Super Typhoon Atsani in the West Pacific Ocean

August 19th, 2015

Himawari-8 infrared (10.4 µm) imagery [click to play MP4 animation]

Himawari-8 infrared (10.4 µm) imagery [click to play MP4 animation]

Super Typhoon Atsani reached Category 5 intensity early in the day on 19 August 2015; the storm displayed a nearly annular eyewall signature during much of the day on Himawari-8 infrared (10.4 µm) images (above; click image to play MP4 movie file). A large (64 Mbyte) animated GIF is available here. Evidence of low-altitude mesovortices within the eye can be seen in the 2-km resolution infrared images.

A comparison of DMSP SSMIS microwave (85 GHz) and MSAT-2 infrared (10.8 µm) images around 20 UTC is shown below (courtesy of the CIMSS Tropical Cyclones site).

DMSP SSMIS microwave (85 GHz) image and MTSAT-2 infrared (10.8 µm) image [click to enlarge]

DMSP SSMIS microwave (85 GHz) image and MTSAT-2 infrared (10.8 µm) image [click to enlarge]

On the topic of eye mesovortices, a more detailed view of these features could be seen on daylight 0.64 µm visible images (below; click image to play MP4 animation). A large (28 Mbyte) animated GIF is available here.

Himawari-8 visible (0.64 um) images [click to play MP4 animation]

Himawari-8 visible (0.64 um) images [click to play MP4 animation]

Twin Typhoons in the western Pacific

August 17th, 2015

Himawari-8 10.35 µm IR images [click to play animated GIF]

Himawari-8 10.35 µm IR images [click to play animated GIF]

Himawari-8 captured the trek of Typhoons Goni (on the left) and Atsani (on the right) as they moved across the central Pacific Ocean on Monday 17 August 2015 (animation also available here as an mp4). Goni has passed through the northern Mariana Islands and is forecast to fluctuate in intensity as it moves towards Asia. Atsani’s predicted path is towards the northwest; it is forecast to intensify to a Category 5 Super Typhoon. Both storms are moving across very warm ocean waters (Goni, Atsani), and deep layer wind shear values are low (below). Sea Surface Ttemperature and Wind Shear products are available from the CIMSS Triopical Cyclones site.

Satellite-derived Wind Shear over the Pacific Ocean, 1800 UTC 17 August 2015 [click to enlarge]

Satellite-derived Wind Shear over the Pacific Ocean, 1800 UTC 17 August 2015 [click to enlarge]

Late in the day on 17 August, a comparison of MTSAT-2 infrared (10.8 µm) and DMSP SSMIS microwave (85 GHz) imagery of Category 3 Typhoon Atsani around 2232 UTC (below) showed a rather ragged-looking eye on the infrared image and evidence of a eyewall replacement cycle (ERC) occurring on the microwave image. The ERC process often indicates that a change in tropical cyclone intensity will soon take place.

MTSAT-2 infrared (10.8 µm) and DMSP SSMIS microwave (85 GHz) images of Typhoon Atsani [click to enlarge]

MTSAT-2 infrared (10.8 µm) and DMSP SSMIS microwave (85 GHz) images of Typhoon Atsani [click to enlarge]

What is remarkable in this case of “twin typhoons” in the West Pacific basin is that the MIMIC-TC product indicated that both Atsani and Goni were undergoing ERCs at about the same time (below).

MIMIC-TC product for Typhoon Atsani [click to enlarge]

MIMIC-TC product for Typhoon Atsani [click to enlarge]

MIMIC-TC product for Typhoon Goni [click to enlarge]

MIMIC-TC product for Typhoon Goni [click to enlarge]

A multi-day YouTube animation of Himawari-8 10.35 µm infrared imagery shows the upscale development of Goni and Atsani in the central Pacific. The loop runs from 13 August through 1200 UTC on 18 August.

Explosion in Tianjin, China

August 12th, 2015

Himawari-8 (3.9 µm, top), MTSAT-2 (3.75 µm, middle) and COMS-1 (3.75 µm, bottom) shortwave infrared imagery, times as indicated [click to animate]

Himawari-8 (3.9 µm, top), MTSAT-2 (3.75 µm, middle) and COMS-1 (3.75 µm, bottom) shortwave infrared imagery, times as indicated [click to animate]

A storage facility in Tianjin, China exploded shortly after 1500 UTC on 12 August 2015 (media story). Himawari-8, MTSAT-2 and COMS-1 all viewed the explosion that generated a strong thermal signature in the shortwave infrared band (3.75 µm – 3.9 µm). The animation above shows the benefit of Himawari-8’s speedier scanning mode: the smoke clouds that emanate from the explosion are easily traced, and data gaps when Full Disk images are being scanned (around 1800 UTC) are not present. Superior spatial resolution of Himawari-8 infrared channels (2-km, compared to 4-km for COMS-1 and MTSAT-2) means hotter brightness temperatures are sensed as well. The fact that smoke resulting from the explosion was seen spreading northeastward, southeastward, and southwestward was due to a marked shift in wind direction with height, as seen in the nearby Beijing rawinsonde report.

