Upper air observations are taken twice a day around the world at 1200 hours and 0000 hours GMT (5 am and 5 pm MST). See fig. 1 for U.S. locations. The observation system consists of an instrument (radiosonde), and a gas filled balloon. The radiosonde instrument contains the various sensors that will gather temperature, humidity, and pressure data while the system ascends. Winds are also derived by using a GPS system that tracks the balloon location to calculate a wind speed and direction. Balloons are usually filled with hydrogen but helium is sometimes also used. The balloon is rather large, inflating to about 6-8 feet in diameter at the release site and increasing to as much as 20 feet in diameter at high altitude.
Balloons typically reach a height of around 100,000 feet before bursting, and these flights usually last about 90-120 minutes. Parachutes are used with the balloons to slow the descent after burst, thereby protecting people and property from potential harm. Distance traveled by the balloons vary greatly, depending on the winds aloft over the area. It is not unusual here at Santa Teresa to see balloons/radiosondes land in far eastern Otero and Hudspeth Counties with strong west winds aloft.
Data from the radiosondes is sent via radio signal to our office where computers analyze and store the data; this data is then transmitted to the National Center for Environmental Prediction (NCEP). NCEP runs a quality control check on the data and then assimilates it with other data from satellites, aircraft, radar, and surface observations, to be used in initializing numerous forecast models. These models forecast the development and movement of weather systems, and are used by the NWS and private companies around the country to issue various forecasts. For more information on the NWS radiosonde system and network, visit the NWS Upper Air page.
On March 1, 2013 WFO El Paso began using the Vaisala Radiosonde RS92-NGP (figure 1). The Vaisala Radiosonde replaces the Lockheed Martin Mark IIA Microsonde (figure 2). The RS92-NGP radiosonde features a GPD receiver for wind findings, has a silicon pressure sensor, a heated twin humidity sensor, and a small, fast temperature sensor.
(Figure 1) (Figure 2)