Updates to the NCAR Dropsonde Sensor Module and Improvements to the Measurements of Tropospheric Pressure, Temperature, Humidity, and Wind Profiles

In 2017, the sensor module of the NCAR dropsonde has been updated and now uses the same sensors to measure pressure, temperature, and humidity as the Vaisala RS41 radiosonde. This update significantly improves the humidity measurements obtained by dropsondes and extends the vertical range over which dropsonde humidity measurements can be used. The update improves the behavior in clouds, where the older RS92 based sensor suffered from icing issues and it removes the software related dry bias, which had been discovered in 2016. The temperature sensor responds significantly faster compared to the older model, requiring less correction in post processing. The pressure measurements use the same sensor; however, a recent software update in the telemetry receiving software reduces the calibration uncertainty of this sensor. The uncertainty for wind and GPS altitude measurements is controlled by the uncertainty of the GPS technology, with the possibility for some artifacts near the ocean surface. These artifacts have been addressed with an update in the GPS receiver that is being used in the dropsondes.