Bismarck Rawinsonde Sounding Comparison

On July 25, 2003, the University of North Dakota's Citation aircraft flew over the Bismarck, North Dakota rawinsonde launch site. The rawinsonde itself was observed by aircraft crew members while making measurement at the first altitude segment. The aircraft could not follow the rawinsonde down wind of the launch site since it was restricted to fly within an airspace box. The aircraft flew approximately 3 minute segments in two directions at four different altitude. Table 1 compares the wind speed and direction from the University of North Dakota's Citation aircraft with the rawinsonde measurements. Figure 1 gives a SkewT plot of the rawinsonde sounding. The Citation aircraft data shows a slight depends on aircraft heading. The Citation and rawinsonde wind speed are within a meter per second and the wind direction are within 5 degrees. This is pretty good agreement when you note the variability of the measured wind (see standard deviation values for the Citation wind measurements). Furthermore, this comparison was done under cloudy condition with a lot of cumulus clouds in the area.

Start Time [seconds]	End Time [seconds]	Heading [degrees]	Pressure [hPa]	Wind Speed [m/s]		Wind Direction [degrees]
Start Time [seconds]	End Time [seconds]	Heading [degrees]	Pressure [hPa]	Citation	Sounding	Citation	Sounding
83287	83483	143	591	15.14 ± 0.80	14.5	272.6 ± 3.6	268
83576	83748	321	591	15.29 ± 0.56	14.5	272.0 ± 3.1	268
84176	84362	317	466	19.92 ± 0.67	20.2	269.3 ± 2.7	266
84460	84650	143	466	19.15 ± 0.63	20.2	270.9 ± 2.9	266
85202	85391	145	376	23.22 ± 1.11	23.7	268.4 ± 1.1	270
85494	85726	321	376	25.43 ± 1.33	23.7	269.3 ± 1.3	270
85977	86170	143	330	21.87 ± 0.70	20.9	269.2 ± 3.3	270
86283	86606	320	330	21.44 ± 0.90	20.9	267.3 ± 3.7	270

Table 1: Summary of the July 25, 2003 wind comparison between the University of North Dakota's Citation aircraft and a rawinsonde sounding. The rawinsonde data are from the July 26, 2003 00Z Bismarck, North Dakota sounding and were interpolated to the pressure level of the aircraft legs.