GOES-12 0.65 µm vs GOES-13 0.63 µm visible images

As of 18:34 UTC on 14 April 2010, GOES-13 (launched May 2006, with a Post Launch Test in December 2006) replaced GOES-12 (launched July 2001) as the operational GOES-East satellite  — for more information, see the NOAA NESDIS Satellite Services Division. A sequence of AWIPS images (above) shows the last three GOES-12 visible images followed by the first three GOES-13 visible images centered over the Upper Midwest region of the US during the satellite transition period. Both the GOES-12 and the GOES-13 visible images are enhanced using the “Linear” AWIPS enhancement (see below for more details).

Note that areas of dense vegetation (for example, over river valleys, and also across much of southern Indiana) appear slightly darker on the GOES-13 visible channel images. This is due to the fact that the visible channel on the newer GOES series — GOES-13 and beyond –  is a narrower channel (centered at 0.63 µm, vs 0.65 µm for the older GOES satellites) that misses the “brighter” portion of the grass/vegetation spectrum (green plot) that begins to increase rapidly at wavelengths higher than about 0.7 µm (below). You will also notice that the cloud features appear slightly brighter in the last three GOES-13 images — this is due to the fact that the GOES visible detector performance tends to degrade over time, so the visible images from the much  older GOES-12 satellite appear slightly “washed out” in comparison.

GOES-12 vs GOES-13 visible channel spectral response function plots

Note to AWIPS users: because of the different characteristics of the GOES-13 visible channel, it is suggested that you change the default GOES visible image enhancement from “ZA” to “Linear” — as seen in a GOES-13 visible image comparison with those 2 enhancements (below), the GOES-13 imagery can appear too dark with the default “ZA” enhancement.

GOES-13 visible image: "ZA" enhancement vs "Linear" enhancement

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GOES-12 vs GOES-13 Sounder 4.5 µm shortwave IR images

There are also significant improvements in the quality of the GOES-13 Sounder data, due to the fact that GOES-12 had been experiencing filter wheel problems for quite some time. AWIPS comparisons of the last GOES-12 and the first GOES-13 Sounder 4.5 µm shortwave IR images (above) and 6.5 µm water vapor channel images (below) clearly demonstrate the dramatic reduction in noise — in these Sounder composite images, the western portion of the image is GOES-11 (GOES-West) data, while the eastern portion of the image is either GOES-12 or GOES-13 (GOES-East) data. In particular, the 6.5 µm water vapor image is “cleaner” on GOES-13 as a result of “colder” detectors on the newer spacecraft design, which more effectively radiate to space.

GOES-12 vs GOES-13 Sounder 6.5 µm water vapor channel images

Blended Total Precipitable Water (AWIPS menu)

Beginning on 09 March 2009, two new Blended Total Precipitable Water (TPW) products were made available to NWS forecast offices who have installed AWIPS Operational Build 9 (OB9) — a Blended TPW product (above; Animated GIF), and a Percent of Normal TPW product (below; Animated GIF).

Percent of Normal TPW (AWIPS menu)

The Blended TPW products incorporate data from a number of polar-orbiting and geostationary satellite platforms. Over water, the algorithm currently uses data from:

• the SSM/I instrument (on the DMSP F13 satellite)
  
• the AMSU instrument (on the NOAA-15, NOAA-16, NOAA-17, NOAA-18, and MetOp-A satellites)

and over land, the algorithm uses data from:

• the  GOES Sounder instrument (on the GOES-11 and GOES-12 satellites)
• ground-based Global Positioning System (GPS-MET) receivers

On AWIPS, the Blended TPW product is generated using the latest data source available for each pixel; it is  then  mapped to a Mercator projection with a spatial resolution of 16 km at the Equator. The products are available in AWIPS on a varying schedule, but in general there will be 1 or 2 Blended TPW images per hour.

The Percent of Normal TPW  (or “Blended TPW Anomaly”) product (below) compares the current Blended TPW values to the mean values derived during the 1988-1999 time period (using a climatology of SSM/I TPW over oceans, and a mix of rawinsonde and TOVS sounding TPW over land). Note that while the raw TPW Anomaly product is capable of calculating  values in excess of 200%, on AWIPS all of the TPW Anomaly values  greater than 200% are simply colored yellow (and displayed as “> 201″ using AWIPS cursor sampling).

Percent of Normal TPW (TPW Anomaly)

A 4-panel comparison of Blended, GOES Sounder, DMSP SSM/I, and POES AMSU TPW products (below, using a different CIMSS TPW enhancement) demonstrates some of the advantages of the blended TPW product, namely (1) no gaps between the individual swaths of polar-orbiting satellite data over water, and (2) the availability of TPW data in areas of dense cloud cover (over both land and water).

Comparison of Blended, GOES Sounder, SSM/I, and AMSU TPW products

A comparison of AWIPS cursor sampling of the Blended, GOES Sounder, DMSP SSM/I, and POES AMSU TPW products (below) shows that in general, the TPW value for any given location should agree to within a few millimeters (or within several hundredths to perhaps one tenth of an inch).

