MTSAT-1R satellite is decommissioned

December 4th, 2015

Himawari-8 (left) and MTSAT-2 (right) water vapor channel images [click to play animation]

Himawari-8 (left) and MTSAT-2 (right) water vapor channel images [click to play animation]

Now that Himawari-8 is their operational geostationary satellite, the Japanese Meteorological Agency (JMA) decommissioned MTSAT-1R (which was relaying the direct broadcast of MTSAT-2 imagery) as of 0630 UTC on 04 December 2015. A comparison of the final 5 hours of available MTSAT-2 6.75 µm water vapor channel images with the coresponding 6.2 µm water vapor channel images from Himawari-8 (above) demonstrated the advantages of improvements in both spatial resolution (2-km with Himawari, vs 4-km with MTSAT) and temproal resolution (10-minute with Himawari, vs 30-minute with MTSAT) for resolving the signature of middle-tropospheric waves within a dry slot in the wake of an occluded storm-force low over the North Pacific Ocean (surface analyses).

In addition, there are 3 water vapor channels on the Himawari-8 AHI instrument – a comparison of these 3 water vapor bands (below) offers a closer look at the aforementioned waves within the dry slot. The weighting functions for each of the 3 water vapor bands (centred at 6.2 µm, 6.9 µm, and 7.3 µm) peak at progressivesly lower altitudes, providing different views of features within those particular atmospheric layers. The same color enhancement is applied to the 3 sets of water vapor images — note that warmer brightness temperatures (yellow to orange colors) dominate the 6.9 µm and 7.3 µm images (which are showing features at lower altitudes, where the atmosphere is warmer).

Himawari-8 AHI 6.2 µm (top), 6.9 µm (middle), and 7.3 µm (bottom) water vapor channel images [click to play animation]

Himawari-8 AHI 6.2 µm (top), 6.9 µm (middle), and 7.3 µm (bottom) water vapor channel images [click to play animation]

Similar improvements in spatial and temporal resolution will be seen with imagery from the upcoming GOES-R ABI, which will also feature 3 similar water vapor bands (weighting functions); however, the ABI will provide full-disk images every 5 minutes.

Typhoon In-fa

November 20th, 2015

MTSAT-2 Infrared (10.8 µm) image with the track of In-fa [click to enlarge]

MTSAT-2 Infrared (10.8 µm) image with the track of In-fa [click to enlarge]

Tropical Depression In-fa (27W) formed well south of the Marshall Islands in the West Pacific Ocean on 17 November 2015, and proceeded to track northwestward to a position south of Guam on 20 November (above). Following a brief decrease in intensity on 18 September, In-fa began another period of intensification during the 19-20 September period. Rapid-scan (2.5-minute interval) Himawari-8 Visible (0.64 µm) images (below; also available as a large 73 Mbyte animated gif) showed a series of eyewall convective bursts and the occasional appearance of a recognizable eye. (Note: the ABI instrument on the upcoming GOES-R satellite will also have a rapid-scan capability, but at 1-minute or even 30-second intervals)

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

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

A longer animation spanning the entire 19-20 September period (below; also available as a large 120 Mbyte animated gif) revealed an improving trend in the overall satellite presentation of In-fa, with the eye becoming well defined by the end of the animation as the tropical cyclone reached Category 3 intensity.  In fact, this became the the 15th Category 3 or stronger typhoon in the Northwest Pacific basin in 2015 – the most on record in any tropical cyclone season by the date of 20 November.

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

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

A comparison of Suomi NPP VIIRS Infrared (11.45 µm) and Day/Night Band (0.7 µm) images at 1547 UTC (below; courtesy of William Straka, SSEC) showed the coldest cloud-top IR brightness temperatures in the southern hemisphere of the eyewall, along with the nighttime glow of lights from the island of Guam.

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

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

A well-defined eye was evident in MTSAT-2 Infrared (10.8 µm) and DMSP SSMIS Microwave (85 GHz) images around 2230 UTC on 20 September (below).

DMSP-19 SSMIS microwave (85 GHz) and MTSAT Infrared (10.8 um) images [click to enlarge]

DMSP-19 SSMIS microwave (85 GHz) and MTSAT Infrared (10.8 um) images [click to enlarge]

Mesovortices within the eye were seen in rapid-scan Himawari-8 Visible (0.64 µm) images beginning late in the day on 20 November as In-fa intensified to a Category 4 typhoon. (below;  also available as a large 50 Mbyte animated GIF).

Himawari-8 Visible (0.64 µm) images [click to play MP4 animation]

Himawari-8 Visible (0.64 µm) images [click to play MP4 animation]

Internal Waves in the Banda Sea

October 30th, 2015
Himawari-8 Band 3 Visible (0.64 µm) images from 29 October [click to play animation]

Himawari-8 Band 3 Visible (0.64 µm) images from 29 October [click to play animation]

Himawari-8 (Imagery courtesy of JMA) captured the northward march of three sets of Internal Waves in the Banda Sea in late October, as shown above (MODIS True Color Imagery showed the waves as well). Because the internal waves affect the ocean surface, sun glint can make them visible via methods described here. The fine spatial and temporal resolution of Himawari-8 (0.5 km for Band 3/0.64µm, 10-minute imagery) allows for a good description of the northward speed of the waves: approximately 10 km/hour.

MTSAT-2 (scheduled to become the backup satellite on Friday 4 December 2015 as Himawari-8 takes over operational duties; MTSAT-1 is to be decommissioned that day because of fuel limitations) and COMS-1 also viewed the waves, as shown below. Sun glint allowed MTSAT-2 to view only three scenes (3:32, 4:32 and 5:32 UTC). COMS-1, above the Equator at 128º E, farther west than MTSAT-2 (at 145º E), viewed the waves earlier (because sunglint was present over the scene earlier). Both MTSAT-2 and COMS-1 visible channels have nominal resolution of only 1 km.

MTSAT-2 Visible (0.73 µm) images from 29 October, 0232-0632 UTC [click to play animation]

MTSAT-2 Visible (0.73 µm) images from 29 October, 0232-0632 UTC [click to play animation]

COMS-1 Visible (0.675 µm) images from 29 October, 0100-0630 UTC [click to play animation]

COMS-1 Visible (0.675 µm) images from 29 October, 0100-0630 UTC [click to play animation]

Hat Tip to Mike Ziobro, NWS Guam, for showing us these very interesting waves!

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]