MODIS 11.0 µm IR + GOES-12 10.7 µm IR + GOES-12 sounder Skin Temperature

Much of the central and southern Florida peninsula experienced temperatures at or below freezing on the morning of 22 January 2009. Surface air temperatures were as cold as 15º F at Archbold in the Tampa NWS County Warning Area (CWA), 16º F at Plymouth in the Melbourne CWA, and 23º F at Palmdale in the Miami CWA. A comparison of AWIPS images of the 1-km resolution MODIS 11.0 µm IR window channel, the 4-km resolution GOES-12 10.7 µm IR window channel, and the 10-km resolution GOES-12 sounder Skin Temperature product (above) showed that IR brightness temperatures and sounder skin temperature values of 32º F and colder (cyan to blue to purple colors) extended well south of Lake Okeechobee at 07:15 UTC (3:15 AM local time). The coldest MODIS IR / GOES-12 IR / GOES-12 Skin Temperature values at that time were -11.5º C (11.3º F) / -9.0º C (15.8º F) / -5.5º C (22.1º F), respectively.

An AWIPS image of the 1-km resolution MODIS Land Surface Temperature (LST) product over central Florida  (below) revealed that the coldest LST values of 17.3 º F (purple color enhancement) were found just southwest of Leesburg (station identifier KLEE), along the border of Lake county and Sumter county.

MODIS Land Surface Temperature product (central Florida)

The MODIS Land Surface Temperature product over southern Florida (below) showed that LST values of 32º F and colder (darker blue color enhancement) were found as far south as the area east of  Naples (station identifier KAPF). Note the relative warmth of Lake Okeechobee, were LST values of 55-56º F (red color enhancement) were seen.

MODIS Land Surface Temperature product (southern Florida)

An animation of the GOES-12 10.7 µm IR window imagery (below) showed the southward progression of below-freezing surface IR brightness temperatures during the night-time hours, as well as the warming of the Florida peninsula after sunrise on 22 January.

GOES-12 10.7 µm IR images

GOES-12 water vapor and IR images

The air mass over Florida was dry enough to allow the 7.4 µm water vapor channel on the GOES-12 sounder to actually sense the surface (above; animation) — in this case, the weighting function (below) for the 7.4 µm water vapor channel (red plot) peaked at a very low altitude, allowing the thermal signal of the contrast between cold land and warm ocean to reach the satellite.

GOES-12 weighting functions (calculated using Miami rawinsonde data)

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GOES-12 and GOES-13 visible images

A comparison of GOES-12 and GOES-13 visible images (above) showed a long lake-effect cloud band that was oriented generally north-to-south across Lake Michigan on 20 January 2009. Convergence of surface winds was helping to sustain the cloud band over the lake, which was producing localized areas of heavy snowfall where it moved onshore in Illinois (5.0 inches reported in Chicago and Burnham) and Indiana (8.0 inches reported at Whiting). One thing that becomes immediately obvious in the above image comparison is the improved navigation on the new GOES-13 satellite: there is much less image-to-image wobble compared to GOES-12. As a result of this improved navigation, one is able to get a better sense of the actual drift of the ice that is floating in parts of the lake — ice along the eastern portion of the lake was drifting slowly westward away from the Michigan shore, while ice in the northwestern part of the lake was drifting slowly southward.

AWIPS images of the GOES-12 visible, 3.9 µm shortwave IR, 10.7 µm IR window, and Sounder Cloud Top Height product (below) suggested that the lake-effect cloud band was likely composed primarily of supercooled water droplets at 17:00 UTC — there was a strong signal of solar reflection on the shortwave IR image (darker gray enhancement), and IR window cloud top brightness temperature values were only as cold as -17 to -20º C  (cyan color enhancement). The GOES-12 sounder Cloud Top Height values were generally in the 10,000-12,000 foot range (green color enhancement). Note that there were only a few GOES-12 satellite-derived wind vectors associated with the cloud band; the number and accuracy of these atmospheric motion vectors would no doubt be improved using the better navigation of the GOES-13 visible imagery.

GOES-12 visible, shortwave IR, IR window, and sounder cloud top height

AWIPS images of the MODIS visible, 3.7 µm shortwave IR, 11.0 µm IR window, and Cloud Phase product (below) were similar to the GOES-12 images shown above — a strong “solar reflection signal” on the shortwave IR image (darker gray enhancement), with IR window cloud top brightness temperature values in the -17 to -20º C range (cyan color enhancement) — and the MODIS Cloud Phase product indicated that most of the cloud band was of the “Mixed Phase” or “Uncertain” category (gray colors).

MODIS visible, shortwave IR, IRT window, and cloud phase

It is interesting to view a series of 250-meter resolution MODIS true color images (below), using the CIMSS MODIS True Color Imagery Viewer on AWIPS (available to  NWS forecast offices in Wisconsin that have installed the CIMSS MODIS imagery scripts) — the ice increased in areal coverage on 15-16 January (when inland surface temperatures were as cold as -35º F or -37º C over southern Wisconsin), but then decreased somewhat on 18 January as temperatures slowly moderated.

250-meter resolution MODIS true color images (January 13-18)

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GOES-12 10.7 µm IR images

A strong “Alberta Clipper” system ushered in some of the coldest air of the 2008/2009 winter season on 12 January 2009 — in fact, it was so cold that AWIPS images of the GOES-12 10.7 µm IR channel data (above) showed that surface brightness temperatures as cold as -20º to -40º C (cyan to green color enhancement) were surging southward from south-central Canada into the north-central US in the wake of the clipper.

