Explosive eruption of the Hunga Tonga volcano

January 15th, 2022 |

JMA Himawari-8 True Color RGB images [click to play animated GIF | MP4]

JMA Himawari-8 True Color RGB images created using Geo2Grid (above) showed the rapid expansion of a volcanic cloud following an explosive eruption of Hunga Tonga on 15 January 2022. An abrupt shock wave was also evident, which propagated radially outward in all directions.

The volcanic cloud also exhibited a striking appearance in GOES-17 (GOES-West) “Clean” Infrared Window (10.35 µm) images (below), with a pronounced arc of cloud-top gravity waves along its eastern edge as the bulk of the cloud material drifted westward. Pulsing concentric shock waves were also seen in the infrared imagery.

GOES-17 “Clean” Infrared Window (10.35 µm) images (credit: Tim Schmit, NOAA/NESDIS/ASPB) [click to play animated GIF | MP4]

Beginning at 0705 UTC, a GOES-17 Mesoscale Domain Sector was positioned over the region, providing imagery at 1-minute intervals — Infrared images during the period 0705-1200 UTC are shown below. The crescent-shaped area of “bow shock wave” ripples persisted, due to the robust and dense volcanic cloud acting as an obstacle to the easterly winds within the stratosphere.  The 1-minute imaging was also able to capture the brief pulse of an overshooting top which exhibited an infrared brightness temperature of -105.18ºC (which could be a record cold cloud-top temperature, as sensed from a geostationary satellite — see this blog post).  

GOES-17 “Clean” Infrared Window (10.35 µm) images [click to play animated GIF | MP4]

VIIRS Infrared Window (11.45 µm) images from NOAA-20 and Suomi-NPP, viewed using RealEarth (below), also showed the region of cloud-top gravity waves (with minimal parallax compared to GOES-17) .  

VIIRS Infrared Window (11.45 µm) images from NOAA-20 and Suomi-NPP [click to enlarge]

 

GOES-17 Mid-level Water Vapor (6.9 µm) Time Difference images (credit: Tim Schmit, NOAA/NESDIS/ASPB) [click to play animated GIF | MP4]

Propagation of the volcanic shock wave across the Pacific Ocean could be followed in GOES-17 (GOES-West) Mid-level Water Vapor (6.9 µm) Time Difference images (above). As the shock wave continued to propagate farther eastward across North/South America and then the Atlantic Ocean, the wave front could be seen in GOES-16 (GOES-East) Water Vapor Time Difference images (below). As the shock wave moved across southern Wisconsin, a brief rise/fall couplet in surface air pressure just prior to 1500 UTC (9:00 am CDT) was evident in plots from the University of Wisconsin – Madison’s Atmospheric, Oceanic and Space Sciences building rooftop tower (as well as the personal weather station of the author of this blog post).

GOES-16 Mid-level Water Vapor (6.9 µm) Time Difference images (credit: Tim Schmit, NOAA/NESDIS/ASPB) [click to play animated GIF | MP4]

Hunga Tonga erupts again

January 13th, 2022 |

GOES-17 imagery revealed another explosive eruption of Hunga Tonga-Hunga Ha?apai in the south Pacific Ocean between 1500 and 1530 UTC on 13 January 2022; an eruption in December 2021 is discussed here. The brightness temperatures in this volcanic plume cooled from -9.4o to -66.7o between 1520 and 1530 UTC. This 1308 UTC NUCAPS profile from 20.5oS / 175.5o W (the profile location is shown here) suggests the plume rose from 445 mb to 188 mb in those 10 minutes (or from 20 thousand to 39 thousand feet).

GOES-17 Clean Window*(see below) (Band 13, 10.3 µm) Infrared Imagery, 1500-1940 UTC on 13 January 2022 (Click to enlarge)

Imagery at 2100 UTC, below, shows the extent of the plume in the visible.

GOES-17 Visible (Band 2, 0.64 µm) Imagery, 2100 UTC on 13 January 2022 (Click to enlarge)

Computed Ash/Dust Cloud Heights, below, from 1510-1600 UTC on 13 January, available at the CIMSS Volcanic Cloud Monitoring Web Portal (link, search under the Wellington VAAC for Hunga Tonga), shows the rapid increase in height, to above 16 km, as well.

