Update on the Deepwater Horizon oil slick in the Gulf of Mexico

May 11th, 2010 |
MODIS true color (bands 1/4/3) and false color (bands 7/2/1) RGB images

MODIS true color (bands 1/4/3) and false color (bands 7/2/1) RGB images

A comparison of MODIS true color (using bands 1/4/3) and false color (using bands 7/2/1) Red/Green/Blue (RGB) images from the SSEC MODIS Today site (above) again revealed the areal extent of the surface portion of the oil slick just off the Louisiana coast in the northern Gulf of Mexico on 11 May 2010.

An animation of MODIS true color RGB images (created using bands 1/4/3) from days when the geometry of the sun glint was favorable (below) showed the changes in areal coverage and shape of the surface oil slick feature during the 21 days following the Deepwater Horizon offshore oil rig explosion (which occurred late in the evening on 20 April: CIMSS Satellite Blog | VISIT Meteorological Interpretation Blog). The first image on 21 April shows the smoke plume drifting southeastward from the oil rig site (before it eventually collapsed).

MODIS true color images (21, 22, 25, and 29 April and 01, 04, 08, 09, 10, and 11 May)

MODIS true color images (21, 22, 25, and 29 April and 01, 04, 08, 09, 10, and 11 May)

With the use of the 16-channel ABI instrument on the upcoming GOES-R satellite, the capability to generate and display these types of RGB images will be possible at high temporal resolution (every 5 minutes on a routine basis).

===== 17 MAY UPDATE =====

MODIS visible image + MODIS Sea Surface Temperature (SST) product

MODIS visible image + MODIS Sea Surface Temperature (SST) product

AWIPS images of MODIS 0.65 µm visible channel data and the MODIS Sea Surface Temperature (SST) product on 17 May 2010 (above) revealed that a long, thin portion of the oil slick had been drawn southward and southeastward, possibly becoming entrained into the far northern circulation of the Gulf of Mexico Loop Current. The MODIS SST values within the Loop Current were very warm — as high as 82º F (darker red color enhancement).

A closer view using 250-meter resolution MODIS true color (using bands 1/4/3) and false color (using bands 7/2/1) RGB images from the SSEC MODIS Today site (below) showed better detail of the long oil slick plume that was moving southward.

It is unclear why the far eastern end of the oil slick plume appears so dark on the MODIS images; one idea is that a great deal of oil dispersant had been spread over the leading edge of the plume, which then greatly reduced the amount of solar energy being reflected back up toward the satellite. Or, perhaps the darker area is oil along the leading edge of the plume that is still sub-surface?

MODIS true color (using bands 1/4/3) and false color (using bands  7/2/1) images

MODIS true color (using bands 1/4/3) and false color (using bands 7/2/1) images

For addition details, see the Weather Underground blog.

POES/AVHRR in AWIPS

May 14th, 2011 |
POES AVHRR Products in AWIPS menu

POES AVHRR Products in AWIPS menu

Starting in July 2010, CIMSS began making a variety of CLAVR-x based POES AVHRR derived products (see menu above) as well as POES AVHRR individual channel images (see menu below) available for NWS offices to add to their local AWIPS workstations via LDM subscription (see the AVHRR Imagery and Products in D-2D site for installation instructions). A VISIT training lesson “POES and AVHRR Satellite Products in AWIPS” is available to help users understand the interpretation of the various images and products, with some examples of their application to weather analysis and forecasting.

 

POES AVHRR individual channels in AWIPS menu

POES AVHRR individual channels in AWIPS menu

A few AWIPS examples of these POES AVHRR products and images are shown below, as they appear in various posts on the CIMSS Satellite Blog (for the complete library of cases, see the “AVHRR” blog category):

AVHRR Band 1 Visible Channel (0.63 µm)

The wave structure of an undular bore was well-depicted on the POES AVHRR 0.63 µm visible image (below) as the feature was propagating southeastward over the Gulf of Mexico on 27 April 2011. Overlays of hourly MADIS atmospheric motion vectors (or cloud-tracked winds) showed that the undular bore was moving southeastward at a speed of 20-30 knots.

