VIIRS imagery and NUCAPS profiles near the North Pole

August 22nd, 2019 |

Suomi NPP VIIRS Visible (0.64 µm), Shortwave Infrared (3.74 µm) and Infrared Window (11.45 µm) images [click to enlarge]

Suomi NPP VIIRS Visible (0.64 µm), Shortwave Infrared (3.74 µm) and Infrared Window (11.45 µm) images [click to enlarge]

A sequence of 4 consecutive Suomi NPP VIIRS Visible (0.64 µm), Shortwave Infrared (3.74 µm) and Infrared Window (11.4 µm) images (above) showed a small swirl of clouds associated with a weak area of low pressure near the North Pole — north of Greenland (surface analyses) — on 22 August 2019.

Suomi NPP VIIRS Visible (0.64 µm) images, with plots of NUCAPS availability [click to enlarge]

Suomi NPP VIIRS Visible (0.64 µm) images, with plots of NUCAPS availability [click to enlarge]

There were Suomi NPP NUCAPS soundings available in the vicinity of the surface low (above) — profiles from the 4 squared green dot locations (green dots indicate successful sounding retrievals from both the CrIS and ATMS instruments) which were closest to both the surface low and the North Pole (below) revealed characteristically-low arctic tropopause heights of around 7-8 km, and surface temperatures dropping to below freezing at the 2 most northerly points of 88.28º and 88.57º N latitude. Note: the Suomi NPP (SNPP) CrIS anomaly that began on 24 March 2019 was resolved via a switch to the redundant Side-2 electronics on 24 June — so CrIS data once again became available for incorporation into SNPP NUCAPS soundings beginning on 01 August. Training material for NUCAPS in AWIPS is available here.

NUCAPS temperature (red) and dew point (green) profiles [click to enlarge]

NUCAPS temperature (red) and dew point (green) profiles [click to enlarge]

According to GCOM-W1 AMSR2 data (source), this weak surface low was over a portion of the Arctic Ocean where sea ice concentration was still high (below).

GCOM-W1 AMSR2 sea ice concentration [click to enlarge]

GCOM-W1 AMSR2 sea ice concentration [click to enlarge]

Cyclone Kenneth makes landfall in Mozambique

April 25th, 2019 |

Meteosat-8 Visible (0.8 µm) images [click to play animation | MP4]

Meteosat-8 Visible (0.8 µm) images [click to play animation | MP4]

EUMETSAT Meteosat-8 Visible (0.8 µm) images (above) and Infrared Window (10.8 µm) images (below) showed Category 4 Cyclone Kenneth (12 UTC JTWC advisory) making landfall along the northeast coast of Mozambique (north of Pemba FQPB: surface observations) on 25 April 2019. Kenneth had been moving over warm water and through an environment of low deep-layer wind shear, factors favorable for its rapid intensification (ADT | SATCON). After making landfall, Kenneth rapidly weakened to Category 1 intensity by 18 UTC — but Metop-A ASCAT winds of 40-49 knots were still sampled along the coast on the rear periphery of the storm. The slow inland movement of the remnants of Kenneth combined with copious amounts of tropical moisture as depicted by MIMIC TPW posed a concern for potential flooding problems.

Meteosat-8 Infrared Window (10.8 µm) images [click to play animation | MP4]

Meteosat-8 Infrared Window (10.8 µm) images [click to play animation | MP4]

VIIRS True Color Red-Green-Blue (RGB) and Infrared Window (11.45 µm) images from Suomi NPP and NOAA-20, viewed using RealEarth (below), provided higher-resolution views of Kenneth a few hours prior to landfall. This was the strongest tropical cyclone landfall on record for the northern portion of Mozambique, as discussed here.

VIIRS True Color RGB and Infrared Window (11.45 µm) images from Suomi NPP and NOAA-20 [click to enlarge]

VIIRS True Color RGB and Infrared Window (11.45 µm) images from Suomi NPP and NOAA-20 [click to enlarge]

GCOM-W1 AMSR2 Microwave (89 GHz) image (below, courtesy of William Straka, CIMSS) showed the eye and spiral band structures near the Mozambique coast at 1030 UTC on 25 April. The evolution of the eye since its initial formation on 23 April was evident in the MIMIC TC product.

GCOM-W1 AMSR2 Microwave (89 GHz) image [click to enlarge]

GCOM-W1 AMSR2 Microwave (89 GHz) image [click to enlarge]

A longer animation of Meteosat-8 Infrared images (below) during the later half of its storm track showed the formation of an eye as Kenneth began its period of rapid intensification on 24 April. Cloud-top infrared brightness temperatures were -90ºC and colder (yellow pixels embedded with darker shades of purple) during the 1030-1800 UTC period on 24 April. Note that the center of Kenneth passed just north of the island of Grande Comore soon after the eye had developed — at Prince Said Ibrahim International Airport FMCH in Moroni, southeast winds gusted to 65 knots at 21 UTC 0n 24 April as the southern eyewall passed over the island.

