Strong cyclone near Antarctica

March 26th, 2019 |

Composites of geostationary and polar orbiter Infrared imagery [click to play animation]

Composites of geostationary and polar orbiter Infrared imagery [click to play animation]

Composites of Infrared imagery (above) and Water Vapor imagery (below) from the AMRC site showed an anomalously strong (MSLP | 925 hPa winds | source) cyclone that was moving southeastward across the South Pacific Ocean toward the coast of Antarctica on 26 March 2019. These composites blend images from both geostationary and polar orbiting satellites; the storm is located in the upper right quadrant of the images. On the Infrared imagery, brighter white shades over much of the middle of Antarctica indicated a very cold surface — in fact, surface air temperatures were as cold as -84ºF over the interior of the continent at 23 UTC.

Composites of geostationary and polar orbiter Water Vapor imagery [click to play animation]

Composites of geostationary and polar orbiter Water Vapor imagery [click to play animation]

The storm was evident along the southern limb of GOES-16 Full Disk scans, as seen on Mid-level Water Vapor (6.9 µm) and “Red” Visible (0.64 µm) images (below). The location of AMRC AWS station 8930 (Thurston Island) near the coast of Ellsworth Land in West Antarctica is indicated in red.

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

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

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

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

This storm was also evident at the bottom center of a GOES-17 + GOES-16 composite of north-to-south True Color Red-Green-Blue (RGB) swaths of 15-minute illumination at local solar noon — beginning at 12 UTC in the east, and ending at 03 UTC in the west — combined and displayed in a Mollweide projection (below; courtesy of Rick Kohrs, SSEC).

GOES-17 + GOES-16 True Color RGB image [click to enlarge]

GOES-17 + GOES-16 True Color RGB image [click to enlarge]

A time series of surface observation data from AWS station 8930 on Thurston Island (below) showed that southeasterly winds peaked at 113 knots (58 m/s) late in the day on 26 March as the strong low pressure system approached. According to AMRC staff, this particular AWS is located on a nunatak near Parker Peak in the Walker Mountains (map) — such an exposure is prone to periods of strong winds, requiring a recent retrofitting of special instrumentation designed to withstand and measure higher wind speeds.

Tiime series of surface observation data from AWS station 8930 Thurston Island [click to enlarge]

Time series of surface observation data from AWS station 8930 Thurston Island [click to enlarge]

A closer look with GOES-16 Visible and Low-level Water Vapor (7.3 µm) images (below) revealed small wave perturbations in the cloud field and the eventual formation of a banner cloud as Peter I Island was acting as an obstacle to the strong boundary layer winds south of the storm center.

GOES-16 "Red" Visible (0.64 µm. left) and Low-level Water Vapor (7.3 µm, right) images [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm. left) and Low-level Water Vapor (7.3 µm, right) images [click to play animation | MP4]

A timely overpass of the Landsat-8 satellite provided a 30-meter resolution Landsat-8 False Color RGB image, viewed using RealEarth (below), of these orographically-induced cloud perturbations.

Landsat-8 False Color image [click to enlarge]

Landsat-8 False Color RGB image [click to enlarge]

The orographic wave clouds downwind of Peter I Island could also be seen on 375-meter resolution Suomi NPP VIIRS True Color RGB and Infrared Window (11.45 µm) images at 19 UTC and 21 UTC (below).

Suomi NPP VIIRS True Color RGB and Infrared Window (11.45 µm) images 1t 19 UTC and 21 UTC [click to enlarge]

Suomi NPP VIIRS True Color RGB and Infrared Window (11.45 µm) images at 19 UTC and 21 UTC [click to enlarge]


Southern Hemisphere summer solstice sunlight

December 21st, 2017 |

GOES-16

GOES-16 “Red” Visible (0.64 µm) Full Disk images [click to play animation]

The Southern Hemisphere Summer Solstice (and the Northern Hemisphere Winter Solstice) occurred at 1628 UTC on 21 December 2017. A 24-hour animation of GOES-16 Full Disk “Red” Visible (0.64 µm) images ending just after the Solstice time (above) showed that the far southern latitudes remained illuminated during the entire time.

GOES-16

GOES-16 “Red” Visible (0.64 µm) images [click to play MP4 animation]

Close-up views of the far Southern Hemisphere portion of the GOES-16 Full Disk are shown using “Red” Visible (0.64 µm) images (above) and Near-Infrared “Snow/Ice” (1.61 µm) images (below). The most prominent feature was the cloud shield of a 960 hPa storm system (surface analysis) moving west of the Antarctic Peninsula and over the Bellingshausen Sea — on the Snow/Ice images, clouds composed of ice crystals appear as darker shades of gray. At the end of each animation, land-fast sea ice can be seen extending northward from the Antarctic coast in the lower left portion of the images (ice appears bright white on the Visible imagery, and dark gray on the Snow/Ice imagery). In the lower center portion of the images, bright sun glint off ice-free water is apparent on 21 December at 0445 and 0500 UTC.

GOES-16 Near-Infrared

GOES-16 Near-Infrared “Snow/Ice” images [click to play MP4 animation]

Large iceberg breaks off the Larsen-C ice shelf in Antarctica

July 12th, 2017 |

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

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

A comparison of Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images on 12 July 2017 (above; courtesy of William Straka, SSEC) shows the large iceberg (named A-68) that had separated from the Larsen-C ice shelf in Antarctica (Project MIDAS).

===== 13 July Update =====

A 12 July vs 13 July comparison of VIIRS Infrared Window and Day/Night Band images (below) revealed a slight expansion of the ice fracture, as Iceberg A-68 slowly drifted away from the Larsen-C ice shelf.

12 July vs 13 July Suomi NPP VIIRS Infrared Window (11.45 µm) images [click to enlarge]

12 July vs 13 July Suomi NPP VIIRS Infrared Window (11.45 µm) images [click to enlarge]

12 July vs 13 July Suomi NPP VIIRS Day/Night Band (0.7 µm) images [click to enlarge]

12 July vs 13 July Suomi NPP VIIRS Day/Night Band (0.7 µm) images [click to enlarge]

2016 Northern Hemisphere winter / Southern Hemisphere summer solstice

December 21st, 2016 |

Meteosat-10 Visible (0.635 µm) images [click to enlarge]

Meteosat-10 Visible (0.635 µm) images [click to enlarge]

The 2016 Northern Hemisphere winter / Southern Hemisphere summer solstice occurred at 1044 UTC on 21 December. EUMETSAT Meteosat-10 Visible (0.635 µm) images (above; source) showed the westward progression of the solar terminator (which separates daylight from darkness) at 3-hour intervals.

Nearly the entire continent of Antarctica was illuminated by 24 hours of daylight, as seen on JMA Himawari-8 Visible (0.64 µm) images (below; also available as a 60 Mbyte animated GIF). Full-disk images are routinely available at 10-minute intervals from Himawari-8 (and can be available as frequently as every 5 minutes from the GOES-R series).

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

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

With the continuous daylight, Antarctic surface air temperatures from AMRC Automated Weather Stations (below; source) were seen to warm above 40ºF along the coast, and above -30ºF in the interior.

AMRC AWS station surface temperatures at 20 December (22 UTC) and 21 December (05 and 11 UTC) [click to enlarge]

AMRC AWS station surface temperatures at 20 December (22 UTC) and 21 December (05 and 11 UTC) [click to enlarge]