Wildfire smoke over ice in Hudson Bay

July 28th, 2014
GOES-13 0.63 µm visible channel images (click to play animation)

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

Large wildfires continued to burn during much of the month of July in the Northwest Territories of Canada, and McIDAS-X images of GOES-13 0.63 µm visible channel data on 28 July 2014 (above; click image to play animation) showed large amounts of smoke aloft streaming southwestward across the western and southwestern portion of Hudson Bay. This pattern of middle-tropospheric smoke transport was caused by the juxtaposition of a highly-amplified ridge of high pressure over central Canada and a deep area of low pressure over Quebec (500 hPa map). During the later part of the day, the clearing of patchy low clouds and the thinning of the smoke aloft revealed the presence of large ice floes over southwestern Hudson Bay. According to the Canadian Ice Service, this was thick first year ice from the previous winter season, with ice concentration values as high as 9-10/10s.

A Suomi NPP VIIRS true-color Red/Green/Blue (RGB) image combination prepared using McIDAS-V (below; courtesy of Joleen Feltz, CIMSS) showed the variety of smoke, ice, and cloud formations over Hudson Bay at 18:45 UTC.

Suomi NPP VIIRS true-color RGB image

Suomi NPP VIIRS true-color RGB image

Long-range transport of Canadian wildfire smoke

July 8th, 2014

GOES-15 (top) and GOES-13 (bottom) 0.63 µm visible channel images [click to play animation]

GOES-15 (top) and GOES-13 (bottom) 0.63 µm visible channel images [click to play animation]

On 08 July 2014 a comparison of GOES-15 (GOES-West) and GOES-13 (GOES-East) 0.63 µm visible channel images (above; click image to play animation; also available as an MP4 movie file) showed the southward and southeastward transport of dense smoke from wildfires that were burning in the Northwestern Territories of Canada. Over the Lower 48 states, the leading edge of the smoke made it as far south as Iowa and northern Illinois. The bulk of the dense smoke was aloft, but at the surface the visibility was reduced to 3-5 miles at some locations in North Dakota.

The above example serves as a good demonstration of the principle of “forward scattering”: the smoke was more evident on visible imagery from GOES-15  early in the day (as the sun was rising), and more evident on visible imagery from GOES-13 later in the day (as the sun was setting).

Suomi NPP VIIRS true-color Red/Green/Blue (RGB) images from the SSEC RealEarth web map server (below) showed the areal coverage of the hazy pall of smoke on 06 July, 07 July, and 08 July.

Suomi NPP VIIRS true-color images

Suomi NPP VIIRS true-color images

The IDEA-I forward airmass trajectory model applied to targets of high Aerosol Optical Depth (AOD) which were detected by the Terra MODIS instrument over Canada on 08 July are shown below. Such a tool can be used as an aid in air quality forecasting.

IDEA-I MODIS Aerosol Optical Depth and forward trajectories (click to play animation)

IDEA-I MODIS Aerosol Optical Depth and forward trajectories (click to play animation)

===== 09 July Update =====

The Terra MODIS AOD product (below; click to play animation) indicated that the leading edge of the Canadian wildfire smoke had advanced as far southward as northwestern Missouri. The bulk of the highest AOD values over the Dakotas was forecast to be transported slowly east-northeastward toward the Great Lakes region.

IDEA-I MODIS Aerosol Optical Depth and forward trajectories (click to play animation)

IDEA-I MODIS Aerosol Optical Depth and forward trajectories (click to play animation)

Hurricane Arthur

July 3rd, 2014
Terra MODIS 11.0 µm IR channel image

Terra MODIS 11.0 µm IR channel image

04 July Update: a 1-km resolution Terra MODIS 11.0 µm IR image (above) showed the eye of Category 2 Hurricane Arthur making landfall along the coast of North Carolina around 03:13 UTC or 11:15 pm Eastern Time. Arthur was the earliest hurricane to make landfall in North Carolina since records began in 1851 (the previous record was 11 July, 1901).

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

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

[5:45 PM EDT 3 July 2014 Update: The animation of GOES-13 visible images above, ending at 21:45 UTC or 5:45 PM Eastern Daylight Time, shows Hurricane Arthur very close to the North Carolina coast. Convection continues redeveloping in the circulation close to the eye.]

Suomi NPP VIIRS True Color Image of Arthur at 1800 UTC 3 July 2014

Suomi NPP VIIRS True Color Image of Arthur at 1800 UTC 3 July 2014

The original VIIRS image, above (courtesy of Russ Dengel), was clipped from this link. An animation of VIIRS True-Color imagery of Arthur (courtesy of Kathy Strabala), taken from the Webmap server at SSEC is shown below.

