MODIS visible + MODIS Red/Green/Blue (RGB) image

A story on the National Weather Service Milwaukee/Sullivan website highlighted the appearance of ice on Lake Michigan on MODIS imagery on 28 January 2010. A comparison of AWIPS images of the 1-km resolution MODIS visible channel and a false color Red/Green/Blue (RGB) image (above) confirms that the brighter features seen on the visible image over the nearshore waters (from Milwaukee, Wisconsin to Chicago, Illinois to Gary, Indiana) were indeed lake ice (snow cover and ice appear as darker red features on the MODIS false color RGB image). This example offers a glimpse at the type of RGB image capability that should be available with the upcoming AWIPS II software.

A closer view using 250-meter resolution true color images from the SSEC MODIS Today site (below) revealed that the northwesterly surface winds were causing a small amount of motion of the ice field between the time of the Terra satellite overpass (17:11 UTC or 11:11 am local time) and the Aqua satellite overpass (18:54 UTC or 12:54 pm local time).

MODIS true color images

A comparison of the 18:54 UTC Aqua MODIS true color and false color images (below) again confirms that the features seen over the nearshore waters were indeed lake ice — snow cover and ice appear as cyan-colored features on this particular false color imagery.

MODIS true color and false color images

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GOES-12 and GOES-13 sounder channel data

The GOES-13 satellite was brought out of on-orbit storage on 27 January 2010 — and a comparison of the 19 channels of the sounder instrument on GOES-12 and GOES-13 (above) shows an improvement in the noise characteristics that were beginning to plague the GOES-12 sounder in late 2009.

GOES-12 imager channel data

The imager instruments on GOES-12 (above) and GOES-13 (below) share the same 5 channels (1 visible and 4 InfraRed). However, the GOES-13 satellite has improved Image Navigation and Registration (INR), which eliminates a great deal of the image-to-image wobble that is often seen with GOES-12. In addition, larger batteries aboard the spacecraft allow GOES-13 to continue to operate through the Spring and Fall season “eclipse periods” (when the satellite is in the Earth’s shadow and the solar panels cannot generate the power needed to operate the various instrument packages).

GOES-13 imager channel data

GOES-13 (launched in May 2006, with a Post Launch Test conducted in December 2006) will replace GOES-12 (launched in July 2001) as the operational GOES-East satellite on 14 April 2010. At that point, GOES-12 will then be moved to a new position at 60º West Longitude to support South American operations. More information on the transition of GOES-13 into operations is available from the NOAA/NESDIS Satellite Services Division.

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MODIS true color image (viewed using Google Earth)

A series of powerful storms affected the southwestern US during the 18-23 January 2010 period, which resulted in record rainfall and snowfall in parts of northern Arizona. Flagstaff recorded 54.2 inches of snow, which was their 2nd largest storm total snowfall on record. A 250-meter resolution MODIS true color image from the SSEC MODIS Today site (above) showed the coverage of snow across the higher elevations of northern Arizona on 25 January 2010.

On the following day, a comparison of AWIPS images of the MODIS visible channel and a false-color Red/Green/Blue (RGB) image (below) shows that most of the bright features seen on the visible were snow cover (which shows up as darker pink features on the false color image).

MODIS visible image + MODIS false color RGB image

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GOES-12 water vapor images + surface pressure and frontal analysis

A cyclone off the mid-Atlantic coast was quickly transitioning to the occluded stage on the morning of 22 January 2010 (above). As the cyclone (in its mature stage) was just beginning to move out over the offshore waters of the Atlantic Ocean, winds gusted to 51 knots at buoy 41025 (Diamond Shoals NC) around 07 UTC and 37 knots at buoy 44014 (64 miles east of Virginia Beach VA) around 11 UTC.

The evolution of a classic “dry swirl” signature was seen on AWIPS images of the 4-km resolution GOES-12 6.5 µm water vapor channel (below) — this dry swirl water vapor signature is a tell-tale sign that a cyclone has reached occlusion (and is often seen with systems over the open oceans).

GOES-12 6.5 µm water vapor images

The appearance of an subtle elongated filament structure on the water vapor imagery (exiting the Georgia / South Carolina coast after about 10 UTC, to the southwest of the occluding cyclone) suggested the presence of a northeastward-propagating jet streak. A plot of 1-hourly MADIS satellite-derived water vapor atmospheric motion vectors (below) revealed one target with a velocity of 151 knots in the general vicinity of the thin filament signature — this wind speed was significantly higher than the 100-110 knots that was initialized by the GFS40 model over that particular area.

GOES-12 water vapor image + satellite winds + GFS 250 hPa isotachs

McIDAS images of the 1-km resolution GOES-12 visible channel data (below) showed finer details in the low-level cloud structure, as well as the formation of convective bursts near the circulation center toward the end of the animation.

GOES-12 visible images + buoy and ship wind reports

A comparison of 1-km resolution NOAA-17 AVHRR visible channel and 10.8 µm IR channel images at 14:10 UTC (below) showed the cloud structures around the time that the dry swirl signature was becoming more well-defined on the GOES-12 water vapor imagery.

NOAA-17 AVHRR visible and 10.8 µm IR images

The AVHRR Cloud Top Temperature (CTT) product (below) indicated that CTT values were as cold as -70º C (black color enhancement) prior to the cyclone transitioning to the occluded stage.

AVHRR Cloud Top Temperature product

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