Animations of GOES-16 Visible, near-Infrared and shortwave Infrared over North America shortly before the Vernal Equinox, and shortly after the Autumnal Equinox, (that is, when the Sun is overhead in the Southern Hemisphere) show bright spots that propagate quickly from west to east (these features were first noted by Frank Alsheimer of the National Weather Service). The animation above shows the visible imagery (0.64 µm) over the Continental United States on 5 March 2018 (Click here for a slower animation speed). Brightening over regions between 30 and 40 N between 1637 UTC and 1732 UTC is apparent. The animation below of the shortwave infrared (3.9 µm) shows slight warming (Click here for a slower animation), as might be expected with reflected solar energy. The brightening is also apparent in the Band 4 “Cirrus”  (1.37 µm) — in fact, a closer look at southern Colorado reveals the bright signature of sunlight reflecting off solar panels at the Alamosa Solar Generating Facility (Google maps).

The increased reflectance can cause the ABI Clear Sky Mask to mis-characterize clear regions as cloudy (See the animation below; click here for a slower animation). Thus, Cloud properties (Cloud-top Height, Temperature, Pressure, etc.) can be identified in clear regions.

The bright spots in the visible, and warms spots in the shortwave infrared, occur when the Earth’s surface, the GOES Satellite and the Sun are aligned on one line. If you were within the bright spot with a powerful telescope trained on the Sun, you would see the GOES Satellite transecting the solar disk. The location of these bright spots changes with season: they appear in the Northern Hemisphere shortly before the (Northern Hemisphere) vernal equinox and shortly after the (Northern Hemisphere) autumnal equinox. Similarly, they appear in the Southern Hemisphere shortly before the (Southern Hemisphere) vernal equinox and shortly after the (Southern Hemisphere) autumnal equinox. On the Equinox, the bright spots are centered on the Equator.

This animation (courtesy Daniel Lindsey, NOAA/CIRA and Steve Miller, CIRA) shows where the reflection disk moves during the days around the Northern Hemisphere Autumnal Equinox; a similar animation for the Northern Hemisphere vernal equinox would show a disk starting at the North Pole and moving southward with time.

The animation below (from this link that is used for calibration exercises), shows the difference in reflectance (Bands 1-6) or Brightness Temperature (Bands 7-16) between 1657 and 1652 UTC on 3 and 5 March 2018. Two things are apparent: The centroid of the largest difference in solar reflectance has moved southward in those two days, as expected; the effect of this solar backscatter is most obvious in the visible, near-infrared and shortwave infrared channels (that is, bands 1-7 on the ABI).  The effect is most pronounced in clear skies.

This reflectance feature is also detectable in legacy GOES Imagery. However, the great improvements in detection and calibration in the GOES-R Series ABI (and AHI on Himawari-8 and Himawari-9) and the better temporal resolution with the GOES-R Series allows for better visualization of the effect.

The feature also shows up in “True Color” Imagery, shown below (from this site). Geocolor imagery (shown here), from CIRA, also shows the brightening.

Thanks to Daniel Lindsey and Tim Schmit, NOAA/ASPB, Steve Miller, CIRA and Mat Gunshor/Scott Bachmeier, CIMSS, for contributions to this blog post.

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A strong Nor’easter affected much of northeastern portion of the US during 02 March and 03 March 2018. As noted in the previous blog post, the storm produced very strong winds which led to widespread wind damage and power outages. A GOES-16 (GOES-East) Mesoscale Sector was positioned over the storm on 02 March, and “Red” Visible (0.64 µm) images (above) provided a detailed view of the center of circulation over the western Atlantic.

A 2-day animation of GOES-16 Mid-level Water Vapor (6.9 µm) images (below) showed the evolution of the storm as it moved from the Great Lakes to the Atlantic Ocean (surface analyses). A summary of the peak wind gusts and highest snowfall/rainfall totals can be seen here and here.

On 03 March, a vortex was seen to develop in GOES-16 “Red” Visible (0.64 µm) images, just behind the occluded frontal boundary — about 30 minutes after a burst of stronger northeasterly winds (with speeds as high as 58 knots) was analyzed in that region by the Metop ASCAT instrument.

