GAINS--An Observing System for the 21st Century

The Global Atmosphere-ocean IN-situ System (GAINS) is a program to develop the systems needed for an operational, global, in-situ observing system. Observations taken from the GAINS platforms will complement existing operational systems by filling in holes in remote land regions and over oceans, and by delivering observations that are at finer temporal and spatial resolutions than are currently possible. The operational program, intended to begin in 2006, is conceived as a network of high-tech balloons evenly distributed over the global lower stratosphere. At 37-m in diameter, designed to carry 350-kg payloads, and intended to be operated at altitude for one year, the GAINS payload will consist of a variety of small "sondes" that will be dropped on command to measure a number of environmental parameters, including weather, climate, and atmospheric chemistry variables. A distributed network of 400 balloons will provide measurements for virtually every 10 degree square of latitude and longitude over the globe. The balloons are designed to circle the globe for one year before returning to Earth to be recovered and refurbished. The GAINS balloon is also designed with aviation safety in mind, being equipped with an aircraft transponder, and flying above domestic air space.

Directability of the system is being tested through trajectory simulations. Based the the concept of" shear direction", management strategies for single balloons and balloon networks are under development using NCEP Reanalysis winds. Algorithms for targeting a balloon to a specified location, and for flying balloons along latitude circles have been tested. A trajectory forecast model has also been developed to predict the balloon's track for field planning and during tests. Current versions of these models employ climatology for the planning stages and a combination of operational raob data and pseudo-sounding forecasts from the RUC during actual tests.

GAINS development also encompasses balloon vehicle and instrument design. In 1999, the current prototype, an 18-m-diameter superpressure balloon capable of carrying a 90-kg payload, will be launched from Tillamook, Oregon. Operating on solar power, with line-of-sight telemetry and over-the-horizon communications, this prototype will float for 48 hours at 60,000 ft. Data from the Global Positioning System (GPS) provide the location of the balloon and winds at float altitude. Atmospheric sounding capability will be demonstrated. The balloon is equipped with an aircraft transponder (for Air Traffic Control during ascent and descent through the national air space) and with redundant safety devices.

This talk will give an overview of the GAINS program discussing the concept, the motivation for this observing system, and the seven-year development program. Trajectory simulations illustrating the feasibility of the proposed GAINS network will be presented. Finally, status of the program and results of experimental flights will be discussed.