Increase in Turbidity near the Texas Gulf Coast following Hurricane Harvey

August 30th, 2017 |

Terra MODIS True-Color imagery off the Texas Gulf Coast on 23 and 30 August, 2017 (Click to enlarge)

MODIS Today imagery from 23 August (pre-Harvey) (cropped) and 30 August (post-Harvey) (cropped), above, show an enormous increase in turbidity in the nearshore waters off the coast of Texas. Further, many of the rivers change their appearance to brown and flooding in the post-Harvey image. (River gauges in flood stage; Source)

A similar toggle using Suomi NPP VIIRS Imagery, from this site, also from 23 August and 30 August, is shown below. The increase in turbidity was due to a combination of strong winds and runoff from very heavy rainfall associated with the hurricane.

Suomi NPP True-Color imagery off the Texas Gulf Coast on 23 and 30 August, 2017 (Click to enlarge)

Suomi NPP VIIRS Products include a River Flood estimate, developed by Sanmei Li and others at George Mason University. The toggle below from RealEarth shows Suomi NPP VIIRS True Color at 1904 UTC, and the River Flood Product for the same time.

Suomi NPP VIIRS True-Color imagery off the Texas Gulf Coast, 1904 UTC on 30 August, 2017, and the Suomi NPP River Flood Product at the same time (Click to enlarge)

(Thanks to Bill Taylor and John Stoppkotte, NWS in N. Platte NE, for noting this!)

Hurricane Harvey makes landfall

August 26th, 2017 |

* GOES-16 data posted on this page are preliminary, non-operational and are undergoing testing *

As Hurricane Harvey moved across warm waters in the northwestern Gulf of Mexico (SST | OHC), it continued to intensify (ADT | SATCON) to a Category 4 hurricane just before making landfall (which occurred around 03 UTC on 26 August 2017, or 10 pm local time on 25 August). A GOES-16 Mesoscale Sector had been positioned over Harvey, providing images at 30-second intervals; some of these are shown with “Red” Visible (0.64 µm) images prior to sunset (below). A GOES-16 vs GOES-13 (GOES-East) Visible image comparison is available here.

GOES-16 Visible (0.64 µm) images, with hourly surface ports plotted in yellow (Click to play MP4 animation)

GOES-16 “Red” Visible (0.64 µm) images, with hourly surface ports plotted in yellow [click to play MP4 animation]

Hurricane Harvey had a large eye on GOES-16 “Clean” Infrared Window (10.3 µm) images at landfall, which persisted — albeit becoming smaller with time — for many hours after it moved inland (below). A longer-term animation of 5-minute GOES-16 Infrared Window images (covering the period 23-27 August) is available here.

GOES-16

GOES-16 “Clean” Infrared Window (10.3 µm) images, with hourly surface reports plotted in yellow [click to play MP4 animation]

A sequence of 4 Infrared Window images, from Suomi NPP VIIRS and Terra/Aqua MODIS, covering the period 0419-0851 UTC (below) showed the shrinking eye and the erratic path of Harvey once it moved inland.

Terra/Aqua MODIS (11.0 µm) and Suomi NPP VIIRS (11.45 µm) Infrared Window images [click to enlarge]

Terra/Aqua MODIS (11.0 µm) and Suomi NPP VIIRS (11.45 µm) Infrared Window images [click to enlarge]

A recap of the torrential rainfall amounts and maximum wind gusts caused by Hurricane Harvey can be seen in the WPC Storm Summary.

Total solar eclipse of 21 August 2017 – a satellite perspective

August 21st, 2017 |

* GOES-16 data posted on this page are preliminary, non-operational and are undergoing testing*

GOES-16 CONUS Sector images (at 5-minute intervals)

GOES-16

GOES-16 “Red” Visible (0.64 µm) images [click to play animation]

During the total solar eclipse of 21 August 2017,  the lunar umbra was evident on imagery from the GOES-16  0.5 km resolution (at satellite sub-point) “Red” Visible band (0.64 µm) (above) and 1.0 km resolution Near-Infrared “Vegetation” band (0.86 µm) (below).

GOES-16 Near-Infrared

GOES-16 Near-Infrared “Vegetation” (0.86 µm) images [click to play animation]

The shadow was also prominent in other Visible and Near-Infrared bands, as shown in a 4-panel comparison of GOES-16 “Blue” Visible (0.47 µm, upper left), “Red” Visible (0.64 µm, upper right), “Vegetation” (0.86 µm, lower left) and “Snow/Ice” (1.61 µm, lower right) images (below).

GOES-16

GOES-16 “Blue” Visible (0.47 µm, upper left), “Red” Visible (0.64 µm, upper right), “Vegetation” (0.86 µm, lower left) and “Snow/Ice” (1.61 µm, lower right) images [click to play animation]

GOES-16 true-color Red/Green/Blue (RGB) images from the SSEC Geostationary Satellite site (below) showed another view of the shadow. A GOES-16 Full-Disk true-color animation (courtesy of  Kaba Bah, CIMSS) is available here.

GOES-16 true-color RGB images [click to play animation]

GOES-16 true-color RGB images [click to play animation]

The 3.9 µm Shortwave Infrared band is also sensitive to reflected solar radiation — particularly that which is reflected from land surfaces and cloud tops composed of small spherical supercooled water droplets (and to a lesser extent, small ice crystals) — which causes this band to sense warmer (darker gray to black) brightness temperatures compared to the other ABI infrared bands. Therefore, a loss of sunlight within the eclipse shadow will lead to cooling (lighter shades of gray) 3.9 µm brightness temperatures (below).

