MTSAT-1R satellite is decommissioned

December 4th, 2015 |

Himawari-8 (left) and MTSAT-2 (right) water vapor channel images [click to play animation]

Himawari-8 (left) and MTSAT-2 (right) water vapor channel images [click to play animation]

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).

Himawari-8 AHI 6.2 µm (top), 6.9 µm (middle), and 7.3 µm (bottom) water vapor channel images [click to play animation]

Himawari-8 AHI 6.2 µm (top), 6.9 µm (middle), and 7.3 µm (bottom) water vapor channel images [click to play animation]

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.

Heavy snowfall across the north-central US

December 2nd, 2015 |

GOES-13 Water Vapor (6.5 µm) images [click to play MP4 animation]

GOES-13 Water Vapor (6.5 µm) images [click to play MP4 animation]

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 November02 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).

Suomi NPP VIIRS true-color and false-color images [click to enlarge]

Suomi NPP VIIRS true-color and false-color images [click to enlarge]

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).

Aqua MODIS true-color and false-color images [click to enlarge]

Aqua MODIS true-color and false-color images [click to enlarge]