scholarly journals An analysis of the dependence of clear-sky top-of-atmosphere outgoing longwave radiation on atmospheric temperature and water vapor

2008 ◽  
Vol 113 (D17) ◽  
Author(s):  
A. E. Dessler ◽  
P. Yang ◽  
J. Lee ◽  
J. Solbrig ◽  
Z. Zhang ◽  
...  
Keyword(s):  
Water Vapor ◽  
Outgoing Longwave Radiation ◽  
Longwave Radiation ◽  
Atmospheric Temperature ◽  
Clear Sky

scholarly journals Trends in spectrally resolved outgoing longwave radiation from 10 years of satellite measurements

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Simon Whitburn ◽  
Lieven Clarisse ◽  
Marie Bouillon ◽  
Sarah Safieddine ◽  
Maya George ◽  
...  
Keyword(s):  
Outgoing Longwave Radiation ◽  
Southern Oscillation ◽  
Longwave Radiation ◽  
Atmospheric Temperature ◽  
Natural Variability ◽  
Satellite Measurements ◽  
Clear Sky ◽  
The Individual ◽  
Spectrally Resolved

AbstractIn recent years, the interest has grown in satellite-derived hyperspectral radiance measurements for assessing the individual impact of climate drivers and their cascade of feedbacks on the outgoing longwave radiation (OLR). In this paper, we use 10 years (2008–2017) of reprocessed radiances from the infrared atmospheric sounding interferometer (IASI) to evaluate the linear trends in clear-sky spectrally resolved OLR (SOLR) in the range [645–2300] cm−1. Spatial inhomogeneities are observed in most of the analyzed spectral regions. These mostly reflected the natural variability of the atmospheric temperature and composition but long-term changes in greenhouse gases concentrations are also highlighted. In particular, the increase of atmospheric CO2 and CH4 led to significant negative trends in the SOLR of −0.05 to −0.3% per year in the spectral region corresponding to the ν2 and the ν3 CO2 and in the ν4 CH4 band. Most of the trends associated with the natural variability of the OLR can be related to the El Niño/Southern Oscillation activity and its teleconnections in the studied period. This is the case for the channels most affected by the temperature variations of the surface and the first layers of the atmosphere but also for the channels corresponding to the ν2 H2O and the ν3 O3 bands.

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 On the decadal increase in the tropical mean outgoing longwave radiation for the period 1984-2000

2004 ◽  
Vol 4 (5) ◽  
pp. 1419-1425 ◽  
Author(s):  
D. Hatzidimitriou ◽  
I. Vardavas ◽  
K. G. Pavlakis ◽  
N. Hatzianastassiou ◽  
C. Matsoukas ◽  
...  
Keyword(s):  
Time Series ◽  
Outgoing Longwave Radiation ◽  
Cloud Cover ◽  
Longwave Radiation ◽  
Atmospheric Temperature ◽  
Tropical Region ◽  
Transfer Model ◽  
Cloud Data ◽  
Low Level ◽  
High Level

Abstract. In the present paper, we have calculated the outgoing longwave radiation at the top of the atmosphere (OLR at TOA) using a deterministic radiation transfer model, cloud data from ISCCP-D, and atmospheric temperature and humidity data from NCEP/NCAR reanalysis, for the seventeen-year period 1984-2000. We constructed anomaly time-series of the OLR at TOA, as well as of all of the key input climatological data, averaged in the tropical region between 20°N and 20°S. We compared the anomaly time-series of the model calculated OLR at TOA with that obtained from the ERBE S-10N (WFOV NF edition 2) non-scanner measurements. The model results display very similar seasonal and inter-annual variability as the ERBS data, and indicate a decadal increase of OLR at TOA of 1.9±0.2Wm-2/decade, which is lower than that displayed by the ERBS time-series (3.5±0.3Wm-2). Analysis of the inter-annual and long-term variability of the various parameters determining the OLR at TOA, showed that the most important contribution to the observed trend comes from a decrease in high-level cloud cover over the period 1984-2000, followed by an apparent drying of the upper troposphere and a decrease in low-level cloudiness. Opposite but small trends are introduced by a decrease in low-level cloud top pressure, an apparent cooling of the lower stratosphere (at the 50mbar level) and a small decadal increase in mid-level cloud cover.

scholarly journals Tropical Outgoing Longwave Radiation and Longwave Cloud Forcing Diurnal Cycles from CERES

2012 ◽  
Vol 69 (12) ◽  
pp. 3652-3669 ◽  
Author(s):  
Patrick C. Taylor
Keyword(s):  
Diurnal Cycle ◽  
Outgoing Longwave Radiation ◽  
Radiant Energy ◽  
Longwave Radiation ◽  
Diurnal Variability ◽  
Cloud Forcing ◽  
Clear Sky ◽  
Surface Temperatures ◽  
Hourly Data ◽  
Diurnal Maximum

