NASA Global Hawk flight to study Tropical Storm Dolly

September 2nd, 2014
NASA Global Hawk flight path, with Cloud Height, Tropical Overshooting Tops, and Lightning data (click to play animation)

NASA Global Hawk flight path, with Cloud Height, Tropical Overshooting Tops, and Lightning data (click to play animation)

The NASA Global Hawk aircraft are once again being used to study tropical cyclones during the 2014 season. As part of CIMSS participation in GOES-R Proving Ground activities, a Global Hawk flight path tool was developed to display important parameters such as ACHA Cloud Top Height, Tropical Overshooting Tops, and lightning (above; click image to play animation). Global Hawk pilots use this product to navigate the aircraft around locations of potential turbulence.

GOES-13 0.63 µm visible channel images (click to play animation)

GOES-13 0.63 µm visible channel images (click to play animation)

To support the Global Hawk investigation of Tropical Storm Dolly on 02 September 2014, the GOES-13 satellite was placed into Rapid Scan Operations (RSO) mode to provide images at 5-7 minute intervals. GOES-13 0.63 µm visible channel images (above; click to play animation) and 10.7 µm IR channel images (below; click to play animation) are shown which cover the 3-hour period of the Global Hawk flight segment shown above. There is evidence of overshooting tops seen in the visible imagery, with cloud-top IR brightness temperatures of -80º C and colder (purple color enhancement).

GOES-13 10.7 µm IR channel images (click to play animation)

GOES-13 10.7 µm IR channel images (click to play animation)

GOES-14 to begin SRSO imaging in August

August 8th, 2014
GOES-14 Visible Channel (0.62 µm) imager (click to enlarge)

GOES-14 Visible Channel (0.62 µm) imager (click to enlarge)

GOES-14 (positioned over the Equator at 105º West Longitude) Imager and Sounder instruments have been activated to support of SRSO-R operations, which are scheduled to begin Thursday 14 August. The first image acquired was shortly after 1530 UTC on 5 August; Image Navigation and Registration start-up was scheduled for 7-9 August, and the image above along the Gulf Coast shows that the navigation today is very accurate. Infrared imagery for the same time shows coldest cloud tops (over eastern Arkansas) near -65º C.

After a north-south maneuver on the 12th, GOES-14 1-minute imagery will begin to flow. The satellite is scheduled to return to standby mode on 29 August.

Satellite messages from NOAA, including those pertaining to GOES-14, can be viewed here.

Offshore mesovortex affecting the inland penetration of marine stratus along the California coast

June 2nd, 2014
GOES-15 0.63 µm visible channel images (click to play animation)

GOES-15 0.63 µm visible channel images (click to play animation)

On 02 June 2014, McIDAS images of 1-km resolution GOES-15 0.63 µm visible channel data (above; click image to play animation) revealed the presence of a cyclonic mesoscale vortex in the vicinity of Point Reyes along the California coast, which appeared to be playing a role in enhancing the inland penetration of marine fog/stratus into areas such as the San Francisco Bay region just south of the mesovortex.

An AWIPS image of 375-meter resolution (projected onto a 1-km AWIPS grid) Suomi NPP VIIRS 0.64 µm visible channel data at 21:07 UTC (below) included overlays of surface station and buoy reports, along with MADIS 1-hour satellite-derived atmospheric motion vectors within the 1050-900 mb layer at 21 UTC. The satellite cloud-tracked winds appeared to be picking up on the cyclonic circulation of the mesovortex. At this particular time, winds at San Francisco (station identifier KSFO) were southwesterly gusting to 23 knots.

Suomi NPP VIIRS 0.64 µm visible channel image, with surface and buoy observations and 1-hour MADIS satellite winds

Suomi NPP VIIRS 0.64 µm visible channel image, with surface and buoy observations and 1-hour MADIS satellite winds

A time series of surface observation at San Francisco International Airport (below) showed the increase in layered stratus clouds (with ceilings of 1000 to 1500 feet) after the southwesterly winds began to increase around 19 UTC.

Time series of surface observations at San Francisco International Airport

Time series of surface observations at San Francisco International Airport

AWIPS images of the GOES-R Cloud Thickness product — with the GOES-R algorithm for Fog and Low Stratus products applied to GOES-15 data — indicated that the thickness of the stratus clouds moving inland across the San Francisco Bay area was only about 500 feet (below; click image to play animation). The thicker stratus clouds with depths of 1000-3000 feet remained off the coast of California.

GOES-15 Cloud Thickness product (click to play animation)

GOES-15 Cloud Thickness product (click to play animation)

The corresponding GOES-15 Marginal Visual Flight Rules (MVFR) product (below; click image to play animation) showed that MVFR probability values were generally below 50-60% in the San Francisco Bay area, with much higher probabilities existing within the offshore marine boundary layer stratus cloud field.

GOES-15 Marginal Visual Flight Rules (MVFR) Probability product (click to play animation)

GOES-15 Marginal Visual Flight Rules (MVFR) Probability product (click to play animation)

GOES-14 SRSOR: from morning fog/stratus to afternoon convection

May 13th, 2014
Suomi NPP VIIRS and POES AVHRR IR brightness temperature difference

Suomi NPP VIIRS and POES AVHRR IR brightness temperature difference “fog/stratus product” images

An AWIPS comparison of nighttime Suomi NPP VIIRS and POES AVHRR IR brightness temperature difference “fog/stratus product” images (above) exhibited signals of fog and/or stratus forming in river valleys straddling the West Virginia and Virginia border on 13 May 2014.

The GOES-14 satellite continued to be operated in Super Rapid Scan Operations for GOES-R (SRSOR) mode, providing images at 1-minute intervals. Early morning 0.63 µm visible channel images (below; click image to play an MP4 animation; also available as a QuickTime movie) showed the narrow fingers of river valley fog/stratus, which began to burn off as heating and mixing increased during the morning hours. There was then a rapid transition to the formation of cumulus clouds across the region, some of which became organized areas of deep convection that produced hail and damaging winds (SPC storm reports).

GOES-14 0.63 µm visible channel images (click to play MP4 animation)

GOES-14 0.63 µm visible channel images (click to play MP4 animation)

A 3-panel comparison showing the difference between standard or routine 15-minute interval, 5-7 minute interval Rapid Scan Operations (RSO), and 1-minute interval SRSO GOES-14 0.63 µm visible channel images (below; click image to play an MP4 animation; also available as a very large Animated GIF) demonstrated the clear advantage of higher temporal resolution for monitoring the rate of dissipation of river valley fog/stratus features, as well as subsequent convective initiation and development.

GOES-14 0.63 µm visible channel images: Standard, RSO, and SRSOR scan strategies (click to play MP4 animation)

GOES-14 0.63 µm visible channel images: Standard, RSO, and SRSOR scan strategies (click to play MP4 animation)

Consecutive overpasses of the Suomi NPP satellite provided a look at the rapid rate of convective cloud development on VIIRS 0.64 µm visible channel images (below).

Suomi NPP VIIRS 0.64 µm visible channel images, with surface observations and frontal boundaries

Suomi NPP VIIRS 0.64 µm visible channel images, with surface observations and frontal boundaries

On a 18:59 UTC MODIS 11.0 µm IR channel image (below), the coldest cloud-top IR brightness temperature was -78º C near the West Virginia/Virginia border.

MODIS 11.0 µm IR channel image

MODIS 11.0 µm IR channel image