Icebreaking in Whitefish Bay on Lake Superior

March 24th, 2018 |

GOES-16 ABI Band 2 “Red” (0.64 µm) Visible imagery, 2202 UTC on 22 and 23 March 2018 (Click to enlarge)

Dan Miller, the Science and Operations Officer (SOO) in Duluth sent the imagery above. Constant icebreaking has been ongoing on Whitefish Bay prior to the opening of the SOO Locks this weekend. A faint black line representing open water is apparent in the 22 March imagery, and it’s even more apparent in the 23 March imagery.

A toggle below, from 24 March 2018, shows the Band 2 “Red” (0.64 µm) Visible and the Band 5 “Snow/Ice” (1.61 µm) Near-Infrared images. The open water is apparent in both images — dark in contrast to the white snow and lake ice in the visible, darker than the adjacent ice in the 1.61 µm. Recall that horizontal resolution in Band 2 is 0.5 km at the sub-satellite point (nadir), and in Band 5 it is 1 km.

GOES-16 ABI Band 2 “Red” (0.64 µm) Visible and Band 5 “Snow/Ice” (1.61 µm) near-infrared imagery, 2202 UTC on 22 and 23 March 2018 (Click to enlarge)

Suomi NPP and NOAA-20 also viewed the icebroken path on 24 March, and favorable orbit geometry for NOAA-20 and Suomi NPP on 24 March (orbit paths from this site) meant 2 sequential passes from both satellites both viewed Whitefish Bay. The 4 images are shown in an animation below, with imagery from NOAA-20 first, then Suomi NPP (the labels all say Suomi NPP erroneously). Note that NOAA-20 data are provisional, non-operational, and undergoing testing still).

VIIRS Visible (0.64 µm, I1) Imagery from NOAA-20 (1708, 1846 UTC) and Suomi-NPP (1756, 1937 UTC) on 24 March 2018 (Click to enlarge)

The break in the ice was also visible in Day Night Band Imagery from VIIRS at 0722 UTC (from NOAA-20) on 24 March 2018.  It is also apparent in the shortwave Infrared imagery from both GOES-16 (very subtly) and from VIIRS (which offers better spatial resolution).

The icebreaking track was also apparent on 250-meter resolution Terra MODIS True-color and False-color Red-Green-Blue (RGB) images from the MODIS Today site (below). In the False-color image, ice and snow (in areas of sparse vegetation) show up as shades of cyan.

Terra MODIS True-color and False-color RGB images [click to enlarge]

Terra MODIS True-color and False-color RGB images [click to enlarge]

Fires over the Texas Panhandle

March 23rd, 2018 |

GOES-16 ABI Shortwave Infrared imagery (3.9 µm), 1905-2058 UTC on 23 March 2018 (Click to animate)

The Storm Prediction Center issued an Extreme Fire Weather advisory for 23 March 2018, and a GOES-16 Mesoscale Sector (#2, from this site) was positioned over the High Plains of Texas to monitor.

The GOES-16 Shortwave Infrared imagery, above, from 1905-2058 UTC on 23 March 2018 shows rapid warming of pixels near Borger TX (KBGD), and then southeast of Borger and northeast of Amarillo (KAMA). Surface observations show gusty southwest winds and low dewpoints, ideal for fire. Under the cirrus shield to the south, decreased solar insolation meant less vertical mixing of dry air and high winds, so dewpoints were higher and winds were weaker, lessening the fire danger.

Note that missing pixels are apparent in the GOES-16 Shortwave IR imagery around 2010 UTC. Quality flags that highlight the extreme warmth of the pixel have been activated, and AWIPS data are reported as missing in those locations.

Visible imagery, both Band 1 (“Blue” Visible, 0.47 µm) and Band 2 (“Red” Visible, 0.64 µm) from the GOES-16 ABI, below, show visible smoke plumes starting around 1940 UTC for the fire near Borger, and closer to 2000 UTC for the fire southeast of Borger. The plumes appear in both visible bands at approximately the same time, although they are more distinct in the blue band because of the enhanced scattering in the atmosphere at that wavelength.