GOES-16 Shortwave Infrared (3.9 µm) images [click to play animation]

GOES-16 Shortwave Infrared (3.9 µm) images [click to play MP4 animation]

Taking a closer look at eastern Missouri and southern Illinois as the solar eclipse shadow was passing over that region shortly after 1800 UTC (1:00 pm local time), GOES-16 “Red” Visible (0.64 µm) images (below) revealed that the pronounced decrease of incoming solar radiation appeared to temporarily suppressed the development of widespread boundary layer cumulus clouds. Note that increase in hourly surface temperatures was also halted, with some locations even experiencing a slight cooling (1-3 ºF) due to reduction of heating within the lunar umbra.

GOES-16

GOES-16 “Red” Visible (0.64 µm) images, with hourly surface reports plotted in yellow [click to play animation]

GOES-16 Shortwave Infrared (3.9 µm) images (below) also showed a slight cooling — seen as a lighter shade of red enhancement — across the region.

GOES-16 Shortwave Infrared (3.9 µm) images, with hourly surface reports plotted in yellow [click to play animation]

GOES-16 Shortwave Infrared (3.9 µm) images, with hourly surface reports plotted in yellow [click to play animation]

GOES-16 Mesoscale Sector images (at 1-minute intervals)

GOES-16 "Red" Visible (0.64 µm) images, with station identifiers plotted in yellow [click to play animation]

1-minute GOES-16 “Red” Visible (0.64 µm) images, with station identifiers plotted in yellow [click to play animation]

A “floating” Mesoscale Sector provided 1-minute imagery during the eclipse (above).

Polar-orbiting satellite images (Terra MODIS, and Suomi NPP VIIRS)

Terra MODIS Visible (0.65 µm). Land Surface Temperature product, Shortwave Infrared (3.7 µm) and Infrared Window (11.0 µm) images [click to enlarge]

Terra MODIS Visible (0.65 µm), Land Surface Temperature product, Shortwave Infrared (3.7 µm) and Infrared Window (11.0 µm) images [click to enlarge]

A toggle between Terra MODIS Visible (0.65 µm), Land Surface Temperature product, Shortwave Infrared (3.7 µm) and Infrared Window (11.0 µm) images (above) showed the eclipse shadow as it was centered over western Nebraska around 1748 UTC. Without a time series of MODIS Land Surface Temperature product images, it is difficult to gauge the exact amount of surface cooling brought about within the shadow of totality. A large-scale high resolution Terra MODIS Visible image is available here (courtesy of Liam Gumley, SSEC).

Suomi NPP VIIRS Visible (0.64 µm), Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images [click to enlarge]

Suomi NPP VIIRS Visible (0.64 µm), Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images [click to enlarge]

A comparison of Suomi NPP VIIRS Visible (0.64 µm), Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images (above) showed the shadow center over eastern Tennessee around 1833 UTC. A closer comparison of Day/Night Band and Infrared images (below) revealed the  presence of cloud features that made it difficult to see a signature of any city lights that may have come on in the Nashville TN (KBNA) metropolitan area.

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

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

Canadian wildfire smoke over Quebec, Maine and the Canadian Maritimes

August 17th, 2017 |

GOES-16 Visible (0.64 µm, top) and Cirrus (1.37 µm, bottom) images [click to play MP4 animation]

GOES-16 Visible (0.64 µm, top) and Cirrus (1.37 µm, bottom) images [click to play MP4 animation]

* GOES-16 data posted on this page are preliminary, non-operational and are undergoing testing *

Filaments of smoke aloft from Canadian wildfires were evident in GOES-16 “Red” Visible (0.64 µm) and Cirrus (1.37 µm) imagery (above; also available as a 24 Mbyte animated GIF) on 17 August 2017, drifting cyclonically eastward over Quebec, Maine and the Canadian Maritimes. The appearance of the smoke signature on Cirrus images was due to the fact that this spectral band is useful for detecting features composed of particles that are efficient scatterers of light (such as cirrus cloud ice crystals, airborne dust or volcanic ash, and in this case, smoke).

A comparison of GOES-16 “Clean” Infrared Window (10.3 µm) and Cirrus (1.37 µm) images (below; also available as a 21 Mbyte animated GIF) demonstrated that no smoke signature was seen on the infrared images (since smoke is effectively transparent at infrared wavelengths).

GOES-16 Infrared Window (10.3 µm, top) and Cirrus (1.37 µm, bottom) images [click to play MP4 animation]

GOES-16 Infrared Window (10.3 µm, top) and Cirrus (1.37 µm, bottom) images [click to play MP4 animation]

A more upstream view of the smoke feature was provided by a comparison of  Terra MODIS Visible (0.65 µm), Cirrus (1.375 µm) and Infrared Window (11.0 µm) images at 1626 UTC (below). Again, note the lack of a smoke signature in the Infrared image.

Terra MODIS Visible (0.65 µm), Cirrus (1.375 µm) and Infrared Window (11.0 µm) images [click to enlarge]

Terra MODIS Visible (0.65 µm), Cirrus (1.375 µm) and Infrared Window (11.0 µm) images [click to enlarge]

Depending on the altitude of these smoke filament features, daily composites of  Suomi NPP VIIRS true-color images covering the 5-day period of 12 August17 August (below) suggest that their source was either widespread fires in the Northwest Territories, or intense fires in British Columbia (which included pyroCb that injected smoke to very high altitudes).

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

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