Interesting pattern of ship tracks in the eastern North Pacific Ocean

September 17th, 2010 |
GOES-11 0.65 µm visible channel images

GOES-11 0.65 µm visible channel images

McIDAS images of GOES-11 0.65 µm visible channel data (above) revealed some interesting cloud features over the far eastern North Pacific Ocean on 17 September 2010: (1) a large “hole” in the stratoculumus cloud field, which contained an intersecting pattern of ship condensation trails (or “ship tracks”), and (2) a subtle train of von Karman vortices extending downwind of Guadeloupe Island off the coast of Baja California. These cloud features were propagating southeastward, due to northwesterly winds within the marine boundary layer.

The pattern of ship tracks on the corresponding GOES-11 3.9 µm shortwave IR images (below) displayed a darker (warmer) signature — this was caused by the reflection of incoming solar radiation off the tops of the ship track plumes (which were composed of rather small water droplets compared to the surrounding stratocumulus clouds) during the day when the sun angle was high. Note how this “dark/warm signal” disappeared at the end of the shortwave IR image animation, when the sun angle became lower in the early evening hours.

GOES-11 3.9 µm shortwave IR channel images

GOES-11 3.9 µm shortwave IR channel images

A bit more detail can be seen in AWIPS images of the MODIS 0.65 µm visible channel, the 3.7 µm shortwave IR channel, and the 11.0 µm IR window channel data (below). Note how the ship tracks exhibited very little signal in the IR window image, since that channel is not sensitive to the reflection of solar radiation.

MODIS 0.65 µm visible, 3.7 µm shortwave IR, and 11.0 µm IR window images

MODIS 0.65 µm visible, 3.7 µm shortwave IR, and 11.0 µm IR window images