Rammasun makes landfall in southern China

July 18th, 2014 |

COMS-1 10.8 µm infrared channel images [click to play animation]

COMS-1 10.8 µm infrared channel images [click to play animation]

Super Typhoon Rammasun has made landfall in southern China – apparently this was the strongest typhoon to hit the South China region in 41 years (news story). The COMS-1 IR animation, above, shows the storm skirting along the north shore of the island of Hainan before hitting the south shore of the Leizhou Peninsula. A plot of the CIMSS Advanced Dvorak Technique indicated that Rammasun went though a period of rapid intensification on 17 July before reaching Super Typhoon intensity around 00 UTC on 18 July. The projected path (from this site) of the storm has it moving across the Gulf of Tonkin (where very warm Sea Surface Temperatures are present) and making landfall near the Vietnam/China border.

Past and Projected path of Rammasun, with Sea Surface Temperatures [click to enlarge]

Past and Projected path of Rammasun, with Sea Surface Temperatures [click to enlarge]

Visible imagery (below) captured the eye as it approached Hainan and then moved into the Qiongzhou strait between the island and the mainland. Note the initially mostly clear eye (with embedded small-scale vortices) rapidly fills after landfall.

COMS-1 0.675 µm infrared channel images [click to play animation]

COMS-1 0.675 µm infrared channel images [click to play animation]

A DMSP SSMIS 85 GHz microwave image (below) showed a well-defined eyewall at 1016 UTC.

DMSP SSMIS 85 GHz microwave image

DMSP SSMIS 85 GHz microwave image

A comparison of Suomi NPP VIIRS 11.45 µm IR and 0.7 µm “visible image at night” Day/Night Band data at 1735 UTC on 17 July (below; courtesy of William Straka, SSEC) revealed an interesting packet of waves in the southeastern quadrant of the eyewall region of the tropical cyclone.

Suomi NPP VIIRS 11.45 µm IR and 0.7 µm Day/Night Band images

Suomi NPP VIIRS 11.45 µm IR and 0.7 µm Day/Night Band images

Typhoon Neoguri threatens Okinawa

July 7th, 2014 |
COMS-1 0.675 µm and MTSAT-2 0.73 µm Visible channel images (Click to enlarge)

COMS-1 0.675 µm and MTSAT-2 0.73 µm Visible channel images (Click to enlarge)

Typhoon Neoguri is forecast to move west of Okinawa later today. The visible images above, from COMS-1 (left) and MTSAT-2 (right) show the storm at around 0800 UTC on 7 July 2014. A distinct eye filled with low-level clouds is apparent.

COMS-1 (left) and MTSAT-2 (right) visible channel images [click to play animation]

COMS-1 (left) and MTSAT-2 (right) visible channel images [click to play animation]

Magnified views of the storm center (above; click image to play animation; also available as an MP4 movie file) revealed the presence of mesovortices within the eye of Neoguri. The more frequent imaging schedule of COMS-1 (generally every 15 minutes, compared to every 30 minutes with MTSAT-2) allowed the cyclonic circulation of the mesovortices to be more easily identified. Another curious feature seen on the early morning visible imagery was a northwest-to-southeast oriented “cloud cliff” shadow just north of the eye, which was cast by the taller clouds of an eyewall convective burst just to the east. This same signature was seen again on the following morning, in nearly the same location relative to the eye (MTSAT-2 visible/IR image comparison).

METOP-B ASCAT winds over Neoguri and Observed SSTs (Click to toggle)

METOP-B ASCAT winds over Neoguri and Observed SSTs (Click to toggle)

ASCAT winds from METOP-B (above) show the structure of the typhoon, with 70-knot winds indicated. The Sea Surface Temperature (SST) image (taken from the CIMSS Tropical Cyclones site) also shows the extreme warmth of the western Pacific Ocean.

COMS-1 10.8 µm and MTSAT-2 10.8 µm Infrared channel images (Click to animate)

COMS-1 10.8 µm and MTSAT-2 10.8 µm Infrared channel images (Click to animate)

Infrared imagery from the past 24 hours show a decline in the satellite structure of the storm. Cold cloud tops have eroded from the northern and western quadrants of the storm, and a circular ring of cold cloud tops around the eye is no longer apparent.

Suomi NPP VIIRS 11.45 µm  Infrared channel image (Click to enlarge)

Suomi NPP VIIRS 11.45 µm Infrared channel image (Click to enlarge)

Suomi NPP overflew the storm on Saturday 5 July at 1620 UTC. The color-enhanced VIIRS 11.45 IR image, above (courtesy William Straka, SSEC/CIMSS), shows very cold cloud tops (185 K) southeast of a developing eye.