POES AVHRR 0.63 µm visible channel image

POES AVHRR 0.63 µm visible channel image

AVHRR Band 2 Visible Channel (0.86 µm)

A series of von Karman vortices was seen on POES AVHRR 0.86 µm visible channel imagery (below), streaming south of the Aleutian Islands of Alaska on 14 April 2011. In addition, the ice that remained farther to the north in the Bering Sea was also very evident.

POES AVHRR 0.86 µm visible channel images

POES AVHRR 0.86 µm visible channel images

AVHRR Band 3B Shortwave IR Channel (3.74 µm)

A large number of “hot spots” (black to red to yellow color enhancement) could be seen on a POES AVHRR 3.74 µm shortwave IR image (below) due to widespread fires that were burning across eastern Oklahoma on 11 March 2011.

POES AVHRR 3.74 µm shortwave IR image

POES AVHRR 3.74 µm shortwave IR image

AVHRR Band 4 IR Window Channel (10.8 µm)

POES AVHRR 10.8 µm IR images (below) showed that Hurricane Tomas was exhibiting IR brightness temperatures as cold as -93º C (darker purple color enhancement) as the storm passed between Jamaica and Hispaniola on 05 November 2010. A distinct “transverse banding” signature was also seen to develop along the western and southwestern periphery of the cloud shield — this satellite signature is an indicator of potential turbulence.

POES AVHRR 10.8 µm IR window images

POES AVHRR 10.8 µm IR window images

AVHRR Band 5 IR Channel (12.0 µm)

A POES AVHRR 12.0 µm IR image (below) very close to the time that a tornado was moving through the St. Louis area is shown with an overlay of the SPC hail, damaging winds, and tornado reports. Note that the storm exhibited a very well-defined “enhanced-v” signature near St. Louis (with a minimum cloud top IR brightness temperature of -83º C) — this enhanced-v IR storm top signature is often observed with areas of strong convection that are producing (or are about to produce) either large hail, damaging winds, or tornadoes.

POES AVHRR 12.0 µm IR image (with overlay of severe storm reports)

POES AVHRR 12.0 µm IR image (with overlay of severe storm reports)

Individual POES AVHRR channels can be combined to create Red/Green/Blue (RGB) images that might be helpful to differentiate between different cloud features or cloud layers. The false color RGB image below uses POES AVHRR channels 1, 2, and 4 as the Red, Green, and Blue components to show the clouds associated with a storm system over the eastern US on 26 January 2011. High-level clouds appear brighter white, while low-level clouds take on more of a pale yellow shade; vegetated land surfaces appear green, while water appears blue.

POES AVHRR false-color Red/Green/Blue (RGB) image

POES AVHRR false-color Red/Green/Blue (RGB) image

AVHRR Fog Product

A comparison of the 1-km resolution POES AVHRR fog/stratus product with the corresponding 4-km resolution GOES-13 fog/stratus product (below) demonstrates the advantage of improved spatial resolution to aid in the detection of small scale river valley fog features across the central Appalachian Mountains region on 08 October 2010.

POES AVHRR fog/stratus product + GOES-13 fog/stratus product

POES AVHRR fog/stratus product + GOES-13 fog/stratus product

AVHRR Sea Surface Temperature Product

AVHRR Sea Surface Temperature product (below) showing that an oil slick (resulting from the Deepwater Horizon oil rig fire and collapse) was exhibiting SST values that were several degrees cooler (green color enhancement) than the surrounding waters in the northern Gulf of Mexico on 29 April 2010.

POES AVHRR Sea Surface Temperature product

POES AVHRR Sea Surface Temperature product

AVHRR Cloud Type Product

The POES AVHRR Cloud Type product can be used to discriminate between water droplet clouds, supercooled water droplet clouds, opaque ice crystal clouds, cirrus clouds, or clouds that are likely overshooting the tropopause. An example of the Cloud Type product (below) is shown for a strong storm off the coast of the northeastern US, which produced heavy rain, heavy snow, and high winds across parts of that region on 08 November 2010.