GOES-16 ABI “Blue” Visible imagery (0.47 µm), 1905-2058 UTC on 23 March 2018 (Click to animate)

GOES-16 ABI “Red” Visible imagery (0.64 µm), 1905-2058 UTC on 23 March 2018 (Click to animate)

A qualitative method of identifying fires is the Fire RGB that combines the shortwave IR (3.9 µm, the red component of the RGB) with the 2.2 µm (Green) and 1.6 µm (Blue) reflectance channels. As fires become progressively hotter, they emit more and more radiation at shorter wavelengths that can be detected by the ABI on GOES-16, and this alters the color of the RGB over the fire. The Fire RGB animation is shown below. When the 3.9 µm imagery is missing from AWIPS (2005 UTC, 2007-2011 UTC, 2015 UTC because the pixels are hot enough that quality control flags are activated, so the data are not shown), the red pixels in the Fire RGB turn green because no Red component is present (Click here to see the Fire RGB and Shortwave IR animated 2004-2016 UTC).

GOES-16 ABI Fire RGB imagery (3.9 µm, 2.2 µm, 1.6 µm), 1905-2058 UTC on 23 March 2018 (Click to animate)

There are Baseline products that allow a quantitative estimate of fire properties. The animation below shows the Mesoscale Domain Band 7 Shortwave Infrared (3.9 µm) imagery zoomed in over the Texas Panhandle, at 1-minute time-steps; superimposed on the imagery are the GOES-16 Fire Detection Fire Temperature pixels. Fire Products at present are not produced over Mesoscale Domains, so CONUS-scale Fire Products (produced every 5 minutes) are shown instead. The Fire Temperature product in this case has a signal before an obvious signal is present in the 3.9 µm signal — although that could be a function of the 3.9 µm enhancement used here.

An observant reader will notice that the pixels in the GOES-16 Fire Product do not align with the GOES-16 3.9 µm pixels. This is because of the double remapping in the GOES-16 ABI Bands that occurs at NESDIS before data are sent to AWIPS. The Baseline product is not doubly remapped at NESDIS. (This double remapping is being removed from the processing stream shortly).

GOES-16 ABI Shortwave Infrared imagery (3.9 µm), shown every minute, and the GOES-16 Fire Temperature Baseline Product, shown every 5 minutes, 1905-2014 UTC on 23 March 2018 (Click to animate)

This animation (from Pete Wolf, SOO in Jacksonville FL), shows a fast-moving fire in the Fire RGB a bit later.  The animation is from the CIRA Slider, similar to this link that shows an animation from 2045 UTC on 23 March to 0045 on 24 March.


Cyclone Marcus west of Australia and south of Java

March 22nd, 2018 |

Himawari-8 AHI Band 13 (10.4 µm) infrared imagery, 0900-1540 UTC on 22 March 2018 (Click to animate)

NOAA-20 Imagery shown in this post is Non-Operational and preliminary and undergoing testing.

Himawari-8 captured the slow southward progress of Cyclone Marcus along 105 E Longitude between 0900 and 1540 UTC, as shown above.  During those six hours, the storm presentation suggested weakening, with a reduction in the central dense overcast and a warming of the eye.

Earlier, on 21 March at around 1800 UTC, the storm was at Category 5 Intensity on the Saffir-Simpson scale, and showed excellent presentation in the Day Night Band imagery, despite the lack of lunar illumination, and in the infrared (Click here for a toggle between the 0.70 µm Day Night Band Visible imagery and the 11.45 µm infrared imagery from Suomi NPP).  Significant Mesospheric Gravity Waves are apparent in all three images, the first (1710 UTC 21 March) and last (1850 UTC 21 March) from NOAA-20, and the middle (1800 UTC 21 March) from Suomi NPP.  (The waves are most prominent in the 1710 UTC Image from NOAA-20) The figure shows how Suomi NPP and NOAA-20 data can be used to create animations. A similar animation with Infrared Imagery (1710, 1800, and 1850 UTC) is below. (Suomi NPP and NOAA-20 Imagery courtesy Will Straka, CIMSS).

