Super Typhoon Megi makes landfall on Taiwan

September 27th, 2016

Himawari-8 0.64 µm Visible (top) and 10.4 µm Infrared Window (bottom) images [click to play MP4 animation]

Himawari-8 0.64 µm Visible (top) and 10.4 µm Infrared Window (bottom) images [click to play MP4 animation]

Super Typhoon Megi (20W) made landfall on the island of Taiwan as a Category 4 storm (CIMSS SATCON) on 27 September 2016, as seen on JMA Himawari-8 Visible (0.64 µm) and Infrared Window (10.4 µm) images (above; also available as a 69 Mbyte animated GIF). It is interesting to note the blossoming of cold cloud-top IR brightness temperatures of -80º C and colder (violet color enhancement) west of the island after landfall.

The MIMIC-TC product (below) showed that Megi was going through an eyewall replacement cycle around the time of landfall.

MIMIC-TC product [click to play animation]

MIMIC-TC product [click to play animation]

Super Typhoon Meranti

September 12th, 2016

Himawari-8 0.64 µm Visible (top) and 10.4 µm Infrared Window (bottom) images [click to play MP4 animation]

Himawari-8 0.64 µm Visible (top) and 10.4 µm Infrared Window (bottom) images [click to play MP4 animation]

Rapid-scan (2.5-minute interval) Himawari-8 AHI Visible (0.64 µm) and Infrared Window (10.4 µm) images (above; also avialable as a 33 Mbyte animated GIF) showed the pin-hole eye and cold cloud-top IR brightness temperatures (-80º C and colder, violet color enhancement) associated with Super Typhoon Meranti (16W) in the Philippine Sea on 11-12 September 2016. Note that the ABI instrument on GOES-R will provide similar 0.5-km resolution Visible and 2-km resolution Infrared imagery.

Himawari-8 Infrared Window (10.4 µm) image at 1230 UTC on 12 September, with 11 September images of Sea Surface Temperature and Ocean Heat Content [click to enlarge]

Himawari-8 Infrared Window (10.4 µm) image at 1230 UTC on 12 September, with 11 September images of Sea Surface Temperature and Ocean Heat Content [click to enlarge]

As Meranti was intensifying from a Category 4 to a Category 5 storm, it was passing over waters that exhibited both warm Sea Surface Temperatures and high Ocean Heat Content as seen on images from the CIMSS Tropical Cyclones site (above), and was also moving through an environment of very low deep-layer wind shear (below) — all factors that are favorable for tropical cyclone intensification.

Himawari-8 Infrared Window (10.4 µm) images, with satellite-derived 850-200 hPa deep layer wind shear [click to play animation]

Himawari-8 Infrared Window (10.4 µm) images, with satellite-derived 850-200 hPa deep layer wind shear [click to play animation]

Himawari-8 Infrared Window (10.4 µm) images (below; also available as an 89 Mbyte animated GIF) showed Meranti as a Category 5 storm during the nighttime hours on 12 September.

Himawari-8 Infrared Window (10.4 µm) images [click to play MP4 animation]

Himawari-8 Infrared Window (10.4 µm) images [click to play MP4 animation]

A comparison of a Himawari-8 Infrared Window (10.4 µm) image at 1830 UTC and a DMSP-15 SSMIS Microwave (85 GHz) image at 1847 UTC (below) again displayed the very small eye.

Himawari-8 Infrared Window (10.4 µm) and DMSP-15 SSMIS Microwave (85 GHz) images [click to enlarge]

Himawari-8 Infrared Window (10.4 µm) and DMSP-15 SSMIS Microwave (85 GHz) images [click to enlarge]

During the subsequent daytime hours (local time) on 12 September, another comparison of rapid-scan (2.5-minute interval) Himawari-8 Visible (0.64 µm) and Infrared Window (10.4 µm) images (below; also available as a 24 Mbyte animated GIF) continued to show a well-defined eye as Meranti maintained Category 5 intensity (ADT plot). Mesovortices could be seen spinning within the eye on the visible imagery during this time.

