Typhoon Maysak in the West Pacific Ocean

March 30th, 2015
Himawari-8 AHI 0.64 µm visible channel images (click to play animation)

Himawari-8 AHI 0.64 µm visible channel images (click to play animation)

McIDAS-V images of Himawari-8 AHI 0.64 µm visible channel data (above; click image to play animation; images courtesy of William Straka, SSEC) showed the evolution of Category 2 Typhoon Maysak over the West Pacific Ocean on 30 March 2015. A number of large convective bursts can be seen surrounding the eye, along with more subtle features such as transverse banding.

An 11:01 UTC MTSAT-2 10.8 µm IR image with an overlay of 11:11 UTC Metop ASCAT surface scatterometer winds from the CIMSS Tropical Cyclones site (below) revealed the wind field in the eastern semicircle of the tropical cyclone.

MTSAT-2 10.8 µm IR image with Metop ASCAT surface scatterometer winds

MTSAT-2 10.8 µm IR image with Metop ASCAT surface scatterometer winds

Several hours later, a comparison of a 19:01 UTC MTSAT-2 10.8 µm IR image with a 19:00 UTC DMSP SSMIS 85 GHz microwave image (below) showed that the microwave instrument was able to “see” through the clouds surrounding the eye to depict the larger size of the eyewall structure.

MTSAT-2 10.8 µm IR image + DMSP SSMIS 85 GHz microwave image

MTSAT-2 10.8 µm IR image + DMSP SSMIS 85 GHz microwave image

During the later hours of 30 March, Typhoon Maysak underwent a period of rapid intensification from a Category 2 to a Category 4 storm, as depicted on a plot of the Advanced Dvorak Technique (ADT) intensity estimate (below). Rapid intensification occurred as the tropical cyclone was moving over an area of relatively high ocean heat content.

Advanced Dvorak Technique (ADT) intensity estimate plot for Typhoon Maysak

Advanced Dvorak Technique (ADT) intensity estimate plot for Typhoon Maysak

MTSAT-2 10.8 µm IR channel images during this period of rapid intensification are shown below (click image to play animation).

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

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

The MIMIC Total Precipitable Water (TPW) product (below; click image to play animation) depicted TPW values in excess of 60 mm or 2.36 inches (darker red color enhancement) associated with Maysak as the tropical cyclone moved between the islands of Guam (PGUM) and Yap (PTYA). Yap recorded over 4 inches of rainfall.

MIMIC Total Precipitable Water product (click to play animation)

MIMIC Total Precipitable Water product (click to play animation)

31 March 2015 Update: Maysak intensified to a Category 5 Super Typhoon (ADT plot). Full-resolution visible imagery from Himawari-8 AHI is shown below; a faster animation is available here. A number of mesovortices could be seen within the eye of Maysak; these mesovortices were also evident in photos of the eye of the typhoon taken by an astronaut on the International Space Station, as posted on Twitter here and here.

Himawari-8 AHI 0.64 µm visible channel images (click to play animation)

Himawari-8 AHI 0.64 µm visible channel images (click to play animation)

Images from all 16 channels from the Himawari-8 AHI can be combined into one animation, showing the different information provided by each of the spectral bands — such an animation is shown below, using data from 0600 UTC on 31 March 2015. The Infrared data is shown at full (2-km) resolution; Visible/near Infrared imagery is scaled down by a factor of 2 (0.46 µm, 0.51 µm, 0.85 µm) or by a factor of 4 (0.64 µm). A similar animation, but without annotation or color enhancement, is available here.

Himawari-8 AHI images for all 16 channels at 0600 UTC (click to enlarge)

Himawari-8 AHI images for all 16 channels at 0600 UTC (click to enlarge)

Maysak had remained in an environment of relatively low deep-layer wind shear (below; click image to play animation), which was favorable for its trend of continued intensification.

MTSAT-2 10.8 µm IR channel images, with deep-layer wind shear (click to play animation)

MTSAT-2 10.8 µm IR channel images, with deep-layer wind shear (click to play animation)

However, in a comparison of MTSAT-2 10.8 µm IR channel and TRMM TMI 85 GHz microwave images around 14 UTC (below), it can be seen that the microwave image indicated that an eyewall replacement cycle might be underway (which would suggest a subsequent decrease in the typhoon’s intensity within the coming hours). This was supported by the ADT intensity estimate plot, which dropped the intensity of Maysak just below 140 knots after 18 UTC on 31 March.