VIIRS Day Night Band Visible (0.70 µm) Imagery at 1710 UTC (from NOAA-20), 1800 UTC (from Suomi NPP), and from 1850 UTC (from NOAA-20) (Click to enlarge)

VIIRS Day Infrared (11.45 µm) Imagery at 1710 UTC (from NOAA-20), 1800 UTC (from Suomi NPP), and from 1850 UTC (from NOAA-20) (Click to enlarge)

Morphed microwave imagery for the 48 hours ending at about 1300 UTC on 22 March (from this site) show the evolution of the strong convection surrounding Marcus.  Eyewall convection has diminished on 22 March.

Morphed Microwave imagery centered on Cyclone Marcus for the 48 hours ending 1300 UTC on 22 March 2018 (Click to enlarge)

Added: Suomi NPP and NOAA-20 also observe the atmosphere at Microwave wavelengths using ATMS (The Advanced Technology Microwave Sounder). This toggle (created using McIDAS-V and data from the NOAA CLASS system) shows the 31 and 88 Ghz observations with the 11.45 VIIRS observations of the eye of Marcus at 1757 UTC on 21 March. The same brightness temperature enhancement is used for each image. Note that each observation shows a slightly different center location for the storm.

Early Spring Nor’easter over the eastern United States

March 21st, 2018 |

NOAA-20 VIIRS Day Night Band Visible (0.70 µm) and I05 Infrared (11.45 µm) Imagery, 0645 UTC 21 March 2018 (Click to enlarge)

NOAA-20 Imagery shown in this post is Non-Operational and preliminary and undergoing testing.

The imagery above shows a toggle between the Day Night Band Visible (0.70 µm) Imagery and the I05 Infrared (11.45 µm) Imagery on NOAA-20. The strong nor’easter affecting the East Coast of the United States is apparent in the imagery. Strong convection over the warm water south of the Gulf Stream to the east of the Carolinas is apparent in cold cloud tops in the infrared, and in lightning streaks in the Day Night Band imagery. The waxing crescent moon at the time was below the horizon; Earthglow is thus the primary illumination source for the clouds over the ocean. Over land, city lights are apparent, even through the thick precipitating clouds associated with the storm.

Additionally, the fine spatial resolution in the Infrared imagery allows for the identification of cloud-top gravity wave features in the warm conveyor belt over eastern Pennsylvania and New York, and also elsewhere.

Microwave imagery from Suomi NPP can be used to estimate rain rate (Here’s the OSPO site that shows this product from NOAA-18 and -19, and also Metop A and B; the Operational Blended Rain Rate product is here). The Real Earth image below shows Rain Rate from Suomi NPP ATMS data as calculated from the Direct Broadcast signal in Madison, WI; the entire system is not quite captured from the antenna in Madison, WI. Data that are used to compute the Rain Rate include 90 Ghz, shown here (also from Real Earth).  The heavy precipitation with the convection over the Atlantic is readily apparent.  Precipitation with this system extends back into Indiana!

Rain Rate computed from ATMS on Suomi NPP early morning passes, 21 March 2018 (Click to enlarge)

GOES-16 captured the temporal evolution of this storm. The animation of low-level water vapor (7.34) infrared imagery, below, shows a well-developed warm conveyor belt well to the east of an upper level feature that is wobbling westward over northern Kentucky. A second upper-level circulation develops northern Virginia and is obvious over West Virginia at the end of the animation. Strong subsidence can be inferred behind the storm as well, where the yellows/oranges appear in this water vapor enhancement, suggesting brightness temperatures around -10ºC. Very dry air is apparent north of the storm: The St Lawrence River is visible in the water vapor animation!

GOES-16 Low-Level Water Vapor Infrared (7.34 µm) animation, 0107 – 1622 UTC (Click to play 110 Mb animation)