Comparison of Blended, GOES sounder, SSM/I, and AMSU TPW products

However, at times there may be some disagreement between TPW values at any particular point (below), due to temporal differences of the data as displayed in AWIPS. In other words, the time displayed in the AWIPS product label may not necessarily apply to all portions of the displayed image.

Comparison of Blended, GOES sounder, SSM/I, and AMSU TPW products

The images below show the coverage of the Blended TPW product when displayed in AWIPS at the Northern Hemisphere, Pacific Mercator, North America, Pacific Satellite, and CONUS scales.

Blended TPW product (displayed on the Northern Hemisphere scale)

Blended TPW product (displayed on the Pacific Mercator scale)

Blended TPW product (displayed on the North America scale)

Blended TPW product (displayed on the Pacific Satellite scale)

Blended TPW product (displayed on the CONUS scale)

The Blended TPW and TPW Anomaly products were developed at the Cooperative Institute for Research in the Atmosphere (CIRA), and over the past few years they have been transitioned from research into NESDIS operations.

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References and related websites:

• Kidder, S.Q. and A.S. Jones, 2007: A blended satellite Total Precipitable Water product for operational forecasting.
• Ferraro et al., 2005: NOAA Operational Hydrological Products Derived From the Advanced Microwave Sounding Unit. IEEE Trans. Geosci. Remote Sens., 43, 1036-1049.
• Alishouse, J.C., S. Snyder, J. Vongsathorn, and R.R. Ferraro, 1990: Determination of oceanic total precipitable water from the SSM/I. IEEE Trans. Geo. Rem. Sens., Vol. 28, 811-816.
• Smith et al., 2007: Short-Range Forecast Impact from Assimilation of GPS-IPW Observations into the Rapid Update Cycle. Mon. Wea. Rev., 135, 2914-2930.
• Schmit et al., 2002: Validation and use of GOES Sounder moisture information. Wea. Forecasting, 17, 139-154.

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- updated 20 March 2009 -

MTSAT High Density Winds (AWIPS menu)

TECHNICAL IMPLEMENTATION NOTICE 08-61
NATIONAL WEATHER SERVICE HEADQUARTERS WASHINGTON DC
317 PM EDT FRI AUG 1 2008 

SUBJECT:  NESDIS HIGH DENSITY GEOSTATIONARY WINDS TO BE
          ADDED TO SBN/NOAAPORT: EFFECTIVE OCTOBER 15 2008 

EFFECTIVE WEDNESDAY OCTOBER 15 2008...BEGINNING AT APPROXIMATELY
1500 COORDINATED UNIVERSAL TIME /UTC/...THE NATIONAL
ENVIRONMENTAL SATELLITE...DATA...AND INFORMATION SERVICE /NESDIS/
AND NWS START DISSEMINATING HIGH DENSITY GEOSTATIONARY /MTSAT/
WIND PRODUCTS VIA SBN/NOAAPORT.

THE MTSAT WINDS /FROM THE JAPANESE SATELLITE/ WILL AUGMENT THE
CURRENT GOES EAST AND WEST HIGH DENSITY WINDS OVER SPARSE DATA
REGIONS...MOST BENEFITING THE ALASKA AND PACIFIC REGIONS AND THE
AVIATION WEATHER CENTER /AWC/.

Coverage of MTSAT High Density Winds vs GOES High Density Winds

A comparison of the areal coverage of the MTSAT vs the GOES high density winds is shown on the Pacific Mercator scale  (above) and Northern Hemisphere scale (below). The MTSAT high density winds will be available north of the Equator every 3 hours (at 02, 05, 08, 11, 14, 17, 20, and 23 UTC), and south of the Equator every 6 hours (at 00, 06, 12, and 18 UTC).

Coverage of MTSAT High Density Winds vs GOES High Density Winds

With the AWIPS cursor sampling function activated, the user will be able to display the valid time, the type of satellite imagery used to derive a particular AMV (Visible, InfraRed, shortwave InfraRed, or Water Vapor), the pressure of the height assignment for that AMV, and the direction/speed of that AMV (below). The wind vectors can be color-coded according to pressure layers (as shown below), or by AMV type (IR, Water Vapor, Visible, or 3.9 µm shortwave IR). Targets are tracked on three consecutive satellite images in order to calculate the direction and speed of each AMV.

MTSAT High Density Winds

These MTSAT winds available on AWIPS should be very similar to those derived using GOES data, since NESDIS is using the same AMV software (which was developed at CIMSS) for both satellites. For more details about the derivation and application of satellite-derived atmospheric motion vector products, see the SHyMet GOES High Density Winds lesson.

Reference:

Velden, C.S. et al., 2005: Recent Innovations in Deriving Winds from Meteorological Satellites. Bull. Amer. Meteor. Soc., 86, 205-223

- Updated 29 January 2009 -