Bennett Island cloud plume

February 14th, 2013
Suomi NPP VIIRS 11.45 µm IR channel images (click image to play animation)

Suomi NPP VIIRS 11.45 µm IR channel images (click image to play animation)

AWIPS II images of 375-meter resolution Suomi NPP VIIRS 11.45 µm IR channel images (above; click image to play animation) captured an example of a “Bennett Island cloud plume” off the north coast of Siberia on 13-14 February 2013. Minimum IR brightness temperature values reached -51 C during the early stages of plume development. Due to the orientation of the AWIPS II Northern Hemisphere map projection, the images were rotated 90 degrees to the left, so that North was approximately toward the top of the images. Full-resolution (375-meter) VIIRS data are now being distributed to Alaska Region AWIPS II users.

Suomi NPP VIIRS 11.45 µm IR image with GFS190 500 hPa wind barbs

Suomi NPP VIIRS 11.45 µm IR image with GFS190 500 hPa wind barbs

A VIIRS IR image with an overlay of GFS190 model 500 hPa winds (above) showed a generally light southeasterly flow of 10-20 knots across the region. This was in good agreement with rawinsonde data (below) from the Chokurdah, Russia site (located south of Bennett Island, over northern Siberia).

 

Chokurdah, Russia rawinsonde data plot

Chokurdah, Russia rawinsonde data plot

 

Kelvin-Helmholtz billows: a satellite signature of turbulence potentital?

February 10th, 2013

MODIS 0.65 µm visible, 11.0 µm IR, and 6.7 µm water vapor channel images

A comparison of AWIPS images of 1-km resolution MODIS 0.65 µm visible channel, 11.0 µm IR channel, and 6.7 µm water channel data (above) revealed subtle Kelvin-Helmholtz (K-H) billow features across parts of eastern Iowa on 10 February 2013 that were only apparent in the water vapor imagery. In the vicinity of these elongated mesoscale wave signatures, there were a few pilot reports of light to moderate turbulence (primarily within the 14,000-21,000 foot altitude range).

An animation of 4-km resolution GOES-13 6.5 µm water vapor images (below) did not show any evidence of these K-H billow features within the dry slot that was wrapping around the center of a large and intense winter storm that was producing blizzard conditions from Nebraska to North Dakota.

GOES-13 6.5 µm water vapor channel images (click image to play animation)

GOES-13 6.5 µm water vapor channel images (click image to play animation)

A comparison of the 1-km resolution MODIS water vapor image with the corresponding 4-km resolution GOES-13 water vapor image (below) demonstrated the advantage of improved spatial resolution for the detection of such potentially-important mesoscale features. The slight northwestward shift of features seen on the GOES-13 water vapor image is due to parallax.

MODIS 6.7 µm and GOES-13 6.5 µm water vapor channel images

MODIS 6.7 µm and GOES-13 6.5 µm water vapor channel images

Blowing dust over New Mexico and Texas

February 9th, 2013
GOES-13 0.63 µm visible channel images (click image to play animation)

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

McIDAS images of GOES-13 0.63 µm visible channel data (above; click image to play animation) showed the development of widespread plumes of blowing dust over parts of New Mexico and Texas on 09 February 2013. Surface wind gusts across the region were as high as 79 mph in New Mexico and 71 MPH in Texas. Most of the blowing dust appeared to have originated from dry lake beds in northern Mexico, but early in the animation a narrow dust plume can be seen whose source region was White Sands, New Mexico. Due to an increasingly favorable forward scattering angle, the dust became more apparent on the visible imagery during the afternoon hours.

A comparison of AWIPS images of 1-km resolution MODIS 0.65 µm visible channel and 1.61 µm near-IR “cirrus detection channel” data (below) demonstrated how the MODIS cirrus channel can be used to more accurately identify the leading edge of the airborne dust over eastern New Mexico — the 1.61 µm channel can detect the presence of partcles that are efficient scatterers of light (such as cirrus cloud ice crystals, volcanic ash, smoke, dust).

