The Interpolated Sounding (INTERPOLATEDSONDE) value-added product (VAP) transforms sounding data into continuous daily files on a fixed time-height grid, from the surface up to a limit of approximately 40 kilometers, at one-minute time resolution.
The grid extends to 332 levels in order to be sure to capture the full height of soundings. Most soundings terminate somewhere between 25 and 30 kilometers, above which no data are provided. Between soundings, the VAP linearly interpolates atmospheric state variables in time for each height level. The INTERPOLATEDSONDE VAP also provides relative humidity scaled to microwave radiometer observations.
INTERPOLATEDSONDE includes many of the same scaling and interpolation schemes that are the hallmark of the MERGESONDE VAP, however, unlike MERGESONDE, INTERPOLATEDSONE does not include ECMWF model output. There are benefits to excluding ECMWF model output, including 1) a shorter time lag in producing thermodynamic profile output, and 2) profiles independent of model input, facilitating model evaluation directly with observations.