Wind Error Check

Description

GPS-derived winds may not be reliable if the wind speed error value is too high. Acceptable values of wind speed error depend on the height of the sonde. The base threshold is acceptable for data between 10km and 100m in altitude. Above 10km the GPS must use a less precise tracking mode, and below 100m it is susceptible to GPS multipath and is therefore less accurate, so for these cases use a more permissive threshold.

Algorithm

• For each wind line with associated wind error:
  • Interpolate GPS altitude for each error-winds pair, using 1s maximum interpolation interval (to associate 2Hz GPS altitude to 4Hz winds)
    • If altitude is below 10km and above 100m, flag and discard winds whose wind error is above the WindErrorLow threshold
    • If altitude is above 10km or below 100m, flag and discard winds whose wind error is above the WindErrorHigh threshold
    • If interpolation fails or there is no GPS altitude data available, use WindErrorHigh threshold as it is more permissive.

Source

NCAR/EOL (Holger Vomel)