GOES-15 is scheduled to replace GOES-11 as the operational GOES-West satellite on 06 December 2011. On 29 November 2011, a test was conducted by NOAA/NESDIS which briefly substituted GOES-15 data for GOES-11 data as the source of GOES-West satellite imagery in AWIPS. In the sequence of AWIPS images shown above, the first 3 images are using GOES-11, while the final set of 3 images are using GOES-15 as the source for GOES-West Imager water vapor channel data. The changes to the GOES-15 Imager water vapor channel are quite obvious — GOES-15 uses a 4-km resolution channel centered at 6.5 µm that has a wider spectral response, compared to the 8-km resolution 6.7 µm channel with a more narrow spectral response on GOES-11. Even at high latitudes (where the large satellite viewing angle shifts the GOES water vapor weighting function to higher altitudes) the improved GOES-15 water vapor channel imagery will do a better job of depicting the moisture gradients and structure associated with mid-tropospheric dynamical features (Gulf of Alaska example | Nunavut, Canada example).

A similar comparison using GOES-11 (the first 3 images) vs GOES-15 (the final set of 3 images) Imager visible channel data is seen below. Immediately obvious is the fact that the GOES-15 visible channel imagery appears “brighter” than the GOES-11 visible channel imagery — this is due to the fact that the performance of the GOES visible detectors degrades over time (GOES-11 was launched in 2000, and became the operational GOES-West satellite in 2006). The 0.63 µm visible channel on GOES-15 is also slightly different than the 0.65 µm visible channel on GOES-11, as is discussed in the “GOES-13 is now the operational GOES-East satellite” blog post. GOES-15 is similar to GOES-13, since it is part of the GOES-N/O/P series of spacecraft.

Finally, below is a comparison of GOES Sounder data, using GOES-11 as the source of GOES-West 6.5 µm Sounder water vapor channel data (the first 2 images) vs GOES-15 (the final set of 2 images). Note that the GOES-15 Sounder water vapor channel imagery has less noise than that from GOES-11.

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Strong northeasterly winds created large plumes of blowing dust across parts of the Baja California region of Mexico on 27 November 2011. GOES-15 0.63 µm visible channel images (above; click image to play animation) showed the development of one blowing dust plume originating near the west coast of mainland Mexico, with another more broad plume fanning out from the Baja California peninsula.

GOES-15 will be replacing GOES-11 as the operational GOES-West satellite on 06 December 2011 — and one of the benefits is improved Image Navigation and Registration (INR), which leads to less image-to-image “wobble” when viewing an animation. The improved GOES-15 INR is quite evident when compared to GOES-11 for this blowing dust case (below; click image to play animation).

A 250-meter resolution MODIS true color Red/Green/Blue (RGB) image from the SSEC MODIS Today site (below) revealed more complex details about the structure of the blowing dust features.

AWIPS images of GOES-11 0.65 µm visible channel data with an overlay of MADIS 1-hour interval satellite winds (below) indicated that the airborne dust feature was moving southwestward at speeds of 15-20 knots.

A comparison of 1-km resolution MODIS 0.65 µm visible channel, 3.7 µm “shortwave IR” channel, and 11.0 µm “IR window” channel images (below) showed that (1) the thickest portions of the blowing dust plumes appeared several degrees warmer (darker black enhancement) on the shortwave IR channel image, due to reflection of incoming solar radiation off the small airborne dust particles, and (2) swaths of land which had significant amounts of blowing dust overhead exhibited a slightly cooler (lighter gray enhancement) signaure on the IR window channel image, since the dust was reducing the amount of solar radiation reaching the surface.

In fact, the corresponding 1-km resolution MODIS Land Surface Temperature (LST) product (below) displayed LST values in the 80s F in areas beneath the blowing dust plumes, in contrast to LST values in the 90s to around 100º F over adjacent areas.

CIMSS participation in GOES-R Proving Ground activities includes making a variety of MODIS images and products available for National Weather Service offices to add to their local AWIPS workstations. Currently there are 49 NWS offices receiving MODIS imagery and products from CIMSS.

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Strong northerly winds in the wake of a cold frontal passsage caused widespread blowing dust across parts of west Texas during the afternoon hours on 26 November 2011. The hazy plumes of blowing dust could be seen on GOES-13 0.63 µm visible channel images (above). At Midland, Texas (located near the center of the images) the winds gusted to 51 mph, and surface visibility was reduced to 0.5 mile at times.

After sunset, when visible imagery was no longer available, the southward progress of the airborne dust could still be tracked using a GOES-11 IR difference product (below), created by subtracting the 12.0 µm IR brightness temperature from the 10.7 µm IR brightness temperature. The larger IR difference values (around 2-3 degrees Kelvin, yellow color enhancement) represented the portions of the airborne dust cloud that were the most concentrated.

It is important to note that GOES-11 (GOES-West) is the only remaining operational GOES satellite that still has the 4-km resolution 12.0 µm IR channel on the Imager instrument (a 10-km resolution 12.0 µm channel is still on the Sounder instrument on all GOES satellites) — and GOES-11 will soon be replaced by GOES-15 on 06 December 2011. After that time, using such an IR difference product to track areas of blowing dust will have to be done using polar orbiting satellites (such as POES, MODIS, or NPP) or the GOES Sounder that still have the 12.0 µm IR channel.

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The VIIRS instrument on NASA’s recently-launched NPP satellite began to acquire imagery on 21 November 2011 (NASA news release). True Color Red-Green-Blue (RGB) images from two of the early satellite passes are shown, which cover a swath from Brazil to eastern Canada from 16:10 to 16:35 UTC (above) and another swath covering much of eastern North America from 18:00 to 18:15 UTC (below).

A VIIRS RGB image covering parts of western Australia from 05:35 to 05:45 UTC on 22 November can be seen below.

Images created at the Space Science and Engineering Center (SSEC), University of Wisconsin-Madison by the NASA NPP Atmosphere PEATE Team.

Technical notes:
– Produced by Liam Gumley and Willem Marais (SSEC)
– SDR products ingested from the NPP SD3E by Bruce Flynn, Steve Dutcher, and Greg Quinn (SSEC)
– VIIRS M-bands SVM05, SVM04, SVM03 (red, green, blue)
– 1000 meter resolution, Cylindrical Equidistant projection
– Atmospheric correction algorithm by Jacques Descloitres (Formerly GSFC)
– Reprojection algorithm by Terry Haran (NSIDC)

Additional NPP VIIRS images can be found on the VIIRS Imagery and Visualization Team site at CIRA/RAMMB.

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