MODIS 11.0 µm IR and GOES-12 10.7 µm IR images

AWIPS images of the 1-km resolution MODIS 11.0 µm IR and the 4-km resolution GOES-12 10.7 µm IR channel data (above) showed that large portions of northwestern Minnesota and eastern North Dakota exhibited surface IR brightness temperatures colder than -40º F (-40º C) at 08:45 UTC (2:45 am local time) on 02 January 2010. In northwestern Minnesota, the coldest IR brightness temperature values on the MODIS image were -45º C, compared to -42º C on the GOES-12 image. Note the significantly warmer signature of the Minneapolis/St. Paul urban area, as well as the unfrozen waters of Lake Superior.

A map of the 24-hour minimum temperatures (below; courtesy of MesoWest) showed that 3 sites (Pokegama Lake Dam, Gatzke, and Debs) reported a low of -40º across northern Minnesota on the morning of 02 January.

24-hour minimum temperatures across northern Minnesota (courtesy of MesoWest)

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POES AVHRR 10.8 µm IR images + surface temperatures (F)

McIDAS images of POES AVHRR 10.8 µm IR channel data (above) showed the development of a large terrain-induced “banner cloud” over the eastern part of the Brooks Range in northeastern Alaska on 01 January – 02 January 2010. The IR cloud top brightness temperature values were as cold as -65º C (darker red color enhancement) around 20:26 UTC, which suggested very high cloud tops (GOES-11 10.7 µm IR cloud top brightness temperatures were as cold as -58º C at that time). The terrain of the Brooks Range was acting as an obstacle to the northerly flow aloft (ECMWF 700 hPa winds | 500 hPa winds), which helped to initiate the formation of the banner cloud.

This cloud feature was also apparently thick enough to have a dramatic influence on surface temperatures — note that the temperature at Arctic Village (station identifier PARC) rose from -35º F before the cloud feature developed to +1º F after the cloud feature had been overhead for several hours. A surface meteorogram plot indicated that this temperature rise occurred during a period of light winds, so warm air advection could not account for the warming; instead, the thick cloud deck acted as a blanket to stop radiational cooling over that particular site.

CIMSS has been evaluating and testing a variety of CLAVR-x AVHRR cloud products in AWIPS, which can be used to further characterize this banner cloud that formed over the Brooks Range. The Cloud Type product (below) classified the feature as a combination of Cirrus, Multi-level Cirrus, and Opaque Ice Cloud categories (yellow, orange, and red color enhancements), which is not surprising given the very cold appearance on IR imagery.

AVHRR Cloud Type product

The AVHRR Cloud Top Temperature (CTT) product (below) showed that the tops of the cirrus feature were even colder than what was indicated by the IR imagery, with CTT values as low as -76º C at 20:20 UTC.

AVHRR Cloud Top Temperature product

The AVHRR Cloud Top Height product (below) showed that the tops of the banner cloud feature were generally around 8 km (cyan color enhancement). This height was close to the altitude of the tropopause, as indicated on the Barrow AK rawinsonde data.

AVHRR Cloud Top Height product

As an aside, the eastern Arctic Slope region of Alaska was experiencing blizzard conditions during this period — at Barter Island (station identifier PABA) along the coast, winds gusted as high as 72 mph. The strong westerly winds were in response to a tightening pressure gradient in advance of an approaching cold front (surface pressure and frontal analysis).

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GOES-11 and GOES-14 visible channel images

McIDAS images of GOES-11 and GOES-14 visible channel data (above) revealed a large hazy plume streaming northeastward from the Hawaiian Islands on 31 December 2009 – 01 January 2010. The primary source of this plume was ongoing emissions from the Kilauea volcano on “The Big Island” of Hawaii — the resulting “vog” (volcanic smog) is air pollution that forms when sulfur dioxide and other gases/particles emitted by an erupting volcano react with oxygen and moisture in the presence of sunlight. On 31 December the haze was reducing visibility to 5 miles at Lahaina on Maui island.

This GOES-11 vs GOES-14 visible image comparison helps to highlight two important points: (1) due to a more favorable “forward scattering” geometry with GOES-14 positioned at 105º West longitude, the extent of the “vog” plume shows up with greater clarity on GOES-14 images later in the day compared to GOES-11 (positioned at 135º West longitude), and (2) the performance of the GOES visible channel detectors degrades over time, so the much older GOES-11 (launched in 2000) visible imagery appears significantly darker (the enhancement of the images is the same). GOES-14 (launched in 2009) was emulating GOES-West during the final days of its NOAA Science Test.

Under typical conditions, the dominant northeasterly trade winds act to advect the plume of “vog” toward the southwest — but in this case, an AWIPS image of the GOES-11 IR channel with an overlay of ASCAT scatterometer winds (below) showed that there was a southwesterly flow in advance of an approaching cold front.

GOES-11 IR image + ASCAT scatterometer winds

An image of the Aura satellite Ozone Measuring Instrument (OMI) Total Column Sulphur Dioxide (SO2) product (below; courtesy of NOAA/NESDIS) confirms that elevated levels of SO2 were present within the “vog” plume seen on GOES visible imagery.

OMI SO2 product (courtesy of NOAA/NESDIS)

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GOES-14 and GOES-12 visible images

McIDAS images of GOES-14 and GOES-12 visible channel data (above) showed that a large portion of the land-fast ice in the southern half of Green Bay began to break away and drift slowly northeastward on 27 December 2009. Unlike a similar case seen on 11 March 2009 with strong surface winds, the southwesterly winds on this particular day were quite light (generally 10 knots or less at inland stations over northeastern Wisconsin) — however, winds were gusting to 13-18 knots farther to the northeast at coastal sites with an upwind exposure to the bay.

As part of its ongoing NOAA Science Test, the GOES-14 satellite had been placed into Rapid Scan Operations (RSO) mode, supplying imagery as frequently as every 5 minutes. The more frequent RSO imaging (along with the improved GOES-14 Image Navigation and Registration) allowed the motion of the drifting ice to be more accurately visualized compared to the 15-minute interval GOES-12 imagery with poorer image navigation.

250-meter resolution MODIS true color images from the SSEC MODIS Today site (below) showed a more detailed view of the motion of the ice between the overpass of the Terra satellite at 17:10 UTC and the Aqua satellite at 18:55 UTC.

MODIS true color images

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