29 Jan

A different view on the measurements today. Below are snapshots from the wind lidar, showing vertical velocities in the boundary layer (between the surface and 500 m) for an entire day. There are nine snapshots from the first nine days of PreEUREC4A. If you remember the patterns of clouds over the past days, with a dearth of clouds in days 5-7 and now more clouds, it wouldn't have been obvious to guess from this, the structure of turbulence in the subcloud layer. What I find interesting is the downdrafts (for instance yesterday around 1/4 of the way through the series, and on days 1 and 3, usually when you find one you can see a good coincidence with the microrain radar. One of the goals of EUREC4A will be to better understand controls on the entropy budget in the subcloud layer. For this downdraft's might be important, but at the moment at least the strong one's don't seem especially plentiful.

The updrafts make Frigate birds happy. Hopefully they will also make a new intern happy as her job (fittingly so because she is also a glider pilot) will be to see how the structure of turbulence in the subcloud layer is (or is not) affected by the clouds that form above it. Anyone willing to wager?  

okay, so much for Sunday's trivia. Bjorn

PS I will not send it around, but the world view and radar show very different structure to the convection today.  Convective blobs with blow off are splotched through the upstream trades, at the center of the blobs are strong rain echoes, associated with systems no more than 3 km in depth but with echoes well above 30 dBZ.

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