MTSAT-2 10.7 µm IR image and TRMM TMI 85 GHz microwave image

MTSAT-2 10.7 µm IR image and TRMM TMI 85 GHz microwave image

Category 5 Cyclone Pam in the South Pacific

March 12th, 2015
MTSAT-2 10.8 µm IR images (click to play animation)

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

Cyclone Pam in the South Pacific Ocean was rated at Category 5 intensity by the Joint Typhoon Warning Center at 18 UTC on 12 March 2015. MTSAT-2 10.8 µm IR channel images (above; click image to play animation; also available as an MP4 movie file) showed the well-defined eye as the storm moved southwestward across the Vanuatu archipelago during the 12-13 March time period.

The corresponding MTSAT-2 0.7 µm visible channel images (below; click image to play animation) revealed a complex structure of gravity waves and transverse banding surrounding the eye.

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

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

A comparison of the 12 March 21:32 UTC MTSAT-2 visible image and the 21:44 UTC Metop ASCAT surface scatterometer winds from the CIMSS Tropical Cyclones site is shown below.

MTSAT-2 visible image and Metop ASCAT surface scatterometer winds

MTSAT-2 visible image and Metop ASCAT surface scatterometer winds

Just prior to the time when Pam was beginning to enter a period of rapid intensification (ADT intensity estimate plot), a nighttime comparison of Suomi NPP VIIRS 0.7 µm Day/Night Band and 11.45 µm Infrared images at 13:37 UTC on 11 March is shown below.

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

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

Improvements in Volcanic Ash detection with Himawari-8

January 25th, 2015
Himawari8_FalseColorVolcano_0230_25January

Himawari-8 False Color Imagery during an eruption of Klyuchevskoy Volcano, 0230 UTC 25 January 2015. Colors derived from bands as indicated (Click to enlarge)

Satellite data are used routinely to monitor Volcanoes for eruptions that can be potential aviation hazards. The Himawari-8 false-color image, above, derived from Himawari-8 AHI data, includes a volcanic plume that, even without the image annotation, is easy to detect. Consider the same scene, below, derived from MTSAT-2 imagery. The volcanic plume is far more difficult to discern. The superior spatial resolution on Himawari-8 IR channel data (2-km, vs 5-km on MTSAT) allows for better detection of this ash plume from Klyuchevskoy.

MTSAT2_FalseColorVolcano_0232_25January

MTSAT-2 False Color Imagery during an eruption of Klyuchevskoy Volcano, 0232 UTC 25 January 2015. Colors derived from bands as indicated (Click to enlarge)

Did weather play a role in the crash of AirAsia Flight 8501?

December 27th, 2014
SSEC RealEarth fade between the regional map and the 23:00 UTC MTSAT-2 10.8 µm IR image

SSEC RealEarth fade between the regional map and the 23:00 UTC MTSAT-2 10.8 µm IR image

During the northwestward flight of AirAsia 8501 from Surabaya, Indonesia to Singapore, contact was lost with the aircraft over the Java Sea (likely east of the island of Pulau Belitung) on 28 December 2014 (late 27 December UTC time). Using the SSEC RealEarth web map server site, a fade between the regional map and the MTSAT-2 10.8 µm IR image at 23:00 UTC is shown above. The satellite image revealed that there were clusters of deep convection (thunderstorms with very high, very cold cloud tops) over the middle portion of the flight path.

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

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

COMS-1 10.8 µm IR channel images (above; click to play animation; also available as an MP4 movie file) indicated that the coldest cloud-top IR brightness temperatures were in the -80º to -85ºC range (violet color enhancement) with these thunderstorms. The location of Surabaya, Indonesia (station identifier WARR) and Singapore (station identifier WSSS) are annotated on the images; the last point of contact (at 23:24 UTC) was approximately within the circle drawn just to the left of the center of the images, when the aircraft was flying at an altitude of 32,000 feet (9.75 km) over the Java Sea. There were reports from various media sources that the pilots had requested to divert their flight path and climb to a higher altitude to avoid adverse weather conditions not long before contact was lost.

