly dependent not only on the ice concentration, but also on the ice type (e.g. whether it is covered with snow, flooded, melting or dry). Detailed ice observations were carried out. Hourly values of the albedo varied from 6% (open water) to 84% (10/10 sea ice with a dry snow cover). The mean net longwave radiation was only modestly negative. The high amount of fractional cloud cover increased the longwave incoming radiation from the atmosphere. A mean value of −40 W m−2 was measured, which displayed only a very weak diurnal course. The sum of the short- and longwave radiation, the total radiation budget, showed the expected diurnal variation, with slightly negative values at night (for 6 h), and a mean maximum at solar noon of around 220 W m−2. A mean daily value of 98 W m−2 was calculated.

scholarly journals Effects of Drifting Snow on Surface Radiation Budget in the Katabatic Wind Zone, Antarctica

1985 ◽  
Vol 6 ◽  
pp. 238-241 ◽  
Author(s):  
Takashi Yamanouchi ◽  
Sadao Kawaguchi
Keyword(s):  
Wind Speed ◽  
Longwave Radiation ◽  
Surface Radiation ◽  
Radiative Properties ◽  
Radiation Budget ◽  
Katabatic Wind ◽  
Drifting Snow ◽  
Radiation Fluxes ◽  
Snow Drift ◽  
The Difference

Effects of drifting snow are examined from measurements of radiation fluxes at Mizuho Station in the katabatic wind zone, Antarctica. A good correlation is found between the difference of downward longwave fluxes measured at two heights and wind speed used as an index of drifting snow. The wind increases the downward flux at a rate of 2 W m-2/m s-2 when wind speed is higher than 13 m/s. Drifting snow suppresses the net longwave cooling at the surface. Direct solar radiation is depleted greatly by the drifting snow; however, the global flux decreases only slightly, compensated by the large increase of the diffuse flux, at a rate of about 1% for each 1 m/s increase in wind speed. At Mizuho Station, the effect on longwave radiation prevails throughout the year. The relation between snow drift content and wind speed is obtained from shortwave optical depth measurements as a function of wind speed. A simple parameterization of radiative properties is given.

scholarly journals Evaluation of Six High-Spatial Resolution Clear-Sky Surface Upward Longwave Radiation Estimation Methods with MODIS

2020 ◽  
Vol 12 (11) ◽  
pp. 1834
Author(s):  
Boxiong Qin ◽  
Biao Cao ◽  
Hua Li ◽  
Zunjian Bian ◽  
Tian Hu ◽  
...  
Keyword(s):  
Spatial Resolution ◽  
High Spatial Resolution ◽  
Hybrid Methods ◽  
Longwave Radiation ◽  
Surface Radiation ◽  
Radiation Budget ◽  
Estimation Methods ◽  
Mean Bias Error ◽  
Clear Sky ◽  
Surface Radiation Budget

Surface upward longwave radiation (SULR) is a critical component in the calculation of the Earth’s surface radiation budget. Multiple clear-sky SULR estimation methods have been developed for high-spatial resolution satellite observations. Here, we comprehensively evaluated six SULR estimation methods, including the temperature-emissivity physical methods with the input of the MYD11/MYD21 (TE-MYD11/TE-MYD21), the hybrid methods with top-of-atmosphere (TOA) linear/nonlinear/artificial neural network regressions (TOA-LIN/TOA-NLIN/TOA-ANN), and the hybrid method with bottom-of-atmosphere (BOA) linear regression (BOA-LIN). The recently released MYD21 product and the BOA-LIN—a newly developed method that considers the spatial heterogeneity of the atmosphere—is used initially to estimate SULR. In addition, the four hybrid methods were compared with simulated datasets. All the six methods were evaluated using the Moderate Resolution Imaging Spectroradiometer (MODIS) products and the Surface Radiation Budget Network (SURFRAD) in situ measurements. Simulation analysis shows that the BOA-LIN is the best one among four hybrid methods with accurate atmospheric profiles as input. Comparison of all the six methods shows that the TE-MYD21 performed the best, with a root mean square error (RMSE) and mean bias error (MBE) of 14.0 and −0.2 W/m2, respectively. The RMSE of BOA-LIN, TOA-NLIN, TOA-LIN, TOA-ANN, and TE-MYD11 are equal to 15.2, 16.1, 17.2, 21.2, and 18.5 W/m2, respectively. TE-MYD21 has a much better accuracy than the TE-MYD11 over barren surfaces (NDVI < 0.3) and a similar accuracy over non-barren surfaces (NDVI ≥ 0.3). BOA-LIN is more stable over varying water vapor conditions, compared to other hybrid methods. We conclude that this study provides a valuable reference for choosing the suitable estimation method in the SULR product generation.

