Microwave Estimates of Total Precipitable Water

July 28th, 2020 |

MIMIC TPW rocking animations from 17-27 July 2020 (and back) [click to play mp4 animation]

Morphed Microwave Imagery at CIMSS (MIMIC) estimates of Total Precipitable Water are derived from microwave sensors such as AMSU and ATMS on different polar-orbiting platforms. MIRS retrievals are used to estimate Total Precipitable Water from each polar swath, and those swaths are then advected forwards and backwards by GFS model winds. In this way, global coverage is achieved; each point on the globe is influenced most by the closest polar pass that most recently sensed the atmosphere. In some cases, that closest pass might occur after the time of the image. Thus, final images in this animation will change with time until about 16 hours after the time of an image. (You can find a training video on this product here, and data are available online here).

The animation above (click here for an animated gif) shows hourly data for ten days ending late on 27 July; during this time, Hurricane Douglas formed and moved just north of the Hawai’ian island chain. The rocking animation clearly shows the initial impulse for Douglas emerging out of the Intertropical Convergence Zone south of Mexico and moving west-northwestward towards Hawai’i. One can speculate on the effect of the moisture associated with Pacific Tropical Depression 7E, which disturbance formed just before Douglas and to its west, had on Douglas’ structure as it moved north of Hawai’i. Did that extra moisture help?

Ten-day rocking animations of MIMIC are routinely available for the eastern Pacific, for North America and for Australia.

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