The corresponding COMS-1 0.675 µm visible channel images (below; click to play animation; also available as an MP4 movie file) showed evidence that there were some overshooting tops associated with these thunderstorms.

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

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

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MTSAT-2 10.8 µm IR channel image (click to enlarge)

MTSAT-2 10.8 µm IR channel image (click to enlarge)

Given that there was a long gap in available COMS-1 images (between 23:00 and 23:45 UTC), a closer view is shown using the 23:32 UTC MTSAT-2 10.8 µm IR channel (above) and 0.675 µm visible channel images (below). A circle is again drawn near the center of the MTSAT-2 images to denote the approximate location of final radar contact with the aircraft at 23:24 UTC — and the intended final destination of Singapore (WSSS) is labelled in the upper left corner of the images. Similar to what was seen in the COMS-1 images, the coldest cloud-top IR brightness temperature in the area at that time was -81.4ºC, and there was evidence of overshooting tops in the near vicinity on the visible image. (Note: due to the far southern location just below the Equator, the flight region on the 22:00 COMS-1 image was actually being scanned around 22:07 UTC, while on the 22:32 UTC MTSAT-2 image the flight region was being scanned around 22:39 UTC).

MTSAT-2 0.675 µm visible channel image (click to enlarge)

MTSAT-2 0.675 µm visible channel image (click to enlarge)

A nearby rawinsonde report from Pangkalpinang (station identifier 96237 on the MTSAT-2 images) showed that the aircraft cruising flight level of 32,000 feet was near 300 hPa (9750 meters above ground level), where the air temperature was -29.3ºC and winds were from the west-southwest at 16 knots (below). The tropopause appeared to be around 100 hPa (at a height of 54,265 feet or 1654 km), with an air temperature of -86.5ºC — close to the coldest cloud-top IR brightness temperatures seen on the COMS-1 and MTSAT-2 IR images. Moisture was abundant throughout the atmospheric column, with a Total Precipitable Water value of 52.4 mm or 2.1 inches.

Pangkalpinang, Indonesia rawinsonde report

Pangkalpinang, Indonesia rawinsonde report

MTSAT-2 water vapor image derived atmospheric motion vectors from the CIMSS Tropical Cyclones site (below) showed that upper-tropospheric winds over the flight region (located at the far top center portion of the images) before, during, and after the flight time were generally southwesterly to westerly in the 15-30 knot range.

MTSAT-2 6.57 µm water vapor channel images with upper-tropospheric atmospheric motion vectors

MTSAT-2 6.57 µm water vapor channel images with upper-tropospheric atmospheric motion vectors

Deep convection is not uncommon in this region during this time of the year, when the Intertropical Convergence Zone (ITCZ) migrates southward during the Southern Hemisphere summer season. The presence of warm sea surface temperatures along with abundant Total Precipitable Water over western Indonesia (below) helps to create an environment that is favorable for the growth and maintenance of large thunderstorms.

Global image of Sea Surface Temperatures on 27 December

Global image of Sea Surface Temperatures on 27 December

25-27 December MIMIC Total Precipitable Water product (click to play animation)

25-27 December MIMIC Total Precipitable Water product (click to play animation)

For an additional detailed meteorological analysis of this event, see the Weather Graphics site.

===== 30 December Update =====

Map of AirAsia Flight 8501, and location of initial debris (credit: New York Times)

Map of AirAsia Flight 8501, and location of initial debris (credit: New York Times)

On the third day of the search, aircraft debris and bodies of passengers were discovered about 66 miles southwest of the last known coordinates of AirAsia Flight 8501 (above). The prevailing ocean current in the Java Sea (below) may have displaced some of the debris southwestward from the actual crash site.

Map of ocean currents (credit: Columbia University Earth Institute)

Map of ocean currents (credit: Columbia University Earth Institute)

The Indonesian Bureau of Meteorology, Climate, and Geophysics (BMKG) released their meteorological analysis of the AirAsia 8501 crash on 31 December.