Atmospheric Radiation Measurement (ARM) Climate Research Facility radiosonde (SONDE) files provide a key reference to the atmospheric state, but this is only available at the time of those radiosonde launches. However, many applications or retrievals may require a quick estimate of the atmospheric state at higher time resolution, or may simply demand a more convenient time-height gridding of these SONDE data. The Merged Sounding (MERGESONDE) value-added products (VAPs) transform ARM radiosonde (SONDE) data into continuous daily files with thermodynamic parameters on fixed time-height grids. MERGESONDE uses a more sophisticated technique for interpolation that blends a combination of observations from SONDE, microwave radiometers (MWR), surface meteorological instruments (MET), and outputs from the European Centre for Medium Range Weather Forecasts (ECMWF) model (or possibly from similar reanalysis, such as ERA5, on request).
There are various benefits to the separate SONDE files and radiosonde VAPs. The MERGESONDE VAP faithfully reports the same thermodynamic profile at the time of the ARM radiosonde launch. By including ECMWF (or similar) model outputs rather than simply linearly interpolating sounding dataset, MERGEDSONDE may be more suitable than ARM’s Interpolated Sounding (INTERPSONDE) products for use during campaigns or at ARM locations where the radiosonde frequency is limited.
For additional information on the VAP interpolation procedures, please consult the technical report for the product.