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Blowing dust along the southwest coast of Greenland

By Scott Bachmeier •

As noted by Santiago Gassó, a long and very narrow plume of airborne dust was evident just off the southwest coast of Greenland on 14 October 2018. Terra MODIS and Suomi NPP VIIRS True Color Red-Green-Blue (RGB) images as viewed using RealEarth are shown below. An exposed (free of snow cover) glacial outlet between Qeqertarsuatsiaat and Paamiut was the point source of the dust plume — the change in water colors (shades of cyan) highlighted the offshore flow of meltwater from this glacier into the Labrador Sea, which then began to curve northward within the West Greenland Current. The strong pressure gradient between high pressure over southern Greenland and a low pressure southeast of the island (surface analyses) along with a passing trough axis caused brisk northerly winds, which lofted the aerosols into the boundary layer.

Terra MODIS and Suomi NPP VIIRS True Color RGB images [click to enlarge]

Terra MODIS and Suomi NPP VIIRS True Color RGB images [click to enlarge]

The plume of aerosols was also apparent on GOES-16 (GOES-East) “Red” Visible (0.64 µm) and Near-Infrared “Snow/Ice” (1.61 µm) images (below). The appearance of the plume on 1.61 µm imagery was due to the bright color of the “glacial flour” particles, which were efficient reflectors of incoming solar radiation — this brighter signature showed up well against the dark appearance of the water (which strongly absorbs radiation at the 1.61 µm wavelength).

GOES-16

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

GOES-16 Near-Infrared

GOES-16 Near-Infrared “Snow/Ice” (1.61 µm) images [click to play animation | MP4]

The plume of airborne dust was also seen on GOES-17 Visible and Near-Infrared images (below), although the viewing angle was less favorable than from GOES-16.

* GOES-17 images shown here are preliminary and non-operational *

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

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

GOES-17 Near-Infrared "Snow/Ice" (1.61 µm) images [click to play animation | MP4]

GOES-17 Near-Infrared “Snow/Ice” (1.61 µm) images [click to play animation | MP4]

Unfortunately, there were no surface observations in the vicinity of the plume source to indicate how strong the surface winds were blowing; the closest active reporting sites along the southwest coast of Greenland were Godthaab/Nuuk to the distant north and Narsarsuaq to the distant south (large-scale Near-Infrared image). However, Metop-B ASCAT winds (source) just offshore of the plume origin area were in the 30-40 knots range around 1440 UTC (below).

Metop-B ASCAT surface scatterometer winds [click to enlarge]

Metop-B ASCAT surface scatterometer winds [click to enlarge]

Categories: GOES-16, GOES-17, Metop, MODIS, RealEarth, Red-Green-Blue (RGB) images, Satellite winds, Suomi NPP, Terra, VIIRS