Hurricane Matthew and the Day/Night Band

October 2nd, 2016 |
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Day/Night Band Visible Imagery (0.70 µm) from VIIRS on Suomi NPP, 0643 UTC on 1 October (Click to enlarge)

The Day/Night Band is a component of the VIIRS Instrument on board Suomi NPP, and it allows for satellite views in the visible portion of the electromagnetic spectrum at night. The nighttime light source is the Moon (if it is above the horizon), or airglow if not (or if the Moon is new). When Suomi NPP overflew Matthew early in the morning on 1 and 2 October, shortly after the New Moon (on 30 September), only airglow was illuminating the storm. Those images are shown above (for 1 October 2016) and below (for 2 October 2016). This imagery was produced using Polar2Grid software that is part of the CSPP Package using data received at a direct broadcast site (in this case, Miami).

There are striking mesospheric airglow gravity waves evident to the east and north of the center on 1 October, at which time Matthew was a Category 5 storm on the Saffir-Simpson scale, having undergone remarkable intensification during the previous 24 hours. On October 2, the gravity waves are not quite so apparent (at this time, the storm was a Category 4 storm). Are the gravity waves a response to the strong intensification?

Lightning streaks are present to the east of the center, within the cluster of deep convection east of Matthew, in both images. City lights on the islands of the Greater Antilles, and over the South American landmass, are also apparent. Haiti is notable for its minimal signature of city lights.

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Day/Night Band Visible Imagery (0.70 µm) from VIIRS on Suomi NPP, 0624 UTC on 2 October (Click to enlarge)

Matthew is forecast to affect Jamaica, eastern Cuba and Haiti on Monday and Tuesday, 3 and 4 October. Consult the website of the National Hurricane Center for more information.

Day/Night Band imagery will be available from JPSS-1, scheduled for launch no earlier than March 2017. After its launch, both Suomi NPP and JPSS-1 will provide Day/Night Band imagery. JPSS-2, -3 and -4 (scheduled for launch in 2021, 2026 and 2031, respectively), will also have a Day/Night Band capability. There are currently no plans for a geostationary Day/Night Band capability (In particular, GOES-R does not have a Day/Night Band).

======================== Added, 3 October =======================
The Day/Night Band image from early on 3 October, below, also shows evidence of gravity waves that are perturbing the airglow, and of lightning in the convective complex well east of the center of Matthew.

Day/Night Band Visible Imagery (0.70 µm) from VIIRS on Suomi NPP, 0605 UTC on 3 October (Click to enlarge)

Shown below is the same VIIRS Day/Night Band image, as viewed using AWIPS II with data received by the Puerto Rico ground station.

Suomi NPP VIIRS Day/Night Band (0.70 µm) image [Click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.70 µm) image [Click to enlarge]

======================== Added, 4 October =======================
The Day/Night Band early on 4 October continues to show gravity waves in the airglow. Note how city lights in Haiti are mostly absent in this image. This could be due to attenuation by the rain in the hurricane bands, or it could be due to infrastructure failure (or both).

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Day/Night Band Visible Imagery (0.70 µm) from VIIRS on Suomi NPP at 0550 UTC on 4 October (Click to enlarge)

======================== Added, 5 October =======================
Here is the storm-centered Day/Night Band image for 5 October (also shown below). The ragged center of Matthew is barely visible over the water north of eastern Cuba. Haiti continues to show no man-made light sources. Parts of western Dominican Republic also show no lights. In both places, thick clouds and heavy rain may be the reason.

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Day/Night Band Visible Imagery (0.70 µm) from VIIRS on Suomi NPP at 0711 UTC on 5 October (Click to enlarge)

======================== Added, 5 October =======================
The image from 6 October is here, with a different version shown below. The center of Matthew is apparent east of the island of Andros in the Bahamas. Note that city lights have returned to Port-au-Prince, Haiti (station MTPP), but they’ve vanished from several Bahama islands. In the zoomed-out version of the Day/Night Band that includes the United States, increased illumination is apparent over the western Gulf of Mexico. The Moon is starting to appear near the horizon during NPP’s overpass; increased illumination in these images should be the result in the next couple days.