The explosion exhibted a signal in other Himawari-8 AHI bands as well. Band 5, at 1.6 µm and Band 6, at 2.3 µm are shown below (animations courtesy of William Straka, CIMSS); Similar animations are available for 3.9 µm, 6.2 µm (very faintly visible in this upper tropospheric water vapor channel), 7.0 µm, 7.3 µm and 8.6 µm and 10.35 µm.

Himawari-8 1.6 µm near-Infrared Imagery, times as indicated [click to enlarge]

Himawari-8 1.6 µm near-Infrared Imagery, times as indicated [click to animate]

Himawari-8 1.6 µm near-Infrared Imagery, times as indicated [click to animate]

Himawari-8 1.6 µm near-Infrared Imagery, times as indicated [click to animate]

A view of Himawari-8 shortwave IR imagery using the SSEC RealEarth web map server is shown below. In addition, an animation of Himawari-8 true-color images showing the dark smoke plume can be seen here.

Himawari-8 shortwave IR (3.9 um) images, displayed using RealEarth [click to enlarge]

Himawari-8 shortwave IR (3.9 um) images, displayed using RealEarth [click to enlarge]


========================== Added 14 August 2015 ===================

Suomi NPP VIIRS Day/Night Band (0.70 um) visible images on 9 August (before explosion) and 13 August (after explosion) [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.70 um) visible images on 9 August (before explosion) and 13 August (after explosion) [click to enlarge]

The Suomi NPP satellite overflew Tianjin before and after the explosion; VIIRS Day/Night Band images afford views that suggest power outages around the explosion site.

Unusual Double Eyewall structure in Himawari-8 Infrared Imagery of Typhoon Nangka

July 13th, 2015
Himawari-8 10.35 µm infrared imagery, 0540-1540 UTC on 13 July 2015 (Click to animate)

Himawari-8 10.35 µm infrared imagery, 0540-1540 UTC on 13 July 2015 (click to animate)

Himawari-8 10.35 µm infrared imagery showed an unusual (for infrared imagery) double-eyewall structure in Typhoon Nangka over the western Pacific Ocean on 13 July 2015. For such a feature to appear in infrared imagery, the secondary circulations of both the inner and outer eyewall need to be intense enough to support the downdraft/cloud-clearing necessary to create the “moats” between them. Microwave imagery of the storm, below, viewed via MIMIC (from this site), also showed the double eyewall structure quite well. This double-eyewall signature typically indicates that a tropical cyclone is experiencing an eyewall replacement cycle (ERC), which signals that a (temporary) decrease in intensity is soon to follow.

MIMIC imagery of Typhoon Nangka, 0000 - 1200 UTC on 13 July 2015 (Click to enlarge)

MIMIC imagery of Typhoon Nangka, 0000 – 1200 UTC on 13 July 2015 (click to enlarge)

Several hours later, a DMSP SSMIS 85 GHz microwave image at 1756 UTC, below, indicated that the ERC was essentially complete. Subsequently, the Joint Typhoon Warning Center slightly downgraded the intensity of Typhoon Nangka for their 21 UTC advisory. While not as well-defined as in the Himawari-8 imagery, the double-eyewall signature was still evident in the lower-resolution (4-km, vs  2-km) MTSAT-2 IR imagery (animation).

DMSP SSMIS 85 GHz microwave image and MTSAT-2 10.8 µm Infrared image (click to enlarge)

DMSP SSMIS 85 GHz microwave image and MTSAT-2 10.8 µm Infrared image (click to enlarge)

The Himawari-8 Target Sector was centered over Typhoon Nangka during this time; an IR image animation with a 2.5-minute timestep, below (courtesy of William Straka, SSEC), showed the evolution of the double eyewall signature, along with 2 pulses of storm-top gravity waves which propagated radially outward away from the center in the northern semicircle of the typhoon.

Himawari-8 10.4 µm IR channel images (click to animate large 115-Megabyte file)

Himawari-8 10.4 µm IR channel images (click to animate large 115-Megabyte file)