NUCAPS Sounding Availability

May 16th, 2019 |

NUCAPS soundings from NOAA-20 at 0653 UTC on 16 May 2019, 34.4 N, 75.8 W (Click to enlarge)

The Cross-Track Infrared Sounder (CrIS) on Suomi NPP suffered an anomaly back in late March and the mid-wave portion of the detectors are not functioning as designed; the wavelengths affected include those sensitive to water vapor. Because of this data outage, NUCAPS soundings are not being produced from Suomi NPP. Suomi NPP was the sole data source for NUCAPS in National Weather Service offices over the contiguous United States.

As shown above, NUCAPS soundings are being produced by NOAA-20, which, like Suomi NPP, carries both the CrIS and the Advanced Technology Microwave Sounder (ATMS). NOAA-20 NUCAPS soundings are scheduled to replace the Suomi NPP NUCAPS soundings in National Weather Service Forecast Offices in late May 2019. NOAA-20 is in the same orbit as Suomi NPP, but offset by half an orbit; overpasses are offset by about 45 minutes, so the NUCAPS data should show up in forecast offices at about the same time of day. (Compare these Suomi NPP orbits over North America to these from NOAA-20; Orbital tracks for most polar orbiters are here.) Time latency for NOAA-20 soundings is improved over Suomi-NPP however; there will be less wait needed for the soundings.

NUCAPS soundings are also produced from Metop-A and Metop-B, satellites that carry the Infrared Atmospheric Sounding Interferometer (IASI) and the Advanced Microwave Sounding Unit (AMSU) and Microwave Humidity Sensor(MHS) instruments.

NUCAPS soundings from NOAA-20, Metop-A and Metop-B are available at this site. That site includes a map (shown here) To access the soundings, move the map to your desired location, and click on the small box in the upper left of the map (under the +/- that cause the map to zoom in and out).  After clicking the box, use a left click and mouse drag on the map to define a region where sounding points will appear. (Alternatively, click the ‘Thumbnail Viewer’ box above the map; as you mouse over the points, a sounding will appear in the window.) The points are color-coordinated based on how old the latest sounding is. Zoom in, and choose your point.  Three profiles are displayed: The initial regression profile (labeled MW+IR Regr), the microwave-only profile (labeled MW phys) and the final physical retrieval profile (labeled MW+IR phys).  The resultant sounding you see will be the latest, but 10 soundings near that point over the past several days can be accessed as well.

NUCAPS soundings from Suomi NPP are not gone for good, however.  The CrIS has redundant electronics, and ‘A’ side — that has partially failed — and a ‘B’ side that has not been tested since before launch (Suomi NPP was launched on 28 October 2011!  Here is one of its first images).  The ‘B’ side electronics can be activated, and if they work, NUCAPS algorithms would have to be recalibrated for an essentially new data source.  This would take several months.  Alternatively, NUCAPS for Suomi NPP could be reformulated to account for the missing data with the ‘A’ side electrontics, something that also would take several months.  A decision on the path to take is forthcoming.

Plume of wildfire smoke from British Columbia

March 25th, 2019 |

GOES-17

GOES-17 “Red” Visible (0.64 µm) and Low-level Water Vapor (7.3 µm) images [click to play animation | MP4]

GOES-17 (GOES-West) “Red” Visible (0.64 µm) and Low-level Water Vapor (7.3 µm) images (above) showed a northeasterly flow (model analyses) off the coast of British Columbia, Canada on 25 March 2019. Contained within this offshore flow was a hazy plume moving over Haida Gwaii and out across the eastern Pacific Ocean.

This aerosol plume was more easily seen in GOES-17 True Color Red-Green-Blue (RGB) images from the AOS site (below).

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

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

In comparisons between VIIRS Visible (0.64 µm) and Day/Night Band (0.7 µm) from Suomi NPP at 2104 UTC and NOAA-20 at 2154 UTC (below), the portion of the plume where aerosols were most dense (and therefore more reflective) was better portrayed in the Day/Night Band images.