Himawari-8 0.64 µm Visible (top) and 10.4 µm Infrared Window (bottom) images [click to play MP4 animation]

Himawari-8 0.64 µm Visible (top) and 10.4 µm Infrared Window (bottom) images [click to play MP4 animation]

===== 13 September Update =====

Himawari-8 Infrared Window (10.4 µm) images [click to play MP4 animation]

Himawari-8 Infrared Window (10.4 µm) images [click to play MP4 animation]

Super Typhoon Meranti went through a secondary round of intensification on 13 September (ADT plot) , with the JTWC estimating maximum sustained winds of 165 knots with gusts to 200 knots at 21 UTC. CIMSS Satellite Consensus (SATCON) plots of wind and pressure indicated that Meranti reached peak intensity near the middle of the day. Himawari-8 Infrared Window (10.4 µm) images (above; also available as a 114 Mbyte animated GIF) continued to display a well-defined eye with an annular storm structure during this period. A faster version of the animated GIF better showed the pronounced trochoidal motion exhibited by the eye of Meranti, as it moved just south of the island of Taiwan.

Himawari-8 Infrared Window (11.45 µm) images [click to enlarge]

Himawari-8 Infrared Window (11.45 µm) images [click to enlarge]

The eye of Meranti passed directly over the small Philippine island of Itbayat, as seen on Himawari-8 Infrared Window (11.45 µm) images viewed using RealEarth (above).

Suomi NPP overflew Meranti around 1730 UTC, just as the eye of the storm was passing over Itbayat. In a toggle between VIIRS Infrared Window (11.45 µm) and Day/Night Band (0.7 µm) images (below; courtesy of William Straka, SSEC) ample lunar illumination provided a very good “visible image at night” which also included a bright lightning streak emanating from the eastern eyewall of the Category 5 storm. The image pair also shows a good example of the “stadium effect” eye geometry (where the eye diameter at the surface is smaller, and opens to a wider distance with increasing height). A larger-scale view of the entire storm from the Day/Night Band is available here; the corresponding 11.45 µm Infrared image is available here.

Suomi NPP VIIRS Infrared Window (11.45 µm) and Day/Night Band visible (0.70 µm) imagery of Meranti, 1735 UTC on 13 September 2016 [click to enlarge]

Suomi NPP VIIRS Infrared Window (11.45 µm) and Day/Night Band visible (0.70 µm) imagery of Meranti, 1735 UTC on 13 September 2016 [click to enlarge]

DMSP-15 SSMI Microwave (85 GHz) and Himawari-8 Infrared Window (11.45 µm) images [click to enlarge]


DMSP-15 SSMI Microwave (85 GHz) and Himawari-8 Infrared Window (11.45 µm) images [click to enlarge]

In a comparison of DMSP-15 SSMI Microwave (85 GHz) and Himawari-8 Infrared Window (11.45 µm) images around 1830 UTC (above), the appearance of concentric eyewalls on the microwave data suggested that Meranti was preparing to go through an eyewalll replacement cycle, which also signaled that the storm was perhaps near maximum intensity.

This formation of concentric eyewalls was nicely depicted by the MIMIC-TC product (below).

MIMIC-TC product [click to play animation]

MIMIC-TC product [click to play animation]

=====14 September Update =====

Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images [click to enlarge]


Less than 2 hours prior to landfall (which was around 1905 UTC on 14 September, over Xiamen City in the Fujian Province of China), a toggle between Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images at 1716 UTC (above) still showed well-defined curved banding structures around the center of of the Category 2 typhoon.

Himawari-8 Infrared Window (10.4 µm) images from pre-landfall at 0600 UTC on 14 September to post-landfall at 0600 UTC on 15 September (below; also available as a 47 Mbyte animated GIF) showed that Meranti quickly dissipated as it moved inland over mainland China. The images are centered on Xiamen (station identifier ZSAM); alternate animation versions with the BD grayscale enhancement are available in MP4 and animated GIF format.

