scholarly journals Comparison of measured and modeled outgoing longwave radiation for clear-sky ocean and land scenes using coincident CERES and AIRS observations

2010 ◽  
Vol 115 (D15) ◽  
Author(s):  
L. A. Moy ◽  
R. O. Knuteson ◽  
D. C. Tobin ◽  
H. E. Revercomb ◽  
L. A. Borg ◽  
...  
Keyword(s):  
Outgoing Longwave Radiation ◽  
Longwave Radiation ◽  
Clear Sky

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 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 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 Diffusivity-Factor Approximation for Spectral Outgoing Longwave Radiation

2019 ◽  
Vol 76 (7) ◽  
pp. 2171-2180
Author(s):  
Jing Feng ◽  
Yi Huang
Keyword(s):  
Outgoing Longwave Radiation ◽  
Longwave Radiation ◽  
Gas Absorption ◽  
Atmospheric Conditions ◽  
Absorption Bands ◽  
Clear Sky ◽  
Correction Scheme ◽  
Analytical Estimation ◽  
Constant Diffusivity ◽  
The Impact

Abstract Accurate integration of directional radiance shows that the conventional diffusivity-factor approximation with a constant diffusivity angle results in an overestimation of the outgoing longwave radiation (OLR) in the window band and an underestimation in the absorption band. We propose an analytical estimation of a spectrally dependent diffusivity angle for clear-sky spectral OLR, considering actual atmospheric conditions and realistic optical path geometry. Beginning with the plane-parallel geometry, we present a new, physical explanation of the conventional diffusivity angle that applies to the gas absorption bands and derives an alternative solution for the window bands. Then a correction scheme is developed to account for the impact of the spherical Earth geometry on the diffusivity angle. The proposed method achieves higher accuracy, reducing biases to generally less than 2% in all spectral regions.

scholarly journals Outgoing Longwave Radiation due to Directly Transmitted Surface Emission

2012 ◽  
Vol 69 (6) ◽  
pp. 1865-1870 ◽  
Author(s):  
S. M. S. Costa ◽  
K. P. Shine
Keyword(s):  
Outgoing Longwave Radiation ◽  
Ad Hoc ◽  
Longwave Radiation ◽  
Detailed Calculation ◽  
Surface Emission ◽  
Clear Sky ◽  
Atmospheric Window ◽  
The Tropics ◽  
The Continuum

Abstract A frequently used diagram summarizing the annual- and global-mean energy budget of the earth and atmosphere indicates that the irradiance reaching the top of the atmosphere from the surface, through the midinfrared atmospheric window, is 40 W m−2; this can be compared to the total outgoing longwave radiation (OLR) of about 235 W m−2. The value of 40 W m−2 was estimated in an ad hoc manner. A more detailed calculation of this component, termed here the surface transmitted irradiance (STI), is presented, using a line-by-line radiation code and 3D climatologies of temperature, humidity, cloudiness, etc. No assumption is made as to the wavelengths at which radiation from the surface can reach the top of the atmosphere. The role of the water vapor continuum is highlighted. In clear skies, if the continuum is excluded, the global- and annual-mean STI is calculated to be about 100 W m−2 with a broad maximum throughout the tropics and subtropics. When the continuum is included, the clear-sky STI is reduced to 66 W m−2, with a distinctly different geographic distribution, with a minimum in the tropics and local peaks over subtropical deserts. The inclusion of clouds reduces the STI to about 22 W m−2. The actual value is likely somewhat smaller due to processes neglected here, and an STI value of 20 W m−2 (with an estimated uncertainty of about ±20%) is suggested to be much more realistic than the previous estimate of 40 W m−2. This indicates that less than one-tenth of the OLR originates directly from the surface.

scholarly journals Satellite-Based Reconstruction of the Tropical Oceanic Clear-Sky Outgoing Longwave Radiation and Comparison with Climate Models

2014 ◽  
Vol 27 (2) ◽  
pp. 941-957 ◽  
Author(s):  
Guillaume Gastineau ◽  
Brian J. Soden ◽  
Darren L. Jackson ◽  
Chris W. O’Dell
Keyword(s):  
Climate Variability ◽  
Outgoing Longwave Radiation ◽  
Climate Models ◽  
Longwave Radiation ◽  
Two Phase ◽  
Tropical Ocean ◽  
Clear Sky ◽  
Observational Uncertainty ◽  
Project Model ◽  
Anthropogenic Forcings

Abstract The changes of the outgoing longwave radiation (OLR) in clear-sky conditions have been calculated using High Resolution Infrared Radiation Sounder (HIRS) observations from 1979 to 2004. After applying corrections for satellite orbital drift and intercalibration of the HIRS/2 data from the NOAA satellites, the OLR is calculated from a multivariate regression over the tropical ocean region. The clear-sky OLR retrievals compare well with the observed top-of-atmosphere radiation measurements, although the precision and stability uncertainties are larger. While the tropical ocean surface temperature has risen by roughly 0.2 K from 1982 to 2004, the reconstructed OLR remains stable over the ocean. Consequently, there is an increase in the clear-sky greenhouse effect (GHE) of 0.80 W m−2 decade−1. This trend is shown to be larger than the uncertainty in the stability of the HIRS retrievals. The observations are compared with two phase 3 of the Coupled Model Intercomparison Project model ensembles: one ensemble includes both natural and anthropogenic forcings [the twentieth-century (20C) ensemble] and the other ensemble only contains natural climate variability (the control ensemble). The OLR trend in the 20C simulations tends to be more negative than observed, although a majority is found to be within the observational uncertainty. Conversely, the response of the clear-sky OLR to SST is shown to be very similar in observations and models. Therefore, the trend differences between the 20C simulations and observations are likely because of internal climate variability or uncertainties in the external forcings. The observed increase in GHE is shown to be inconsistent with the control ensemble, indicating that anthropogenic forcings are required to reproduce the observed changes in GHE.

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