Ice motion in the Great Lakes

February 14th, 2018 |
GOES-16 "Red" Visible (0.64 µm) images, with hourly plots of surface wind barbs in cyan and wind gusts (kn0ts) in red (click to play Animated GIF)

GOES-16 “Red” Visible (0.64 µm) images, with hourly plots of surface wind barbs in cyan and wind gusts (knots) in red (click to play Animated GIF | MP4 also available)

GOES-16 “Red” Visible (0.64 µm) images showed ice motion in the western Great Lakes (above) and the central/eastern Great Lakes (below) on 14 February 2018. A flow of southwesterly winds at the surface was helping to move the lake ice toward the northeast. With increasing winds and a return of warmer air, the ice coverage of Lake Superior, Lake Michigan and Lake Huron had decreased slightly from their seasonal peaks a few days earlier — while the ice coverage for Lake Erie remained neared its seasonal peak. The total ice coverage for the Great Lakes as a whole was 57.9% on this day.

GOES-16

GOES-16 “Red” Visible (0.64 µm) images, with hourly plots of surface wind barbs in cyan and wind gusts (knots) in red (click to play Animated GIF | MP4 also available)

Closer views of southern Lake Michigan and southern Lake Huron are shown below. In Lake Huron, small ice floes can be seen breaking away from the land fast ice.

GOES-16

GOES-16 “Red” Visible (0.64 µm) images, with hourly plots of surface wind barbs in cyan and wind gusts (knots) in red (click to play Animated GIF | MP4 also available)

GOES-16

GOES-16 “Red” Visible (0.64 µm) images, with hourly plots of surface wind barbs in cyan and wind gusts (knots) in red (click to play Animated GIF | MP4 also available)

250-meter resolution Terra and Aqua MODIS True-color Red-Green-Blue (RGB) images from the MODIS Today site (below) provided more detailed views of the ice floes in southern Lake Michigan, southern Lake Huron and western Lake Erie. The Aqua satellite overpass was about 90 minutes later than that of Terra.

Terra and Aqua MODIS True-color RGB images of southern Lake Michigan [click to enlarge]

Terra and Aqua MODIS True-color RGB images of southern Lake Michigan [click to enlarge]

Terra and Aqua MODIS True-color RGB images of southern Lake Huron [click to enlarge]

Terra and Aqua MODIS True-color RGB images of southern Lake Huron [click to enlarge]

Terra and Aqua MODIS True-color RGB images of western Lake Erie [click to enlarge]

Terra and Aqua MODIS True-color RGB images of western Lake Erie [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]

Pyrocumulonimbus cloud in Argentina

January 29th, 2018 |

GOES-16 Visible (0.64 µm, top), Shortwave Infrared (3.9 µm, center) and Infrared Window (10.3 µm) images [click to play animation]

GOES-16 Visible (0.64 µm, top), Shortwave Infrared (3.9 µm, center) and Infrared Window (10.3 µm, bottom) images [click to play animation]

A large cluster of fires burning in central Argentina became hot enough to generate a brief pyrocumulonimbus (pyroCb) cloud on 29 January 2018; according to media reports, on that day there were winds of 55 km/hour (34 mph) and temperatures of 37 ºC (98.6 ºF) in the vicinity of these La Pampa province fires. GOES-16 (GOES-East) “Red” Visible (0.64 µm), Shortwave Infrared (3.9 µm) and “Clean” Infrared Window (10.3 µm) images (above; also available as an MP4 animation) showed the smoke plumes, fire thermal anomalies or “hot spots” (red pixels) and the cold cloud-top infrared brightness temperatures, respectively. The minimum 10.3 µm temperature was -32.6 ºC at 1745 UTC. Note the relatively warm (darker gray) appearance on the 3.9 µm image — this is a characteristic signature of pyroCb clouds tops, driven by the aerosol-induced shift toward smaller ice particles (which act as more efficient reflectors of incoming solar radiation).

An Aqua MODIS True-color Red-Green-Blue (RGB) image viewed using RealEarth (below) showed the dense lower-tropospheric smoke drifting southward and southeastward from the fire source region, as well as the narrow upper-tropospheric anvil of the pyroCb cloud. Suomi NPP VIIRS fire detection locations are plotted as red dots on the final zoomed-in image. The actual time of the Aqua satellite pass over Argentina was 1812 UTC.

Aqua MODIS True-color RGB image, with Suomi NPP VIIRS fire detection locations [click to enlarge]

Aqua MODIS True-color RGB image, with Suomi NPP VIIRS fire detection locations [click to enlarge]

According to Worldview the coldest MODIS Infrared Window (11.0 µm) cloud-top  brightness temperature was -41.2 ºC, thus surpassing the -40 ºC threshold that is generally accepted to classify it as a pyroCb. This is believed to be the first confirmed pyroCb event in South America.

Approximately 120 km north-northeast of the pyroCb cloud, rawinsonde data from Santa Rosa, Argentina (below) indicated that the -41 ºC cloud-top temperature corresponded to altitudes in the 10.8 to 11.6 km range. The air was very dry at that level in the upper troposphere, contributing to the rapid dissipation of the pyroCb cloud material as seen in GOES-16 imagery.

Plots of rawinsonde data from Santa Rosa, Argentina [click to enlarge]

Plots of rawinsonde data from Santa Rosa, Argentina [click to enlarge]

48-hour HYSPLIT forward trajectories originating from the center of the pyroCb cloud at altitudes of 7, 9 and 11 km (below) suggested that a rapid transport of smoke over the adjacent offshore waters of the Atlantic Ocean was likely at those levels.

