![\"Himawari-8](\"https:\/\/cimss.ssec.wisc.edu\/satellite-blog\/wp-content\/uploads\/sites\/5\/2019\/06\/190616_himawari8_visible_shortwaveInfrared_infraredWindow_Ulawun_volcano_anim.gif\")
<\/a>Himawari-8 Visible (0.64 \u00b5m, left),<\/em> Shortwave Infrared (3.9 \u00b5m, center)<\/em> and Infrared Window (10.4 \u00b5m, right)<\/em> images [click to play animation | MP4<\/strong><\/a>]<\/p><\/div>The Ulawun<\/strong><\/a> volcano erupted just after 0430 UTC on 26 June 2019 — a comparison of Himawari-8 Visible (0.64 \u00b5m), Shortwave Infrared (3.9 \u00b5m) and Infrared Window (10.4 \u00b5m) images (above)<\/strong><\/em> showed the thermal anomaly (yellow to red 3.9 \u00b5m pixels)<\/em> preceding the eruption and the development of a well-defined umbrella cloud after the eruption. The coldest cloud-top infrared brightness temperature was -83.6\u00baC in conjunction with a prominent overshooting top at 0600 UTC<\/strong><\/a>. Note the eastward-moving cloud material that originated from this overshooting top — judging from Merauke\/Mopah, Indonesia rawinsonde data (plot<\/strong><\/a> | data<\/strong><\/a>), the westerly winds required for such transport existed in the stratosphere at altitudes of 20-24 km. The pocket of warmer cloud-top 10.4 \u00b5m brightness temperatures associated with this stratospheric cloud material was the warmest at (-57.2\u00baC) at 0640 UTC<\/strong><\/a> (which, with the adjacent -82.7\u00baC overshooting top, created a cold\/warm couplet whose magnitude was 25.5\u00baC). In addition, concentric gravity waves propagating outward across the volcanic cloud top were evident on the imagery.<\/p>\n Himawari-8 Infrared Window images (below)<\/strong> <\/em>showed that the volcanic cloud dissipated fairly quickly. The eastward drift of the stratospheric cloud material also became difficult to follow after a couple of hours — even in Low-level Water Vapor (7.3 \u00b5m) imagery<\/strong><\/a> (which is also sensitive to SO2 absorption<\/strong><\/a>).<\/p>\n Himawari-8 Infrared Window (10.4 \u00b5m)<\/em> images [click to play animation | MP4<\/strong><\/a>]<\/p><\/div>Himawari-8 Shortwave Infrared (3.9 \u00b5m) images (below)<\/strong><\/em> revealed a thermal anomaly or “hot spot” (yellow to red pixels)<\/em> for several hours leading up to the 0430 UTC volcanic eruption.<\/p>\n Himawari-8 Shortwave Infrared (3.9 \u00b5m)<\/em> images [click to play animation | MP4<\/strong><\/a>]<\/p><\/div>Regarding the intensity of the thermal anomaly, a plot of volcano radiative power (VRP) and volcanic cloud longwave infrared brightness temperature (below)<\/strong><\/em> showed that the VRP exceeded 1 GW several hours prior to the formation of the eruption umbrella cloud.<\/p>\n Time series plot of volcano radiative power (red)<\/em> and volcanic cloud longwave infrared brightness temperature (green),<\/em> courtesy of Mike Pavolonis (NOAA\/NESDIS) [click to enlarge]<\/p><\/div>Himawari-8 False Color RGB imagery along with radiometrically retrieved Ash Height, Ash Effective Radius and Ash Loading products (below<\/em>) <\/em><\/strong>revealed a volcanic cloud characterized by high ash loading of large particles, having height values generally in the 16-20 km range (with a maximum height of 22 km).<\/p>\n False Color RGB (top left),<\/em> Ash Height (top right),<\/em> Ash Effective Radius (bottom left)<\/em> and Ash Loading (bottom<\/em> right),<\/em> courtesy of Mike Pavolonis (NOAA\/NESDIS) [click to play animation | MP4<\/strong><\/a>]<\/p><\/div>An oblique view of of the Ulawun volcanic cloud was provided by GOES-17 “Red” Visible (0.64 \u00b5m<\/strong><\/a>) images (below). <\/strong><\/em>This view accentuated the vertical extent of overshooting tops<\/strong><\/a>, and the large solar angle helped to highlight the cloud-top gravity waves<\/strong><\/a>. The 3-dimensional aspect of the two distinct eruption pulses (with umbrella clouds at two different altitudes) along with the westward-drifting stratospheric plume were a bit more obvious in the GOES-17 images.<\/a><\/a><\/a><\/a>
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