Ship tracks in the East Pacific, and eddy circulations near the California coast

April 24th, 2019 |

GOES-17 "Red" Visible (0.64 µm) and Shortwave Infrared (3.9 µm) images [click to play animation | MP4]

GOES-17 “Red” Visible (0.64 µm) and Shortwave Infrared (3.9 µm) images [click to play animation | MP4]

GOES-17 (GOES-West) “Red” Visible (0.64 µm) and Shortwave Infrared (3.9 µm) images (above) showed a number of ship condensation trails (or “ship tracks”) over the East Pacific Ocean on 24 April 2019. Aerosols from the exhaust of ships cause a “cloud seeding effect”, which results in a higher concentration of smaller cloud droplets compared to the surrounding unperturbed clouds. These smaller cloud droplets are more effective reflectors of sunlight, leading to a warmer (darker red) 3.9 µm signature.

GOES-17 Visible images (below) revealed a few eddy circulations within the marine boundary layer stratocumulus off the coast of southern California, along with other interesting Channel Island cloud interactions — some of the eddy circulations exhibited a small cloud-free center. Surface winds were light and variable over the Channel Islands (surface analyses), with a thermal low situated well inland over the Desert Southwest (the national high temperature on 24 April was 106ºF at Death Valley, California).

GOES-17

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

Lake Superior ship tracks

November 16th, 2017 |

GOES-16

GOES-16 “Red” Visible (0.64 µm, left), Near-Infrared “Snow/Ice” (1.61 µm, center) and Shortwave Infrared (3.9 µm, right) images, with hourly surface wind barbs plotted in yellow [click to play animation]

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

GOES-16 “Red” Visible (0.64 µm), Near-Infrared “Snow/Ice” (1.61 µm) and Shortwave Infrared (3.9 µm) images (above) revealed the presence of ship tracks across Lake Superior on 16 November 2017. Aerosols from the exhaust of ships cause a “cloud seeding effect”, which results in a higher concentration of smaller cloud droplets compared to the surrounding unperturbed clouds. These smaller cloud droplets are more effective reflectors of sunlight, resulting in a brighter white signature on the Snow/Ice imagery and a warmer (darker gray) signature on the Shortwave Infrared imagery.

A view of the entire lake — using similar Visible, Snow/Ice and Shortwave Infrared images from the Terra MODIS instrument — is shown below. In addition to the ship tracks, plumes from power plants and/or industrial sites can be seen in southern Ontario, streaming southward near Thunder Bay (station identifier CYQT) and southwestward near Upsala (CWDV); another plume was evident in northeastern Wisconsin, to the southeast of Eagle River (KEGV).

Terra MODIS Visible (0.65 µm), Near-Infrared

Terra MODIS Visible (0.65 µm), Near-Infrared “Snow/Ice” (1.61 µm) and Shortwave Infrared (3.7 µm) images [click to enlarge]

Ship tracks in the Atlantic Ocean

April 13th, 2013 |

GOES-13 0.63 µm visible (left) and 3.9 µm shortwave IR (right) images (click image to play animation)

GOES-13 Visible (0.63 µm, left) and Shortwave Infrared (3.9 µm, right) images [click to play animation]

A comparison of McIDAS images of 1-km resolution GOES-13 (GOES-East) Visible (0.63 µm) and 4-km resolution Shortwave Infrared (3.9 µm) data (above) revealed a number of ship tracks in the marine boundary layer stratocumulus cloud deck over the western Atlantic Ocean on 13 April 2013. Aerosols from the exhaust of ships causes a “cloud seeding effect”, which results in a higher concentration of smaller cloud droplets compared to the surrounding undisturbed cloud deck. These smaller cloud droplets are more effective reflectors of sunlight, resulting in a warmer (darker gray) signature on the 3.9 µm imagery.

A more detailed view of the ship tracks was provided using AWIPS images of 1-km resolution MODIS Visible (0.65 µm), Shortwave Infrared (3.7 µm) and Infrared Window (11.0 µm) images (below). Note that the ship track features could not be identified on the 11.0 µm image, since the cloud-top infrared brightness temperatures were essentially the same over that region.

MODIS 0.65 µm visible channel, 3.7 µm shortwave IR channel, and 11.0 µm longwave IR channel images

MODIS Visible (0.65 µm), Shortwave Infrared (3.7 µm) and Infrared Window (11.0 µm) images [click to enlarge]

Ship tracks in the East Pacific Ocean, and valley fog in British Columbia

October 6th, 2012 |
Suomi NPP VIIRS 0.7 µm Day/Night Band and 11.45 µm IR channel images

Suomi NPP VIIRS 0.7 µm Day/Night Band and 11.45 µm IR channel images

A comparison of AWIPS images of Suomi NPP VIIRS 0.7 µm Day/Night Band and 11.45 µm IR channel data at 11:32 UTC (4:32 AM local time) on 06 October 2012 (above) demonstrated the value of using the Day/Night Band as “visible imagery at night” to aid in the detection of features such as ship tracks that were difficult to identify in the IR image. Snow cover in the higher terrain of western British Columbia cuould also be seen, appearing as brighter white areas on the Day/Night Band image.

Additional ship tracks could be identified within the marine boundary layer stratus clouds by examining the coresponding Suomi NPP VIIRS IR brightness temperature difference “Fog/stratus product” image (below) — as well as numerous fingers of valley fog across interior British Columbia.

Suomi NPP VIIRS 0.7 µm Day/Night Band and Fog/stratus product images

Suomi NPP VIIRS 0.7 µm Day/Night Band and Fog/stratus product images