The Relative Accuracy of ALPEX Aircraft Data / an Evaluation of the ALPEX Intercomparison Flight With the NCAR Electra, the NOAA P3, and the DFVLR Falcon

Using the data frcm this flight, this report lists the relative accuracies for position, pressure, temperature, humidity, horizontal and vertical winds, radio altitude, and radiation (some of these quantities were measured by two aircraft only). The results are presented in form of basic statistical data such as mean differences, standard deviations, and correlation coefficients, as well as in form of power, coherence and - for some quantities - phase spectra.

Notable results are: - Generally, the differences observed are within the accuracies specified for the three aircraft. - The standard deviation of differences in temperature never exceed 0.1 ��C, the differences themselves are of the order of 0.5 ��C. - Humidity data for the Electra exhibits intervals with strong oscillations; the time averaged data shows good agreenent with the measurements frcm the P3 and the Falcon. - The wind measurements of the P3 differ significantly from correlated measurements of the Electra and the Falcon. the well - Longwave radiation data downward for the Falcon appears to be too high.