POES AVHRR Cloud Type product

POES AVHRR Cloud Type product

AVHRR Cloud Top Temperature Product

An example of the POES AVHRR Cloud Top Temperature product is shown below for the same strong storm off the coast of the northeastern US.

POES AVHRR Cloud Top Temperature product

POES AVHRR Cloud Top Temperature product

AVHRR Cloud Height Product

An example of the POES AVHRR Cloud Top Height product is shown below for the same strong storm off the coast of the northeastern US.

POES AVHRR Cloud Height product

POES AVHRR Cloud Height product

AVHRR Cloud Optical Depth Product

A comparison of 1-km resolution POES AVHRR Cloud Optical Depth products at 18:41 and 19:18 UTC (below) showed that the primary convergence band along the eastern side of a cyclonic circulation feature over Lake Superior exhibited significantly higher cloud optical depth values (blue to cyan color enhancement). This feature was responsible for later producing several inches of lake-effect snow along the Minnesota north shore of Lake Superior on 07 March 2011.

POES AVHRR Cloud Optical Depth product

POES AVHRR Cloud Optical Depth product

AVHRR Cloud Particle Effective Radius Product

Numerous ship condensation tracks could be seen in both the POES AVHRR visible image and the POES AVHRR Cloud Particle Effective Radius product (below) off the coast of California on 31 March 2011. The Cloud particle Effective Radius product indicated that the ship tracks were composed of slightly smaller particles (lighter cyan color enhancement) than the surrounding stratocumulus clouds that they were embedded within.

POES AVHRR Cloud Particle Effective Radius product (with corresponding visible image)

POES AVHRR Cloud Particle Effective Radius product (with corresponding visible image)

In addition to the CONUS region, a similar collection of POES AVHRR images and products are also created that cover the Alaska region (available under the “1km Resolution – Alaska” menu).

Update on the Gulf of Mexico oil slick

June 25th, 2010 |
MODIS true color (using bands 1/4/3) and false color (using bands 7/2/1) RGB images

MODIS true color (using bands 1/4/3) and false color (using bands 7/2/1) RGB images

A comparison of 250-meter resolution MODIS true color (created using bands 1/4/3) and false color (created using bands 7/2/1) images on 25 June 2010 from the SSEC MODIS Today site (above) showed the extent of the surface oil slick from the Deepwater Horizon offshore oil rig accident.

AWIPS images of early morning POES AVHRR 0.63 µm visible and 3.7 µm shortwave IR data (below) revealed a thin smoke plume drifting northwestward from a small fire hot spot (orange color enhancement) due to a fire that was set to burn off some of the surface oil.

POES AVHRR 0.63 µm visible and 3.7 µm shortwave IR images

POES AVHRR 0.63 µm visible and 3.7 µm shortwave IR images

Gulf of Mexico oil slick update

June 19th, 2010 |
MODIS true color and false color RGB images

MODIS true color and false color RGB images

The comparison of a 250-meter resolution MODIS true color Red/Green/Blue (RGB) image (created using Bands 1/4/3) with the corresponding MODIS false color (created using Bands 7/2/1) image from the SSEC MODIS Today site (above) showed intricate details of the surface oil slick in the far northern Gulf of Mexico on 19 June 2010. The glaciated cloud tops of deep convection appeared as darker shades of cyan on the false color image.

On the true color image, note the small black features located over the bright oil slick, toward the lower left portion of the image — this was smoke from small fires which were apparently being set to burn off some of the surface oil (the fire hot spots show up as shades of pink on the false color image). This was Day 61 following the explosion of the Deepwater Horizon offshore oil rig on 20 April.

The MODIS true color image displayed using Google Earth (below; courtesy of Liam Gumley, CIMSS) offers a different perspective and a larger-scale view of the oil slick.

MODIS true color image (displayed using Google Earth)

MODIS true color image (displayed using Google Earth)