GOES-16 and Fog Detection

October 18th, 2017 |

GOES-16 Brightness Temperature Difference (10.3 µm – 3.9 µm) “Fog Product” from 0202 – 0357 UTC on 18 October 2017 (Click to animate)

GOES-16 data posted on this page are preliminary, non-operational and are undergoing testing.

Stratus and Fog formed over the valleys of Kentucky (and in surrounding states) early on 18 October 2017 (It was there on 17 October as well). When was the fog first obvious from Satellite imagery? It very much depends on the spatial resolution of the Satellite viewing the scene. The Brightness Temperature Difference field (10.3 µm – 3.9 µm) from GOES-16, shown above, can be used to identify regions of stratus clouds that are made up of water droplets. Carefully examine the animation; the time when fog is definitively present over valleys of eastern Kentucky (around 84º W Longitude) is around 0327 UTC.

GOES-16 has 2-km resolution (at the sub-satellite point — 89.5º W Longitude during GOES-16 Check-out); this is superior to GOES-13’s nominal 4-km resolution at the subpoint (75º West Longitude). The GOES-13 Brightness Temperature Difference Field (10.7 µm – 3.9 µm) at 0330 UTC shows no distinct indication of Fog/Stratus over eastern Kentucky. A series of animations of the GOES-13 Brightness Temperature Difference field, from 0215-0345 UTC, from 0415-0500, from 0545-0700 and from 0700-0815 suggest GOES-13 identified the region of fog about 4 hours after GOES-16, at 0730 UTC.

The GOES-13 vs. GOES-16 toggle below, from 0700 UTC on 18 October 2017, shows how the resolution improvement with GOES-16 facilitates earlier detection of fog and stratus as it develops overnight.

Toggle between 0700 UTC 18 October 2017 Brightness Temperature Differences from GOES-13 (10.7 µm – 3.9 µm) and GOES-16 (10.3 µm – 3.9 µm) (Click to enlarge)

Ex-hurricane Ophelia over Ireland and the United Kingdom

October 16th, 2017 |

Meteosat-10 Water Vapor (6.25 µm) images, with hourly surface wind gusts (knots) plotted in red [click to play MP4 animation]

Meteosat-10 Water Vapor (6.25 µm) images, with hourly surface wind gusts (knots) plotted in red [click to play MP4 animation]

After reaching Category 3 intensity over the eastern Atlantic Ocean on 14 October, Hurricane Ophelia rapidly underwent transition to an extratropical storm which spread high winds across much of Ireland and the United Kingdom on 16 October 2017. EUMETSAT Meteosat-10 upper-level Water Vapor (6.25 µm) images (above) revealed the familiar “scorpion tail” signature of a sting jet (reference). Hourly wind gusts (knots) for primary reporting stations are plotted in red.

The sting jet signature was also seen on Meteosat-10 lower-level Water Vapor (7.35 µm) images (below).

Meteosat-10 Water Vapor (7.35 µm) images, with hourly surface wind gusts (knots) plotted in red [click to play MP4 animation]

Meteosat-10 Water Vapor (7.35 µm) images, with hourly surface wind gusts (knots) plotted in red [click to play MP4 animation]

Two sites with notable wind gusts were Cork, Ireland (67 knots at 0930 UTC) and Valley, UK (70 knots at 1500 UT), shown below. A wind gust of 103 knots (119 mph or 191 km/hour) was reported at the Fastnet Rock Lighthouse off the southwest coast of Ireland.

Time series plot of surface data at Cork, Ireland [click to enlarge]

Time series plot of surface data at Cork, Ireland [click to enlarge]

Time series plot of surface data at Valley, United Kingdom [click to enlarge]

Time series plot of surface data at Valley, United Kingdom [click to enlarge]

42-year anniversary of the GOES program

October 16th, 2017 |

A sample Visible (0.65 µm) image from GOES-1 is shown below (courtesy of Tim Schmit, NOAA/NESDIS/ASPB and the SSEC Data Center), after the satellite had been positioned over the Indian Ocean to support the Global Atmospheric Research Program. The first GOES-1 image was broadcast on 25 October 1975.

GOES-1 Visible (0.65 µm) image, 0930 UTC on 01 January 1979 [click to enlarge]

GOES-1 Visible (0.65 µm) image, 0930 UTC on 01 January 1979 [click to enlarge]

Hurricane Ophelia

October 14th, 2017 |

GOES-13 Visible (0.63 µm, left) and Infrared Window (10.7 µm, right) images, with hourly surface reports (in metric units) plotted in yellow [click to animate]

GOES-13 Visible (0.63 µm, left) and Infrared Window (10.7 µm, right) images, with hourly surface reports (in metric units) plotted in yellow [click to animate]

Hurricane Ophelia — the record-tying 10th consecutive Atlantic basin hurricane of the 2017 season — reached a satellite-estimated Category 3 intensity at 15 UTC on 14 October 2017. GOES-13 (GOES-East) Visible (0.63 µm) and Infrared Window (10.7 µm) images (above) showed a well-defined circular eye as the storm moved well south of the Azores. The tweet below underscores the unusual nature of the intensity and location of Ophelia (which also occurred over unusually-cold waters).

A DMSP-17 SSMIS Microwave (85 GHz) image (below) also revealed a circular eye structure.

DMSP-17 SSMIS Microwave (85 GHz) image [click to enlarge]

DMSP-17 SSMIS Microwave (85 GHz) image [click to enlarge]

One factor that might have aided this increase of intensity was the recent passage of Ophelia through an environment of higher Maximum Potential Intensity (reference), where maximum wind speed values of 100 knots resided (below).

Maximum Potential Instability wind speed plot from 13 October, with the track of Ophelia as of 18 UTC on 14 October [click to enlarge]

Maximum Potential Instability wind speed plot from 13 October, with the track of Ophelia as of 18 UTC on 14 October [click to enlarge]