A closer view using GOES-12 IR imagery with a different color enhancement (below) displayed a large area of surface IR brightness temperatures colder than -40º C (violet colors) across much of eastern North Dakota and northwestern Minnesota during the pre-dawn hours of 13 January. The coldest GOES-12 IR brightness temperature values seen were -47º C (-53º F) at 13 UTC (7 AM local time) just to the north of Waskish (station identifier KVWU) in northeastern Minnesota.

GOES-12 10.7 µm IR images

The 1-km resolution MODIS 11.0 µm IR image at 08:57 UTC (3:57 AM local time) on 13 January (below) showed similar values of cold IR brightness temperatures, with a minimum of -48º C (-54º F). The coldest surface air temperature reported that morning was -42º C (-44º F) by the Cooperative Observer at Embarrass in northeastern Minnesota, with lows of -41º C (-42º F) at Babbit, Bigfork, Effie, and International Falls. Prior to this date, the coldest temperature recorded in the Lower 48 states this 2008/2009 winter season was -39º C (-38º F) at Simpson, Montana on 21 December 2008.

MODIS 11.0 µm IR image

— 15 January Update —

GOES-12 10.7 µm IR images

The coldest temperature recorded in the Lower 48 states during this particular cold outbreak was -44º C (-48º F) at Babbitt in northern Minnesota on 14 January. On the morning of 15 January, the core of the coldest air in the north-central US was found farther to the west, from central North Dakota into northeastern South Dakota: Garrison, North Dakota had a minimum temperature of -44º C (-47º F), Bismarck, North Dakota dropped to -42º C (-44º F) (only 1 degree F shy of their all-time record low), and Aberdeen, South Dakota recorded a low of -41º C (-42º F) (which was only 4 degrees F shy of their all-time record low). However, GOES-12 10.7 µm IR images (above) displayed surface IR brightness temperatures as cold as -47º C (-53º F) in North Dakota.

A comparison of 1-km resolution MODIS and 4-km resolution GOES-12 surface IR brightness temperatures at around 08:45 UTC or 3:45 AM local time (below) displayed very similar minimum values of -48º C (-54º F) and -47º C (-53º F), respectively.

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

With such a cold and dry air mass in place over the north, the GOES-12 6.5 µm “water vapor channel” imagery (below) was able to display a signature of the large surface temperature contrast between the relatively warm waters of the Great Lakes and the St. Lawrence River and the surrounding colder land surfaces. GOES-12 water vapor weighting functions calculated using the Detroit MI rawinsonde data indicated that many of the GOES imager and sounder water vapor channels were peaking at unusually-low altitudes.

GOES-12 6.5 µm water vapor images

MODIS true color imagery showed that ice formation was rapidly increasing over far western and southern Lake Michigan with the presence of the cold air over the Great Lakes region.

— 16 January Update —

The cold air continued to move eastward, and on the morning of 16 January had settled over the northeastern US.

PUBLIC INFORMATION STATEMENT
NATIONAL WEATHER SERVICE CARIBOU ME
0955 AM EST FRI JAN 16 2009

**POTENTIAL STATEWIDE RECORD MINIMUM TEMPERATURE**

AT 0730 AM EST THIS MORNING A USGS GAGE AT BIG BLACK RIVER RECORDED A LOW TEMPERATURE OF -50F. THIS EXCEEDS THE CURRENT STATEWIDE RECORD LOW TEMPERATURE OF -48F SET ON JANUARY 19TH…1925 AT VAN BUREN. THIS REPORT IS CONSIDERED UNOFFICIAL UNTIL A REVIEW OF THE EQUIPMENT AND DATA BY THE STATE CLIMATE EXTREMES COMMITTEE AS TO THE VALIDITY OF THIS REPORT. IF THE COMMITTEE ASCERTAINS THAT THIS IS INDEED A VALID REPORT…A SEPARATE PUBLIC INFORMATION STATEMENT WILL BE ISSUED AT THAT TIME.

Several hours prior to this, 1-km resolution NOAA-18 10.8 µm IR imagery (below) showed cold air drainage into the valleys of northern Maine, with surface IR brightness temperatures as cold as -45.4º C (-49.7º F) at 06:41 UTC (02:41 AM local time). The low that morning of -38º C (-37º F) at Caribou, Maine was the coldest temperature recorded at that location for the entire month of January.

NOAA-18 10.8 µm IR image

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MODIS Sea Surface Temperature + RTG-SST model analysis

AWIPS images of the MODIS Sea Surface Temperature (SST) product at 16:22 UTC on 08 January 2009 and the closest corresponding RTG-SST model analysis at 00:00 UTC on 09 January (above) demonstrated some important advantages of the 1-km resolution MODIS satellite imagery for the analysis of small-scale water temperature details. The two obvious warm water features on the MODIS image were (1) a portion of the Gulf of Mexico Loop Current, and (2) the axis of the Gulf Stream over the far western Atlantic Ocean (off the Southeast US coast). While the RTG-SST model analysis did a good job with the placement of the position of the axis of the Loop Current, it was unable to capture many of the subtle water temperature structures and eddies that were present. In particular, note that the MODIS SST image displayed water temperatures that were slightly cooler (75-76º F) in the core of the Loop Current plume, which was surrounded by warmer SST values of 77-78ºF. The RTG-SST model analysis placed the “bulls-eye” of the warmest SST values just southwest of Buoy 42054, where the MODIS image indicated that the pocket of slightly cooler SST values were located.

The RTG-SST model analysis also appeared to have placed the axis of the Gulf Stream a bit far to the east.

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