scholarly journals TURAC—A New Instrument Package for Radiation Budget Measurements and Cloud Detection

2005 ◽  
Vol 22 (10) ◽  
pp. 1473-1479 ◽  
Author(s):  
C. Ruckstuhl ◽  
R. Philipona
Keyword(s):  
Numerical Algorithms ◽  
Cloud Amount ◽  
Longwave Radiation ◽  
Surface Radiation ◽  
Radiation Budget ◽  
Cloud Detection ◽  
Radiation Fluxes ◽  
New Instrument ◽  
Temperature And Humidity ◽  
Flux Measurements

Abstract Atmospheric radiation flux measurements and the resulting surface radiation budget are important quantities for greenhouse effect and climate change investigations. Accurate net shortwave and longwave fluxes, in conjunction with numerical algorithms, also allow monitoring of the radiative effect of clouds and the nowcasting of the cloud amount. To achieve certain advantages on the accuracy of flux measurements a new instrument is developed that measures downward and upward shortwave and longwave radiation with the same sensors. Two high-quality instruments—a pyranometer for shortwave and a pyrgeometer for longwave measurements—are mounted on a pivotable sensor head, which is rotated up and down in 10-min intervals. To keep the instrument domes free from dew and ice, and to minimize the pyranometer thermal offset, both sensors are ventilated with slightly heated air. Additionally, a ventilated temperature and humidity sensor is integrated in the new instrument. The combination of measurements of radiation fluxes, temperature, and humidity allows for instrument use for autonomous and automatic cloud amount detection. The Temperature, Humidity, Radiation and Clouds (TURAC) sensor has been successfully tested under harsh alpine winter conditions, as well as under moderate lowland conditions. Comparisons to reference instruments showed all radiation fluxes to be within a maximum bias and rms difference of 1.6% or 1.4 W m−2 on daily averages.

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.

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;

Validation of Clear-Sky Global LAnd Surface Satellite (GLASS) Longwave Radiation Product

2020 ◽  
Author(s):  
Qi Zeng ◽  
Jie Cheng ◽  
Feng Yang
Keyword(s):  
Land Surface ◽  
Water Cycle ◽  
Radiant Energy ◽  
Remote Sensing Data ◽  
Longwave Radiation ◽  
Energy System ◽  
Surface Radiation ◽  
Radiation Budget ◽  
Clear Sky ◽  
Global Land

&lt;p&gt;Surface longwave (LW) radiation plays an important rolein global climatic change, which is consist of surface longwave upward radiation (LWUP), surface longwave downward radiation (LWDN) and surface longwave net radiation (LWNR). Numerous studies have been carried out to estimate LWUP or LWDN from remote sensing data, and several satellite LW radiation products have been released, such as the International Satellite Cloud Climatology Project&amp;#8208;Flux Data (ISCCP&amp;#8208;FD), the Global Energy and Water cycle Experiment&amp;#8208;Surface Radiation Budget (GEWEX&amp;#8208;SRB) and the Clouds and the Earth&amp;#8217;s Radiant Energy System&amp;#8208;Gridded Radiative Fluxes and Clouds (CERES&amp;#8208;FSW). But these products share the common features of coarse spatial resolutions (100-280 km) and lower validation accuracy.&lt;/p&gt;&lt;p&gt;Under such circumstance, we developed the methods of estimating long-term high spatial resolution all sky&amp;#160; instantaneous LW radiation, and produced the corresponding products from MODIS data from 2000 through 2018 (Terra and Aqua), named as Global LAnd Surface Satellite (GLASS) Longwave Radiation product, which can be free freely downloaded from the website (http://glass.umd.edu/Download.html).&lt;/p&gt;&lt;p&gt;In this article, ground measurements collected from 141 sites in six independent networks (AmerciFlux, AsiaFlux, BSRN, CEOP, HiWATER-MUSOEXE and TIPEX-III) are used to evaluate the clear-sky GLASS LW radiation products at global scale. The bias and RMSE is -4.33 W/m&lt;sup&gt;2 &lt;/sup&gt;and 18.15 W/m&lt;sup&gt;2 &lt;/sup&gt;for LWUP, -3.77 W/m&lt;sup&gt;2 &lt;/sup&gt;and 26.94 W/m&lt;sup&gt;2&lt;/sup&gt; for LWDN, and 0.70 W/m&lt;sup&gt;2 &lt;/sup&gt;and 26.70 W/m&lt;sup&gt;2&lt;/sup&gt; for LWNR, respectively. Compared with validation results of the above mentioned three LW radiation products, the overall accuracy of GLASS LW radiation product is much better. We will continue to improve the retrieval algorithms and update the products accordingly.&lt;/p&gt;

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