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)

Tropical Storm Dolly in the southern Gulf of Mexico

September 2nd, 2014 |
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)

Tropical Storm Dolly has formed in the western Gulf of Mexico. The Suomi NPP VIIRS Day Night Band imagery, above, shows the exposed low-level swirl of the storm (then still a tropical depression). North-northwesterly shear (shown here, from this site) means the deep convection (shown below) is displaced to the east of south of the the low-level circulation (click here for a toggle between the Day Night Band and the 11.45µm imagery). Cloud-top IR brightness temperatures from VIIRS were as cold as -87º C. ASCAT winds from 0230 UTC show a region of tropical storm-force winds associated with convection east and north of the circulation center.

Suomi NPP VIIRS Infrared (11.45 µm) image (click to enlarge)

Suomi NPP VIIRS Infrared (11.45 µm) image (click to enlarge)

Early-morning visible imagery from GOES-13, below, shows the large area of convection over the southern Gulf. The NHC-reported positions of the storm at 0900 UTC and 1500 UTC (22.6º N, 94.8º W and 23.4º N, 96.5º, respectively) are indicated by the red boxes on the images. Strong convection just south of the surface circulation developed at sunrise, obscuring the low-level swirl. That strong convection is especially apparent in the GOES-13 10.7 imagery, at bottom. GOES IR Brightness Temperatures were as cold as -84º C in the animation. (For more on Dolly from the National Hurricane Center, see this link).

GOES-13 Visible Imagery (0.63 µm) (click to animate)

GOES-13 Visible Imagery (0.63 µm) (click to animate)

GOES-13 Infrared Imagery (10.7 µm) (click to animate)

GOES-13 Infrared Imagery (10.7 µm) (click to animate)