VIIRS Visible (0.64 µm) and Day/Night Band (0.7 µm) from Suomi NPP at 2104 UTC and NOAA-20 at 2154 UTC [click to enlarge]

VIIRS Visible (0.64 µm) and Day/Night Band (0.7 µm) from Suomi NPP at 2104 UTC and NOAA-20 at 2154 UTC [click to enlarge]

Similarly, the portion of this plume having a higher aerosol concentration was highlighted using Terra MODIS Near-Infrared “Cirrus” (1.61 µm) imagery (below). The corresponding MODIS Water Vapor (6.7 µm) image showed that while the plume was generally contained within a ribbon of drier air, a narrow tongue of moisture existed within the core of the band of dry air. Both the VIIRS and the MODIS imagery indicated that the plume was passing over Sandspit (surface identifier CYZP), where the surface visibility briefly dropped to 7 miles at 21 UTC during a short period of northwesterly winds.

Terra MODIS Visible (0.65 µm), Near-Infrared

Terra MODIS Visible (0.65 µm), Near-Infrared “Cirrus” (1.61 µm) and Water Vapor (6.7 µm) images at 1936 UTC [click to enlarge]

A toggle between the 2015 UTC Suomi NPP VIIRS True Color RGB image and Aerosol Optical Depth product as viewed using RealEarth (below) also showed the plume was passing over station CYZP on Haida Gwaii. Note that there were a few VIIRS fire detection points (red dots) in central British Columbia — which suggests that this aerosol plume was likely smoke from biomass burning.

Suomi NPP VIIRS True Color RGB image and Aerosol Optical Depth product at 2015 UTC [click to enlarge]

Suomi NPP VIIRS True Color RGB image and Aerosol Optical Depth product at 2015 UTC [click to enlarge]

Regarding the moisture gradient seen on the MODIS Water Vapor image, it is interesting to examine 3 adjacent closely-spaced NUCAPS soundings immediately south of CYZP (below). The Total Precipitable Water values increased from 0.18″ to 0.26″ within a distance of only 60 miles.

Suomi NPP VIIRS Visible (0.64 µm) image, with available NUCAPS locations [click to enlarge]

Suomi NPP VIIRS Visible (0.64 µm) image, with available NUCAPS locations [click to enlarge]

NUCAPS profiles at Points 1, 2 and 3 [click to enlarge]

NUCAPS profiles at Points 1, 2 and 3 [click to enlarge]

Intense central US midlatitude cyclone

March 13th, 2019 |

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

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

An unusually deep midlatitude cyclone — which easily met the criteria of a “bomb cyclone”, with its central pressure dropping 25 hPa in only 12 hours (surface analyses) — developed over the central US on 13 March 2019 (WPC storm summary). GOES-16 (GOES-East) Air Mass RGB images from the AOS site (above) showed the large size of the cloud shield — and the deeper red hues over the High Plains indicated the presence of ozone-rich air (from the stratosphere) within the atmospheric column as the tropopause descended. A preliminary new all-time low surface pressure of 975.1 hPa occurred at Pueblo, Colorado just after 13 UTC; to the east of Pueblo, a 970.4 hPa minimum pressure recorded at Lamar (plot) possibly set a new state record for Colorado.

On a map of NWS warnings/advisories valid at 14 UTC (below), Blizzard Warnings (red) extended from Colorado to the US/Canada border. South of the Blizzard Warnings, High Wind Warnings (brown) were in effect to the US/Mexico border.

Map of NWS warnings and advisories at 14 UTC [click to enlarge]

Map of NWS warnings and advisories at 14 UTC [click to enlarge]

GOES-16 Mid-level Water Vapor (6.9 µm) images (below) displayed a hook-like signature resembling that of a sting jet, which developed over the Texas/Oklahoma Panhandle area after 11 UTC. At 14 UTC an interesting burst of surface wind gusts occurred at 3 sites — Burlington CO, Goodland KS and Colby KS — which may have been related to the downward transfer of momentum along the leading edge of the sting jet flow. The corresponding 7.3 µm Low-level Water Vapor animations are also available: GIF | MP4.

GOES-16 Mid-level Water Vapor (6.9 µm) images [click to play animation | MP4]

GOES-16 Mid-level Water Vapor (6.9 µm) images [click to play animation | MP4]

The MIMIC Total Precipitable Water product (below) showed the northward surge of moisture from the Gulf of Mexico.

