PyroCumulonimbus cloud in Australia

January 25th, 2019 |

Himawari-8

Himawari-8 “Red” Visible (0.64 µm, top), Shortwave Infrared (3.7 µm, middle) and Infrared Window (10.3 µm, bottom) images [click to play to animation | MP4]

JMA Himawari-8 “Red” Visible (0.64 µm), Shortwave Infrared (3.7 µm) and Infrared Window (10.3 µm) images (above) showed the development of a pyroCumulonimbus (pyroCb) cloud from a bushfire that was burning in the eucalypt forests of eastern Victoria, Australia on 25 January 2019. A rapid-scan “Target” sector was positioned over the region beginning at 0522 UTC, providing images every 2.5 minutes (instead of the routine 10-minute interval). Cloud-top infrared brightness temperatures became colder than -40ºC (the threshold for pyroCb classification) after 0230 UTC, and eventually cooled to around -55ºC (orange enhancement). This temperature roughly corresponded to an altitude around 12 km, according to nearby Melbourne rawinsonde data (plot | text).

A closer view of Himawari-8 “Red” Visible (0.64 µm) and Shortwave Infrared (3.7 µm) images (below) revealed the rapid southeastward run of the fire, as shown by the growth of the “hot spot” (black to red pixels) on Shortwave Infrared images. The darker gray appearance of the pyroCb cloud is due to the presence of smaller ice crystals at the cloud top — these smaller ice crystals are more efficient reflectors of incoming solar radiation, making the cloud tops appear warmer than those of conventional cumulonimbus. Vigorous updrafts driven by the intense heat of the fire limit the in-cloud residence time for ice crystal growth, which leads to smaller particles being ejected at the pyroCb cloud top.

Himawari-8 "Red" Visible (0.64 µm, left) and Shortwave Infrared (3.7 µm, right) images [click to play to animation | MP4]

Himawari-8 “Red” Visible (0.64 µm, left) and Shortwave Infrared (3.7 µm, right) images [click to play to animation | MP4]

In a comparison of VIIRS True Color Red-Green-Blue (RGB) and Infrared Window (11.45 µm) images from Suomi NPP (at 0311 UTC) and NOAA-20 (at 0501 UTC) images viewed using RealEarth (below), cloud-top infrared brightness temperatures were in the -55 to -58ºC range (darker shades of orange).

VIIRS True Color RGB and Infrared Window (11.45 µm) images from Suomi NPP (0311 UTC) and NOAA-20 (0501 UTC) images [click to enlarge]

VIIRS True Color RGB and Infrared Window (11.45 µm) images from Suomi NPP (0311 UTC) and NOAA-20 (0501 UTC) images [click to enlarge]

Stereoscopic views of a small storm over the North Pacific Ocean

January 16th, 2019 |

Himawari-8 AHI and GOES-17 ABI Band 13 (10.41 µm and 10.35 µm, respectively) at 0400 UTC on 16 January 2019 (Click to enlarge)


GOES-17 Data in this post are preliminary and non-operational.

The toggle above shows clean window imagery from the Advanced Himawari Imager (Band 13, 10.41 µm) on Himawari-8 (data courtesy JMA) and clean window imagery from the Advanced Baseline Imager (ABI, Band 13, 10.3 µm) on GOES-17 (GOES-17 data are non-operational). There is a small developing storm between the Hawai’ian Islands and Alaska that is resolved by both satellites.  The storm is in between the two satellites and therefore ideal for stereoscopic views created from Visible 0.64 µm imagery (Band 3 for AHI, Band 2 for GOES-17).  That is shown below.  Thirty-minute timesteps are used because GOES-17 scans a full disk every 15 minutes (in Mode 3 that is currently operational; Mode 6, if used, scans a Full Disk every 10 minutes; and Mode 4, continuous Full Disk, the highest data rate for the GOES-R series, scans a Full Disk every 5 minutes). Himawari scans a Full Disk every 10 minutes. The three-dimensional representation facilitates the identification of warm conveyor belts associated with this developing storm. (This link shows the same animation but with the imagery flipped so it can be viewed in Google Daydream).