Himawari-8 Infrared Window (10.4 µm) images [click to play MP4 animation]

Himawari-8 Infrared Window (10.4 µm) images [click to play MP4 animation]

About 4 hours after landfall, good curved banding structure was still observed in DMSP-18 SSMIS Microwave (85 GHz) imagery at 2314 UTC, while the overall presentation of the storm on Himawari-8 Infrared Window (11.45 µm) imagery began to deteriorate (below).

DMSP-18 SSMIS Microwave (85 GHz) and Himawari-8 Infrared Window (11.45 µm) images [click to enlarge]

DMSP-18 SSMIS Microwave (85 GHz) and Himawari-8 Infrared Window (11.45 µm) images [click to enlarge]

Typhoon Lionrock in the West Pacific

August 27th, 2016

Track of Typhoon Lionrock [click to enlarge]

Track of Typhoon Lionrock [click to enlarge]

Typhoon Lionrock (12W) in the West Pacific Ocean briefly intensified to Category 4 during the northeastward motion segment of its rather unusual track (above) — the intensity estimate from the Advanced Dvorak Technique peaked at 112.4 knots from 2140 UTC on 26 August to 0630 UTC on 27 August (plot | text).

During this period of intensification, 2.5 minute interval rapid-scan Himawari-8 Visible (0.64 µm) and Infrared Window (10.4 µm) images (below; also available as a large 85 Mbyte animated GIF) revealed complex patterns of cloud-top radial and transverse banding. Surface mesoscale vortices were also seen at times within the open eye feature.

Himawari-8 0.64 µm Visible (top) and 10.4 µm Infrared Window (bottom) images [click to play MP4 animation]

Himawari-8 0.64 µm Visible (top) and 10.4 µm Infrared Window (bottom) images [click to play MP4 animation]

A few hours later, the Category 3 intensity typhoon continued to exhibit a well-defined eye structure in both DMSP-15 SSMI Microwave (85 GHz) and Himawari-8 Infrared Window (10.4 µm) images around 18 UTC (below).

DMSP-15 SSMI Microwave (85 GHz) and Himawari-8 Infrared Window (10.4 µm) images [click to enlarge]

DMSP-15 SSMI Microwave (85 GHz) and Himawari-8 Infrared Window (10.4 µm) images [click to enlarge]

During the nighttime hours preceding the intensification to Category 4, a comparison of Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images (below; courtesy of William Straka, SSEC) showed the eye of Lionrock at 1631 UTC on 26 August.

Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images [click to enlarge]

===== 28 August Update =====

Himawari-8 0.64 µm Visible (top) and 10.4 µm Infrared Window (bottom) images [click to play MP4 animation]

Himawari-8 0.64 µm Visible (top) and 10.4 µm Infrared Window (bottom) images [click to play MP4 animation]

Typhoon Lionrock again intensified to a Category 4 storm on 28 August; a comparison of 2.5 minute interval rapid-scan Himawari-8 Visible (0.64 µm) and Infrared Window (10.4 µm) images is shown above (also available as a large 68 Mbyte animated GIF).

Super Typhoon Nepartak

July 7th, 2016

Track of Super Typhoon Nepartak (03 to 07 July 2016) [click to enlarge]

Track of Super Typhoon Nepartak (03 to 07 July 2016) [click to enlarge]

Super Typhoon Nepartak (02W) formed as a tropical depression in the West Pacific Ocean south of Guam on 02-03 July 2016, and tracked northwestward until making landfall in southern Taiwan on 07 July (above). Nepartak rapidly intensified to a Category 4 storm on 05 July, peaking at Category 5 intensity on 06 July (ADT | SATCON wind | SATCON pressure). Two factors helping the storm to reach and maintain Category 5 intensity for a relatively long period of time were (1) the passage over water having large Ocean Heat Content and Sea Surface Temperature values, and (2) an environment characterized by low deep-layer wind shear (06 July/15 UTC | 07 July/21 UTC).

2.5-minute interval rapid-scan Himawari-8 Infrared Window (10.4 µm) images (below) showed the formation of a well-defined eye with an annular storm structure early in the day on 07 July. The eye became less organized as Nepartak approached the island of Taiwan and made landfall as a Category 4 typhoon around 2150 UTC.