MIMIC Total Precipitable Water product [click to play animation | MP4]

MIMIC Total Precipitable Water product [click to play animation | MP4]

During the afternoon hours, the strong surface winds began to create plumes of blowing dust across parts of southeastern New Mexico and western Texas — a blowing dust signature first became apparent on GOES-16 Split Window Difference imagery as plumes of yellow, but then became more obvious on “Red” Visible (0.64 µm) images as the afternoon forward scattering angle increased (below). Blowing dust reduced the surface visibility to 1-2 miles at Snyder (KSNK) and Lubbock (KLBB).

GOES-16 "Red" Visible (0.64 µm) and Split Window Difference images [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm) and Split Window Difference images [click to play animation | MP4]

The blowing dust signature (lighter shades of brown) was also easily seen in late-afternoon GOES-16 True Color RGB images (below) — the dust plume reached southwestern Oklahoma by the end of the daytime hours, restricting the visibility to 5 miles at Frederick (KFDR). The blowing dust was also evident in True Color imagery from GOES-17, as seen here.

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

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

Not long after the cyclone reached its lowest analyzed surface pressure of 968 hPa at 18 UTC, an overpass of the Suomi NPP satellite around 19 UTC provided a swath of NUCAPS soundings covering much of the storm (below). The air was very dry and stable near the near the center of the surface low in eastern Colorado (TPW=0.29″, CAPE=0 J/kg), in western Texas (TPW=0.31″, CAPE=0 J/kg) and near the frontal triple point in southeastern Nebraska (TPW=0.30″, CAPE=0 Jkg) — and out ahead of the warm front, the air was moist but stable behind a line of thunderstorms in northeastern Arkansas (TPW=1.09″, CAPE=0 J/kg) but both moist and unstable in western Mississippi (TPW=1.36″, CAPE=3506 J/kg).

Suomi NPP VIIRS Visible (0.64 µm) image, with overlays of the surface analysis and available NUCAPS soundings [click to enlarge]

Suomi NPP VIIRS Visible (0.64 µm) image, with overlays of the surface analysis and available NUCAPS soundings [click to enlarge]

During the early stages of cyclone development, this system spawned severe thunderstorms that produced tornadoes, large hail and damaging winds across New Mexico and Texas (SPC storm reports) late in the day on 12 March. A GOES-17 (GOES-West) Mesoscale Domain Sector had been positioned over that region — which was helpful during a brief GOES-16 data outage — providing images at 1-minute intervals (below).

GOES-17

GOES-17 “Clean” Infrared Window (10.3 µm) images, with plots of SPC storm reports [click to play animation | MP4]

===== 14 March Update =====

GOES-16 Mid-level Water Vapor (6.9 µm) images, with hourly plots of surface winds and gusts in knots [click to play animation | MP4]

GOES-16 Mid-level Water Vapor (6.9 µm) images, with hourly plots of surface winds and gusts in knots [click to play animation | MP4]

GOES-16 Mid-level Water Vapor (6.9 µm) images (above) showed the storm moving slowly northeastward across Kansas, Nebraska and Iowa on 14 March — with strong winds continuing north and west of the surface low, blizzard conditions persisted across much of the Midwest.

Farther to the east, severe thunderstorms produced large hail, damaging winds and tornadoes as far north as northern Illinois/Indiana/Ohio and southern Lower Michigan (SPC storm reports | NWS Detroit) — as shown with 1-minute Mesoscale Domain Sector GOES-16 Visible images (below). The corresponding GOES-16 Infrared image animation is available here; the coldest cloud-top infrared brightness temperatures were only in the -30 to -40ºC range

GOES-16 "Red" Visible (0.64 µm) Visible images, with SPC storm reports plotted in red [click to play MP4 animation]

GOES-16 “Red” Visible (0.64 µm) Visible images, with SPC storm reports plotted in red [click to play MP4 animation]

NUCAPS Profiles across a Saharan Air Layer (SAL) Outbreak

March 12th, 2019 |

Split Window Difference imagery over the Atlantic Basin, 1800 UTC 11 March through 1800 UTC 12 March 2019 (Click to animate)