Suomi NPP VIIRS True Color Imagery of Arthur, 30 June - 3 July 2014 (click to enlarge)

Suomi NPP True Color Imagery of Arthur, 30 June – 3 July 2014 (click to enlarge)

GOES-13 10.7 µm infrared channel images (click to play animation)

GOES-13 10.7 µm infrared channel images (click to play animation)

Tropical Storm Arthur has strengthened overnight to become the first hurricane of the Atlantic Tropical Season. The storm-centered animation above, from GOES-East, (click here for an animation without the map) shows evidence of the relaxation in wind shear that has allowed intensification. At the beginning of the animation, most convection is to the east and south of the system. By 3 July, convection is much closer to the center of the strengthening storm and an outflow channel to the southeast has developed; a distinct eye is present by 2045 UTC on 3 July. Note that in the color enhancement that the coldest cloud tops — purple — are cooler than -80° C. This image (from this website) shows Arthur, at 1500 UTC on 3 July 2014, under a minimum in wind shear. (Zoomed-in version of wind shear).

The tropical cyclone has been moving due north over the past 24 hours, but the National Hurricane Center notes that a recurvature to the northeast is occurring now. Interests along the South and North Carolina coasts should pay special attention to forecasts for today and tomorrow.

GOES-13 0.63 µm visible channel image with surface observations, 1400 UTC 3 July 2014 (click to enlarge)

GOES-13 0.63 µm visible channel image with surface observations, 1400 UTC 3 July 2014 (click to enlarge)

Visible imagery from 1400 UTC, above, does not yet show an eye, and strongest winds at that time remained offshore. Moored Buoy 41004 (41 miles southeast of Charleston, SC, at 32°30’2″ N 79°5’58″ W) shows tropical-storm force-winds; a plot of the pressure and winds at the station, below, suggests an approaching storm.

Surface Pressure and Winds at Moored Buoy 41004 (click to enlarge)

Surface Pressure and Winds at Moored Buoy 41004 (click to enlarge)

Toggle between Suomi NPP VIIRS 11.45µm Infrared Imagery and Day/Night Band at 0639 UTC 3 July (click to enlarge)

Toggle between Suomi NPP VIIRS 11.45µm Infrared Imagery and Day/Night Band at 0639 UTC 3 July (click to enlarge)

Suomi NPP overflew Arthur in the early morning of July 3rd, affording a high-resolution view of the convective clouds. The coldest overshooting tops, around -85°C are far to the east of the surface circulation, but a large cirrus shield with temperatures near -75°C is over the storm center. The Day/Night band shows little contrast because the Quarter Moon set at 0400 UTC and therefore no lunar illumination is available. A few lightning streaks in the convection around Arthur are present. Lightning is far more common in the convection over the northeast Gulf of Mexico.

MODIS Imagery over Arthur at 1613 UTC 3 July (click to cycle through channels)

MODIS Imagery over Arthur at 1613 UTC 3 July (click to cycle through channels)

MODIS imagery over Arthur was available from Terra at 1613 UTC today. A variety of channels are shown above — Visible imagery (0.64 µm), the Snow/Ice Channel (a wavelength of 1.6 µm, at which snow/ice strongly absorb radiation and therefore appear dark), the Cirrus channel (a wavelength of 1.38 µm, at which cirrus clouds are strongly reflective and are therefore highlighted), the Water Vapor channel (6.7 µm, showing the height of the top of the moist layer) and the Infrared channel near 11 µm.

Previous Tropical Storm Arthurs passed near the North Carolina coast in 1996 (a swirl in mid-level clouds with little deep convection) and in 2002 (a mass of convection that obscured any circulation).

Saharan Air Layer dust over the Gulf of Mexico

June 21st, 2014
GOES-13 0.63 µm visible channel images (click to play animation)

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

McIDAS images of GOES-13 0.63 µm visible channel data on 20 June 2014 (above; click image to play animation; also available as an MP4 movie file) and on 21 June 2014 (below; click image to play animation; also available as an MP4 animation file) revealed the hazy signature of a veil of Saharan Air Layer (SAL) dust aloft over much of the southern and western portions of the Gulf of Mexico.

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

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

The hazy dust signature also showed up well in Suomi NPP VIIRS true-color Red/Green/Blue (RGB) images, as visualized using the SSEC RealEarth web map server (below).

Suomi NPP VIIRS true-color RGB images

Suomi NPP VIIRS true-color RGB images

The SAL tracking product showed the strong pulse of SAL dust emerging from the African continent on 10 June, then moving rapidly westward across the Atlantic Ocean and over the Caribbean Sea by 17 June (below; click image to play animation).

Meteosat-10 Saharan Air Layer tracking product (click to play animation)

Meteosat-10 Saharan Air Layer tracking product (click to play animation)