Himawari-8 Water Vapor Imagery, and AHI Webapps

January 25th, 2015 |
Himawari-8 Water Vapor Imagery at 0230 UTC on 25 January 2015 (click to enlarge)

Himawari-8 Water Vapor Imagery at 0230 UTC on 25 January 2015 (click to enlarge)

Himawari-8, launched by the Japanese Meteorological Agency in October 2014, is in its check-out phase with the satellite located near 0º North 140º East. The animation above shows the three water vapor bands (Bands 8, 9 and 10 centered at 6.2 µm, 6.9 µm and 7.3 µm, respectively) from the AHI on Himawari-8.

The strength of three water vapor channels is that they provide information about moisture at three different levels in the atmosphere. Water vapor channel weighting functions (computed from this website) for ABI on GOES-R (an instrument that is very similar to the AHI on Himawari-8) show a peak response near 350-400 mb for the 6.2 µm channel but a peak response near 600-700 mb for the 7.3 µm channel (the 6.9 µm channel is in between). The longer-wavelength water vapor channel can provide information about features located farther down into the atmosphere. In the imagery above, the 7.3 µm imagery shows open cellular convection in the cold advection south of the occluded low pressure system over the northern Pacific, east of Japan. In contrast, the 6.2 µm imagery shows only the higher clouds and moisture.

The effect is far more pronounced at full resolution, below. The 6.2 µm data shows only high clouds and moisture; those high-altitude features are not well represented at 7.3 µm. In contrast, low clouds that cannot be seen in the 6.2 µm data are very apparent in the 7.3 µm imagery.

Full Resolution Himawari-8 Water Vapor Imagery at 0230 UTC on 25 January 2015 (click to enlarge)

Full Resolution Himawari-8 Water Vapor Imagery at 0230 UTC on 25 January 2015 (click to enlarge)

Similarly, over south central Australia, there is a strong cold signal in the 6.2 µm imagery east of Adelaide. The 6.9 µm and 7.3 µm imagery does not show such a strong signal, suggesting that only high clouds are present.

Multiple water vapor channels are present now on the GOES Sounder (see here), and those data are used in the CIMSS NearCasting product. GOES Sounder data has a limited domain, however, and relatively coarse resolution. Himawari-8 (and GOES-R) offers a great increase in spatial and temporal resolution over the three GOES Sounder water vapor channels.

These AHI Images are from data posted at JMA‘s AHI webpage: Link. A comparison of Himawari-8 and MTSAT-2 visible and IR images is available here.

Himawari-8 AHI Satellite Band Webapp page

Himawari-8 AHI Satellite Band Webapp page

A collection of “webapps” (above) was created which allows one to explore the different spectral bands of the Himawari-8 AHI from the 25 January 2015 First Images. An example from the Full Disk webapp is shown below.

http://cimss.ssec.wisc.edu/goes/blog/wp-content/uploads/2015/01/ahi_webapp_full_disk.png

Example from the AHI Full Disk image webapp

Cold night in Labrador, Canada

January 22nd, 2015 |
Suomi NPP VIIRS 11.45 um IR channel image, with METAR surface reports

Suomi NPP VIIRS 11.45 um IR channel image, with METAR surface reports

With a cloud-free sky and light winds under a dome of high pressure, strong radiational cooling over a deep snowpack allowed the overnight low temperature to drop to -47º F (-43.9º C) at Wabush Lake (station identifier CYWK) in far western Labrador — this was quite possibly the coldest site in North America on 22 January 2015 (the coldest overnight low temperature in Alaska that morning was -39º F or -39.4º C at Galena). AWIPS images of Suomi NPP VIIRS 11.45 µm IR channel data (above) and MODIS 11.0 µm IR channel data (below) showed minimum surface IR brightness temperatures of -47º C or -52.6º F (darker blue color enhancement) in the western Labrador.

MODIS 11.0 um IR channel image, with METAR surface reports

MODIS 11.0 um IR channel image, with METAR surface reports

A comparison of 1-km resolution Soumi NPP VIIRS 11.45 µm and 4-km resolution GOES-13 10.7 µm IR images (below) showed the advantage of higher spatial resolution for more accurately locating the coldest regions.

Suomi NPP VIIRS 11.45 um and GOES-13 10.7 um IR channel images

Suomi NPP VIIRS 11.45 um and GOES-13 10.7 um IR channel images

FY-2G sends its first image

January 22nd, 2015 |
FY-2G Color Composite Image from 0500 UTC 8 January 2015

FY-2G Color Composite Image from 0500 UTC 8 January 2015 (Click to enlarge)

The Chinese Meteorological Satellite FY-2G was launched on 31 December 2014 from Xichang Launch Center in Sichuan Province. It has achieved Geostationary Orbit at 99.5º E and its first full disk Color Composite image, above, from 8 January 2015, has been released.

For more information on FY-2G, click here. FY-2G is the eventual replacement for FY-2E at 105º E.

VIIRS Sea Surface Temperature patterns in the Gulf of Mexico

January 21st, 2015 |
Suomi NPP VIIRS Sea Surface Temperature (SST) product

Suomi NPP VIIRS Sea Surface Temperature (SST) product

A sequence of four AWIPS images of the Suomi NPP VIIRS Sea Surface Temperature (SST) product (above) showed very detailed information about the SST patterns in the Gulf of Mexico on 21 January 2015. Two features in particular are worth noting: (1) what appears to be a train of Kelvin-Helmholtz instability waves along one of the northern boundaries of the Loop Current (best seen on the 06:52 UTC image), and (2) a small-scale cyclonic eddy located between the far northern edge of the Loop Current and the Mississippi River Delta. On the final 19:57 UTC image, SST values in the general region of this small-scale eddy ranged from 46.7º F at the Mississippi River Delta (cyan color enhancement) to 79.7º F (darker red color enhancement) near the northern edge of the Loop Current – a difference of 33º F within a distance of only about 100 miles.