Sea fog along the northeast Florida coast

March 21st, 2015
GOES-13 0.63 µm visible channel images (click to play animation)

GOES-13 0.63 µm visible channel images (click to play animation)

GOES-13 (GOES-East) 0.63 µm visible channel images (above; click to play animation) showed a patch of sea fog just off the coast of northeastern Florida on 21 March 2015. As daytime inland heating increased, a sea breeze circulation began to draw some of the offshore sea fog toward the coast.

A closer view is provided by a Suomi NPP VIIRS true-color Red/Green/Blue (RGB) image at 18:08 UTC (below), visualized using the SSEC RealEarth web map server site. The surface visibility at New Smyrna Beach was reduced to 1 mile at the time.

Suomi NPP VIIRS true-color image

Suomi NPP VIIRS true-color image

A web camera image at 18:17 UTC or 2:17 PM local time (below) showed the dramatic reduction in visibility as the dense sea fog moved inland at Dunlawton Beach (near Daytona Beach).

Dunlawton Beach webcam image

Dunlawton Beach webcam image

A comparison of Suomi NPP VIIRS 0.64 µm visible channel, 3.74 µm shortwave IR channel, and 11.45 µm longwave IR images (below) showed that the patch of sea fog exhibited a strong signal on the shortwave IR image (due to the efficient reflection of incoming solar radiation by the spherical water droplets), but no signal at all on the longwave IR image (since the temperature of the sea fog feature was nearly identical to that of the surrounding ocean waters).

Suomi NPP VIIRS 0.64 µm visible channel, 3.74 µm shortwave IR channel, and 11.45 µm longwaveIR channel images

Suomi NPP VIIRS 0.64 µm visible channel, 3.74 µm shortwave IR channel, and 11.45 µm longwaveIR channel images

The easterly to northeasterly onshore flow along the coast (enhanced by the sea breeze circulation) was well-depicted by the 18 UTC Real-Time Mesoscale Analysis (RTMA) surface winds (below).

Suomi NPP VIIRS 0.64 µm visible channel image, with RTMA surface winds

Suomi NPP VIIRS 0.64 µm visible channel image, with RTMA surface winds

Mesovortex over Lake Ontario

February 17th, 2015
GOES-13 0.63 µm visible channel images (click to play animation)

GOES-13 0.63 µm visible channel images (click to play animation)

GOES-13 (GOES-East) 0.63 µm visible channel images (above; click to play animation) revealed the presence of a mesocale vortex (“mesovortex”) propagating eastward across the ice-free waters of western Lake Ontario on on 17 February 2015. At the beginning of the animation, also note that there were numerous “hole punch clouds” seen in the stratus cloud deck that covered the western Lake Ontario region during the early morning hours; these holes were likely caused by aircraft inbound/outbound from the Toronto International Airport — particles in jet engine exhaust act as ice nuclei, causing supercooled water droplets to turn into larger, heavier ice particles which then fall out of the cloud to create holes (sometimes described as “fall streaks” due to their appearance).

A closer view using a sequence of MODIS and VIIRS true-color Red/Green/Blue (RGB) images from the SSEC RealEarth web map server site is shown below. There was a significant amount of ice in the northeastern section of Lake Ontario, as well as a ring of offshore ice around other parts of the lake.

MODIS and VIIRS true-color images

MODIS and VIIRS true-color images

A comparison of the 16:31 UTC Terra MODIS 0.65 µm visible channel and the corresponding Sea Surface Temperature product (below) showed that SST values in the ice-free portions of the mesovortex path were generally in the 30 to 34º F  range.

Terra MODIS 0.65 µm visible channel image and Sea Surface Temperature product

Terra MODIS 0.65 µm visible channel image and Sea Surface Temperature product

African dust blowing across the Mediterranean Sea

February 2nd, 2015
Suomi NPP VIIRS true-color image composites

Suomi NPP VIIRS true-color image composites

A sequence of daily Suomi NPP VIIRS Red/Green/Blue (RGB) true-color image composites from the SSEC RealEarth web map server site (above) showed the northeastward transport of African dust across the Mediterranean Sea during the 31 January – 02 February 2015 period. On 02 February, orange snow was observed in Saratov, Russia (news story), a city about 580 miles or 936 km northeast of Stavropol (which is located in the far upper right corner of the VIIRS images).

Airborne glacial silt over the Gulf of Alaska

February 1st, 2015
GOES-15 0.63 µm visible channel images (click to play animation)

GOES-15 0.63 µm visible channel images (click to play animation)

Due to a tight pressure gradient between a high over the Yukon and a low over the Gulf of Alaska (surface analysis), strong offshore winds (with gusts as high as 78 mph) were lofting glacial silt from the northern portion of the Alaska Panhandle region and carrying it westward over the Gulf of Alaska on 01 February 2015. Hints of the narrow light grey plumes could be seen streaming southwestward then westward on GOES-15 (GOES-West) 0.63 µm visible channel images (above; click to play animation).

A closer look using a comparison of Suomi NPP VIIRS 0.7 µm Day/Night Band (DNB) and 0.64 µm visible channel images (below) showed that the areal extent of the airborne aerosols was much more evident on the DNB image (in part due to it’s more broad spectral response). However, other more intricate patterns were seen on the DNB image in the general vicinity of Middleton Island (station identifier PAMD) that did not appear to match the character of the airborne glacial silt features being blown westward from the Alaska Panhandle region.

Suomi NPP VIIRS 0.7 µm Day/Night Band and 0.64 µm visible channel images

Suomi NPP VIIRS 0.7 µm Day/Night Band and 0.64 µm visible channel images

A Suomi NPP VIIRS true-color Red/Green/Blue (RGB) image from the SSEC RealEarth web map server (below) offers a clue to help explain the meandering features that stretched from the coast east of Prince William Sound toward the Middleton Island area: strands of phytoplankton, fed by nutrients in the river waters draining from the interior into the Gulf of Alaska. Sun glint along the edge of the VIIRS scan may have helped to highlight these features in the DNB image above. In fact, these water features were less obvious — and the airborne glacial silt more obvious — in a subsequent VIIRS DNB vs Visible image at 23:20 UTC.

Suomi NPP VIIRS true-color image

Suomi NPP VIIRS true-color image