There have been recent changes to web browsers with a result that ftp:// protocols are only rarely supported (and that can be with difficulty). Accordingly, ftp access to UW-Madison CIMSS Direct Broadcast imagery has been altered so that https:// protocols can be used. This can allow direct visualization of imagery through a web-browser, eliminating the need to download it first. To access NOAA-20 data, for example, start at https://ftp.ssec.wisc.edu/pub/eosdb/j01/ (similar urls access Suomi-NPP, Terra and Aqua imagery);  then select an instrument (VIIRS or ATMS, for example), a day/time, and the type of imagery. The imagery shown above came from much larger images at https://ftp.ssec.wisc.edu/pub/eosdb/j01/viirs/2021_04_27_117_1716/images/. It shows True Color imagery over the Gulf Stream just east of North Carolina’s Outer Banks, along with M12 (3.7 µm) and M13 (4.05 µm) imagery. There is both a color change and temperature change to the water as one travels across the North Wall of the Gulf Stream.

The CIMSS Direct Broadcast site is one of very few that allows access to imagery for all 22 VIIRS channels: 5 I-bands, 16 M-bands, and the Day Night band.

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1-minute Mesoscale Domain Sector GOES-17 (GOES-West) Shortwave Infrared (3.9 µm) and Fire Temperature RGB along with 5-minute  GOES-16 (GOES-East) Fire Power and GOES-16 Fire Temperature derived products (above) showed the thermal signature of the rapidly-growing Three Rivers Fire in New Mexico on 26 April 2021. The maximum GOES-17 Shortwave Infrared brightness temperature was 138.7ºC — which is the saturation temperature for those ABI detectors — every minute for a solid hour between 1901-2001 UTC. Peak GOES-16 Fire Power and Fire Temperature values during that time were in excess of 2960 MW and 2960 K, respectively. At nearby Ruidoso, southwesterly winds were gusting as high 39 knots.

GOES-16 True Color RGB images created using Geo2Grid (below) revealed 2 distinct “fire jump” events (after 20 UTC, and again after 22 UTC), when smoke/cloud material was ejected to higher altitudes than the primary smoke plume. In addition, southwest of the large smoke plume a smaller and more diffuse plume of blowing gypsum dust could be seen streaming northeastward from White Sands National Park.

#Sentinel5P #TROPOMI captured high concentrations of trace gases from #ThreeRiversFire in #NewMexico on 26 Apr: tropospheric column NO2 (left) & total column CO (right). Per @inciweb, fire is 4000 acres, 0% contained.@NMClimate @NWSElPaso @LincolnUSForest @CIMSS_Satellite pic.twitter.com/zLqgRYQ3yC

— AerosolWatch (@AerosolWatch) April 27, 2021

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GOES-17 (GOES-West) CIMSS Natural Color RGB images (above) depicted a large offshore surge of airborne glacial silt from Southeast Alaska on 25 April 2021. During the preceding week, abnormally warm and dry conditions across much of Southeast Alaska (Juneau | Ketchikan | Sitka | Yakutat) promoted significant snow melt which exposed a great deal of surface glacial silt.

The leading edge of the aerosol could also be seen in GOES-17 Near-Infrared “Cirrus” (1.37 µm) images (below). The presence of a very dry air mass over the region (rawinsonde data: Yakutat | Annette Island) allowed some of the lower-tropospheric aerosol to be sensed by this spectral band.

GOES-17 True Color RGB images created using Geo2Grid (below) provided a clearer view of the areal coverage of glacial silt moving westward off the coast.

With ample illumination from the Moon (which was in the Waxing Gibbous phase, at 96% of Full),  the emergence of airborne particles off the Southeast Alaska coast was seen in a Suomi NPP VIIRS Day/Night Band (0.7 µm) image at 1221 UTC (below).

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April showers developed over the upper Midwest on the afternoon of 24 April 2021. The toggle above shows atmospheric lapse rates (as derived from NUCAPS Sounding observations) at 1818 UTC in 3 different layers: 925-850 mb, 900-700 mb, and 850-500 mb.  A very tight gradient in low-level lapse rates exists southwest-to-northeast over Wisconsin.  How do the cloud patterns change in that region?  Can you use NUCAPS Lapse Rate distributions to anticipate when and where convection might develop?

The toggle below shows the visible imagery and the 925-850 mb lapse rate. The character of the clouds in the visible imagery (0.64 µm) west of the strong lapse rate gradient over southwestern Wisconsin is much different from the more cumuliform clouds over south-central and southeast Wisconsin.

When using gridded NUCAPS fields, it’s important to know what kind of data are used. That is: was the NUCAPS retrieval successful? The toggle below shows the NUCAPS Sounding Availability points from AWIPS overlain on top of the visible imagery: Green Dots show where the infrared retrieval converged to a solution; yellow dots show regions where the infrared retrieval did not converge — but the microwave retrieval did; red dots show where neither the infrared nor microwave retrievals converged.  There are many ‘green’ sounding points over Wisconsin in the region of the strong horizontal gradient in lapse rates.

One can also view stability fields such as Total Totals index, shown below, in a toggle with the low-level lapse rates.  Note that a pronounced gradient in the Total Totals index is not apparent.  A user who wants to find a gradient along which convection might develop should look at more than one field (or level).  It’s useful to create 4-panels in AWIPS and develop AWIPS Procedures to load and display the imagery.

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The Day Cloud Phase Distinction RGB stood in nicely for radar imagery in the region where showers developed (this also happened on 21 April, as discussed in this blog post).  The toggle below cycles through the Day Cloud Phase Distinction with and without radar overlain, and also shows the radar data alone. Rain showers are occurring where the Day Cloud Phase Distinction RGB has a chartreuse/yellow hue.  In regions with more wide-spread cirrus clouds (over the Upper Peninsula of Michigan for example), the relationship between chartreuse/yellow and showery precipitation is less noticeable.

Visible (1636-2131 UTC on 24 April) and Day Cloud Phase Distinction (1651 – 2146 UTC) animations can be viewed here (visible) and here (Day Cloud Phase Distinction)

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The alert reader will notice above that the time stamp of the gridded NUCAPS fields (1818 UTC) differs from the timestamp of the NUCAPS Sounding Availability points (1757 UTC).  Why is that the case for this ascending NOAA-20 overpass?  Satellite imagery is typically timestamped with the first line of data in the image.  That’s usually around 40 S Latitude for Sounding Availability plots in NUCAPS.  The gridded fields, however, use smaller portions of the NOAA-20 orbit.  The gridded fields shown on this day started at about 30 N Latitude;  it took NOAA-20 about 20 minutes to move from 40 S to 30 N!

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