Himawari-8 AHI 0.64 µm visible channel images (click to play animation)

The AHI Instrument on Himawari-8 has 16 different channels sensing the atmosphere. The instrument is still in Post-Launch Testing, a period when instrument performance is monitored and adjusted. Extratropical cyclogenesis that occurred east of Japan on 30 March was captured by the different channels.

The 0.64 µm visible imagery, above, is the highest-resolution channel on AHI, with nominal 0.5-km resolution at the subsatellite point. The imagery above — at 1.5 km resolution and every 10 minutes — shows the development of an extratropical cyclone east of the main island of Japan (visible at the left edge of the imagery). Thin cirrus is spreading north of the storm and convection is developing both in the cool air north of the surface circulation center and along the cold front that is just to the west of the cirrus shield associated with the warm conveyor belt. Northerly surface winds north of the system and southern surface winds south of the system speak to the strengthening of the frontal boundary along which the storm is developing.

Himawari-8 AHI 0.85 µm infrared channel images (click to play animation)

The 0.85 µm imagery, above, is in the near-infrared part of the electromagnetic spectrum, at wavelengths just a bit longer than red visible light (which is at 0.7 µm). It does an excellent job highlighting the land/water contrast (because bodies of water strongly absorb 0.85 µm solar radiation and land and clouds reflects it). This channel also is sensitive to vegetation. The larger-scale view shows jetstream cirrus south and southwest of the developing storm and an occluded system decaying to the east of Kamchatka.

The 0.46 µm imagery, below, is in the visible part of the electromagnetic spectrum, and is quite sensitive to aerosols (Click here for a fact sheet on ABI’s 0.46 µm “Blue Band”; fact sheets for all ABI Bands will be here in the future). The smog and pollution that surrounds Tokyo is more apparent in this imagery. Smog is also indicated near Osaka and Nagoya. A toggle between 0.64 µm, 0.46 µm and 0.85 µm imagery, here, from 30 March 2015 at 0000 UTC allows a comparison of the imagery.

Himawari-8 AHI 0.46 µm visible channel images (click to play animation)

The 1.60 µm imagery on AHI is useful because it can distinguish between clouds with water droplets (that scatter and reflect solar 1.60 µm radiation very effectively) and clouds with ice crystals (that absorb 1.60 µm radiation). In a standard enhancement, clouds with ice crystals appear grey, clouds with water droplets appear white. In the animation below, the glaciated cirrus canopy of the warm conveyor belt is readily apparent. Note also how the convection developing along the warm front has glaciated by the end of the animation.

Himawari-8 AHI 1.60 µm infrared channel images (click to play animation)

The 3.9 µm on Himawari-8 provide detailed information about the sea surface temperature if clouds are not present, as was the case over the Kuroshio Current just east of Japan on 30 October. The animation below shows little change over 2 hours, as expected, except along the north wall of the current. Brightness Temperatures drop 10 C across the temperature gradient at the north end of the current.

Himawari-8 AHI 3.90 µm infrared channel images (click to play animation)

View only this post Read Less

Suomi NPP VIIRS Visible Image (0.64 µm), Day Night Band Visible Image (0.70 µm) and 1.61 µm near-infrared Image (click to enlarge)

Clear skies over the Eastern and Midwestern United States on 28 March allowed the wide swath of Suomi NPP VIIRS to record ice conditions over the five Great Lakes. The visible and Day/Night Band imagery shows good contrast between the dark open waters and brighter melting ice. Ice strongly absorbs 1.61 µm radiation: regions in the near-infrared 1.61 µm imagery that are dark (where radiation is absorbed, not reflected/scattered) include pack ice on the lakes, and snow cover (southeast Minnesota and southwest Wisconsin; southern Ontario bordering Lake Erie; southwestern Ontario near Lake Huron; the Upper Peninsula of Michigan, northern Wisconsin and northwestern Lower Michigan) on land. Regions of clouds comprised of water droplets (extreme eastern Lower Michigan and northern Ohio, much of central Pennsylvania and the Adirondacks of northern New York) are white on all three images.

View only this post Read Less

Himawari-8 Visible (0.64µm) Imagery (click to animate)

Infrared imagery from Himawari-8 has a nominal resolution of two km (at the sub-satellite point), but a visible channel has a nominal resolution of 0.5 km which can provide imagery with great detail. In the example above, the visible imagery captures the eruption, beginning around 2210 UTC on 25 March 2015, of the Shiveluch volcano on Russia’s Kamchatka Peninsula. The volcanic plume then moves downstream in northwesterly flow. Himawari-8 remains in post-launch testing, the period when the satellite calibration and navigation is thoroughly checked.

Suomi NPP overflew this region multiple times on 26 March 2015. VIIRS data from a 0126 UTC overpass, below, taken from this website, show satellite-based diagnostics of this event. The animation cycles through a Brightness Temperature Difference (11µm – 12µm), Ash Loading, Ash Height and a False Color RGB presentation of the volcanic plume.

Suomi NPP VIIRS Brightness Temperature Difference (11µm -12µm), Ash Loading, Ash Height, and False Color Imagery, 0126 UTC 26 March 2015 (click to enlarge)

Update: On 26 March, a Suomi NPP VIIRS true-color RGB image from the SSEC RealEarth site provided a nice view of the Shiveluch volcanic plume (below); also evident on the true-color image (as well as on images from the previous two days) to the north of Shiveluch were a pair of volcanic ash “fall streaks”, where the tan-colored ash landed on top of the existing snow cover.

