Atmos Composition Hydrology A-Train AIRS Modeling MAIRS Measures Precipitation

Product Summary

Data Set Short Name: MERG
Data Set Long Name: NCEP/CPC 4km Global (60N - 60S) IR Dataset
Data Set Version: 1
Data Set Creator: Climate Prediction Center/NCEP/NWS
Temporal Resolution: 30 min
Temporal Coverage: 2000-02-07 - present
Data Holdings Page: View

 Product Description

The Climate Prediction Center/NCEP/NWS is now making available via anonymous ftp (in
digital form) globally-merged (60N-60S) pixel-resolution IR brightness temperature
data (equivalent blackbody temps), merged from all available geostationary satellites
(GOES-8/10, METEOSAT-7/5 & GMS). The availability of data from METEOSAT-5, which is
located at 63E at the present time, yields a unique opportunity for total global
(60N-60S) coverage.

The global IR composites available are now available in digital form for every 1/2
hour via a weekly rotating file. The data have been corrected for "zenith angle
dependence", i.e. IR temperatures for locations far from satellite nadir are
erroneously cold due to a combination of geometric effects and radiometric path
extinction effects. This correction allows for the merging of the IR data from the
various geostationary satellites with greatly reduced discontinuities at their
boundaries. Some residual differences among the data exist since the IR channels
aboard the various spacecraft have slightly different characteristics and no
intercalibration among the sensors has been performed. We are in the process of
performing such an intercalibration, although this effect is considerably smaller
than the zenith angle effects.

The data availability are delayed by 3 days from real-time to abide by international
data exchange agreements between NOAA and EUMETSAT (the METEOSAT data providers). We
are working on a web page that will have an image browse capability (at reduced
resolution) along with tools to make data downloading easier.

The data are too voluminous (33 MB per 1/2 hour) to service requests for historical data
or spatial subsets of the data. However, the National Climatic Data Center (NCDC) has
agreed to be the official archive & distribution center for these data, although the
infrastructure for this activity is not yet in place.

Please note that, at present, we are using a makeshift assortment of existing in-house
hardware to perform these tasks and, while reliable over the course of the past few
months, is not optimal for the tasks at hand. We are in the process of procuring a
dedicated system for this activity which should be installed within the next 2-3 months.
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  • Last updated: October 15, 2010 00:27:36 GMT