Eruption of the Taal Volcano in the Philippines

January 12th, 2020 |

Himawari-8

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

The Taal Volcano erupted in the Philippines around 0850 UTC on 12 January 2020. JMA Himawari-8 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.4 µm) images (above) displayed the volcanic cloud during the initial 3 hours post-eruption. Note the presence of a pronounced “warm wake” (red enhancement) downwind (north) of the summit of Taal — this appeared to be an Above-Anvil Cirrus Plume (AACP), as seen in a toggle between the Visible and Infrared images at 1910 UTC (below).

Himawari-8 "Red" Visible (0.64 µm) and "Clean" Infrared Window (10.4 µm) images at 1910 UTC [click to enlarge]

Himawari-8 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.4 µm) images at 1910 UTC [click to enlarge]

The warmest Himawari-8 10.4 µm brightness temperatures within the Above-Anvil Cirrus Plume were around -60ºC (red enhancement), which corresponded to approximately 21 km on data from 3 rawinsonde sites in the Philippines (Legaspi, Mactan and Laoag) (below).

Plots of rawinsonde data from Legaspi, Mactan and Laoag in the Philippines [click to enlarge]

Plots of rawinsonde data from Legaspi, Mactan and Laoag in the Philippines [click to enlarge]

The TROPOMI detected SO2 at altitude of 20km on 13 January:


A longer animation of Himawari-8 Infrared imagery revealed the intermittent presence of the warm wake feature until about 1400 UTC. The coldest 10.4 µm cloud-top brightness temperature was -89.7ºC.

Himawari-8 "Clean" Infrared Window (10.4 µm) images [click to play animation | MP4]

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

A large-scale view of Himawari-8 Infrared images (below) showed that the volcanic cloud was advected a great distance north-northeastward.

Himawari-8 "Clean" Infrared Window (10.4 µm) images [click to play animation | MP4]

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

A toggle between NOAA-20 VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images (below) showed the volcanic cloud at 1649 UTC.

NOAA-20 VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images at 1648 UTC (credit: William Straka, CIMSS) [click to enlarge]

NOAA-20 VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images at 1648 UTC (credit: William Straka, CIMSS) [click to enlarge]

In a sequence of Split Window Difference (11-12 µm) images (Terra MODIS, NOAA-20 VIIRS and Suomi NPP VIIRS) from the NOAA/CIMSS Volcanic Cloud Monitoring site (below), there was only a subtle ash signature (blue enhancement) immediately downwind of the Taal summit — due to the large amount of ice within the upper portion of the volcanic cloud, the infrared spectral ash signature was significantly masked.

Split Window Difference (11-12 um) images from Terra MODIS, NOAA-20 VIIRS and Suomi NPP VIIRS [click to enlarge]

Split Window Difference (11-12 µm) images from Terra MODIS, NOAA-20 VIIRS and Suomi NPP VIIRS [click to enlarge]

Of interest was the fact that Manila International Airport (RPLL) reported a thunderstorm at 15 UTC — there was a large amount of lightning produced by Taal’s volcanic cloud.

===== 14 January Update =====

GOES-17 SO2 RGB images [click to play animation | MP4]

GOES-17 SO2 RGB images [click to play animation | MP4]

2 days after the eruption, the leading edge of Taal’s SO2-rich volcanic plume (brighter shades of yellow over areas of cold clouds) began to appear within the far western view of GOES-17 (GOES-West) Full Disk SO2 Red-Green-Blue (RGB) images (above), about 1000 miles southeast of Japan. There were also some thin filaments of SO2 (brighter shades of white over warm ocean areas) moving southward, about 1500 miles west of Hawai’i.

