Vog plume streaming off the island of Hawaii

January 10th, 2013 |
Suomi NPP VIIRS 0.64 µm visible channel, 3.74 µm shortwave IR channel, and 11.45 µm IR channel images

Suomi NPP VIIRS 0.64 µm visible channel, 3.74 µm shortwave IR channel, and 11.45 µm IR channel images

A comparison of AWIPS images of Suomi NPP VIIRS 0.64 µm visible channel, 3.74 µm shortwave IR channel, and 11.45 µm IR channel data (above) showed a broad “vog” plume streaming westward off the Big Island of Hawaii on 10 January 2013. The primary source of this vog plume was likely the active Kilauea volcano — and the 3.64 µm shortwave IR image revealed a small “hot spot” at the summit of the volcano, which exhibited a brightness temperature value of 49.5º C (orange color enhancement).

The VIIRS 0.64 µm visible channel image with an overlay of 1-hour interval MADIS atmospheric motion vectors (or “satellite cloud-tracked winds”) showed the typical easterly trade wind flow regime that usually transports the vog plume westward away from the Hawaiian Islands (below). However, synoptic-scale disturbances that disrupt this trade wind flow can cause the vog plume to move over inhabitied portions of the islands, causing air quality problems.

Suomi NPP VIIRS 0.64 µm visible channel image + MADIS 1-hour interval atmospheric motion vectors

Suomi NPP VIIRS 0.64 µm visible channel image + MADIS 1-hour interval atmospheric motion vectors

Other examples of Hawaiian vog plumes can be found here on the CIMSS Satellite Blog.

Hawaiian “vog” plume

January 1st, 2010 |
GOES-11 and GOES-14 visible channel images

GOES-11 and GOES-14 visible channel images

McIDAS images of GOES-11 and GOES-14 visible channel data (above) revealed a large hazy plume streaming northeastward from the Hawaiian Islands on 31 December 2009 – 01 January 2010. The primary source of this plume was ongoing emissions from the Kilauea volcano on “The Big Island” of Hawaii — the resulting “vog” (volcanic smog) is air pollution that forms when sulfur dioxide and other gases/particles emitted by an erupting volcano react with oxygen and moisture in the presence of sunlight. On 31 December the haze was reducing visibility to 5 miles at Lahaina on Maui island.

This GOES-11 vs GOES-14 visible image comparison helps to highlight two important points: (1) due to a more favorable “forward scattering” geometry with GOES-14 positioned at 105º West longitude, the extent of the “vog” plume shows up with greater clarity on GOES-14 images later in the day compared to GOES-11 (positioned at 135º West longitude), and (2) the performance of the GOES visible channel detectors degrades over time, so the much older GOES-11 (launched in 2000) visible imagery appears significantly darker (the enhancement of the images is the same). GOES-14 (launched in 2009) was emulating GOES-West during the final days of its NOAA Science Test.

Under typical conditions, the dominant northeasterly trade winds act to advect the plume of “vog” toward the southwest — but in this case, an AWIPS image of the GOES-11 IR channel with an overlay of ASCAT scatterometer winds (below) showed that there was a southwesterly flow in advance of an approaching cold front.

GOES-11 IR image + ASCAT scatterometer winds

GOES-11 IR image + ASCAT scatterometer winds

An image of the Aura satellite Ozone Measuring Instrument (OMI) Total Column Sulphur Dioxide (SO2) product (below; courtesy of NOAA/NESDIS) confirms that elevated levels of SO2 were present within the “vog” plume seen on GOES visible imagery.

OMI SO2 product (courtesy of NOAA/NESDIS)

OMI SO2 product (courtesy of NOAA/NESDIS)

Lava flow from Kilauea in Hawai’i

June 6th, 2018 |

GOES-15 Shortwave Infrared (3.9 µm) images, with hourly plots of surface reports [click to play MP4 animation]

GOES-15 Shortwave Infrared (3.9 µm) images, with hourly plots of surface reports [click to play MP4 animation]

The Kilauea volcano on the Big Island of Hawai’i continued to be active into early June 2018 — and GOES-15 (GOES-West) Shortwave Infrared (3.9 µm) imagery (above) showed the thermal anomaly or “hot spot” (black to yellow to red enhancement) associated with lava flows from active fissures in the East Rift Zone on 06 June.

