Strong jet stream over the North Pacific Ocean

January 2nd, 2019 |
GOES-17 Mid-level Water Vapor (6.9 µm) images, with 250 hPa wind isotachs [click to play animation | MP4]

GOES-17 Mid-level Water Vapor (6.9 µm) images, with 250 hPa wind isotachs [click to play animation | MP4]

* GOES-17 images shown here are preliminary and non-operational *

GOES-17 Mid-level Water Vapor (6.9 µm) images with an overlay of 250 hPa wind isotachs from the GFS90 model (above) showed a string of disturbances (surface analysis) along the axis of a 180-knot “Japan Jet” across the North Pacific Ocean on 02 January 2019.

GOES-17 Split Ozone (9.6 µm10.3 µm) Brightness Temperature Difference images (below) include an overlay of PV1.5 pressure (an indicator of the height of the “dynamic tropopause”) — they showed the difference between cold polar air having a low tropopause (shades of cyan to blue) north of the jet stream and warm tropical air having a much higher tropopause (shades of yellow). The Split Ozone BTD is the Green component of the Air Mass Red-Green-Blue (RGB) product.

GOES-17 Split Ozone (9.6 - 10.3 µm) images, with contours of PV1.5 pressure [click to play animation | MP4]

GOES-17 Split Ozone (9.6 – 10.3 µm) images, with contours of PV1.5 pressure [click to play animation | MP4]

Rawinsonde data also showed the significant difference in tropopause height between St. Paul Island, Alaska (pressure=314 hPa, height=8.1 km) in the polar air of the Bering Sea and Lihue, Hawai’i (pressure=82 hPa, height=17.9 km) in the tropical air of the central Pacific (below).

Plots of rawinsonde data from St. Paul Island, Alaska [click to enlarge]

Plots of rawinsonde data from St. Paul Island, Alaska [click to enlarge]

Plots of rawinsonde data from Lihue, Hawai'i [click to enlarge]

Plots of rawinsonde data from Lihue, Hawai’i [click to enlarge]

GOES-17 Air Mass RGB images from the UW-AOS site (below) further illustrated the sharp contrast between the cold/dry polar air to the north and warm/moist tropical air to the south of the strong jet stream. The purple hues along the northwestern edge of the scan are a result of the “limb cooling” effect, as the satellite’s infrared detectors sense radiation from colder upper levels of the atmosphere at large viewing angles.

GOES-17 Air Mass RGB images [click to play animation | MP4]

GOES-17 Air Mass RGB images [click to play animation | MP4]

In addition to the series of larger disturbances along the jet stream axis, there were also some smaller-scale storms apparent in the Bering Sea (surface analyses). Better detail of these high-latitude features could be seen using Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images separated by 10 hours (below).

Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images at 1427 UTC and 0022 UTC [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images at 1427 UTC and 0022 UTC [click to enlarge]

Regarding the strong Japan Jet, GOES-15 (GOES-West) Derived Motion Winds (source) tracked targets having velocities as high as 200 knots at 03 UTC (below).

GOES-15 Water Vapor (6.5 µm) Derived Motion Winds [click to enlarge]

GOES-15 Water Vapor (6.5 µm) Derived Motion Winds [click to enlarge]

Eruption of Mount Etna in Italy

December 24th, 2018 |

VIIRS True Color RGB images from NOAA-20 (at 1110 and 1220 UTC) and Suomi NPP (at 1200 UTC) [click to enlarge]

VIIRS True Color RGB images from NOAA-20 (at 1110 and 1220 UTC) and Suomi NPP (at 1154 UTC) [click to enlarge]

A sequence of VIIRS True Color Red-Green-Blue (RGB) images from NOAA-20 and Suomi NPP viewed using RealEarth (above) showed the volcanic ash plume from an eruption of Mount Etna in Italy on 24 December 2018.

A toggle between NOAA-20 VIIRS True Color RGB and Infrared Window (11.45 µm) images (below) revealed a colder cloud plume at higher altitude along the southern edge of the tan/brown volcanic ash plume. A thermal anomaly or “hot spot” (dark black pixels) could be seen at the snow-covered volcano summit.

