An L-band radar wind profiler was established at National Atmospheric Research Laboratory, Gadanki, India (13.5°N, 79.2°E), to provide continuous high-resolution wind measurements in the lower atmosphere. This system utilizes a fully active array and passive beam-forming network. It operates at 1280 MHz with peak output power of 1.2 kW. The active array comprises a 16 × 16 array of microstrip patch antenna elements fed by dedicated solid-state transceiver modules. A 2D modified Butler beam-forming network is employed to feed the active array. The combination of active array and passive beam-forming network results in enhanced signal-to-noise ratio and simple beam steering. This system also comprises a direct intermediate frequency (IF) digital receiver and pulse compression scheme, which result in more flexibility and enhanced height coverage. The scientific objectives of this profiler are to study the atmospheric boundary layer dynamics and precipitation. Observations made by this profiler have been validated using a collocated GPS sonde. This paper presents the detailed system description, including sample observations for clear-air and precipitation cases.

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A simple approach is presented to implement an active aperture radar with a constrained beam-forming network that is adequate enough to generate multiple beams for atmospheric wind profiling. In this approach, elements of the antenna array are fed directly by dedicated transceiver modules, which are realized with commercially available communication components, making them low cost. A passive 2D beam-forming network distributes the exciter output signal and feeds the transceivers with appropriate phase distribution to generate different beams. This configuration, which is a simplified active array, eliminates the feed loss and achieves the best signal-to-noise ratio (SNR), thereby increases range coverage. Consequently, this scheme allows for a smaller antenna size when compared to a conventional passive array system, for the given range performance, and makes the wind profiler compact and transportable. A 1280-MHz, 64-element simplified active array radar has been developed, successfully validated, and is being operated at Gadanki, a tropical station in south India. Measured winds are in good agreement with those obtained with a collocated GPS sonde technique. This paper presents the configuration and sample results of the system.

The Indian Space Research Organization (ISRO)'s Vikram Sarabhai Space Centre (VSSC) has developed a new GPS radiosonde, called Pisharoty sonde, with its ground station for atmospheric research and operational meteorology. The latest version of this radiosonde weighs 125 g and uses a bead thermistor, a capacitive humidity sensor, and a GPS receiver module. It computes geopotential heights and pressures using the temperature and GPS altitude profile. This paper describes the radiosonde and its associated ground system, summarizes its different versions, and discusses balloon tests of the newly developed version, including comparisons with internationally accepted high-quality radiosondes. * Retired.

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