GOES sounder « CIMSS Satellite Blog

GOES-15: improved spatial resolution water vapor channel

September 14th, 2011

GOES-11 6.7 µm (left) and GOES-15 6.5 µm (right) water vapor channel images (click image to play animation)

McIDAS images of 8-km resolution GOES-11 6.7 µm and 4-km resolution GOES-15 6.5 µm water vapor channel data (above) demonstrated the advantage of improved spatial resolution for the detection of features and gradients in the water vapor imagery associated with a weak upper level low moving eastward across the southwestern US on 14 September 2010. GOES-15 is scheduled to replace GOES-11 as the operational GOES-West satellite in December 2011.

AWIPS images of the GOES-11 sounder Convective Available Potential Energy (CAPE) product (below) showed that the atmosphere was destabilizing in advance of the upper low, with CAPE values in the 1000-2000 J/kg range.

GOES-11 sounder Convective Available Potential Entegy (CAPE)

With the increasing instability and large scale lift ahead of the upper low, areas of thunderstorms developed over parts of Nevada, Arizona, and Utah, as seen on a MODIS 11.0 µm IR image with an overlay of cloud-to-ground lightning strikes (below). About an hour after the time of the MODIS image, one of these storms produced 1.0-inch diameter hail that covered the ground near Munds in northern Arizona (SPC storm reports).

MODIS 11.0 µm IR image + cloud-to-ground lightning strikes

CIMSS participation in GOES-R Proving Ground activities includes making a variety of MODIS and additional GOES Sounder 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.

Posted in GOES sounder, GOES-11, GOES-15, GOES-R, Lightning, MODIS, Severe convection | No Comments »

NWS forecast office use of MODIS TPW product

August 27th, 2011

MODIS Total Precipitable Water product

The National Weather Service forecast office in Salt Lake City, Utah referred to the MODIS Total Precipitable Water (TPW) product (above) in their afternoon forecast discussion on 27 August 2011:

FXUS65 KSLC 272201
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
355 PM MDT SAT AUG 27 2011

.SYNOPSIS...HIGH PRESSURE NEAR THE FOUR CORNERS WILL DRIFT WEST AND
WEAKEN ON SUNDAY. A VERY MOIST AIRMASS WILL REMAIN IN PLACE SUNDAY
BRINGING SCATTERED THUNDERSTORMS TO UTAH. WESTERLY FLOW WITH A
GRADUAL DRYING TREND IS THEN EXPECTED ON MONDAY AND TUESDAY.

.DISCUSSION...UPPER LEVEL AREA OF HIGH PRESSURE REMAINS CENTERED
NEAR THE FOUR CORNERS AREA THIS AFTERNOON...KEEPING A VERY MOIST
AIRMASS IN PLACE ACROSS UTAH. GPS-MET SENSOR CONTINUES TO SHOW THAT
COLUMN PRECIPITABLE WATER IS HOVERING AROUND 1.20 INCHES IN SALT
LAKE CITY.  AFTERNOON MODIS IMAGERY INDICATES THAT PRECIPITABLE
WATER VALUES ARE GENERALLY 1.0 TO 1.25 INCHES STATEWIDE.

The MODIS TPW values were in general agreement with those seen on the GOES sounder TPW product (below), but with finer spatial resolution (4-km MODIS, vs 10-km GOES) the various TPW gradients appear smoother on the MODIS image.

GOES sounder Total Precipitable Water product

The Blended TPW product (below) displayed complete coverage (even in cloudy areas), but lacked the finer scale definition of the MODIS or GOES products due to the use of only Global Positioning System derived TPW data over inland areas.

Blended Total Precipitable Water product

The Percent of Normal TPW product (below) indicated that the TPW values present across the region were generally 150-200% above normal for the date.

Percent of Normal TPW product

Their forecast discussion went on to state:

AIRMASS QUICKLY DESTABILIZED IN THE EARLY AFTERNOON WITH SCATTERED
CONVECTION FORMING IN THE SOUTH AND EAST AND MORE ISOLATED COVERAGE
IN THE NORTHWEST.

The MODIS 0.65 µm visible channel image (below) showed the areas where organized convection had already developed across Utah and the surrounding states.

MODIS 0.65 µm visible chanel image

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. In addition, the VISIT training lesson “MODIS Products in AWIPS” is available to help users understand these products and their applications to weather analysis and forecasting.

Posted in GOES sounder, GOES-R, MODIS | No Comments »

Long-range transport of wildfire smoke arriving over Wisconsin

August 25th, 2011

GOES-13 0.63 µm visible channel images (click image to play animation)

AWIPS images of GOES-13 0.63 µm visible channel data (above; click image to play animation) showed an interesting swirl of smoke aloft which moved eastward across the Upper Midwest region during the late afternoon hours on 25 August 2011.

The curved shape of the smoke feature was due to the cyclonic circulation associated with a transient potential vorticity (PV) anomaly, which was lowering the dynamic tropopause (taken to be the pressure level of the PV1.5 surface) as it moved eastward. A comparison of 1-km resolution MODIS 0.65 µm visible channel, 1-km resolution MODIS 6.7 µm water vapor channel, and 10-km resolution GOES-13 Total Column Ozone product images (below) showed that the PV anomaly was lowering the tropopause to about the 375 hPa pressure level. Upward vertical motion ahead of the PV anomaly was producing a “moist signal” on the MODIS water vapor image (but no clouds were yet seen on the corresponding MODIS visible image). In addition, GOES sounder Total Column Ozone levels were slightly elevated in the vicinity of this PV anomaly (as high as 340 Dobson Units, green color enhancement), compared to the background ozone levels of 100-110 Dobson Units.

MODIS visible and water vapor images + GOES-13 sounder Total Column Ozone product

It is interesting to note that the smoke feature did not exhibit any signal on the 1-km resolution MODIS 3.7 µm shortwave IR or 11.0 µm IR window images (below) — such thin smoke layers are effectively transparent to the warmer thermal radiation reaching the satellite from below. On the other hand, the hot signatures of cities and urban areas (showing up as darker black pixels) were quite obvious on the IR images.

MODIS 0.63 µm visible, MODIS 3.7 µm shortwave IR, and MODIS 11.0 µm IR window channel images

However, the smoke feature did exhibit a well-defined signature on the MODIS 1.4 µm near-IR “cirrus detection channel” image (below) — this channel is sensitive to any airborne particles that are efficient scatters of light (such as ice crystals, smoke, dust, volcanic ash, etc).

MODIS 0.65 µm visible channel and MODIS 1.4 µm "cirrus detection channel" images

As the smoke aloft began to approach Madison (station identifier KMSN on the satellite images) the feature was captured by the west-facing camera on top of the Atmospheric, Oceanic, and Space Sciences building on the University of Wisconsin campus (below; click image to play QuickTime animation). The airborne smoke layer contributed to a colorful yellow/orange sunset.

AOSS building west-facing rooftop camera images (click to play QuickTime animation)

NOAA ARL HYSPLIT model backward trajectories (below) showed that air parcels arriving over Madison (around the time that the leading edge of the smoke aloft moved overhead) had likely originated over Idaho and Wyoming, where several large wildfires had been burning during the previous days. Other fires burning across southeastern Montana may have also contributed to this smoke.