April 28th, 2015
Himawari-8 11.22 µm infrared imagery, 0000 – 1830 UTC on 28 April 2015 (click to play animation)
The 10-minute full-disk imagery that is available from Himawari-8 captures the evolution of Tropical Depression 24S northwest of Australia. Convection is evolving on time-scales of 10 minutes or less, so the high temporal resolution is vital to describing the storm evolution. Of particular note are the development (and decay) of central dense overcast features near the storm center, which have a timescale of less than 30 minutes. Note also the well-developed outflow channel curving anticyclonically to the south and east of the storm.
Sea surface temperature fields (from this site) show very warm ocean waters (SSTs exceed 30º C). Wind shear over the system is small; strengthening is expected.
29 April Update: As anticipated, Tropical Depression 24S continued to intensify, becoming Tropical Storm Quang. A comparison of an MTSAT-2 visible image at 0132 UTC with an overlay of 0135 UTC ASCAT scatterometer winds, below, shows surface winds in the 40.0-45.9 knot range (yellow) in both the western and eastern hemispheres of the storm. A large convective burst (with overshooting tops) was apparent on the visible image, just south of the center of Quang.
MTSAT-2 visible image with ASCAT surface scatterometer winds
Himawari-8 Infrared imagery on 29 April show eye development between 1600 and 1800 UTC. Quang was upgraded to a Cyclone at 1800 UTC. (Link)
Himawari-8 11.22 µm infrared imagery, 0000 – 1830 UTC on 29 April 2015 (click to play animation)
The scanning strategy of the current operational MTSAT satellites is such that the Southern Hemisphere only receives 1 image per hour. The Himawari-8 satellite performs a Full Disk scan every 10 minutes — and as an MTSAT-2 10.8 µm IR vs Himawari-8 10.4 µm IR image comparison demonstrates (below; click image to play animation; also available as an MP4 movie file), the improved Himawari-8 spatial resolution (2 km vs 4 km) and more frequent scans allowed the formation of the eye of Quang to be more accurately followed as it rapidly intensified from a Tropical Storm to a Category 4 Severe Cyclone. A nighttime comparison of Suomi NPP VIIRS Day/Night Band and Infrared images on 29 April/1820 UTC (30 April/02:20 AM local time) can be seen here.
MTSAT-2 10.8 µm (top) and Himawari-8 10.4 µm (bottom) IR images [click to play animation]
April 28th, 2015
Himawari-8 3.9 µm shortwave IR images (click to play animation)
The Kilauwea Volcano on the Big Island of Hawai’i began erupting in March 2008 (blog post | USGS reference), and has been in a nearly continuous phase of activity since then. During the pre-dawn hours of 28 April 2015, thermal signatures of the Kilauwea summit lava lake and nearby lava flows could be seen on McIDAS-V images of 10-minute interval Himawari-8 3.9 µm shortwave IR images (above; click image to play animation). The dark black pixels represent the hottest IR brightness temperatures.
On the corresponding Himawari-8 2.3 µm near-IR channel images (below; click image to play animation), the clusters of bright white pixels represent the glow of the hot lava features.
Himawari-8 2.3 µm near-IR channel images (click to play animation)
A different view is provided by the polar-orbiting Suomi NPP satellite — a comparison of AWIPS II images of VIIRS 0.7 µm Day/Night Band and 3.74 µm shortwave IR data (below) revealed the locations of the hottest lava features (black to yellow to red color enhancement) at 11:40 UTC (1:40 am local time).
Suomi NPP VIIRS 0.7 µm Day/Night Band and 3.74 µm shortwave IR images
A longer animation using GOES-15 (GOES-West) 3.9 µm shortwave IR images (below; click image to play animation) showed considerable temporal fluctuation in the location and intensity of the hot lava pixels (black to yellow to red color enhancement). For the latest information on the Kilauea eruption, visit the Hawaiian Volcano Observatory.
GOES-15 3.9 µm shortwave IR images (click to play animation)
April 23rd, 2015
Suomi NPP VIIRS 11.45 µm imagery, 0509 UTC 23 April 2015 (Click to enlarge)
Suomi NPP overflew the erupting Calbuco Volcano in southern Chile around 0509 UTC or 2:09 am local time on 23 April 2015. The image above is the VIIRS 11.45 µm infrared imagery (click here for a similar view).
The shock of the volcanic eruption generated mesospheric gravity waves (or “mesospheric airglow waves”) that were evident in the Day/Night Band, shown in the toggle below between the 11.45 µm and the night-time visible imagery. No lunar illumination was present, so the waves were apparent via the Earth’s airglow as the primary light source; this “night glow” is emitted from a variety of high-altitude (80-105 km) gases located near the mesopause (reference).
Toggle between VIIRS 11.45 µm infrared image and 0.70 µm Day/Night Band image, 0509 UTC 23 April 2015 (Click to enlarge)
(VIIRS images courtesy of William Straka, SSEC)
April 19th, 2015
Himiwari-8 AHI 0.63 µm visible channel images (click to play animation)
0.5-km resolution Himawari-8 AHI 0.63 µm visible channel images from the SSEC RealEarth web map server (above; click image to play animation) revealed a number of interesting features from the Sea of Okhotsk to the Bering Sea during the 18 April – 19 April 2015 period, which included (1) a series of lee waves immediately west of the Kuril Islands (the chain of islands south of the Kamchatka Peninsula), (2) the cyclonic circulation that formed over the western Bering Sea off the Russian coast, along the far northern edge of a remnant frontal boundary, and (3) cloud streets in the central Bering Sea, streaming southward and southwestward from the sea ice across the open waters.
A comparison of Suomi NPP VIIRS 0.7 µm Day/Night Band and 11.45 µm IR channel images with an overlay of the19 April / 00 UTC surface analysis (below) showed the location of the remnant frontal boundary, which was an axis of convergence between strong northerly winds over the central Bering Sea (causing the cloud streets and heavy freezing spray which would be a concern for shipping activities in that area) and a ridge of high pressure southeast of the Kamchatka Peninsula.
Suomi NPP VIIRS 0.7 µm Day/Night Band and 11.45 µm IR channel images.