Exploring the effect of parallax

January 10th, 2020 |

GOES-16 "Red" Visible (0.64 µm) images, including plot of SPC Storm Reports (with and without parallax correction) [click to play animation]

GOES-16 “Red” Visible (0.64 µm) images, including plot of SPC Storm Reports (with and without parallax correction) [click to play animation]

Overlapping 1-minute GOES-16 (GOES-East) Mesoscale Domain Sectors provided images at 30-second intervals over the Kansas/Missouri/Oklahoma/Arkansas area on 10 January 2019 — and “Red” Visible (0.64 µm) images (above) included plots of SPC Storm Reports (with and without parallax correction) during the time period which produced the first 2 tornadoes (1 in southwestern Missouri, and 1 in northeastern Oklahoma) of a large-scale severe weather outbreak that continued into the subsequent nighttime hours and the following day.

The GOES-16 Visible images for the times corresponding to the 2 tornado reports (below) include “parallax-corrected” — shifted upward to match a 13 km cloud top, the Maximum Parcel Level calculated from the 18 UTC Springfield, Missouri sounding — and actual surface locations for each report. For the Oklahoma tornado report, the parallax-corrected location more closely matches the location of overshooting tops; for the Missouri tornado report, the parallax-corrected location more closely matches the location where a cluster of overshooting tops had passed several minutes earlier.

GOES-16 "Red" Visible (0.64 µm) image at 2030 UTC, including plot of SPC Storm Reports (with and without parallax correction) [click to enlarge]

GOES-16 “Red” Visible (0.64 µm) image at 2030 UTC, including a Tornado report in Missouri (with and without parallax correction) [click to enlarge]

GOES-16 "Red" Visible (0.64 µm) image at 2051 UTC, including plot of Tornado report (with and without parallax correction) [click to enlarge]

GOES-16 “Red” Visible (0.64 µm) image at 2051 UTC, including a Tornado report in Oklahoma (with and without parallax correction) [click to enlarge]

GOES-16 parallax direction vectors and magnitude (km) for a cloud top feature at 50,000 feet (or 15.2 km) are shown below for select locations across the GOES-16 CONUS domain — a webapp that displays a current infrared image with user-selectable cloud heights is available here. Circled is a vector and magnitude in an area close to that shown in the images above.  Note: the length of the vectors does not correspond to the actual distance of parallax correction.

GOES-16 parallax direction vectors and magnitude (km) for a cloud top feature at 15 km [click to enlarge]

GOES-16 parallax direction vectors and magnitude (km) for a cloud top feature at 50,000 feet (15.2 km) [click to enlarge]

Similar webapps are available for the GOES-16 Full Disk, GOES-17 CONUS and GOES-17 Full Disk sectors.

GOES-17 parallax correction direction vectors and magnitude (km) for a cloud top feature at 50,000 feet (15.2 km) [click to enlarge]

GOES-17 parallax direction vectors and magnitude (km) for a cloud top feature at 50,000 feet (15.2 km) [click to enlarge]

Can you use NUCAPS soundings to determine the rain/snow line?

January 9th, 2020 |

NUCAPS Horizontal Temperature field, 925 hPa, at 1704 UTC on 9 January 2020, toggled with NUCAPS sounding observation points from the same orbit (Click to enlarge)

NOAA-Unique Combined Atmospheric Processing System vertical profiles of moisture and temperature are derived from retrievals that consider both infrared sounder data (from the Cross-track Infrared Sounder, CrIS) and microwave sounder data (from the Advanced Technology Microwave Sounder, ATMS). In AWIPS, the profiles are from NOAA-20 but they are also produced with data from Suomi-NPP. NUCAPS profiles from NOAA-20 and Suomi-NPP are available here (the site also includes NUCAPS profiles from MetOp satellites; those NUCAPS profiles use IASI infrared and MHS microwave data).