MODIS 0.65 µm visible channel image and 1.61 µm near-IR

MODIS 0.65 µm visible channel image and 1.61 µm near-IR “cirrus detection channel” image

A closer view using 250-meter resolution Terra (18:28 UTC) and Aqua (20:04 UTC) MODIS true-color Red/Green/Blue (RGB) images from the SSEC MODIS Today site (below) helped to identify a few of the blowing dust source regions in far northern Mexico.

Terra and Aqua MODIS true-color Red/Green/Blue (RGB) images

Terra and Aqua MODIS true-color Red/Green/Blue (RGB) images

Development of an intense winter storm off the US East Coast

February 8th, 2013
POES AVHRR 0.86 µm, MODIS 0.65 µm, and Suomi NPP VIIRS 0.64 µm visible channel images

POES AVHRR 0.86 µm, MODIS 0.65 µm, and Suomi NPP VIIRS 0.64 µm visible channel images

A winter storm began to intensify just off the East Coast of the US on 08 February 2013. A sequence of 1-km resolution POES AVHRR 0.86 µm, MODIS 0.65 µm, and Suomi NPP VIIRS 0.64 µm visible channel images (above) revealed the formation of gravity waves in the lower-tropospheric cloud field within the southwest quadrant of the area of low pressure (corresponding IR images).

GOES-13 4-km resolution 6.5 µm water vapor channel images (below; click image to play animation) showed a very well-defined dry slot and the development of a distinct comma head. Strong northwesterly winds were also causing mountain waves to the lee of the Appalachians.

GOES-13 6.5 µm water vapor channel images (click image to play animation)

GOES-13 6.5 µm water vapor channel images (click image to play animation)

The MIMIC Total Precipitable Water (TPW) product (below; click image to play animation) showed TPW values as high as 48 mm or 1.9 inches being drawn northward into the intensifying low.

MIMIC Total Precipitable Water product (click image to play animation)

MIMIC Total Precipitable Water product (click image to play animation)

Similarly, the Blended Total Precipitable Water product (below; click image to play animation) also showed high values of TPW (up to 36 mm or 1.4 inches) off the Virginia/North Carolina coast as the low was intensifying.

Blended Total Precipitable Water product (click image to play animation)

Blended Total Precipitable Water product (click image to play animation)

These TPW values were in excess of 200% of normal for this region and this time of year (below; click image to play animation).

Percent of Normal TPW product (click image to play animation)

Percent of Normal TPW product (click image to play animation)

A MODIS 11.0 µm IR image at 03:04 UTC on 09 February (10:04 PM local time on 08 February) revealed a distinct hook-shaped pattern to the cloud features near the storm center as it continued to intensify (below). Peak wind gusts at this time were 58 knots at Nantucket and 54 knots at Boston.

MODIS 11.0 µm IR image with overlays of surface/buoy resports and surface analysis

MODIS 11.0 µm IR image with overlays of surface/buoy resports and surface analysis

===== 09 February Update =====

MODIS 0.65 µm visible image with surface/buoy reports and surface analysis

MODIS 0.65 µm visible image with surface/buoy reports and surface analysis

As the storm was nearing peak intensity on the morning of 09 February 2013, the formation of a tight circulation around its center was becoming evident in 1-km resolution visible channel images with overlays of surface data from MODIS at 15:06 UTC (above) and VIIRS at 17:01 UTC (below).

Suomi NPP VIIRS 0.64 µm visible image with surface/buoy reports

Suomi NPP VIIRS 0.64 µm visible image with surface/buoy reports

A 250-meter resolution MODIS true-color Red/Green/Blue (RGB) image from the SSEC MODIS Today site (below; displayed using Google Earth) showed the locations of maximum snowfall totals for select states (which included 40.0 inches at Hamden, Connecticut), as well as some of the maximum wind gusts (which included 83 mph at Cuttyhunk, Massachusetts).

MODIS true-color Red/Green/Blue (RGB) image with maximum storm total snowfall amounts and peak wind gusts

MODIS true-color Red/Green/Blue (RGB) image with maximum storm total snowfall amounts and peak wind gusts

GOES-13 Water Vapor imagery, displayed in a 2-day loop below, captures many interesting aspects of this potent storm.

GOES-13 6.5 µm water vapor channel images (click image to play animation)

GOES-13 6.5 µm water vapor channel images (click image to play animation)