HYSPLIT forward trajectories originating at altitudes of 7, 9 and 11 km [click to enlarge]

HYSPLIT forward trajectories originating at altitudes of 7, 9 and 11 km [click to enlarge]

On 30 January, Suomi NPP OMPS Aerosol Index values (below; courtesy of Colin Seftor, SSAI at NASA Goddard) were as high as 4.3 over the South Atlantic (at 41.81º South latitude, 53.22º West longitude, 17:31:34 UTC) — consistent with the HYSPLIT transport originating at 7 km.

Suomi NPP OMPS Aerosol Index on 30 January [click to enlarge]

Suomi NPP OMPS Aerosol Index on 30 January [click to enlarge]

Additional Suomi NPP VIIRS True-color and OMPS Aerosol Index images can be found on the OMPS Blog.

===== 01 February Update =====

This analysis of CALIPSO CALIOP data (courtesy of Mike Fromm, NRL) suggests that the upper-tropospheric smoke from this pyroCb event was transported as far as the eastern South Atlantic Ocean by 02 UTC on 01 February, having ascended to altitudes in the 9-10 km range.

Blowing dust in Texas and Oklahoma

January 21st, 2018 |

GOES-16

GOES-16 “Moisture” Infrared brightness temperature difference (10.3-12.3 µm) images, with hourly surface reports plotted in cyan [click to play animation]

Strong winds in the wake of a cold frontal passage created large areas of blowing dust across the Panhandle Plains of northwestern Texas after 16 UTC on 21 January 2018. GOES-16 “Moisture” or “split-window difference” (10.3 µm12.3 µm) images (above) showed that the leading edge of this airborne dust moved over far southwestern Oklahoma after 20 UTC. (Note to AWIPS users: the default enhancement for this GOES-16 “Moisture” Channel Difference product was changed to “Grid/lowrange enhanced” to better highlight the dust with shades of yellow)

GOES-16 “Red” Visible (0.64 µm) and Near-Infrared “Cirrus” (1.37 µm) images (below) also displayed blowing dust signatures; the surface visibility was restricted to 2-3 miles at some locations, with Big Spring briefly reporting only 1/4 mile from 20-21 UTC. The dust signature was apparent on the Cirrus imagery because this spectral band can be used to detect any airborne particles that are effective scatterers of light (such as cirrus ice crystals, volcanic ash, dust/sand or haze).

GOES-16

GOES-16 “Red” Visible (0.64 µm) images, with hourly reports of surface weather plotted in red and surface visibility (miles) plotted in red [click to play animation]

GOES-16 Near-Infrared

GOES-16 Near-Infrared “Cirrus” (1.37 µm) images, with hourly reports of surface weather plotted in red and surface visibility (miles) plotted in red [click to play animation]

A Cirrus band is also available with the MODIS instrument on the Terra and Aqua satellites (as well as the VIIRS instrument on Suomi NPP and NOAA-20) — a comparison of Visible (0.65 µm), Cirrus (1.37 µm), Shortwave Infrared (3.7 µm) and Infrared Window (11.0 µm) images from Terra and Aqua (below) highlighted the differing appearance of the blowing dust features as sensed by each of those spectral bands. The airborne dust exhibited a darker signature in the Shortwave Infrared images since the small dust particles were efficient reflectors of incoming solar radiation, thus appearing warmer at 3.7 µm.

Terra MODIS Visible (0.65 µm), Cirrus (1.37 µm), Shortwave Infrared (3.7 µm) and Infrared Window (11.0 µm) images, with surface reports plotted in cyan [click to enlarge]

Terra MODIS Visible (0.65 µm), Cirrus (1.37 µm), Shortwave Infrared (3.7 µm) and Infrared Window (11.0 µm) images, with surface reports plotted in cyan [click to enlarge]

Aqua MODIS Visible (0.65 µm), Cirrus (1.37 µm), Shortwave Infrared (3.7 µm) and Infrared Window (11.0 µm) images, with surface reports plotted in cyan [click to enlarge]

Aqua MODIS Visible (0.65 µm), Cirrus (1.37 µm), Shortwave Infrared (3.7 µm) and Infrared Window (11.0 µm) images, with surface reports plotted in cyan [click to enlarge]

Pilot reports within 20-45 minutes after the Terra overpass time (below) revealed Moderate to Severe turbulence at an elevation of 8000 feet, just southeast of the most dense dust plume feature (highlighted by the cooler, lighter gray infrared brightness temperatures) — this was likely due to strong wind shear in the vicinity of the rapidly-advancing cold front. Farther to the southwest, another pilot report indicated that the top of the blowing dust was at 7000 feet, with a flight-level visibility of 3 miles at 10,000 feet.

Terra MODIS Infrared Window (11.0 µm) image, with a pilot report of turbulence highlighted in red [click to enlarge]

Terra MODIS Infrared Window (11.0 µm) image, with a pilot report of turbulence highlighted in red [click to enlarge]

Terra MODIS Infrared Window (11.0 µm) image, with a pilot report of dust layer top and flight level visibility highlighted in red [click to enlarge]

Terra MODIS Infrared Window (11.0 µm) image, with a pilot report of dust layer top and flight level visibility highlighted in red [click to enlarge]