Cyclone Gita in the South Pacific Ocean

February 12th, 2018 |

Himawari-8

Himawari-8 “Red” Visible (0.64 µm, top) and “Clean” Infrared Window (10.4 µm, bottom) images, with hourly plots of surface reports [click to play Animated GIF | MP4 also available]

Himawari-8 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.4 µm) images (above) showed Cyclone Gita as it moved toward Tonga in the South Pacific Ocean during 11 February – 12 February 2018. The tropical cyclone reached Category 4 intensity (ADT | SATCON) near the end of the animation period.

A longer animation of Himawari-8 Infrared images (below) revealed that the center of Gita moved just south of the main island of Tongatapu. Surface observations from Fua’Amotu (NFTF) ended after 0735 UTC.

Himawari-8

Himawari-8 “Clean” Infrared Window (10.4 µm) images, with hourly surface plots [click to play Animated GIF | MP4 also available]

MIMIC-TC morphed microwave imagery (below) showed that Gita underwent an eyewall replacement cycle after moving to the southwest of Tongatapu — a small eyewall was replaced by a larger eyewall, which was very apparent in DMSP SSMIS Microwave (85 GHz) images at 1533 and 1749 UTC.

MIMIC-TC morphed microwave imagery

MIMIC-TC morphed microwave imagery

Metop ASCAT scatterometer surface winds (below) showed Gita around the time that the storm center was just south of Tongatapu at 0850 UTC.

Metop ASCAT scatterometer surface winds [click to enlarge]

Metop ASCAT scatterometer surface winds [click to enlarge]

Large hail in Argentina

February 8th, 2018 |

GOES-16

GOES-16 “Red” Visible (0.64 µm, top) and “Clean” Infrared Window (10.3 µm, bottom) images, with hourly surface reports (metric units) for Córdoba, Argentina [click to play animated GIF — MP4 also available]

GOES-16 (GOES-East) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.3 µm) images (above) showed the development of severe thunderstorms which produced very large hail in Córdoba, Argentina on 08 February 2018. Distinct above-anvil plumes were evident on the Visible imagery, with pulses of overshooting tops exhibiting Infrared brightness temperatures in the -70 to -80ºC range (black to white enhancement). The hail reportedly began around 1930 UTC or 4:30 PM local time.

The above-anvil plumes could also be seen in GOES-16 Near-Infrared “Snow/Ice” (1.61 µm) images (below).

GOES-16 Near-Infrared

GOES-16 Near-Infrared “Snow/Ice” (1.61 µm) images, with hourly surface reports (metric units) for Córdoba, Argentina [click to play animated GIF — MP4 also available]

An Aqua MODIS True-color Red-Green-Blue (RGB) image viewed using RealEarth (below) showed the thunderstorm just west of Córdoba around 1850 UTC.

Aqua MODIS True-color RGB image [click to enlarge]

Aqua MODIS True-color RGB image [click to enlarge]

According to the Worldview site, the coldest Aqua MODIS cloud-top infrared brightness temperature at that time was -78ºC (below).

Aqua MODIS True-color and Infrared Window (11.0 µm) images [click to enlarge]

Aqua MODIS True-color and Infrared Window (11.0 µm) images [click to enlarge]

A time series plot of surface observations at Córdoba (below) showed the warm temperatures and high dew points prior to the arrival of the thunderstorms; there were a number of hail reports between 19 UTC and 02 UTC (4 PM to 11 PM local time).

Time series of surface observations at Córdoba, Argentina [click to enlarge]

Time series of surface observations at Córdoba, Argentina [click to enlarge]

Satellite signatures of SpaceX Falcon Heavy rocket launch

February 6th, 2018 |

GOES-16 "Red" Visible <em>(0.64 µm, top),</em> Near-Infrared "Snow/Ice" <em>(1.61 µm, middle)</em> and Shortwave Infrared <em>(3.9 µm, bottom)</em> images, with plots of surface reports [click to play animation]

GOES-16 “Red” Visible (0.64 µm, top), “Blue” Visible (0.47 µm, middle) and Near-Infrared “Snow/Ice” (1.61 µm, bottom) images, with plots of surface reports [click to play animation]