Himawari-8 Infrared Window (10.4 µm) images [click to play MP4 animation]

Himawari-8 Infrared Window (10.4 µm) images [click to play MP4 animation]

Surface observations (plot | text) from Feng Nin airport (station identifier RCFN) in Taitung City showed sustained winds of 70 knots (81 mph) with a gust to 99 knots (114 mph) from the north-northeast at 21 UTC, and a pressure of 964.0 hPa (27.47″). iCyclone chaser Josh Morgerman recorded a minimum pressure of 957.7 hPa at 2043 UTC (4:43 am local time) in Taitung City:


Shortly before landfall, a comparison of DMSP-18 SSMIS Microwave (85 GHz) and Himawari-8 Infrared Window (10.4 µm) images around 20 UTC (below) showed that the eye was still rather distinct on the microwave image.

DMSP-16 SSMIS Microwave (85 GHz) and Himawari-8 Infrared Window (10.4 µm) images [click to enlarge]

DMSP-16 SSMIS Microwave (85 GHz) and Himawari-8 Infrared Window (10.4 µm) images [click to enlarge]

However, the MIMIC-TC product (below) revealed how quickly the eyewall structure eroded once the circulation of Nepartak encountered the rugged terrain of Taiwan.
MIMIC-TC product [click to enlarge]

MIMIC-TC product [click to enlarge]

Looking back to earlier periods in the storm history, a 2-panel comparison of Himawari-8 Visible (0.64 µm) and Infrared Window (10.4 µm) images from 06-07 July (below) revealed the presence of mesovortices within the eye on the visible imagery. The spatial resolution of these Visible (0.5 km) and Infrared (2 km) AHI images is identical to what will be provided by the ABI instrument on GOES-R.
Himawari-8 0.64 µm Visible (top) and 10.4 µm Infrared Window (bottom) images [click to play MP4 animation]

Himawari-8 0.64 µm Visible (top) and 10.4 µm Infrared Window (bottom) images [click to play MP4 animation]

A Suomi NPP VIIRS true-color Red/Green/Blue (RGB) image from 07 July (viewed using RealEarth) is shown below; the actual satellite overpass time for this image was around 0444 UTC.
Suomi NPP VIIRS true-color image on 07 July [click to enlarge]

Suomi NPP VIIRS true-color image on 07 July [click to enlarge]

During the period of rapid intensification on 06 July, 2.5-minute interval rapid-scan Himawari-8 Infrared Window (10.4 µm) images (below) revealed pulses of storm-top gravity waves which were propagating radially outward away from the eye of Nepartak (especially evident during the later half of the animation period).
Himawari-8 Infrared Window (10.4 µm) images [click to play MP4 animation]

Himawari-8 Infrared Window (10.4 µm) images [click to play MP4 animation]

It is also interesting to note that nighttime mesospheric gravity waves could be seen propagating away from the eye/eyewall region of Nepartak at 1729 UTC or 1:29 am local time on a 06 July Suomi NPP VIIRS Day/Night Band (0.7 µm) image (below, courtesy of William Straka, SSEC). Since very little illumination was provided by the Moon (which was in the Waxing Crescent phase, at only 5% of Full), these waves were being illuminated by airglow.
Suomi NPP VIIRS Infrared Window (11.45 µm) and Day/Night Band (0.7 µm) images [click to enlarge]

Suomi NPP VIIRS Infrared Window (11.45 µm) and Day/Night Band (0.7 µm) images [click to enlarge]

The MIMIC-TC product (below) also showed that Nepartak completed an eyewall replacement cycle on 06 July.
MIMIC-TC product [click to enlarge]

MIMIC-TC product [click to enlarge]

Animations of 10-minute interval Himawari-8 Infrared Window (10.4 µm) images spanning nearly the entire life cycle of Nepartak — from a tropical depression south of Guam on 03 July to landfall over mainland China on 08 July — are available as an MP4 movie (139 Mbytes) or an animated GIF (493 Mbytes).