Meteosat-8 Infrared Window (10.8 µm) images [click to play animation | MP4]

Meteosat-8 Infrared Window (10.8 µm) images [click to play animation | MP4]

NOAA-20 VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images (below, courtesy of William Straka, CIMSS) showed Kenneth at 2232 UTC on 24 April, shortly before the tropical cyclone had reached Category 4 intensity. Ample illumination from the Moon — in the Waning Gibbous phase, at 73% of Full — provided an excellent example of the “visible image at night” capability of the VIIRS Day/Night Band.

NOAA-20 Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images [click to enlarge]

NOAA-20 VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images [click to enlarge]

Tropical Cyclone Veronica north of Australia

March 21st, 2019 |

Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared Window (1145 µm) images at 1716 UTC [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images at 1716 UTC [click to enlarge]

A toggle between Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images (above) showed Category 4 Cyclone Veronica off the northern coast of Western Australia at 1716 UTC on 21 March 2019. Ample illumination from a Full Moon maximized the “visible image at night” capability of the Day/Night Band.

In a comparison of Microwave images from Suomi NPP ATMS at 1716 UTC and from GCOM-W1 AMSR2 at 1732 UTC (below), an eyewall that was nearly completely closed was apparent. Suomi NPP and GCOM-W1 images courtesy of William Straka, CIMSS.

Microwave images from Suomi NPP ATMS at 1716 UTC and from GCOM-W1 AMSR2 at 1732 UTC [click to enlarge]

Microwave images from Suomi NPP ATMS at 1716 UTC and from GCOM-W1 AMSR2 at 1732 UTC [click to enlarge]

A DMSP-17 SSMIS Microwave (85 GHz) image at 2246 UTC from the CIMSS Tropical Cyclones site is shown below. The deep-layer Wind Shear at 21 UTC was low (green contours), and Sea Surface Temperature values were quite high — both factors favorable for continued intensification as Veronica moved slowly toward the coast.

DMSP-17 SSMIS Microwave (85 GHz) image at 2246 UTC, with an overlay of 21 UTC deep-layer Wind Shear, and Sea Surface Temperature [click to enlarge]

DMSP-17 SSMIS Microwave (85 GHz) image at 2246 UTC, with an overlay of 21 UTC deep-layer Wind Shear, and Sea Surface Temperature [click to enlarge]

2.5-minute interval rapid scan Himawari-8 Infrared Window (10.4 µm) images (below) showed increasing organization to the eyewall structure. At times the cloud-top infrared brightness temperatures were -90ºC and colder (yellow pixels embedded within darker purple). Note: the rapid scan sector was re-poositioned eastward at 0100 UTC (to monitor Cyclone Trevor), so 10-minute imaging resumed after that time.

Himawari-8 Infrared Window (10.4 µm) images [click to play animation | MP4]

Himawari-8 Infrared Window (10.4 µm) images [click to play animation | MP4]

After sunrise, rapid scan Himawari-8 “Red” Visible (0.64 µm) images (below) revealed that the large eye was completely cloud-filled.

Himawari-8 "Red" Visible (0.64 µm) images [click to play animation | MP4]

Himawari-8 “Red” Visible (0.64 µm) images [click to play animation | MP4]

Unusual early ice loss in the Bering Sea

March 9th, 2019 |

GCOM-W2 AMSR2 Sea Ice Concentration, 01 February - 09 March 2019 [click to play animation | MP4]

GCOM-W1 AMSR2 Sea Ice Concentration, 01 February – 09 March 2019 [click to play animation | MP4]

A persistent northward transport of anomalously-warm air across the Bering Sea during the month of February 2019 led to an unusual loss of sea ice there — daily images of GCOM-W1 AMSR2 Sea Ice Concentration (source) from 01 February to 09 March (above) showed the northward retreat of ice from the Bering Sea into the Chukchi Sea. The ice reached its maximum northward extent on 04 March; northward ice motion was very pronounced during the 25-26 February and 27-28 February periods. In early March a synoptic pattern change then allowed cold arctic air to flow back toward the south, helping the ice concentration to begin increasing again in the northern portion of the Bering Sea.

Minimal cloudiness on 28 February allowed the northward flow of ice through the Bering Strait to be seen on GOES-17 (GOES-West) “Red” Visible (0.64 µm) images (below).

GOES-17

GOES-17 “Red” Visible (0.64 µm) images [click to play animation | MP4]