Landsat-8 Imagery

January 16th, 2016 |

Landsat-8 false-color image overpass [click to enlarge]

Landsat-8 false-color image overpass [click to enlarge]

Landsat-8 imagery — with a spatial resolution of 15 to 30 meters — is available for viewing via the SSEC RealEarth web map server. An example of a swath of false-color Red/Green/Blue (RGB) imagery across the central US between the times of 1630-1640 UTC on 16 January 2016 is shown above. Snow cover and ice (as well as ice crystal clouds) appear as varying shades of cyan in this type of RGB image.  Let’s take a closer look at 3 regions along this overpass to examine some interesting features.

The northerly flow of arctic air over the still-unfrozen waters of Lake Superior was aiding the development of lake effect snow (LES) bands, some of which were moving inland over the eastern portion of the Upper Peninsula of Michigan. One of the more well-defined LES bands was seen to be moving across the Grand Marais area — a cooperative observer 10 miles south of the city reported 8.5 inches of new snow during the 24-hour period from 12 UTC on 16 January to 12 UTC on 17 January.

Landsat-8 false-color RGB image over Lake Superior [click to enlarge]

Landsat-8 false-color RGB image over Lake Superior [click to enlarge]

Looking farther to the south, an interesting feature was seen in the southern part of ice-covered Green Bay, Wisconsin (below): a channel through the ice (red arrows) had been cut by the US Coast Guard icebreaker Mackinaw during the evening of 14 January, to allow passage for a ship to unload cargo at a dock along the mouth of the Fox River (which empties into the southern end of Green Bay). Hat tip to the NWS Green Bay for providing the information on which icebreaker was involved.

Landsat-8 Panchromatic Visible (0.59 µm) and False-color RGB images [click to enlarge]

Landsat-8 Panchromatic Visible (0.59 µm) and False-color RGB images [click to enlarge]

Finally, a look to the southern portion of the overpass: the Mississippi River, between the states of Louisiana and Mississippi. The Landsat satellites fly over the same portion of the Earth every 17 days, so taking advantage of this fact we can visualize the profound changes in the southern Mississippi River due to the flow of large amounts of water resulting from heavy rainfall farther to the north — over the Middle Mississippi River and Ohio River Valley regions — during December 2015 (as discussed in this blog post). Water appears as darker shades of blue in these particular Landsat RGB images, aiding in the identification of areas where flooding is occurring.

Landsat-8 false-color RGB images on 31 December 2015 and 16 January 2016 [click to enlarge]

Landsat-8 false-color RGB images on 31 December 2015 and 16 January 2016 [click to enlarge]

Hurricane Alex

January 13th, 2016 |

GOES-13 Visible (0.63 µm) images [click to play animation]

GOES-13 Visible (0.63 µm) images [click to play animation]

Subtropical Storm Alex (NHC advisory archive) formed in the far eastern Atlantic Ocean on 13 January 2016. Animations of GOES-13 (GOES-East) 0.63 µm Visible (above) and 10.7 µm Infrared images (below) showed the initial evolution and northeastward motion of the storm. Alex is only the 4th known January tropical or subtropical storm to have formed in the Atlantic since the historical record began in 1851.

GOES-13 Infrared (10.7 µm) images [click to play animation]

GOES-13 Infrared (10.7 µm) images [click to play animation]

===== 14 January Update =====

A comparison of Suomi NPP VIIRS Infrared (11.45 µm) and Day/Night Band (0.7 µm) images at 0320 UTC (below) showed the well-defined eye of Alex. With the Moon in the Waxing Crescent phase (at 30% of Full) there was enough illumination to demonstrate the “visible image at night” capability of the Day/Night Band. A magnified version of the Infrared image showing the eye can be seen here.

Suomi NPP VIIRS Infrared (11.45 µm) and Day/Night Band (0.7 µm) images [click to enlarge]

Suomi NPP VIIRS Infrared (11.45 µm) and Day/Night Band (0.7 µm) images [click to enlarge]

As of 15 UTC on 14 January, Alex had made the transition from subtropical storm to Category 1 hurricane (eastern Atlantic Ocean surface analyses). GOES-13 Infrared (10.7 µm) images (below) showed the well-defined eye that had formed. Alex became the first known hurricane to form in the Atlantic Ocean since 1938, and only the second hurricane on record to from north of 30ºN latitude and east of 30ºW longitude.

GOES-13 Infrared (10.7 µm) images [click to play animation]

GOES-13 Infrared (10.7 µm) images [click to play animation]

A DMSP-16 SSMIS Microwave (85 GHz) image (below) revealed the eye structure at 1653 UTC.

DMSP-16 SSMIS 85Ghz microwave brightness temperature image [click to enlarge]

DMSP-16 SSMIS 85Ghz microwave brightness temperature image [click to enlarge]

===== 15 January Update =====

While still classified as a hurricane, Alex was undergoing a weakening trend as it approached the Azores Islands during the early morning hours on 15 January. GOES-13 Infrared (10.7 µm) images (below) showed a strong convective band that produced a brief period of heavy rain at Ponta Delgata and Lajes Acores several hours prior to the passage of the eye of Alex (which occurred in the 11-14 UTC time frame — and Alex was downgraded at that point to a Tropical Storm). At Ponta Delgata a peak wind gust of 50 knots was recorded at 1130 UTC.

GOES-13 Infrared (10.7 µm) images [click to play animation]

GOES-13 Infrared (10.7 µm) images [click to play animation]

ISS-Rapidscat surface scatterometer winds (below) showed the center of circulation of Alex just south of the Azores Islands at 1118 UTC.