GOES-17 non-operational Visible (0.64 µm) imagery (left) and Himawari-8 Visible (0.64 µm) imagery (right), every half-hour from 2000 UTC on 15 January to 0400 UTC on 16 January (Click to animate)

Thanks to Mary Ellen Craddock, Northrop-Grumman, for the reminder that stereo imagery is possible with GOES-17 and Himawari.  (It should be even better with Himawari-8 and South Korea’s GEOKOMPSAT-2A!)

Partial solar eclipse shadow

January 6th, 2019 |

Himawari-8

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

A partial solar eclipse occurred on 06 January 2019 (UTC) — and JMA Himawari-8 “Red” Visible (0.64 µm) images (above) showed the shadow moving eastward across parts of Asia and the North Pacific Ocean.

Although it was less obvious, the shadow was also evident on GOES-17 “Red” Visible (0.64 µm) images as it moved across the North Pacific Ocean toward Alaska (below).

GOES-17

GOES-17 “Red” Visible (0.64 µm) images [click to play animation | MP4]

* GOES-17 images shown here are preliminary and non-operational *

Eruption of the Anak Krakatau volcano in Indonesia

December 22nd, 2018 |

Himawari-8

Himawari-8 “Clean” Infrared Window (10.4 µm) images, with hourly plots of surface reports from Jakarta (station identifier WIII) [click to play animation | MP4]

Himawari-8 “Clean” Infrared Window (10.4 µm) images (above) showed the volcanic cloud from an eruption of Anak Krakatau in Indonesia on 22 December 2018. Two distinct pulses were evident: the first began around 1340 UTC, with the second starting around 1520 UTC. At times the cloud-top infrared brightness temperatures were -80ºC or colder (violet enhancement) — which roughly corresponded to altitudes around 15-16 km on rawinsonde data from nearby Jakarta (WIII) (below). The eruption process appears to have played a role in generating a tsunami that was responsible for over 400 fatalities — via a partial collapse of the southern flank of the volcano which then triggered an undersea landslide (visualization).

Plots of rawinsonde data from Jakarta, Indonesia [click to enlarge]

Plots of rawinsonde data from Jakarta, Indonesia [click to enlarge]

After sunrise, the volcanic cloud was evident in Himawari-8 “Red” Visible (0.64 µm) images (below) — a toggle between Visible and Infrared images at 0110 UTC showed an example of one of the cold overshooting tops.

Himawari-8 "Red" Visible (0.64 µm) images. with hourly plots of surface reports [click to play animation | MP4]

Himawari-8 “Red” Visible (0.64 µm) images, with hourly plots of surface reports from Jakarta (station identifier WIII) [click to play animation | MP4]

At the onset of the eruption, multi-spectral retrievals from the NOAA/CIMSS Volcanic Cloud Monitoring site showed Ash Height values of 12-14 km and Ash Loading values of 9-10 g/m2 (below). However, after about 1.5 hours the extremely high water and ice content of the volcanic cloud prevented further retrievals of such parameters.

Himawari-8 Ash Height retrievals [click to play animation]

Himawari-8 Ash Height retrievals [click to play animation]

Himawari-8 Ash Loading retrievals [click to play animation]

Himawari-8 Ash Loading retrievals [click to play animation]

A toggle between NOAA-20 VIIRS True Color Red-Green-Blue (RGB) and Infrared Window (11.45 µm) images viewed using RealEarth (below) showed the volcanic cloud at 0610 UTC on 23 December.

NOAA-20 VIIRS True Color RGB and Infrared Window (11.45 µm) images at 0610 UTC [click to enlarge]

NOAA-20 VIIRS True Color RGB and Infrared Window (11.45 µm) images at 0610 UTC [click to enlarge]

A comparison of Infrared Window images from NOAA-20 VIIRS (11.45 µm) and Himawari-8 AHI (10.4 µm) at 0610 UTC (below) demonstrated the advantage of improved spatial resolution — the minimum cloud-top infrared brightness temperature of the overshooting top feature was significantly colder on the 375-m resolution VIIRS image (-87ºC, darker shade of violet) than on the corresponding AHI image with 2-km resolution at satellite sub-point (-74.2ºC).

