ECMWF analysis plots for SCAVEX flight 20020424








"Surface" maps
Level (hPa) - - - - - - - -
2002042400+012 Total CC Low CC Medium CC High CC H2O column 6hr LS Prec 6hr Con Prec BL Height
2002042412+006 Total CC Low CC Medium CC High CC H2O column 6hr LS Prec 6hr Con Prec BL Height


Pressure level maps
Level (hPa) 300 300 500 300 500 850 500 300 300 500 700 700 - 1000-500 1000-500 - -
2002042412 PV Z Z Wind Wind Wind W Spec hum RH RH RH EpotT Pot.Inst. Int.hum.flux Div.int.hum.flux MSL Press NS-gradient MSLP



Vertical X-sections
2002042412 EW at 48N from 5 to 20E PV Eq pot T Spec hum RH Wetb potT U V W Cloud water Cloud ice Cloud cover -
20020424 time vs P PV Eq pot T Spec hum RH Wetb potT U V W Cloud water Cloud ice Cloud cover




ECMWF and measured parameters as a function of UT
Pressure PV T Pott. T Wind speed Wind dir W RH H2O mix.ratio Cloud cover Liquid/Ice water
Model data along track: file1// file2 (cloud parameters)




5-day 3D backward trajectories for every 2 min of flight
By half-hour
11:14-11:30 11:32-12:00 12:02-12:30 12:32-13:00 13:02-13:30 13:32-14:00 14:02-14:30 14:32-15:00 15:30-15:30




Summary

This flight included an eastward flight segment in the mid-troposphere towards and below a PV filament/upper level trough and back, followed by a profile in the high over Germany (see PV map, east-west PV X-section, and PV X-section versus time). The PV was all the time below about 1 PVU (PV versus time).

At 500 hPa there is a high over southwestern Europe and a low over eastern Europe. The flight took place where the 500 hPa height isocontours have a strong gradient (front).

The aircraft crossed the frontal zone to the west of the trough several times, first while flying to the east during the east-west flight segment, then while returning to the west, and subsequently while making the profile. See the densely packed red contours in the EW X-section and X-section versus time of eq. potential temperature. The front is also visible as the boundary between warm (yellow) and cold air in the map of eq. potential temperature at 700 hPa. There it can be seen that the front was more pronounced (stronger gradient) north of where the aircraft crossed it.

Winds at 500 hPa and 300 hPa are from the northnortheast. The jet maximum at 300 hPa is quite strong (55 m/s) but well above the east-west flight leg while the profile was west of the jet (EW X-section of meridional wind). The maximum observed wind speed (45 m/s) was measured at the top of the profile between 13h45 and 15h30 (wind speed versus time). Observed and modelled wind speeds agree well. The observed and modelled wind directions were most of the time around 15 degrees and agree also very well.

The relative humidity in the high was large, in the mid troposphere below the filament it was dry RH X-section. In the high between 400 and 350 hPa there was also a relatively dryer layer. The cloud cover X-section strongly resembles the RH X-section, with large cloud cover in the upper and lower parts of the profile. The observed and modelled RH also correspond quite well, with dry air along the east-west leg and moist air during the profile in the high (after 13h).
The map of high cloud cover corresponds well with the IR cloud photograph at 14h and shows frontal cloud band on the anticyclonic (high pressure) side of the jet. The cloud photograph shows a very pronounced upper level front (sharp boundary to the white upper level clouds).

The trajectories during the profile in the high show considerable uplift, e.g. 13h02-13h30, 13h32-13h44, and 14h14-14h30, originating in the western Atlantic marine boundary layer. The trajectories 12h02-12h28 originate in a low over the Atlantic (and correspond to the leg below the upper level trough/filament).