Day/Night Band Visible Imagery (0.70 µm) from VIIRS on Suomi NPP at 0652 UTC on 5 October (Click to enlarge)

At 0633 UTC on 7 October, Matthew was located east of the Atlantic coast of Florida. Lightning streaks are apparent well to the east of the center. This Day/Night Band image centered over Haiti shows that electricity has been restored to most of the island.

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Day/Night Band Visible Imagery (0.70 µm) from VIIRS on Suomi NPP at 0633 UTC on 7 October (Click to enlarge)

Christmas Full Moon Day/Night Band images

December 25th, 2015 |

Suomi NPP VIIRS Day/Night Band image swaths [click to enlarge]

Suomi NPP VIIRS Day/Night Band image swaths [click to enlarge]

A rare Full Moon on Christmas — the last occurrence was in 1977, and the next will be in 2034 — was reached at 1111 UTC, and provided some compelling “visible images at night” from the Suomi NPP VIIRS 0.7 µm Day/Night Band (DNB). The animation above shows the coverage of 4 consecutive DNB image swaths across much of North America, as viewed using RealEarth.

Taking a closer look at various regions and features, we will begin with the Northeast US at 0610 UTC (below). One item of interest was the narrow fingers of valley fog that were forming in parts of Pennsylvania and New York, where strong radiational cooling under cloud-free skies was allowing the surface air temperatures to cool into the 30s and 40s F.

Suomi NPP VIIRS 0.7 µm Day/Night Band image centered over the Northeast US [click to enlarge]

Suomi NPP VIIRS 0.7 µm Day/Night Band image centered over the Northeast US [click to enlarge]

Over the Southeast US at 0749 UTC (below), ample illumination by the Full Moon provided a very detailed nighttime view of the tops of numerous thunderstorms that had developed along and ahead of a cold frontal boundary (surface analysis). Note the appearance of several bright white areas at the tops of some thunderstorms, a signature of cloud illumination by intense lightning activity. In addition, temperatures ahead of the cold front were unusually warm for 25 December — for example, new records for the warmest low temperature for the date were set at both Mobile, Alabama and Pensacola, Florida (with 75º F and 71º F, respectively).

Suomi NPP VIIRS Day/Night Band image centered over the Southeast US [click to enlarge]

Suomi NPP VIIRS Day/Night Band image centered over the Southeast US [click to enlarge]

Farther to the north, a DNB image centered over South Dakota (below) showed a great deal of variability in snow cover across that area; the effect of deeper snow cover on surface air temperatures could also be seen in the surface observations at that time, with the colder readings generally coinciding with sites having snow on the ground.

Suomi NPP VIIRS Day/Night Band image centered over South Dakota [click to enlarge]

Suomi NPP VIIRS Day/Night Band image centered over South Dakota [click to enlarge]

Even farther to the north, it could be seen that ice covered a significant portion of Hudson Bay, Canada (below). In southern parts of Hudson Bay where open water still existed, numerous “lake effect” cloud bands could be seen due the northwesterly flow of very cold arctic air across the water.

Suomi NPP VIIRS Day/Night Band image centered over Hudson Bay, Canada [click to enlarge]

Suomi NPP VIIRS Day/Night Band image centered over Hudson Bay, Canada [click to enlarge]

A DNB image centered over the Western US at 0930 UTC (below) revealed features such as snow pack over the higher terrain of the Sierra Nevada in California (where temperatures at the time ranged from 55º F in the desert at Needles KEED to 1º F in the mountains at South Lake Tahoe KTVL), and a variety of open-cell and closed-cell convection over the adjacent offshore waters of the Pacific Ocean.

