===== 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 altitudes.  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 (sec)  ^  End Time (sec)  ^  Heading (deg) ^  Pressure (hPa) ^  Wind Speed (m/s)  ^  Wind Direction (deg)  ^
^                    ^                  ^                ^                 ^ Citation \Sounding ^ Citation \ Sounding    ^
|     83287          |      83483       |     143        |     591         | 15.14 ± 0.80 \ 14.5| 272.6 ± 3.6 \ 268      |
|     83576          |      83748       |     321        |      "          | 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        |     "           | 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        |     "           | 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        |     "           | 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.

{{:atmos:citation:cals:winds:03_07_26_00z_bis_raw.gif|}}
   * **Figure 1**:  SkewT plot of the Bismarck, North Dakota sounding data at 00Z on July 26, 2003.  The SkewT plot is from the NOAA's Forecast Systems Laboratory.