NOAA-20 VIIRS True Color RGB and Infrared Window (11.45 µm) images at 1250 UTC [click to enlarge]

NOAA-20 VIIRS True Color RGB and Infrared Window (11.45 µm) images at 1250 UTC [click to enlarge]

The volcanic plume could be quantitatively analyzed using Suomi NPP VIIRS Ash Probability, Ash Height, Ash Loading and Ash Effective Radius products from the NOAA/CIMSS Volcanic Cloud Monitoring site at 1154 UTC (below).

Suomi NPP VIIRS Ash Probability, Ash Height, Ash Loading and Ash Effective Radius at 1154 UTC [click to play enlarge]

Suomi NPP VIIRS Ash Probability, Ash Height, Ash Loading and Ash Effective Radius at 1154 UTC [click to play enlarge]

Since the bulk of the volcanic plume was high in ash content with minimal water or ice cloud, a good signature was seen using Meteosat-11 Split Window (11-12 µm) Brightness Temperature Difference images (below).

Meteosat-11 Split Window (11.12 µm) Brightness Temperature Difference images [click to play animation]

Meteosat-11 Split Window (11.12 µm) Brightness Temperature Difference images [click to play animation]

Eruption of the Anak Krakatau volcano in Indonesia

December 22nd, 2018 |

Himawari-8

Himawari-8 “Clean” Infrared Window (10.4 µm) images, with hourly plots of surface reports from Jakarta (station identifier WIII) [click to play animation | MP4]

Himawari-8 “Clean” Infrared Window (10.4 µm) images (above) showed the volcanic cloud from an eruption of Anak Krakatau in Indonesia on 22 December 2018. Two distinct pulses were evident: the first began around 1340 UTC, with the second starting around 1520 UTC. At times the cloud-top infrared brightness temperatures were -80ºC or colder (violet enhancement) — which roughly corresponded to altitudes around 15-16 km on rawinsonde data from nearby Jakarta (WIII) (below). The eruption process appears to have played a role in generating a tsunami that was responsible for over 400 fatalities — via a partial collapse of the southern flank of the volcano which then triggered an undersea landslide (visualization).

Plots of rawinsonde data from Jakarta, Indonesia [click to enlarge]

Plots of rawinsonde data from Jakarta, Indonesia [click to enlarge]

After sunrise, the volcanic cloud was evident in Himawari-8 “Red” Visible (0.64 µm) images (below) — a toggle between Visible and Infrared images at 0110 UTC showed an example of one of the cold overshooting tops.

Himawari-8 "Red" Visible (0.64 µm) images. with hourly plots of surface reports [click to play animation | MP4]

Himawari-8 “Red” Visible (0.64 µm) images, with hourly plots of surface reports from Jakarta (station identifier WIII) [click to play animation | MP4]

At the onset of the eruption, multi-spectral retrievals from the NOAA/CIMSS Volcanic Cloud Monitoring site showed Ash Height values of 12-14 km and Ash Loading values of 9-10 g/m2 (below). However, after about 1.5 hours the extremely high water and ice content of the volcanic cloud prevented further retrievals of such parameters.

Himawari-8 Ash Height retrievals [click to play animation]

Himawari-8 Ash Height retrievals [click to play animation]

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

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

A toggle between NOAA-20 VIIRS True Color Red-Green-Blue (RGB) and Infrared Window (11.45 µm) images viewed using RealEarth (below) showed the volcanic cloud at 0610 UTC on 23 December.

NOAA-20 VIIRS True Color RGB and Infrared Window (11.45 µm) images at 0610 UTC [click to enlarge]

NOAA-20 VIIRS True Color RGB and Infrared Window (11.45 µm) images at 0610 UTC [click to enlarge]

A comparison of Infrared Window images from NOAA-20 VIIRS (11.45 µm) and Himawari-8 AHI (10.4 µm) at 0610 UTC (below) demonstrated the advantage of improved spatial resolution — the minimum cloud-top infrared brightness temperature of the overshooting top feature was significantly colder on the 375-m resolution VIIRS image (-87ºC, darker shade of violet) than on the corresponding AHI image with 2-km resolution at satellite sub-point (-74.2ºC).

Infrared Window images from NOAA-20 VIIRS (11.45 µm) and Himawari-8 AHI (10.4 µm) [click to enlarge]

0610 UTC Infrared Window images from NOAA-20 VIIRS (11.45 µm) and Himawari-8 AHI (10.4 µm) [click to enlarge]

There was also a significant amount of lightning associated with this volcanic cloud:


A comparison of Himawari-8 Visible and Infrared images showed the persistent volcanic cloud following sunrise on 23 December (below). The pulsing overshooting tops continued to exhibit infrared brightness temperatures as cold as -80ºC at times.