Suomi NPP VIIRS true-color images from 24, 25, and 26 March

GOES-15 also viewed the eruption, at the extreme edge of its limb, as seen on the sequence of 0.63 µm visible channel images below (Shiveluch is at the center of the images).

GOES-15 0.63 µm visible channel images (click to play animation)

View only this post Read Less

GOES-13 0.63 µm visible channel images (click to play animation)

Severe thunderstorms developed in the vicinity of a quasi-stationary frontal boundary which stretched from northeastern Oklahoma into northern Arkansas and southern Missouri late in the day on 25 March 2015. A plot of the SPC storm reports shows that these storms produced widespread large hail, damaging winds, and tornadoes —  including the first tornado-related fatality of 2015 at a trailer home park near Sand Springs, Oklahoma (just west/southwest of Tulsa). Storm reports also included hail as large as 4.25 inches in diameter, and wind gusts as high as 80 mph. 1-km resolution GOES-13 (GOES-East) 0.63 µm visible channel images (above; click image to play animation) showed the development of numerous thunderstorms across the region, some of which grew to be very large discrete supercells late in the afternoon and toward sunset. The tell-tale signature of cloud-top shadows from small-scale “overshooting tops” could be seen with many of these storms, indicating the presence of vigorous updrafts which penetrated the thunderstorm top (and likely the tropopause). Also note the presence of parallel bands of stable wave clouds over parts of northeastern Kansas and northwestern Arkansas: these clouds highlighted areas where boundary layer warm air advection was over-running shallow pockets of cool, stable air north frontal boundary.

The corresponding 4-km resolution GOES-13 10.7 µm IR channel images (below; click image to play animation) revealed very cold cloud-top IR brightness temperatures (as cold as -71º C, dark black color enhancement), along with the formation of a well-defined Enhanced-V/Thermal Couplet (EV/TC) signature with the storm that produced large hail, damaging winds, and the fatal tornado southwest of Tulsa (station identifier KTUL). The EV/TC signature was first evident on the 22:00 UTC IR image, with cold/warm thermal couplet values of -65º/-53º C; the maximum thermal couplet spread was at 22:25 UTC, with -71º/-52º C, after which time the minimum IR brightness temperatures of the overshooting tops then began a warming trend: -67º C at 22:30 UTC, and -64º C at 22:37 UTC (suggesting a collapse of the vigorous updraft and overshooting top). Note that the storm-top EV/TC signature was displaced to the northwest of the surface hail/wind/tornado storm reports just west of Tulsa, due to parallax resulting from the large satellite viewing angle of GOES-East (which is positioned over the Equator at 75º W longitude). In addition, see the bottom of this blog post for examples of the NOAA/CIMSS ProbSevere product applied to these storms.

GOES-13 10.7 µm IR channel images (click to play animation)

Automated overshooting top (OT) detection icons (small yellow thunderstorm symbols) are also plotted on the GOES-13 IR images. The initial OT detections began at 20:15 UTC, over the general area where there was later a report of 1.0-inch diameter hail at 20:40 UTC. A comparison of the 4-km resolution GOES-13 10.7 µm IR image at 20:15 UTC with a 375-meter (projected onto a 1-km AWIPS grid) Suomi NPP VIIRS 11.45 µm IR image at 20:16 UTC (below) demonstrates (1) the advantage of improved spatial resolution for detecting the minimum cloud-top IR brightness temperature of thunderstorm overshooting tops (-60º C with GOES, vs -75º C with VIIRS), and (2) minimal parallax effect with polar-orbiting satellite imagery such as that from Suomi NPP, for more accurate geolocation of such potentially important storm features.

GOES-13 10.7 µm IR and Suomi NPP VIIRS 11.45 µm IR channel images

A comparison of 1-km resolution POES AVHRR 0.86 µm visible channel and 12.0 µm IR channel images (below) provided a detailed view of the storms at 22:54 UTC, which were electrically very active at that time (producing over 1900 cloud-to-ground lightning strikes in a 15-minute period). The coldest cloud-top IR brightness temperature was -77º C, located just southwest of Tulsa — this was likely the overshooting top associated with the supercell thunderstorm that produced the fatal tornado.

POES AVHRR 12.0 µm IR channel and 0.86 µm visible channel images, with METAR surface reports, lightning, and SPC storm reports

10-km resolution GOES-13 sounder Convective Available Potential Energy (CAPE) derived product images (below; click image to play animation) showed the rapid trend in destabilization of the air mass along and south of the frontal boundary, with CAPE values eventually exceeding 4300 J/kg (purple color enhancement).

GOES-13 sounder Convective Available Potential Energy (CAPE) derived product images (click to play animaton)

10-km resolution GOES-13 sounder Total Precipitable Water (TPW) derived product images (below; click image to play animation) indicated that TPW values of 30 mm or 1.18 inch and greater (yellow enhancement) were present along and south the frontal boundary in northeastern Oklahoma.

GOES-13 sounder Total Precipitable Water derived product imagery (click to play animation)

At 19:19 UTC, the 4-km resolution MODIS Total Precipitable Water derived product image (below) showed a plume of moisture with TPW values as high as 41.7 mm or 1.64 inches (red enhancement) moving toward the Tulsa area.

MODIS 0.65 um visible channel and Total Precipitable Water derived product images

Additional information about this event can be found at the NWS Tulsa and United States Tornadoes sites.

View only this post Read Less