Wednesday, March 11, 2015

March 11th 4PM and 7:45PM soundings


7:45PM radiosonde launch
This radiosonde was launched at 7:45PM to correspond with the RASS measurements. It was filled with 20 cubic feet and ascended at a rate of ~3m/s. 
The nocturnal boundary layer is starting to develop as seen by the shallow surface inversion. Surface winds are very weak and shifted from southerly from the 4pm sounding to easterly in this sounding.There's nearly a 180 degree shift in wind direction at 650mb. There's also mid-level dry air.


4PM radiosonde launch 

 The radiosonde was filled with 17 cubic feet of helium and initially had an ascent rate near 4m/s. However, it took two hours to reach 200mb. There were very light southwesterly winds at the surface that didn't cause any problems between the balloon and tower. The winds were generally westerly and southwesterly throughout the midlayers. The lower levels were mainly dry adiabatic, except for a shallow super adiabatic layer at the surface. An odd cooling feature occurs around 750mb. I'm not quite sure what is going on there. It's unclear if the BL extends up to 600mb or if that layer between 750mb and 600mb is a residual layer from the previous day.  The jet at 200mb appears to be bringing in more moisture as seen by a decrease in separation between the temperature and dewpoint. There were also cirrostratus clouds.










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