Suomi NPP VIIRS Day/Night Band image centered over the western US [click to enlarge]

Suomi NPP VIIRS Day/Night Band image centered over the western US [click to enlarge]

Finally, a DNB image centered over Alaska and the Yukon Territory of Canada at 1111 UTC (below) showed widespread snow cover over the cloud-free interior regions, with the thick cloud shield from a Gulf of Alaska storm moving over southwestern and southcentral Alaska. Very cold surface air temperatures at or below -30º F could be seen at a number of sites in the interior areas, with -42º F being reported at the time in Arctic Village, Alaska PARC (their minimum temperature later dropped to -45º F).

Suomi NPP VIIRS Day/Night Band image centered over Alaska and the Yukon Territory [click to enlarge]

Suomi NPP VIIRS Day/Night Band image centered over Alaska and the Yukon Territory [click to enlarge]

Aurora Borealis as seen by VIIRS Day/Night Band imagery

September 9th, 2015 |
Aurora Forecast issued by the Space Weather Prediction Center

Aurora Forecast issued by the Space Weather Prediction Center

The Aurora Forecast shown above was issued on the night of 08 September 2015 by the NOAA Space Weather Prediction Center, with the accompanying text:

Following the G2 (moderate) geomagnetic storms from last night, observations of the solar wind at the ACE spacecraft near L1 indicate the potential again this evening for more activity. G1 (minor) conditions have already been observed by the global network of ground-based near real-time magnetometers. A forecast warning for G2 has been issue from 09/0500 – 09/1000 UTC (1am to 6am EST). These could be some prime hours to possibly see the Aurora in the northern most regions of the lower 48 states.

Suomi NPP VIIRS Day/Night Band (0.7 µm) image composite [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.7 µm) image composite [click to enlarge]

A composite of Suomi NPP VIIRS Day/Night Band (0.7 µm) images viewed using the SSEC RealEarth web map server (above) showed the bright and complex signature of the aurora borealis across southern Canada and the northern United States during the subsequent nighttime hours. Two of the individual Day/Night Band image swaths as viewed using AWIPS-2 are shown below.

Suomi NPP VIIRS Day/Night Band (0.7 µm) image at 0756 UTC [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.7 µm) image at 0756 UTC [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.7 µm) image at 0939 UTC [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.7 µm) image at 0939 UTC [click to enlarge]

Smoke and Fog in the VIIRS Day/Night Band

July 2nd, 2015 |
Suomi NPP VIIRS 0.70 µm visible Day/Night Band and 11.45 µm - 3.74 µm Brightness Temperature Difference images, and Ceilings and Visibilities, ~0800 UTC (click to enlarge)

Suomi NPP VIIRS 0.70 µm visible Day/Night Band and 11.45 µm – 3.74 µm IR Brightness Temperature Difference images, and Ceilings and Visibilities, ~0800 UTC (click to enlarge)

July’s first Full Moon occurred at 0219 UTC on 2 July (a second full moon occurs later this month on 31 July). Strong illumination from the moon showed river valley fog in several tributaries of the Mississippi River (for example, the Wisconsin River in southwest Wisconsin; the Upper Iowa River in Iowa) across the Upper Midwest. The Suomi NPP VIIRS Day/Night Band also shows a plume of Canadian wildfire smoke aloft, stretching from central Iowa northwestward to western Minnesota. This smoke (visible on 1 July in Aqua true-color imagery from the MODIS Today site) is not apparent in the IR Brightness Temperature Difference field, although the river valley fog certainly is. Smoke is transparent to most infrared channels and detection at night is very difficult if visible information such as that provided by the Day/Night Band is not present.

The VIIRS Day/Night Band also enabled detection of the dense plume of Canadian wildfire smoke as it moved off the US East Coast and over the adjacent offshore waters of the western Atlantic Ocean at 0614 UTC  (below). Again, note that the smoke aloft does not exhibit a signature on the corresponding VIIRS Infrared imagery.

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

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