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This study introduced and evaluated the calibration schemes of a newly developed upper-air radiosonde instrument, "Storm Tracker" (ST), with data collected in field observations during 2016–2022. The ST is a radiosonde instrument developed and tested in 2016 (Hwang et al., 2020). In a series of field campaigns in the Taiwan area, more than one thousand co-launches of ST and Vaisala RS41-SGP (VS) are conducted. Using the VS measurements as the reference, we developed data correction methods and examined the characteristics of the ST sounding. The corrected ST soundings have 1-K temperature and 7 % relative humidity root mean square difference to the VS soundings. These error differences can be reduced to 0.66-K and 4.61 % below the 700-hPa height. The GPS estimated ST wind error difference is about 0.05 ms-1. The results suggested that the ST can perform similarly to the reference sounding and has reached the level required for environmental sampling and scientific research. The geostrophic adjustment dynamics indicate that the spatial temperature variation in the free atmosphere may not be large. However, the lower atmosphere may have large wind, temperature, and moisture variations. Due to the relatively low cost and accuracy after correction, ST can complement regular upper-air observations for high spatial and temporal resolution. [ABSTRACT FROM AUTHOR]

Since 2003, a field program has been conducted under the name of Dropwindsonde Observations for Typhoon Surveillance near the Taiwan Region (DOTSTAR). As the name DOTSTAR suggests, targeted observation is one of its key objectives. The prerequisite for designing the observing strategy is to identify the sensitive areas, which would exert great influence on the results of numerical forecast or the extent of the forecast error. In addition to various sensitivity products already adopted in DOTSTAR, a new way to identify the sensitive area for the targeted observation of tropical cyclones based on the fifth-generation Pennsylvania State University-National Center for Atmospheric Research (NCAR) Mesoscale Model (MM5) is proposed in this paper. By appropriately defining the response functions to represent the steering flow at the verifying time, a simple vector, adjoint-derived sensitivity steering vector (ADSSV), has been designed to demonstrate the sensitivity locations and the critical direction of typhoon steering flow at the observing time. Typhoons Meari and Mindulle of 2004 have been selected to show the use of ADSSV. In general, unique sensitive areas 36 h after the observing time are obtained. The proposed ADSSV method is also used to demonstrate the signal of the binary interaction between Typhoons Fungwong and Fengshen (2002). The ADSSV is implemented and examined in the field project, DOTSTAR, in 2005 as well as in the surveillance mission for Atlantic hurricanes conducted by the Hurricane Research Division. Further analysis of the results will be vital to validate the use of ADSSV.