Airborne glacial silt from the Copper River Valley in Alaska

October 28th, 2014
GOES-15 0.63 µm visible channel images (click to play animation)

GOES-15 0.63 µm visible channel images (click to play animation)

McIDAS images of GOES-15 0.63 µm visible channel data (above; click image to play animation) showed the hazy signature of airborne glacial silt drifting southward out of the Copper River valley and over the adjacent waters of the Gulf of Alaska on 28 October 2014. The strong winds lofting the silt were very localized to the Copper River valley itself, with cold dense arctic air from further inland (air temperatures were 8 to 10º F at Gulkana, PAGV) accelerating through narrow mountain passes — note how winds at nearby Cordova (PACV) were generally calm during much of the period. As the western edge of the airborne silt reached Middleton Island (PAMD), the surface visibility dropped as low as 5 miles.

AWIPS II images of Suomi NPP VIIRS data provided a better view of the aerial coverage of the glacial silt: a comparison of VIIRS 0.64 µm visible channel and 1.61 µm near-IR “snow/ice channel” images (below) showed that the 1.61 µm image offered better contrast to help locate the edges of the feature. This 1.61 µm channel imagery will be available from the Advanced Baseline Imager (ABI) on GOES-R.

Suomi NPP VIIRS 0.64 µm visible channel and 1.61 µm near-IR

Suomi NPP VIIRS 0.64 µm visible channel and 1.61 µm near-IR “snow/ice channel” images

Two consecutive VIIRS 1.61 µm images (below) revealed the changes in aerosol coverage between 21:43 UTC and 23:22 UTC.

Suomi NPP VIIRS 1.61 µm near-IR

Suomi NPP VIIRS 1.61 µm near-IR “snow/ice channel” images

The more dense portion of the airborne glacial silt particle feature exhibited a slightly warmer (darker gray) appearance on VIIRS 3.74 µm shortwave IR images, due to efficient reflection of incoming solar radiation.

Suomi NPP VIIRS 3.74 µm shortwave IR images

Suomi NPP VIIRS 3.74 µm shortwave IR images

A VIIRS true-color Red/Green/Blue (RGB) image from the SSEC RealEarth site (below) offered a good view of the coverage of the glacial silt at 21:45 UTC.

Suomi NPP VIIRS true-color image

Suomi NPP VIIRS true-color image

GOES Cloud Top Cooling Rate product used for SPC Mesoscale Discussion

September 17th, 2014
Storm Prediction Center Mesoscale Discussion #1724

Storm Prediction Center Mesoscale Discussion #1724

Using the GOES-R Cloud Top Cooling Rate product (applied to GOES-13 data), the Storm Prediction Center issued a Mesoscale Discussion (above) highlighting the risk of strong thunderstorms producing hail and/or strong wind gusts over parts of the Georgia/South Carolina border region on 17 September 2014. According to the SPC storm reports, there was hail up to 1.0 inch in diameter in addition to some tree and power line damage in southern South Carolina.

AWIPS II image combinations of the Cloud Top Cooling (CTC) rate product (colors) and the GOES-13 10.7 µm IR channel gray-scale images  (below; click image to play animation) showed that CTC rate values for the storm north of Augusta, Georgia (KAGS) at 19:00 UTC were as high as -16º C per 15 minutes; at 19:15 UTC, the CTC rate value for that storm was as high as -39º C per 15 minutes. The first Severe Thunderstorm Warning for this storm was later issued at 19:34 UTC.

Cloud Top Cooling Rate (colors) and GOES-13 10.7 µm IR (grayscale) images [click to play animation]

Cloud Top Cooling Rate (colors) and GOES-13 10.7 µm IR (grayscale) images [click to play animation]

GOES-13 10.7 µm IR channel images (below; click image to play animation) showed the rapidly cooling cloud-top IR brightness temperatures associated with these thunderstorms as they moved southeastward and intensified: the coldest value for the aforementioned thunderstorm was -40º C at 19:00 UTC, dropping to -62º C by 20:45 UTC.

GOES-13 10.7 µm IR channel images [click to play animation]

GOES-13 10.7 µm IR channel images [click to play animation]

About an hour later, another Severe Thunderstorm Warning was issued at 20:30 UTC for a storm near and south of Orangeburg, South Carolina (KOGB).

NASA Global Hawk flight to study Tropical Storm Dolly

September 2nd, 2014
NASA Global Hawk flight path, with Cloud Height, Tropical Overshooting Tops, and Lightning data (click to play animation)

NASA Global Hawk flight path, with Cloud Height, Tropical Overshooting Tops, and Lightning data (click to play animation)

The NASA Global Hawk aircraft are once again being used to study tropical cyclones during the 2014 season. As part of CIMSS participation in GOES-R Proving Ground activities, a Global Hawk flight path tool was developed to display important parameters such as ACHA Cloud Top Height, Tropical Overshooting Tops, and lightning (above; click image to play animation). Global Hawk pilots use this product to navigate the aircraft around locations of potential turbulence.

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

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

To support the Global Hawk investigation of Tropical Storm Dolly on 02 September 2014, the GOES-13 satellite was placed into Rapid Scan Operations (RSO) mode to provide images at 5-7 minute intervals. GOES-13 0.63 µm visible channel images (above; click to play animation) and 10.7 µm IR channel images (below; click to play animation) are shown which cover the 3-hour period of the Global Hawk flight segment shown above. There is evidence of overshooting tops seen in the visible imagery, with cloud-top IR brightness temperatures of -80º C and colder (purple color enhancement).

GOES-13 10.7 µm IR channel images (click to play animation)

GOES-13 10.7 µm IR channel images (click to play animation)

GOES-14 to begin SRSO imaging in August

August 8th, 2014
GOES-14 Visible Channel (0.62 µm) imager (click to enlarge)

GOES-14 Visible Channel (0.62 µm) imager (click to enlarge)

GOES-14 (positioned over the Equator at 105º West Longitude) Imager and Sounder instruments have been activated to support of SRSO-R operations, which are scheduled to begin Thursday 14 August. The first image acquired was shortly after 1530 UTC on 5 August; Image Navigation and Registration start-up was scheduled for 7-9 August, and the image above along the Gulf Coast shows that the navigation today is very accurate. Infrared imagery for the same time shows coldest cloud tops (over eastern Arkansas) near -65º C.

After a north-south maneuver on the 12th, GOES-14 1-minute imagery will begin to flow. The satellite is scheduled to return to standby mode on 29 August.

Satellite messages from NOAA, including those pertaining to GOES-14, can be viewed here.