GOES-16 (GOES-East) “Red” Visible (0.64 µm), “Blue” Visible (0.47 µm) and Near-Infrared “Snow/Ice” (1.61 um) images (above) captured the signature of rocket plumes from the SpaceX Falcon Heavy launch at Kennedy Space Center, Florida on 06 February 2018. Bright areas of water droplet clouds were seen both at the surface near Launch Complex 39A and aloft just east of the Florida coast on the 20:47:28 UTC and 20:52:28 UTC images (the satellite was scanning those cloud features at 20:48:33 / 20:55:33 UTC or 3:48:33 / 3:55:33 PM Eastern Standard Time, respectively). The plume aloft looked like this from the surface. Due to significant lower-tropospheric wind shear, the near-surface launch pad plume drifted slowly toward the northwest, while the higher-altitude plume moved more quickly toward the northeast. Strong upper-tropospheric winds — 86 knots at 140 hPa or 14.4 km on the 12 UTC sounding — led to a 2 hour launch delay until speeds dropped to within safe flight criteria.

Looking farther to the east-northeast over the Atlantic Ocean, a pair of warm thermal anomalies — likely from the recently-separated twin Side Core booster engines (left) and the still-active single Center Core booster engine (right) — were seen on the corresponding 20:47:28 UTC GOES-16 Upper-level (6.2 µm), Mid-level (6.9 µm) and Low-level (7.3 µm) Water Vapor images (below). A similar warm signature in Water Vapor imagery was observed following a previous SpaceX rocket launch in March 2017.

GOES-16 Upper-level (6.2 µm, top), Mid-level (6.9 µm, middle) and Low-level (7.3 µm) images [click to play animation]

GOES-16 Upper-level (6.2 µm, top), Mid-level (6.9 µm, middle) and Low-level (7.3 µm, bottom) images [click to play animation]

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 signature (darker gray) was much less distinct compared to what was seen on the water vapor imagery (below).

GOES-16 Upper-level (6.2 µm, top), Mid-level (6.9 µm, middle) and Shortwave Infrared (3.9 µm, bottom) image [click to enlarge]

GOES-16 Upper-level (6.2 µm, top), Mid-level (6.9 µm, middle) and Shortwave Infrared (3.9 µm, bottom) image [click to enlarge]

Sensing the surface with water vapor imagery

February 6th, 2018 |

GOES-16 Low-level (7.3 µm) Water Vapor images [click to play animation]

GOES-16 Low-level (7.3 µm) Water Vapor images [click to play animation]

As a cold, dry arctic air mass moved across the western Great Lakes on 06 February 2018, portions of the land-water boundaries of Lake Superior, Lake Michigan and Lake Huron were very distinct on GOES-16 (GOES-East) Low-level (7.3 µm) Water Vapor images (above). The motion of low-altitude lake effect clouds were also apparent in the imagery.

Plots of weighting functions for the three GOES-16 ABI Water Vapor bands (7.3 µm, 6.9 µm and 6.2 µm) are shown below, calculated using rawinsonde data from Green Bay, Wisconsin and Gaylord, Michigan. With cold air and low values of Total Precipitable Water at these 2 sites (1.53 mm / 0.06 in and 1.88 mm / 0.07 in, respectively), the height of their weighting functions was shifted to significantly lower altitudes compared to what would be observed in a standard atmosphere. This enabled the contrasting thermal signature of the land/water boundaries to easily reach the satellite sensors, passing through what little moisture existed within the atmospheric column. While the peak of the violet 7.3 µm weighting function plots descended to the 879 hPa pressure level at both sites (which was approximately 1.2 km above the surface), a significant contribution could be seen originating from the surface itself.

Weighting function plots for the three GOES-16 Water Vapor bands, calculated using rawinsonde data from Green Bay, Wisconsin [click to enlarge]

Weighting function plots for the three GOES-16 Water Vapor bands, calculated using rawinsonde data from Green Bay, Wisconsin [click to enlarge]

Weighting function plots for the three GOES-16 Water Vapor bands, calculated using rawinsonde data from Gaylord, Michigan [click to enlarge]

Weighting function plots for the three GOES-16 Water Vapor bands, calculated using rawinsonde data from Gaylord, Michigan [click to enlarge]

Note that the peaks of the blue 6.9 µm weighting function plots were also anomalously low, reaching the 802 and 754 hPa pressure levels — however, in contrast to the 7.3 µm plots there was very little contribution from the actual surface, and the presence of secondary peaks at higher altitudes led to some absorption and subsequent re-emission of upwelling radiation by that layer of colder moisture aloft. As a result, only the faint outline of Lake Superior and its lake effect clouds were occasionally seen on Mid-level 6.9 µm Water Vapor imagery (below).

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

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