MTSAT « CIMSS Satellite Blog

Fatal tornado event in Japan

May 6th, 2012

MTSAT-2 6.7 µm water vapor channel images (click image to play animation)

Tornadoes are relatively rare in Japan, and the majority of them occur in association with tropical cyclones — but a tornado struck the city of Tsukuba, Japan on 06 May 2012, and was responsible for one fatality, over 40 injuries, and damage (rated F2 to F3) to nearly 500 homes and buildings. MTSAT-2 6.7 µm water vapor channel images (above; click image to play animation) showed that strong convection developed over Japan along the eastern periphery of a large upper-level low. The location of Tokyo Narita International Airport (station identifier RJAA) is overlaid on the images — Tsukuba is about 30 miles northwest of RJAA.

Also important to note on the water vapor imagery (prior to 05 UTC) was the appearance of a small area of lee waves immediately downwind of the Mt. Fuji area (just to the west of RJAA), suggesting the presence of a strong jet streak moving northeastward over the Japanese island of Honshu. A longer animation showed the development of a number of distinct cyclonic vortices, many marked by a pronounced warm/dry signature on the water vapor imagery. These vortices corresponded to individual Potential Vorticity (PV) anomalies; one of the stronger PV anomalies moved just south of RJAA and helped to initiate a new cluster of convection offshore toward the end of the long animation.

A closer view using MTSAT-2 10.8 µm IR channel images (below; click image to play animation) showed that cloud top IR brightness temperatures associated with the tornadic supercell quickly cooled to the -55 to -60º C range (darker red color enhancement), and exhibited subtle cold/warm thermal couplets and brief enhanced-V signature at 04:01 UTC.

MTSAT-2 10.8 µm IR channel images (click image to play animation)

MTSAT-2 0.7 µm visible channel images (below; click image to play animation) revealed subtle indications of overshooting tops, as well as a brief anvil plume (at 06:32 UTC). The hazy signature of a blowing dust plume was also evident just to the south and east of Japan.

MTSAT-2 0.7 µm visible channel images (click image to play animation)

The tornado was reported to have occurred at Tsukuba around 1 pm local time (05:00 UTC), with hail at Mito around 1:20 pm local time (05:20 UTC). The location of the tornado (T) and hail (H) are overlayed on a close-up view of the 05:01 UTC MTSAT-2 0.7 µm visible channel image (below), which showed a well-defined flanking line boundary of convection feeding northwestward into the parent thunderstorm.

MTSAT-2 0.7 µm visible image + Surface reports + Tornado and Hail report locations

Posted in MTSAT, Severe convection | No Comments »

Using polar-orbiter MODIS and AVHRR imagery to supplement degraded geostationary GOES imagery

March 22nd, 2012

MODIS 6.7 µm water vapor image + GOES-13 6.5 µm water vapor image

After 20:30 UTC on 21 March 2012, GOES-15 (GOES West) experienced a bad momentum unload, and at this point the satellite went into a sun acquisition mode (a “safe mode”) and stopped transmitting data (latest GOES-15 status messages). NOAA/NESDIS immediately began to operate GOES-13 (GOES East) in continuous Full Disk scan mode, in order to provide imagery as far west as possible every 30 minutes. However, due to the extreme viewing angle from GOES-13 (positioned over the Equator at 75 degrees West longitude), the image quality over the western US was degraded (since the effective pixel resolution was so large). In addition, Alaska, Hawaii, and the Pacific Region were effectively without useful GOES imagery (although some of these areas could make use of Japanese MTSAT imagery to help fill the GOES-15 imagery gap).

Shortly after the GOES-15 outage, AWIPS comparisons of a 1-km resolution MODIS 6.7 µm water vapor image with the corresponding GOES-13 6.5 µm water vapor image (above) as well as the MODIS 11.0 µm IR channel image and the corresponding GOES-13 10.7 µm IR image (below) demonstrate the value of using higher spatial resolution polar-orbiter (from the Terra and Aqua satellites) MODIS imagery to supplement the degraded geostationary GOES-13 imagery during the GOES-15 outage. In these 2 examples, the GOES-13 viewing angle for San Francisco, California is 65 degrees, making the effective resolution of the “4 km” IR and water vapor image pixels closer to 16 km. In addition, the large satellite viewing angles were creating a significant “parallax error“, shifting the apparent location of high cloud features to the northwest.

MODIS 11.0 µm IR image + GOES-13 10.7 µm IR image

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MODIS 6.7 µm water vapor image + GOES-13 6.5 µm water vapor image

On the following day, AWIPS comparisons of a MODIS 6.7 µm water vapor image with the corresponding GOES-13 6.5 µm water vapor channel image (above) as well as a MODIS 11.0 µm IR channel image with the corresponding GOES-13 10.7 µm IR channel image (below) showed a storm moving into the far southern panhandle of Alaska. In the case, the GOES-13 satellite viewing angles for Seattle, Washington and Juneau, Alaska were 71 degrees and 82 degrees, respectively.

MODIS 11.0 µm IR image + GOES-13 10.7 µm IR image

Similarly, an AWIPS comparison of a 1-km resolution POES AVHRR 12.0 µm IR image with the corresponding GOES-13 10.7 µm IR image (below) shows another source for polar-orbiter satellite imagery to supplement GOES in this type of situation.

POES AVHRR 12.0 µm IR image + GOES-13 10.7 µm IR image

CIMSS participation in GOES-R Proving Ground activities includes making a variety of POES AVHRR and MODIS images and products available for National Weather Service forecast offices to add to their local AWIPS workstations. Currently there are 57 NWS offices receiving MODIS imagery and products from CIMSS.

Posted in AVHRR, General interpretation, GOES-13, GOES-R, MODIS, MTSAT, POES | No Comments »

Occluding cyclone south of Australia

January 8th, 2012

MTSAT-2 6.75 µm water vapor channel images (click image to play animation)

A large area of low pressure over the Southern Ocean between Australia and Antarctica on 07 January – 08 January 2012 (surface analyses) exhibited a beautiful signature of an occluding cyclone on 5-km ressolution MTSAT-2 6.75 µm water vapor channel imagery (above; click image to play animation). This storm prompted the issuance of Gale Warnings for widespread areas of winds of 30-45 knots producing high seas.

A closer view of the MTSAT-2 water vapor imagery (below) revealed very intricate detail to the plume of dry air wrapping into the ceter of the storm, along with several small vortices of dry air that became cut off and isolated along the periphery of the system as it began to decay just southwest of the island of Tasmania.