Himawari-8

Himawari-8 “Red” Visible (0.64 µm, top) and “Clean” Infrared Window (10.4 µm, bottom) images [click to play animation | MP4]

===== 24 December Update =====

NOAA-20 VIIRS True Color RGB and Infrared Window (11.45 µm) images [click to enlarge]

NOAA-20 VIIRS True Color RGB and Infrared Window (11.45 µm) images [click to enlarge]

NOAA-20 VIIRS True Color RGB and Infrared Window (11.45 µm) images (above) provided a detailed view of the volcanic cloud at 0550 UTC on 24 December.

A long animation of Himawari-8 “Clean” Infrared Window (10.4 µm) images spanning over 48 hours from the onset of the eruption (below) showed the remarkably persistent volcanic cloud, with pulsing overshooting tops anchored over Anak Krakatau.

Himawari-8

Himawari-8 “Clean” Infrared Window (10.4 µm) images, with hourly surface report plots from Jakarta WIII {click to play animation | MP4]

===== 25 December Update =====

NOAA-20 VIIRS True Color RGB and Infrared Window (11.45 µm) images [click to enlarge]

NOAA-20 VIIRS True Color RGB and Infrared Window (11.45 µm) images [click to enlarge]

In a toggle between NOAA-20 VIIRS True Color RGB and Infrared Window (11.45 µm) images at 0710 UTC on 25 December (above), a few -90ºC pixels could be seen embedded within the darker purple area of the overshooting top on the Infrared image. Note that there was some westward parallax shift of the image features, due to the scene being near the edge of the VIIRS scan.

The coldest pixels on another NOAA-20 VIIRS Infrared image at 1810 UTC (below) were still within the -80 to -87ºC range.

NOAA-20 VIIRS Infrared Window (11.45 µm) image [click to enlarge]

NOAA-20 VIIRS Infrared Window (11.45 µm) image [click to enlarge]

An updated long animation of Himawari-8 Infrared images (below) continued to show periodic bursts of cold pixels within overshooting tops above the eruption site.

Himawari-8

Himawari-8 “Clean” Infrared Window (10.4 µm) images, 22-25 December [click to play MP4 animation]

===== 28 December Update =====

Himawari-8 "Clean" Infrared Window (10.4 µm) images, 22-28 December [click to play MP4 animation]

Himawari-8 “Clean” Infrared Window (10.4 µm) images, 22-28 December [click to play MP4 animation]

An updated long animation of Himawari-8 Infrared images (above) revealed that the volcanic thunderstorm — which had persisted over the eruption site nearly continuously since 1350 UTC on 22 December — underwent its final pulse around 0640 UTC on 28 December, and was no longer seen after 0900 UTC. The volcanic thunderstorm began its transition from being nearly continuous to a phase of discrete discontinuous pulses after about 0500 UTC on 27 December; the last image with cloud-top infrared brightness temperatures of -80ºC or colder was 2110 UTC on that day.

NOAA-20 captured one of the final convective pulses around 0620 UTC on 28 December (below), when the coldest cloud tops were in the -50 to -55ºC range (yellow to orange enhancement).

NOAA-20 VIIRS True Color RGB and Infrared Window (11.45 µm) images [click to enlarge]

NOAA-20 VIIRS True Color RGB and Infrared Window (11.45 µm) images [click to enlarge]



Orographic standing wave cloud over the Mid-Atlantic states

December 17th, 2018 |

Topography + GOES-16 Low-level (7.3 µm), Mid-level (6.9 µm) and Upper-level (6.2 µm) Water Vapor images, with pilot reports of turbulence [click to play MP4 animation]

Topography + GOES-16 Low-level (7.3 µm), Mid-level (6.9 µm) and Upper-level (6.2 µm) Water Vapor images, with pilot reports of turbulence [click to play MP4 animation]

GOES-16 (GOES-East) Low-level (7.3 µm), Mid-level (6.9 µm) and Upper-level (6.2 µm) Water Vapor images (above) showed the development of an orographic standing wave cloud — downwind of the Appalachian Mountains (topography) — over the Mid-Atlantic states on 17 December 2018. North of the wave cloud, widespread short-wavelength mountain waves were seen at lower elevations over and to the lee of the high terrain (even extending out over the Atlantic Ocean off the coast of New Jersey and New York). There were scattered pilot reports of turbulence across the region, with Severe turbulence being reported around 18 UTC and 00 UTC.