A Saharan Air Layer (SAL) outbreak is occurring over the eastern Atlantic Ocean on 11-12 March 2019. The animation above shows the Split-Window Difference (10.3 µm – 12.3 µm) (link, from this website) color-enhanced to accentuate in red/pink/white the regions where Saharan Dust has been lofted into the atmosphere. This outbreak has been developing — this animation (courtesy Arunas Kuciauskas, NRL in Monterey) from 0400 UTC on 8 March to 1400 UTC on 11 March of the DEBRA product (now the Dynamic Enhanced Background Reduction Algorithm, from this website) shows the dust originating west of a departing cyclone over northwest Africa).

NUCAPS Profiles sampled a region of the SAL on Tuesday 12 March, and those are shown below. (This has been discussed previously on this blog, here)  The swath of points is shown on top of a GOES-16 Red/Green/Blue image composite designed to highlight dust in pink. Sounding locations shown are denoted by the orange dot, and Precipitable Water associated with the sounding is indicated.  The accentuated mid-level drying associated with the SAL air, inferred by the pink in the RGB, is readily apparent.

GOES-16 Dust RGB at 1530 UTC on 12 March 2019 superimposed with NUCAPS sounding locations. Inset: NUCAPS Sounding in the location indicated by the orange dot. Total Precipitable Water for the sounding as indicated (Click to enlarge)


============= Update 13 March 2019 ==============

DEBRA dust product from MSG Seviri data, hourly from 0000 UTC on 11 March to 1500 UTC 12 March 2019 (Click to enlarge)

The animation above and the one below are courtesy Arunas Kuciauskas from the Naval Research Lab in Monterey CA. The Dynamic Enhanced Background Reduction Algorithm (DEBRA) dust product animation, above, is a product developed at both NRL and the Cooperate Institute for Research in the Atmosphere (CIRA) by Steve Miller. DEBRA was derived from the MSG SEVIRI dataset. The background is gray-scaled to enhance the yellow-shaded lofted dust. Brighter yellow shades suggest greater confidence that a pixel is dusty.

The animation below shows output from the ICAP model;  this is an Aerosol optical depth (AOD) prediction model that was initialized with data from 0000 UTC 11 March 2019; it provides 6-hourly forecasts of AOD (colored contours) through 0000 UTC on 16 March 2019.   This ICAP Multi Model Ensemble (ICAP MME) is a consensus style 550 nm aerosol optical thickness (AOT) forecast ensemble from the following systems: ECMWF MACC, JMA MASINGAR, NASA GSFC/GMAO, FNMOC/NRL NAAPS, NOAA NGAC,  Barcelona Supercomputing Centre NMMB/BSC-CTM and UK Met office unified model.

Aerosol Optical Depth predictions from the ICAP MME, 0000 UTC 11 March through 0000 UTC 16 March 2019 (Click to enlarge)

Suomi NPP overflew the leading edge of the SAL in the eastern Atlantic around 1500 UTC on 13 March 2019. The animation below shows the NUCAPS points superimposed on the GOES-16 Baseline Total Precipitable Water Product (very dry air is indicated) and on the Dust RGB that highlights the SAL in Red. Additionally, 6 NUCAPS Soundings are shown. They captured the very dry air associated with the SAL.  Total Precipitable Water estimates from the GOES Baseline Product and from the NUCAPS sounding are indicated.  The GOES moisture estimates are heavily constrained by GFS model data as the Advanced Baseline Imager (ABI) has only 3 infrared bands (at 6.19 µm, 6.95 µm and 7.34 µm, Bands 8, 9 and 10) that are sensitive to water vapor.  In contrast, the Cross-track Infrared Sounder (CrIS) on Suomi NPP has many more bands that are sensitive to Water Vapor.  More than 60 are used in the NUCAPS retrieval.

NUCAPS Sounding Points at 1520 UTC on 13 March 2019, along with Baseline Total Precipitable Water and the Dust RGB at 1515 UTC 13 March 2019. NUCAPS soundings at the points indicated are shown. Total Precipitable Water from GOES and from NUCAPS are indicated as well (Click to enlarge)