Tropical Western Pacific (TWP) GOES-9 (TWPGOES9)

Information updated on Thu Feb 7 20:05:59 2008

General Data Description

Prior to May 2003, the Geostationary Meteorological Satellite (GMS-5) operated by the Japan Meteorological Agency (JMA) provided meteorological data over the Asia-Pacific Region. However, due to technical problems with the main imaging instrument on GMS-5, an American instrument the Geostationary Operational Environmental Satellite (GOES)-9 took over as a backup in May 2003.

The GOES-9 images are qualitatively very similar to GMS-5 images;

geostationary coverage area is altered due to a different satellite position (GOES-9 is 15^o further east than GMS-5);
hourly imagery is generally available;
full-disc coverage is available (this was not available for some GMS-5 scans in early 2003);
an additional infrared channel at 3.9 microns is available;
the GOES-9 visible channel is affected by coherent noise and this data is of slightly lower quality than might otherwise be expected;
the satellite operator, USA's National Oceanic & Atmospheric Administration (NOAA), needs to undertake regular maintenance of the GOES-9 satellite and there are also eclipse periods, so that during the year there are occasions when some images are not available due to these protective actions by the operator;

Upper Tropospheric Relative Humidity (UTH) which corresponds roughly to the mean relative humidity between 200-500 hPa is derived from GOES channel 3 (6.7mum) channel 4 (11 mum) and satellite zenith angle. UTH is available in two separate data streams: one with the same resolution as the GOES data and another with a 0.5 degree gridded output.

Data Stream Names

twpgoes9X1.a1

twpgoes9uthX1.c1
twpgoes9uthgridX1.c1

Measurement Description

twpgoes9X1.a1.yymmdd.hhmmss.hdf

GOES 9 images Variable Type Units Ch 1 'albedo' gvar_ch1 short albedo*100% Ch 2 brightness temperature gvar_ch2 short temp_deg_c Ch 3 brightness temperature gvar_ch3 short temp_deg_c Ch 4 brightness temperature gvar_ch4 short temp_deg_c Ch 5 brightness temperature gvar_ch5 short temp_deg_c satellite-solar azimuth angle rel_azimuth float degrees satellite zenith angle sat_zenith float degrees solar zenith angle sun_zenith float degrees time ^* time float minutes in the day

^* This is the time at which the pixel measurement was made. Note that several pixels will appear to have the same time. In the along-scan direction this is a consequence of the finite time increment used in the calculation of the pixel time, and can be improved upon, if necessary, by least-squares fitting a curve to the the pixels times to obtain times unique to each pixel. In the across-scan direction, the replication of pixel times is correct and results from the multiple detectors used in each channel. These detectors are aligned in a 'north-south' configuration, but away from the sub-satellite point and the Equator, the curvature of the earth causes inclination of the detector array when projected onto the Earth's surface away from the local meridians.

twpgoes9uthX1.c1 and twpgoes9uthgridX1.c1

latitude and longitude (degrees)
upper tropospheric relative humidity (percent)
time (seconds since midnight (GMT)

In addition for twpgoes9uthgridX1.c1

Ch 3 brightness temperature (degrees K)
Ch 4 brightness temperature (degrees K)
satellite zenith angle (degrees)
number of valid channel 3 observations in grid cell average
number of valid channel 4 observations in grid cell average
number of valid UTH samples in grid cell average

Temporal Coverage

These data streams begin on May 12, 2003 and end on July 14, 2005.

Area Covered

These images cover longitude: 90E to 200E, latitude: 30S to 30N.

Data Stream Inputs

g9.yyjjj.hhss (e.g. g9.04080.2325)

Notification Form Link

twpgoes9X1.a1 notification form
twpgoes9compositeX1.a1 notification form
UTH notification form

Contacts

ARM Mentor

Peter Minnett
Richard Wagener

ARM Software Developer

Laurie Gregory