Retrieved Cloud Heights, 1510 – 1600 UTC on 13 January 2022 (Click to enlarge)

An animation of GOES-17 visible imagery, below, (courtesy Scott Bachmeier, CIMSS) shows the evolution of the pulsing eruption throughout the day on 13 January.

GOES-17 Visible (0.64 µm) imagery, 1700 UTC 13 January – 0010 UTC 14 January 2022 (Click to enlarge)

* You might notice that this AWIPS Full Disk imagery is at full resolution! In NWS Forecast Offices, full-disk imagery in AWIPS is degraded to 6-km resolution, meaning that interesting events outside of GOES-16 CONUS (or GOES-17 PACUS) that do not fall within a mesoscale sector can only be shown such that they’re zoomed out (as in this tweet from WFO Seattle about this event). The full-res imagery herein was created by inputting the full-resolution full-disk imagery (obtained at CIMSS from the GRB datastream) into AWIPS, replacing the subsected data.

Potential “neutercane” in the Southeast Pacific Ocean

January 12th, 2022 |

GOES-16 True Color RGB images [click to play animated GIF | MP4]

GOES-16 (GOES-East) True Color RGB images created using Geo2Grid (above) displayed the eye-like signature of a potential subtropical cyclone or “neutercane” over the Southeast Pacific Ocean on 12 January 2022. This type of mesoscale “hybrid” system has been observed near decaying cold fronts, or (as in this case) near the centers of aged occluded extratropical cyclones.

VIIRS Infrared Window (11.45 µm) images from NOAA-20 and Suomi-NPP as viewed using RealEarth (below) showed that deep convection — exhibiting cloud-top brightness temperatures of -40°C and colder, shades of green) — existed around the immediate edge of of the small eye.

VIIRS Infrared Window (11.45 µm) images from NOAA-20 and Suomi-NPP [click to enlarge]

Surface analyses from the Chile Navy Weather Service (below) depicted the small occluded cyclone as it was moving southeastward off the coast of Chile.

Surface analysis at 12 UTC and 18 UTC [click to enlarge]

Sensing the surface in GOES-16 Water Vapor imagery

January 10th, 2022 |

GOES-16 Low-level (7.3 µm) and Mid-level (6.9 µm) Water Vapor images, with and without map overlays [click to play animated GIF | MP4]

GOES-16 (GOES-East) Low-level (7.3 µm) and Mid-level (6.9 µm) Water Vapor images (above) showed that portions of the coastline of Lake Superior, Lake Michigan and Lake Huron were apparent during the day on 10 January 2022. When a very cold/dry arctic air mass is present over a particular area, the water vapor “weighting functions” are shifted to lower altitudes — which in this case allowed the strong thermal contrast between (1) the cold, snow-covered land surface across Minnesota, Wisconsin, Michigan and Ontario and (2) the warmer ice-free nearshore waters of the Great Lakes to be sensed by GOES Water Vapor spectral bands. The coldest surface air temperatures that morning across the region included -34ºF at Badoura MN, -27ºF at Grantsburg WI and -15ºF at Ironwood MI.

Plots of GOES-16 Low-level (7.3 µm) and Mid-level (6.9 µm) Water Vapor weighting functions (below) — calculated using 12 UTC rawinsonde data from Green Bay, Wisconsin (KGRB) — showed peak radiation contributions for the 7.3 µm and 6.9 µm spectral bands were at the 853 hPa and 730 hPa pressure levels, respectively, with some contribution coming directly from the surface. This example underscores the fact that “water vapor” spectral bands are essentially infrared bands — and with very little water vapor within the atmospheric column to absorb then re-radiate any upwelling energy (at its colder ambient temperature aloft), the signature of this land vs. water thermal contrast was able to reach the satellite sensors with minimal attenuation. 

Plots of GOES-16 Low-level (7.3 µm) and Mid-level (6.9 µm) Water Vapor weighting functions at Green Bay WI [click to enlarge]

According to the Green Bay WI rawinsonde Total Precipitable Water (TPW) climatology (source), the TPW value of 0.04 inch at 12 UTC on 10 January was very close to the record low value (0.03 inch) for that date/time (below).

Green Bay WI rawinsonde Total Precipitable Water climatology [click to enlarge]

Other examples of GOES water vapor imagery sensing the surface in a cold/dry air mass: Feb 2020 | Jan 2019 | Dec 2019.