METARS over south-central Wisconsin

The animation above shows three hours of METAR plots, with the first one — 0900 UTC — overlaying a MODIS Infrared image. Note how the temperature at Madison (KMSN) in the center of the image rises from 34 with calm winds at 0900 UTC to 37 with light southwest winds at 1000 UTC to 47 at 1100 UTC.

MODIS Estimates of Lake Surface Temperature

Madison’s Truax airport is northeast of Lake Mendota, a lake with a surface area of approximately 40 square miles. MODIS SSTs esimates, above, show surface temperatures near 60 degrees Fahrenheit, in agreement with in situ observations (Click here for real-time observations). Land surface temperature estimates, below, show that most of the Wisconsin is near freezing, although a pocket of low 20s (Fahrenheit) exists in northeast Dane County. The elevated terrain of the Military Ridge in Iowa County shows up nicely as somewhat warmer. (Click here for a toggle between Land Surface Temperature and Topography). Land-surface temperatures over Lake Mendota (yellow) are in the low 60s. Both land-surface and lake-surface temperature estimates are warmer than the 11-µm brightness temperature because those algorithms consider more than just the 11-µm brightness temperature.

MODIS Estimates of Land Surface Temperature

The southwest winds that developed in the early morning hours were able to move warmer lake-modified air to the observating station at the airport, resulting in the dramatic temperature rise. The National Weather Service in Sullivan also noted this temperature rise. GOES-West imagery in that plot (GOES-West is used because GOES-East at the time had shut down due to an anomaly) suggests that the airport warmth was sub-pixel scale.

View only this post Read Less

Tropical Storm Nadine IR images

IR images from the CIMSS Tropical Cyclones site (above) show increased organization and convection associated with Tropical Storm Nadine on 23 September 2012. Nadine was declared “post-tropical” on 21 September, after having initially formed as a tropical depression on 11 September. Nadine eventually reached Category 1 hurricane intensity late in the day on 14 September as it recurved eastward over the central Atlantic Ocean (below).

Track of tropical cyclone Nadine

View only this post Read Less

GOES-14 0.63 µm visible channel images (click image to play animation)

The autumnal equinox occurred at 14:49 UTC on 22 September 2012. On this day, GOES-14 was providing Full Disk images at 30-minute intervals (as opposed to the normal operational 3-hour interval) as a part of the SRSOR testing period.

View only this post Read Less

Toggle between GOES-13 6.5 µm and MODIS 6.76 µm imagery at 0740 UTC on 21 September

The GOES Imager infrared channels are displaying increasing amounts of small-scale noise that is manifest in imagery as herringbone or checkerboard features, as shown in the comparison above with a MODIS water vapor imagery. The animation below, an AWIPS composite of GOES-13 and GOES-15, shows increasing amounts of noise with a peak near 0830 UTC (when the loop pauses), before the noise relaxes. There seems, then, to be a diurnal component to the noisy behavior.

GOES-13/GOES-15 6.5 µm imagery (click Image for Animation)

The noise is apparent in the GOES-13 imagery in the loop above, but not in the GOES-15 imagery that is displayed on the western side of the north-south seam from eastern Washington southward to Baja California.

GOES-13 and GOES-14 6.5 µm imagery, 1045 UTC 21 September 2012

Similarly, a comparison of GOES-13 and GOES-14 data over the north-central United States shows a clean signal in GOES-14. Compare, for example, the checkerboard signal over northern Illinois in the GOES-13 imagery to the same region in the GOES-14 imagery.

GOES-13 3.9 µm imagery, 0815 UTC 21 September 2012

The noise is also apparent, though more subtle, in other channels, especially the shortwave Infrared (3.9 µm), as evidenced above. The herringbone/checkboard pattern is present both in the very cold cloud tops of the convection over southern Missouri and in the mid- and high-level clouds over the central Mississippi Valley. The noise in the 3.9 channel is also apparent in the heritage fog product that simply takes the difference between the 10.7 µm and 3.9 µm brightness temperatures. (The noise is not apparent on this day in the GOES-R IFR Probability Product that fuses the brightness temperature difference field with model data).

GOES-13 6.5 µm imagery (click Image for Animation)

An animation of GOES-13 Water Vapor imagery at 0815 UTC from 7 September 2012 through 21 September 2012 shows that the noise is a recent, but now persistent, issue with the Imager. It may have started around September 12.

GOES-13 6.5 µm imagery from Imager (top) and Sounder (bottom), 0845 UTC 21 September 2012

The noise is present in both Imager and Sounder data. This suggests that the root cause may be with the satellite platform itself, not necessarily with the instruments on board. NOAA/NESDIS scientists are actively working to determine the cause of the noise in the signal.

View only this post Read Less