Infrared Window images from NOAA-20 VIIRS (11.45 µm) and Himawari-8 AHI (10.4 µm) [click to enlarge]

0610 UTC Infrared Window images from NOAA-20 VIIRS (11.45 µm) and Himawari-8 AHI (10.4 µm) [click to enlarge]

There was also a significant amount of lightning associated with this volcanic cloud:


A comparison of Himawari-8 Visible and Infrared images showed the persistent volcanic cloud following sunrise on 23 December (below). The pulsing overshooting tops continued to exhibit infrared brightness temperatures as cold as -80ºC at times.

Himawari-8

Himawari-8 “Red” Visible (0.64 µm, top) and “Clean” Infrared Window (10.4 µm, bottom) images [click to play animation | MP4]

===== 24 December Update =====

NOAA-20 VIIRS True Color RGB and Infrared Window (11.45 µm) images [click to enlarge]

NOAA-20 VIIRS True Color RGB and Infrared Window (11.45 µm) images [click to enlarge]

NOAA-20 VIIRS True Color RGB and Infrared Window (11.45 µm) images (above) provided a detailed view of the volcanic cloud at 0550 UTC on 24 December.

A long animation of Himawari-8 “Clean” Infrared Window (10.4 µm) images spanning over 48 hours from the onset of the eruption (below) showed the remarkably persistent volcanic cloud, with pulsing overshooting tops anchored over Anak Krakatau.

Himawari-8

Himawari-8 “Clean” Infrared Window (10.4 µm) images, with hourly surface report plots from Jakarta WIII {click to play animation | MP4]

===== 25 December Update =====

NOAA-20 VIIRS True Color RGB and Infrared Window (11.45 µm) images [click to enlarge]

NOAA-20 VIIRS True Color RGB and Infrared Window (11.45 µm) images [click to enlarge]

In a toggle between NOAA-20 VIIRS True Color RGB and Infrared Window (11.45 µm) images at 0710 UTC on 25 December (above), a few -90ºC pixels could be seen embedded within the darker purple area of the overshooting top on the Infrared image. Note that there was some westward parallax shift of the image features, due to the scene being near the edge of the VIIRS scan.

The coldest pixels on another NOAA-20 VIIRS Infrared image at 1810 UTC (below) were still within the -80 to -87ºC range.

NOAA-20 VIIRS Infrared Window (11.45 µm) image [click to enlarge]

NOAA-20 VIIRS Infrared Window (11.45 µm) image [click to enlarge]

An updated long animation of Himawari-8 Infrared images (below) continued to show periodic bursts of cold pixels within overshooting tops above the eruption site.

Himawari-8

Himawari-8 “Clean” Infrared Window (10.4 µm) images, 22-25 December [click to play MP4 animation]

===== 28 December Update =====

Himawari-8 "Clean" Infrared Window (10.4 µm) images, 22-28 December [click to play MP4 animation]

Himawari-8 “Clean” Infrared Window (10.4 µm) images, 22-28 December [click to play MP4 animation]

An updated long animation of Himawari-8 Infrared images (above) revealed that the volcanic thunderstorm — which had persisted over the eruption site nearly continuously since 1350 UTC on 22 December — underwent its final pulse around 0640 UTC on 28 December, and was no longer seen after 0900 UTC. The volcanic thunderstorm began its transition from being nearly continuous to a phase of discrete discontinuous pulses after about 0500 UTC on 27 December; the last image with cloud-top infrared brightness temperatures of -80ºC or colder was 2110 UTC on that day.

NOAA-20 captured one of the final convective pulses around 0620 UTC on 28 December (below), when the coldest cloud tops were in the -50 to -55ºC range (yellow to orange enhancement).

NOAA-20 VIIRS True Color RGB and Infrared Window (11.45 µm) images [click to enlarge]

NOAA-20 VIIRS True Color RGB and Infrared Window (11.45 µm) images [click to enlarge]