GOES-15 Visible (0.63 µm) images (below) showed clouds of steam from the East Rift Zone drifting to the south-southwest; a hazy plume of volcanic fog or “vog” was also evident, which was being transported farther to the southwest by the northeasterly trade wind flow.

GOES-15 Visible (0.63 µm) images, with hourly plots of surface reports [click to play MP4 animation]

GOES-15 Visible (0.63 µm) images, with hourly plots of surface reports [click to play MP4 animation]

A Suomi NPP VIIRS Visible (0.64 µm) image at 2307 UTC (below) showed clear skies over Kapoho on the eastern tip of the Big Island, with steam plumes from the active East Rift Zone fissures flowing southwestward.

Suomi NPP VIIRS Visible (0.64 µm) image [click to enlarge]

Suomi NPP VIIRS Visible (0.64 µm) image [click to enlarge]

The corresponding VIIRS Shortwave Infrared (3.74 µm) image (below) helped to discriminate between the hot brightness temperatures of recent (and old) lava flows and the cooler brightness temperatures exhibited by regions of vegetation.

Suomi NPP VIIRS Shortwave Infrared (3.74 µm) image [click to enlarge]

Suomi NPP VIIRS Shortwave Infrared (3.74 µm) image [click to enlarge]

A closer look at the Kilauea East Rift Zone (below) provided a detailed view of the recent lava flow and active fissures, including the lava field that entered and covered Kapoho Bay a few days earlier. Note the appearance of numerous multi-colored pixels in the center of the lava field — the 3.74 µm I04 band detectors on the VIIRS instrument saturate around 385 K, so the hottest lava features which exceeded that brightness temperature threshold ended up being displayed as cold pixels (the so-called “wrap-around” effect). There is a Moderate-resolution M13 band (4.05 µm) on VIIRS which saturates at a much hotter 700 K; while it is a lower spatial resolution (750 meters, vs 375 meters for the I04 band), the M13 band can be useful for sampling the actual temperature of very hot features such as lava flows or wildfires.

Suomi NPP VIIRS Shortwave Infrared (3.74 µm) image [click to enlarge]

Suomi NPP VIIRS Shortwave Infrared (3.74 µm) image [click to enlarge]

Thanks to Jordan Gerth (CIMSS) and Eric Lau (NWS Pacific Region Headquarters) for providing the VIIRS imagery for this case.

Update: This link shows Landsat-8 and Sentinel-2 imagery before and after the Kapoho Bay lava flow.

Minor explosive eruption of Kilauea in Hawai’i

May 19th, 2018 |

Himawari-8 Ash Cloud Height product {click to play animation]

Himawari-8 Ash Cloud Height product [click to play animation]

An explosive eruption from the Halema’uma’u crater at the Kilauea summit on the Big Island of Hawai’i occurred around 1550 UTC on 19 May 2018. Using Himawari-8 data, multispectral retrievals of parameters such as Ash Cloud Height (above) and Ash Loading (below) from the NOAA/CIMSS Volcanic Cloud Monitoring site helped to characterize the volcanic ash plume.

Himawari-8 Ash Loading product [click to play animation]

Himawari-8 Ash Loading product [click to play animation]

Later in the day, a Suomi NPP VIIRS True-color Red-Green-Blue (RGB) image viewed using RealEarth (below) showed the hazy signature of volcanic smog or “vog” which had spread out to the south, southwest and west of the Big Island. Light amounts of ash fall were reported downwind of Kilauea.

Suomi NPP VIIRS True-color RGB image [click to enlarge]

Suomi NPP VIIRS True-color RGB image [click to enlarge]