Rapidscat surface scatterometer winds [click to enlarge]

Rapidscat surface scatterometer winds [click to enlarge]

===== 16 January Update =====

Using a long animation of GOES-13 Water Vapor (6.5 µm) images covering the 06-16 January period (below; also available as a large 165-Mbyte animated gif), the origination of Hurricane Alex could be traced back to a strong baroclinic mid-latitude cyclone that rapidly intensified off the southeast coast of the US on 07 January.

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]

The origin and motion of Alex could also be identified using the satellite-derived atmospheric motion vector 850 hPa Relative Vorticity product (below). A region of lower-tropospheric vorticity over Cuba on 06 January began moving northeastward across the Bahamas, then eastward across the Atlantic Ocean on 07 January.

850 hPa Relative Vorticity product [click to play animation]

850 hPa Relative Vorticity product [click to play animation]

For another perspective on the history of the development of Alex, see this article from The Weather Channel.

Tropical Storm Pali in the central Pacific

January 8th, 2016 |

Himawari-8 Water Vapor (6.2 µm) infrared Imagery [click to animate], imagery Courtesy JMA

Himawari-8 Water Vapor (6.2 µm) infrared Imagery [click to animate], imagery Courtesy JMA

Tropical Storm Pali has formed in the central Pacific, in a region east-southeast of Kwajalein Atoll (which atoll is at 9 N, 168 E), just west of warm Sea Surface Temperature anomalies (Source) associated with the ongoing El Nino. For the Central Pacific basin, Pali set new records for being the earliest-forming tropical cyclone on record (21 UTC on 7 January), as well as the most Equatorward-forming (at 4.7º N). The Himawari animation, above, of the 6.2 µm Water Vapor imagery from 0000 UTC on 7 January through 1500 UTC 8 January 2016 (mp4 available here), shows impressive upper-level outflow from the region of convection surrounding the storm center. A longer animation of Himawari 10.4 µm Infrared imagery (from 0000 UTC 06 January to 0650 UTC on 8 January) is available here. The Composite Infrared Imagery from AWIPS II, below, shows the slow but steady organization of the storm. Infrared brightness temperatures are very cold, with temperatures occasionally colder than -95º C.

Composite Infrared Imagery (10.7 µm) 0600 UTC 6 January 2016 - 1500 UTC on 8 January 2016 [click to animate]

Composite Infrared Imagery (10.7 µm) 0600 UTC 6 January 2016 – 1500 UTC on 8 January 2016 [click to animate]

Pali is forming in a region that allows views from both GOES-15 (overhead at the Equator and 135º W) and Himawari-8 (overhead at the Equator and 140º E). The Infrared animation below shows GOES-15 at Full Resolution from the Full Disk Imagery that is used to view Pali. Note that Himawari data has been degraded both spatially and temporally in the animation (to match that of GOES).

GOES-15 Infrared Imagery (10.7 µm) (left) and Himawari-8 Infrared (right) (10.35) at full GOES Resolution 0600 UTC 8 January 2016 - 1800 UTC 8 January 2016 [click to animate]

GOES-15 Infrared Imagery (10.7 µm) (left) and Himawari-8 Infrared (right) (10.35) at full GOES Resolution 0600 UTC 8 January 2016 – 1800 UTC 8 January 2016 [click to animate]

An animation that is at full resolution for Himawari-8, for just 3 hours, from 0600-0900 UTC, is below. Only two GOES-15 Images are available during this time period that includes 19 Himawari-8 images. (Note also the increase in spatial resolution with Himawari, from 4 km for GOES to 2 km for Himawari) There is considerable evolution to the storm during these three hours that present-day GOES cannot view because of limited scanning capabilities. GOES-R will provide spatial resolution and image scan rates identical to Himawari-8 so meteorologists will be better able to monitor storm evolution.

GOES-15 Infrared Imagery (10.7 µm) (left) and Himawari-8 Infrared (right) (10.35) at full Himawari-8 Resolution 0600 UTC 8 January 2016 - 0900 UTC 8 January 2016 [click to animate]

GOES-15 Infrared Imagery (10.7 µm) (left) and Himawari-8 Infrared (right) (10.35) at full Himawari-8 Resolution 0600 UTC 8 January 2016 – 0900 UTC 8 January 2016 [click to animate]

Himawari True-Color Imagery, below, shows both Pali, a large relatively disorganized system in the central north Pacific and Cyclone Ula, a compact and more organized system in the tropical south Pacific. Himawari True-Color (actually a 4-banded composite meant to emulate True Color) imagery is routinely available here.

Himawari-8 True-Color Visible Imagery [click to enlarge], imagery Courtesy JMA

Himawari-8 True-Color Visible Imagery [click to enlarge], imagery Courtesy JMA

Storms Enter California

January 6th, 2016 |
GOES-15 Water Vapor (6.5 µm) infrared Imagery  [click to animate]

GOES-15 Water Vapor (6.5 µm) infrared Imagery [click to animate]

Water Vapor Imagery, above, from GOES-15, shows a parade of storms that have hit California (now over the intermountain West and the Plains), are hitting California, or will hit California. MIMIC Total Precipitable Water, below, shows the the ribbons of moisture associated with each storm. The storm hitting California on 6 January appears not to access as much moisture as previous systems (although rainfall will still be heavy as the forcing is strong). However, the cellular structures in the water vapor imagery (above) suggest very cold air aloft that will support the development of showers on 7 January. In addition, moisture is pooling north of Hawaii in this animation and that moisture may be drawn into California by the end of the week. Click for an animated gif (100+ Megabytes) (mp4) of the GOES-15 Water Vapor Imagery from 1-7 January, showing the progression of storms into California.

MIMIC Total Precipitable Water for the 72 hours ending 1800 UTC on 6 January [click to enlarge]

MIMIC Total Precipitable Water for the 72 hours ending 1800 UTC on 6 January [click to animate]