The impact of simulated super pressure balloon data on regional weather analyses and forecasts

Summary This paper highlights results from a series of observing system simulation experiments (OSSEs) designed to assess the impact of assimilating data from a hypothetical network of constant density, super pressure balloons on regional weather analyses and forecasts over the continental U.S. These super pressure balloons would be carried passively by the wind at various levels in the atmosphere taking measurements of pressure, temperature, moisture, and wind velocity similar to other Lagrangian drifters that have been used in meteorology for nearly 50 years. The super pressure balloons or probes are envisioned to be the main component of a new observing system called Global Environmental Micro Sensors (GEMS). The novel aspect of the GEMS system is the integration of micro and eventually nanotechnology to develop probes with significantly lower mass, size, and cost. Given these attributes, thousands of probes could be deployed for research and operational missions thereby greatly expanding the amount of in situ observations, especially over data sparse oceanic regions. As part of a multi-year feasibility study on the GEMS system, modeling and simulation were used extensively to study probe deployment, dispersion, and data impacts using OSSEs. The OSSEs were designed to mimic an operational regional forecast cycle by running a series of 48 h forecasts initialized using a four-dimensional data assimilation scheme. Results showed statistically significant improvements of temperature, dew point, and vector wind over forecasts assimilating only conventional in situ surface, upper air, and aircraft observations. Sensitivity experiments indicated that the OSSEs produced nearly identical forecast impacts with a 90% reduction in the amount of data assimilated. This result is important in defining the requirements for system and probe cost.