Abstract The diurnal cycle is a fundamental earth system variability driven by daily variations in solar insolation. Understanding diurnal variability is important for characterizing top-of-atmosphere and surface energy budgets. Climatological and seasonal first diurnal cycle harmonics of outgoing longwave radiation (OLR) and longwave cloud forcing (LWCF) are investigated using the Clouds and the Earth’s Radiant Energy System (CERES) synoptic 3-hourly data. A comparison with previous studies indicates generally similar results. However, the results indicate that the CERES OLR diurnal cycle amplitudes are 10%–20% larger in desert regions than previous analyses. This difference results from the temporal interpolation technique overestimating the daily maximum OLR. OLR diurnal cycle amplitudes in other tropical regions agree with previous work. Results show that the diurnal maximum and minimum OLR variability contributes equally to the total OLR variance over ocean; however, over land the diurnal maximum OLR variance contributes at least 50% more to the total OLR variability than the minimum OLR. The differences in maximum and minimum daily OLR variability are largely due to differences in surface temperature standard deviations at these times, about 5–6 and 3–4 K, respectively. The OLR variance at diurnal maximum and minimum is also influenced by negative and positive correlations, respectively, between LWCF and clear-sky OLR. The anticorrelation between LWCF and clear-sky OLR at diurnal OLR maximum indicates smaller cloud fractions at warmer surface temperatures. The relationship between LWCF and clear-sky OLR at diurnal minimum OLR appears to result from a preference for deep convection, more high clouds, and larger LWCF values to occur with warmer surface temperatures driving a narrower diurnal minimum OLR distribution.

scholarly journals Evolution and Trend of the Outgoing Longwave Radiation Spectrum

2009 ◽  
Vol 22 (17) ◽  
pp. 4637-4651 ◽  
Author(s):  
Yi Huang ◽  
V. Ramaswamy
Keyword(s):  
Water Vapor ◽  
Outgoing Longwave Radiation ◽  
General Circulation ◽  
Circulation Model ◽  
Longwave Radiation ◽  
Natural Variability ◽  
Lapse Rate ◽  
Vapor Concentration ◽  
Geophysical Fluid Dynamics Laboratory ◽  
The Difference

Abstract The variability and change occurring in the outgoing longwave radiation (OLR) spectrum are investigated by using simulations performed with a Geophysical Fluid Dynamics Laboratory coupled atmosphere–ocean–land general circulation model. First, the variability in unforced climate (natural variability) is simulated. Then, the change of OLR spectrum due to forced changes in climate is analyzed for a continuous 25-yr time series and for the difference between two time periods (1860s and 2000s). Spectrally resolved radiances have more pronounced and complex changes than broadband fluxes. In some spectral regions, the radiance change is dominated by just one controlling factor (e.g., the window region and CO2 band center radiances are controlled by surface and stratospheric temperatures, respectively) and well exceeds the natural variability. In some other spectral bands, the radiance change is influenced by multiple and often competing factors (e.g., the water vapor band radiance is influenced by both water vapor concentration and temperature) and, although still detectable against natural variability at certain frequencies, demands stringent requirements (drift less than 0.1 K decade−1 at spectral resolution no less than 1 cm−1) of observational platforms. The difference between clear-sky and all-sky radiances in the forced climate problem offers a measure of the change in the cloud radiative effect, but with a substantive dependence on the temperature lapse rate change. These results demonstrate that accurate and continuous observations of the OLR spectrum provide an advantageous means for monitoring the changes in the climate system and a stringent means for validating climate models.

scholarly journals An Improved Parameterization for Retrieving Clear-Sky Downward Longwave Radiation from Satellite Thermal Infrared Data

2019 ◽  
Vol 11 (4) ◽  
pp. 425
Author(s):  
Shanshan Yu ◽  
Xiaozhou Xin ◽  
Qinhuo Liu ◽  
Hailong Zhang ◽  
Li Li
Keyword(s):  
Water Vapor ◽  
Simulated Data ◽  
Longwave Radiation ◽  
Thermal Infrared ◽  
Reanalysis Data ◽  
Atmospheric Parameter ◽  
Near Surface ◽  
Modis Data ◽  
Clear Sky ◽  
Downward Longwave Radiation

Surface downward longwave radiation (DLR) is a crucial component in Earth’s surface energy balance. Yu et al. (2013) developed a parameterization for retrieving clear-sky DLR at high spatial resolution by combined use of satellite thermal infrared (TIR) data and column integrated water vapor (IWV). We extended the Yu2013 parameterization to Moderate Resolution Imaging Spectroradiometer (MODIS) data based on atmospheric radiative simulation, and we modified the parameterization to decrease the systematic negative biases at large IWVs. The new parameterization improved DLR accuracy by 1.9 to 3.1 W/m2 for IWV ≥3 cm compared to the Yu2013 algorithm. We also compared the new parameterization with four algorithms, including two based on Top-of-Atmosphere (TOA) radiance and two using near-surface meteorological parameters and water vapor. The algorithms were first evaluated using simulated data and then applied to MODIS data and validated using surface measurements at 14 stations around the globe. The results suggest that the new parameterization outperforms the TOA-radiance based algorithms in the regions where ground temperature is substantially different (enough that the difference between them is as large as 20 K) from skin air temperature. The parameterization also works well at high elevations where atmospheric parameter-based algorithms often have large biases. Furthermore, comparing different sources of atmospheric input data, we found that using the parameters interpolated from atmospheric reanalysis data improved the DLR estimation by 7.8 W/m2 for the new parameterization and 19.1 W/m2 for other algorithms at high-altitude sites, as compared to MODIS atmospheric products.

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