Super Typhoon Haiyan

November 7th, 2013 |
COMS-1 10.8 µm IR channel images (click to play animation)

COMS-1 10.8 µm IR channel images (click to play animation)

Super Typhoon Haiyan (31W) formed as a tropical depression at low latitudes in the West Pacific Ocean on 03 November 2013 — and by 18 UTC on 07 November was estimated to have peaked at an intensity of sustained 170 knot winds with gusts to 205 knots (Storm track map | ADT plot | JTWC warning text). McIDAS images of 15-minute interval 10.8 µm IR channel data from the Korean COMS-1 satellite (above; click image to play animation; a YouTube video is also available) showed the intense tropical cyclone as it moved westward and made landfall in the Philippines on 07 November. There was a large, nearly symmetric ring of very cold cloud-top IR brightness temperatures in the -80 to -90º C range (violet colors) — and at times there were a few isolated pixels colder than -90º C (yellow enhancement). For comparison, a YouTube video of MTSAT-1 10.8 µm IR imagery is also available.

As the eye was still east of the Philippines, a McIDAS-V image comparison of 375-m resolution Suomi NPP VIIRS 0.7 µm Day/Night Band (DNB) and 11.45 µm IR channel data at 16:15 UTC on 07 November (below; courtesy of William Straka, CIMSS) revealed intricate banding structures within the eyewall region on the IR image, as well as bright streaks on the DNB image due to cloud illumination by intense lightning activity.

Suomi NPP VIIRS 0.7 µm Day/Night Band and 11.45 µm IR channel images

Suomi NPP VIIRS 0.7 µm Day/Night Band and 11.45 µm IR channel images

The eye and eyewall of Haiyan moved over the eastern Philippine islands of Samar and Leyte (near the city of Tacloban) during the early morning hours, as can be seen in COMS-1 0.675 µm visible channel images (below; click image to play animation; a YouTube video is also available)

COMS-1 0.675 µm visible channel images (click to play animation)

COMS-1 0.675 µm visible channel images (click to play animation)

 

DMSP SSMIS 85 GHz microwave brightness temperature image

DMSP SSMIS 85 GHz microwave brightness temperature image

The nearly annular structure of the eyewall at 21:08 UTC on 07 November was revealed on a DMSP SSMIS 85 GHz microwave image (above) from the CIMSS Tropical Cyclones site. In addition, a sequence of eyewall replacement cycles can be seen during the 06-07 November period using the MIMIC-TC product (below). It appears as though Super Typhoon Haiyan was in the process of undergoing another eyewall replacement cycle as it was making landfall in the Philippines.

MIMIC-TC morphed microwave imagery (click image to play animation)

MIMIC-TC morphed microwave imagery (click image to play animation)

Regarding the size of and very cold cloud-top IR brightness temperatures seen with Super Typhoon Haiyan, the IR images below (courtesy of Rick Kohrs, SSEC) show a side-by-side comparison with Category 5 Hurricane Katrina (Haiyan has been artifically superimposed at the same location over the Gulf of Mexico). Note the significantly colder cloud-top IR brightness temperatures associated with Haiyan (-80 to -89 C, violet colors), due to its location in the tropics (near 10 N latitude) where the tropopause was much higher and much colder.

IR image comparison of Haiyan (left) and Katrina (right)

IR image comparison of Haiyan (left) and Katrina (right)

It is interesting to note that during the previous daytime hours (on 06 November), a series of mesovortices could be seen within the eye of Haiyan on COMS-1 visible images (below; click image to play animation; a YouTube video is also available). For more discussion on these mesovortices, see the From the Lee Side blog.

COMS-1 0.675 µm visible channel images (click to play animation)

COMS-1 0.675 µm visible channel images (click to play animation)

 

Sea Surface Temperature analysis (with track of Haiyan)

Sea Surface Temperature analysis (with track of Haiyan)

As pointed out in the Joint Typhoon Warning Center prognostic reasoning bulletin, factors that favored the intensification of Super Typhoon Haiyan included warm sea surface temperatures (above) and low values of deep layer wind shear (below).

MTSAT IR images with overlay of Deep Layer Wind Shear contours

MTSAT IR images with overlay of Deep Layer Wind Shear contours

11 November Update: A McIDAS-V image comparison of  “before Haiyan” (31 October) and “after Haiyan” (09 November) night-time Suomi NPP VIIRS 0.7 µm Day/Night Band data (below; courtesy of William Straka, SSEC/CIMSS) showed the extent of the power outages in the Tacloban City area and other towns in the northern portion of Leyte province, caused by devastating damage sustained during the landfall of the powerful typhoon.

Suomi/NPP Day/Night Band Imagery before and after Haiyan

Suomi/NPP Day/Night Band Imagery before and after Haiyan

21 November update: Rick Kohrs (SSEC) created a large (72 megabyte) animation of hourly MTSAT-1 6.75 µm water vapor channel imagery — covering the life span of Haiyan during the 03-11 November period — superimposed on a Sea Surface Temperature background (below; click image to play animation; a YouTube video is also available).

MTSAT-1 6.75 µm water vapor images, superimposed on a Sea Surface Temperature background (click to play animation)

MTSAT-1 6.75 µm water vapor images, superimposed on a Sea Surface Temperature background (click to play animation)