MODIS Sea Surface Temperature (SST) product with overlay of RTG_SST High-Resolution model SST field

An AWIPS image of the MODIS Sea Surface Temperature (SST) product on 09 November 2012 with an overlay of SST contours from the RTG_SST High-Resolution model valid about 6 hours later (above) showed the residual impact of Hurricane Sandy on the axis of the Gulf Stream, almost 2 weeks after Sandy moved through that area. There were large eddy perturbations seen in the axis of the Gulf Stream, and MODIS SST values of 80º F or higher (darker red color enhancement) that were not captured by the model analysis.

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GOES-15 6.5 µm water vapor channel images (click image to play animation)

McIDAS images of 4-km resolution GOES-15 6.5 µm “water vapor channel” data (above; click image to play animation) showed the development of a series of well-defined mountain waves immediately downwind of the high terrain of the Sierra Nevada mountains in California on 08 November 2012. This mountain wave signature indicates the potential for turbulence — and there were a few pilot reports of light to moderate turbulence in that region between the altitudes of 25,000 and 38,000 feet above ground level (17:02 UTC, 01:00 UTC).

Occasionally the crests of these mountain waves are marked by “rotor clouds” — but they also frequently occur in clear air, which underscores the importance of using water vapor imagery for their detection. AWIPS images of 1-km resolution MODIS 6.7 µm water vapor channel, 0.65 µm visible channel. and 11.0 µm IR channel data at 20:32 UTC (below) showed that there were no cloud features present with some of the mountain waves (or with the entire portion of any given mountain wave).

MODIS 6.5 µm water vapor channel, 6.5 µm visible channel. and 11.0 µm IR channel images

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VIIRS DayNight Band on Suomi/NPP, GOES-R IFR Probabilities and surface observations (Click image to play animation)

The animation above, showing the VIIRS Day/Night Band on Suomi NPP, as well as the GOES-R IFR Probability field that fuses together information from GOES-East and the Rapid Refresh, is offered as testimonial to the use of the Day/Night band in detecting the presence of low clouds. The Day/Night Band (that is “night-time visible”, which band uses reflected moonlight as an illumination source) and the 6.5-µm water vapor imagery and the traditional brightness temperature difference (10.7 µm – 3.9 µm) both show the presence of high-level cirrus over central and southern Florida. This high cloud deck will prevent the traditional fog detection algorithm from returning a useful signal. The comparison between the DayNight Band and the IFR probabilities is especially simple using this simple applet. Where the IFR Probabilities are large in regions free of cirrus, the Day/Night band does suggest the presence of clouds. As with other methods using satellites to detect fog, whether of not the cloud is at the surface is difficult to discern. Note that IFR Probabilities are smaller underneath the cirrus clouds. Both predictors — satellite and Rapid Refresh — must show strong signals for the highest IFR probability to occur, and that cannot happen underneath a cirrus canopy.

More examples of the GOES-R Fog detection algorithm, including a more detailed write-up on this Florida case, can be found at the Fog Blog. A Day/Night band image over the southeast with limited fog over coastal South Carolina and northern Florida is here.

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GOES-14 0.62 µm Visible Image

GOES-14 came out of storage in mid-August for an annual north-south maneuver and for GOES-R Testing. While in normal mode, GOES-13 suffered an anomaly, and GOES-14 replaced GOES-13 temporarily as GOES-East before GOES-13 returned to service.

After operating in SRSO-R mode for Hurricane Sandy, GOES-14 was switched off after the 1845 UTC image on 1 November 2012 (above). It will remain in stand-by mode until recalled because of anomalies with GOES-West (GOES-15) or GOES-East (GOES-13). For more information on the future plans for GOES-14, click here.

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