Polar2Grid software can be used to create horizontal fields of thermodynamic information from the vertical profiles (as discussed here). For the National Weather Service forecast offices, an extra step is taken that interpolates (in the vertical) the NUCAPS data from the pressure levels in the Radiative Transfer Model that is used in the retrievals to standard pressure levels. The toggle above compares the vertical profile points at 1648 UTC on 9 January 2020 to the  925-hPa temperature field. Note that derived field does extend outwards from the outermost NUCAPS profile: the sphere of influence for an individual NUCAPS point can be adjusted.  Note that the bounds of the temperature field have been adjusted from AWIPS defaults, and the color table has been modified so that 0º C occurs between the green and cyan values.  (A more intuitive color table for rain-snow discernment would include more color gradations in the -5º C to +5º C range).  Where the low-level thermal gradient occurs should help a forecaster determine where rain is more likely and where snow is more likely.

Dewpoint Depression at 925 hPa, 1704 UTC on 9 January 2020 (Click to enlarge)

Moisture fields are available as well at thermal fields.  Thus, the effects of evaporation might be considered.  The image above shows the dewpoint depression at 925 hPa.  Lapse rates derived from NUCAPS are also available (the one below shows the temperature change from 850 to 500 hPa). If strong vertical motion is forecast, the lapse rate and/or the dewpoint depressions fields can help you anticipate how much cooling might occur.

850-500 mb Lapse Rate, 1704 UTC on 9 January 2020 (Click to enlarge)

Note that horizontal fields as presented in NUCAPS include data from all NUCAPS profiles, thereby including points that may be ‘green’ (the infrared and microwave retrievals both converge to solutions), ‘yellow’ (the infrared retrieval failed, but the microwave retrieval converged) and ‘red’ (neither retrieval converged). It’s incumbent on the analyst to consider the impact of those profiles where convergence to a solution did not occur when using these fields.

(Thanks to Christopher Stumpf, WFO MKX, for assistance in getting these images)

Eruption of Popocatépetl in Mexico

January 9th, 2020 |

GOES-16 Low-, Mid- and Upper-level Water Vapor (7.3 µm, 6.9 µm and 6.2 µm), Split Window Difference (10.3-12.3 µm) and Cloud Top Height product [click to play animation | MP4]

GOES-16 Low-, Mid- and Upper-level Water Vapor (7.3 µm, 6.9 µm and 6.2 µm), Split Window Difference (10.3-12.3 µm) images [click to play animation | MP4]

Popocatépetl erupted at 1226 UTC on 09 January 2019 — GOES-16 (GOES-East) images of Low-level (7.3 µm), Mid-level (6.9 µm) and Upper-level Water Vapor (6.2 µm) and Split Window Difference (10.3-12.3 µm) (above) showed a higher-altitude ash plume moving rapidly south-southeastward, while ash at a lower altitude moved slowly north-northeastward.

The difference in speed and direction of ash transport was explained by plots of rawinsonde data from Mexico City and Acapulco at 12 UTC (below), which revealed stronger northwesterly winds within the 200-250 hPa pressure layer, with lighter southerly to southwesterly winds existing between 400 and 600 hPa.

Plots of rawinsonde data from Mexico City and Acapulco at 12 UTC [click to enlarge]

Plots of rawinsonde data from Mexico City (yellow) and Acapulco (cyan) at 12 UTC [click to enlarge]

At 1402 UTC a Mesoscale Domain Sector was positioned over Mexico — and 1-minute GOES-16 Ash RGB images created using Geo2Grid (below) tracked the distinct signature of the northern lower-altitude ash (brighter shades of pink to red) while the southern higher-altitude ash signature faded as it was more quickly dispersed by the stronger winds.

GOES-16 Ash RGB images {click to play animation | MP4]

GOES-16 Ash RGB images [click to play animation | MP4]

A GOES-16 Ash Height product from the NOAA/CIMSS Volcanic Cloud Monitoring site (below) indicated that the southern ash plume exhibited heights in the 6-8 km range, with similar heights seen for the slow-moving northern ash feature.

GOES-16 Ash Height product [click to play animation MP4]

GOES-16 Ash Height product [click to play animation MP4]