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CLASS

The CLASS was developed by the National Center for Atmospheric Research (NCAR) and licensed to the Radian Corporation. Cross-chain Loran refers to the triangulation procedure used to specify the radiosonde position required to determine the vertical wind profile; where a `chain' of three to five Loran stations track the radiosonde instrument package.

Temporal resolution of the radiosonde is 10 seconds; yielding a vertical spatial resolution of 30 to 50 m for a 200 g balloon, dependent upon balloon ascent rate. A Väisälä radiosonde instrument package was used for all retrievals. Table 2 indicates the specifications for the Väisälä sonde.    

Variable Range Uncertainty Resolution

Pressure 3 to 1060 mb 0.5 mb 0.1 mb

Temperature -90 to 60 K 0.2 K 0.1 K

Dewpoint Temperature 2 K 1 K

Relative Humidity 0 to 96 %