I understand that the Version 3 and 4 QuikSCAT L2B data includes corrections for rain when rain is detected, so do I still need to use the flags variable?
Since wind is retrieved and corrected in all conditions, the quality flag is generally not needed unless there is sufficient cause for concern, at the data user's discretion, that rain corrections are either insufficient or perhaps introducing a spurious bias to the wind speed data. The eflags variable is meant to help provide additional support to users who may be concerned with the quality of the rain corrections, which provides additional information including: whether the rain corrections were applied, whether the rain corrections produced a negative speed bias, or if the rain corrections were unusually large (i.e., producing a correction larger than 1 m/s). It also should be noted that the rain correction method was only optimized for wind speeds between 0 and 20 m/s, and it's a known issue that for wind speeds beyond 20 m/s the rain correction may often degrade the accuracy of the corrected wind speed. As a result of this known issue, the user should still use the flags and eflags variables as a backup to ensure that either negative or unusually large wind speed biases are not a result of the rain correction while rain is present.