Now that Himawari-8 is their operational geostationary satellite, the Japanese Meteorological Agency (JMA) decommissioned MTSAT-1R (which was relaying the direct broadcast of MTSAT-2 imagery) as of 0630 UTC on 04 December 2015. A comparison of the final 5 hours of available MTSAT-2 6.75 µm water vapor channel images with the coresponding 6.2 µm water vapor channel images from Himawari-8 (above) demonstrated the advantages of improvements in both spatial resolution (2-km with Himawari, vs 4-km with MTSAT) and temproal resolution (10-minute with Himawari, vs 30-minute with MTSAT) for resolving the signature of middle-tropospheric waves within a dry slot in the wake of an occluded storm-force low over the North Pacific Ocean (surface analyses).

In addition, there are 3 water vapor channels on the Himawari-8 AHI instrument – a comparison of these 3 water vapor bands (below) offers a closer look at the aforementioned waves within the dry slot. The weighting functions for each of the 3 water vapor bands (centred at 6.2 µm, 6.9 µm, and 7.3 µm) peak at progressivesly lower altitudes, providing different views of features within those particular atmospheric layers. The same color enhancement is applied to the 3 sets of water vapor images — note that warmer brightness temperatures (yellow to orange colors) dominate the 6.9 µm and 7.3 µm images (which are showing features at lower altitudes, where the atmosphere is warmer).

Similar improvements in spatial and temporal resolution will be seen with imagery from the upcoming GOES-R ABI, which will also feature 3 similar water vapor bands (weighting functions); however, the ABI will provide full-disk images every 5 minutes.

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A large and slow-moving occluded mid-latitude cyclone left a large swath of heavy snowfall across much of the north-central US during the 30 November – 02 December 2015 period. The GOES-13 water vapor (6.5 µm) images shown above (also available as a 62 Mbyte animated gif) revealed the unusually large size of the circulation associated with this storm system. Storm total snowfall amounts included 12.0 inches at Valentine, Nebraska, 11.0 inches at Chamberlain, South Dakota, 8.7 inches at Sibley, Iowa, and 7.2 inches at Madison, Minnesota. The 8.7 inches at Sioux Falls, South Dakota was a record daily snowfall accumulation for 30 November.

As the storm moved eastward over the Great Lakes region on 02 December, clouds cleared to reveal the large areal extent of the snow cover on Suomi NPP VIIRS true-color and false-color Red/Green/Blue (RGB) images (visualized using RealEarth) at 1948 UTC on 02 December (below). On the false-color image, snow cover (as well as lake ice) appears as shades of cyan, in contrast to supercooled water droplet clouds which are shades of white; glaciated (ice crystal) clouds also appear cyan. The deep snow cover, clear skies, and light winds aided strong radiational cooling during the following night, with minimum temperatures on the morning of 03 December as cold as -5º F at Brookings, South Dakota and -4º F at Sheldon, Iowa (KFSD RTP).

An alternative true-color vs false-color comparison (below) uses different spectral bands from the Aqua MODIS instrument — is this case, snow cover and lake ice appear as darker shades of red. The creation of these types of true-color and false-color RGB images will be possible using bands from the upcoming GOES-R ABI (scheduled to be launched in late 2016).

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The sequence of 5 daily Suomi NPP VIIRS true-color Red/Green/Blue (RGB) images shown above are centered on Beijing in northeastern China — these images (viewed using RealEarth) showed the transition from the Beijing area being sunny and snow-covered on 26 November to enshrouded in dense smog on 30 November 2015. The smog exhibited a distinct gray-colored appearance, in contrast to the brighter white clouds and snow cover. Much of this smog was driven by the burning of coal, both on a local level and by regional power plants (as discussed in this Capital Weather Gang blog post).

The corresponding daily time series plots of surface weather data at Beijing Capital International Airport (below) revealed that the surface visibility remained below 1.0 statute miles for extended periods. Although not indicated on the 26 November plot, the surface visibility began at 19 statute miles on that day, before the wind speeds became 4 knots or less beginning at 10 UTC and the visibility eventually began to decrease.

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GOES-13 (GOES-East) Visible (0.63 µm) images (above) showed the growth of offshore ice in the western and northwestern portions of Hudson Bay on 24 November 2015. Also evident on the imagery was cloud streets aligned with the northerly/northwesterly flow of cold arctic air over the water, as well as the presence of a mesoscale low moving southeastward. Apparently this mesoscale low was behind the primary low (with its associated trailing occluded front), which was depicted to be over the eastern portion of Hudson Bay (surface analyses) during the daylight hours of the visible imagery.

A better view of the offshore ice (as well as the ice in central Hudson Bay, northeast of the aforementioned mesoscale low) was provided by Suomi NPP VIIRS true-color and false-color images, visulized using the SSEC RealEarth web map server (below). In the false-color image, snow cover and ice appear as darker shades of cyan.

A comparison of Canadian Ice Service analyses from 16 November and 23 November (below) showed the growth of the offshore ice along the western and northwestern edges of Hudson Bay, as well as the larger area of ice growing southward in the central portion of Hudson Bay during that 1-week period. The departure from normal images at the bottom indicated that ice concentration along the western and northwestern edges was well below normal (red), while the concentration of the large area of ice in central Hudson Bay was greater than normal (blue).

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