A signature of this vortex was also evident in GOES-16 Low-level Water Vapor (7.3 µm) images (below). A toggle between Visible and Water Vapor images at 1605 UTC is available here.

Finally, a NOAA-20 VIIRS True-color Red-Green-Blue (RGB) image centered over Lake Erie at 1839 UTC on 03 March (below) showed the fresh snow cover left by the storm as it moved across the Great Lakes on 02 March. Snow can be seen across parts of Lower Michigan, southern Ontario, northern Ohio, and far northwestern Pennsylvania. NOAA-20 is the first of the JPSS series of satellites (note: the data are still considered preliminary and non-operational as the instruments and products are being evaluated and tested).

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The evolution of a very strong Nor’easter on the East Coast of the United States for the twelve hours ending at ~1800 UTC on 2 March 2018 is shown above. During this time period, the storm produced winds that shut down schools and Government in the Nation’s Capitol (and elsewhere), with High Wind Warnings widespread from North Carolina to Massachusetts (Link, from this site). Significant Coastal Flooding is likely in New England with this storm.

One of the Level 2 Products produced with GOES-R Series Satellite (GOES-16 and soon, GOES-17) data are Derived Motion Wind Vectors at various levels. The images below show winds of up to 70 knots (!!) at or below 900 hPa over the Chesapeake Bay between 1627 and 1657 UTC on 2 March. Observations (bottom) show numerous surface gusts exceeding 50 knots in the region during that time.

 

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The GOES-S satellite was launched (video) from Space Launch Complex 41 on Cape Canaveral Air Force Station, Florida at 22:02 UTC on 01 March 2018 — and after a period of post-launch testing and evaluation, it will become the operational GOES-West satellite positioned at 137º West longitude. Signatures of the rocket exhaust condensation plume could be seen using 1-minute Mesoscale Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) and Near-Infrared “Cirrus” (1.37 µm) images (above). The Cirrus imagery was able to unambiguously track the rocket condensation plume for a longer period of time — while much of it continued to drift eastward, a portion of the plume began to drift westward back toward the launch site (this was also seen in the Visible imagery). The condensation plume was not necessarily composed of ice crystals, but the 1.37 µm spectral band is very effective at detecting features that are efficient scatters of light (such as cirrus ice crystals, small liquid cloud droplets, volcanic ash, blowing dust); since the rocket plume was located in the dry air situated above the moist boundary layer (Cocoa Beach soundings) its detection and motion was not masked by the extensive cumulus clouds closer to the surface.

Warm thermal anomalies from the Atlas V rocket boosters were also evident on GOES-16 Upper-level (6.2 µm), Mid-level (6.9 µm) and Low-level (7.3 µm) Water Vapor images, moving rapidly eastward (below). The cooler signature of the lower-altitude rocket condensation plume was also evident as it slowly drifted offshore just east of the launch site.

While Shortwave Infrared (3.9 µm) imagery is useful for detection of thermal anomalies associated with wildfires or volcanic eruptions, in this case the warm rocket booster signature (darker gray to black pixels) was much less distinct (using a conventional “hot spot” enhancement) compared to what was seen on the water vapor imagery (below).

A multi-panel animation (below) showed that a signature of the rocket plume and/or the thermal anomaly was seen on all 16 bands of the GOES-16 ABI. Note that a 3.9 µm Shortwave Infrared thermal signature (black pixels) was first seen on the 22:02:00 UTC image (GOES-16 was actually scanning that point at 22:02:30 UTC, just before the rocket reached Mach 1 velocity) —  prior to the condensation cloud plume becoming apparent beginning at 22:03:00.

A 4-panel animation of GOES-16 Water Vapor and Shortwave Infrared images from AWIPS is shown below. With a color enhancement applied to the 3.9 µm Shortwave Infrared images, the thermal anomaly signature — the long streak of high-altitude superheated air from the rocket boosters — was better highlighted on the 22:05 UTC image (compared to the grayscale McIDAS version seen above).

Below is an animation of GOES-16 “Red” Visible (0.64 µm) images from AWIPS, providing another view of the rocket condensation plume.

 

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