A comparison of GOES-16 Mid-level Water Vapor, Cloud Top Phase and Cloud Top Height products at 2007 UTC (below) indicated that this wave cloud was composed of Cirrus with maximum cloud tops around 30,000 feet.

GOES-16 Mid-level Water Vapor (6.9 µm), Cloud Top Phase and Cloud Top Height products [click to enlarge]

GOES-16 Mid-level Water Vapor (6.9 µm), Cloud Top Phase and Cloud Top Height products [click to enlarge]

GOES-16 Mid-level Water Vapor (6.9 µm) image at 2102 UTC, showing the orientation of a nortwest-southeast cross section [click to enlarge]

GOES-16 Mid-level Water Vapor (6.9 µm) image at 2102 UTC, showing the orientation of a northwest-southeast cross section [click to enlarge]

A GOES-16 Water Vapor image at 2102 UTC (above) showed the orientation of a northwest-to-southeast cross section of RUC40 model Relative Humidity, Wind Speed and Adiabatic Omega fields (below). In the middle of the cross section, a couplet of downward/upward motion aloft was seen over the Glen Allen VA area, with higher relative humidity values (shades of blue) above the 500 hPa pressure level corresponding to the wave cloud.

Northwest-southeast cross section of RUC40 model Relative Humidity, Wind Speed and Adiabatic Omega [click to enlarge]

Northwest-southeast cross section of RUC40 model Relative Humidity, Wind Speed and Adiabatic Omega [click to enlarge]

The standing wave cloud developed in the exit region of a branch of the polar jet stream that was diving southeastward across the Great Lakes — strong deceleration created an axis of deformation oriented from southwest to northeast (below), helping the stretch the wave cloud  feature as it slowly pivoted toward the southeast and along the coast. The strong downward motion component of the Omega couplet seen in the cross section was responsible for the relatively sharp upwind (northwest) edge exhibited by the wave cloud.

GOES-16 Mid-level Water Vapor (6.9 µm) images, with RAP40 model 250 hPa isotachs and deformation vectors [click to play animation | MP4]

GOES-16 Mid-level Water Vapor (6.9 µm) images, with RAP40 model 250 hPa isotachs and deformation vectors [click to play animation | MP4]

A toggle between NOAA-20 VIIRS True Color Red-Green-Blue (RGB) and Infrared Window (11.45 µm) images viewed using RealEarth (below) provided a detailed view of the wave cloud at 1825 UTC. The coldest cloud-top infrared brightness temperatures were around -50ºC (bright yellow enhancement), which was just above the 300 hPa pressure level on 00 UTC soundings at Roanoke/Blacksburg and Wallops Island Virginia.

NOAA-20 VIIRS True Color RGB and Infrared Window (11.45 µm) images [click to enlarge]

NOAA-20 VIIRS True Color RGB and Infrared Window (11.45 µm) images [click to enlarge]

As pointed out by Jonathan Blaes (NWS Raleigh), these standing wave clouds can have an effect on surface temperatures beneath the feature:



A comparison of 1812 UTC Aqua MODIS Visible (0.65 µm), Infrared Window (11.0 µm), Near-Infrared “Cirrus” (1.37 µm) and Water Vapor (6.7 µm) images with plots of maximum temperatures on 17 December (below) revealed that high temperatures were confined to the upper 50s F beneath the wave cloud, in contrast to low 60s F on either side where incoming solar radiation was not diminished.

Aqua MODIS Visible (0.65 µm), Infrared Window (11.0 µm), Near-Infrared "Cirrus" (1.37 µm) and Water Vapor (6.7 µm) images, with plots of maximum temperatures on 17 December [click to enlarge]

Topography + Aqua MODIS Visible (0.65 µm), Infrared Window (11.0 µm), Near-Infrared “Cirrus” (1.37 µm) and Water Vapor (6.7 µm) images, with plots of maximum temperatures on 17 December [click to enlarge]