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| Titel |
Assessment for global longwave radiative fluxes estimated by GEWEX Surface Radiative Budget (SRB) project and the Calipso-CloudSat-CERES-MODIS (CCCM). |
| VerfasserIn |
A. Viudez-Mora, P. W. Stackhouse, S. Kato |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250061152
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| Zusammenfassung |
| Accurate estimates of the cloud radiative effect and greenhouse effect are required to better
estimate the climate variability on regional and global scales. The radiation budget at the
surface is a key interface for energy exchange and therefore for detecting climate change.
Surface longwave radiative fluxes (LRFs) are an important component of this terrestrial
energy budget.
These LRFs are measured from ground-based instruments but accurate satellite-based
estimates are required to understanding the flux variability at larger spatial scales. To date
most satellite based longwave flux algorithms make assumptions regarding the vertical
profiles of clouds. New methods, using CALIPSO and CloudSat now specify cloud vertical
profiles explicitly, although are limited in time and space.
This study assesses the LRFs estimated by two different projects the GEWEX (Global
Energy and Water Cycle Experiment) SRB (Surface Radiative Budget) and CCCM
(CALIPSO-CloudSat-CERES-MODIS) during an overlapping time period for the year 2007.
The assessment compares the NASA/GEWEX Surface Radiation Budget (SRB) dataset and
CCCM LW archived fluxes derived on a 1Ë x 1Ë global grid. The study quantifies the
agreement between both data sets on different spatial and temporal scales, showing a mean
annual differences of -1.4±4.4 Wm-2 (All sky)and -2.8±2.4 Wm-2 (Clear sky) for
dowelling fluxes, while about -0.8±2.4 Wm-2 for upwelling fluxes and considers
differences in monthly and annual zonal averages for land/ocean and day/night time
periods.
The zonal differences between GEWEX-SRB and C3M are mainly at the Polar Regions
due to the different cloud properties in both algorithms. The difference at the tropical regions
could be due to on the cloud random overlap assumptions in SRB. The difference for upward
fluxes is in the skin temperature prescription. Both upward and downward longwave
flux difference standard deviations are reduced when larger scale SRB grid box
averages are compared to C3M footprint averages using a minimum threshold.
This technique is being developed to better classify and understand differences. |
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