6.4
High-latitude winds from Molniya orbit: A mission concept for NASA’s ESSP program
Lars Peter Riishojgaard, NASA/GSFC/JCSDA, Greenbelt, MD
Polar winds derived using MODIS imagery are known to have a substantial positive impact on forecast skill well into the mid-latitudes. The coverage provided by these observations extends to all latitudes poleward of about 65o, and this dataset is therefore a natural complement to the geostationary AMVs. The successful application of the MODIS winds illustrates the continued need for high-quality observations in the high latitudes in general as well as the need for direct, mass-independent observations of the atmospheric flow. One of the main disadvantages of using low earth orbiters such as MODIS for feature tracking is the fact that the image repeat cycle is tied to the orbital period of the platform, roughly 100 minutes. The assumption that the moisture and cloud fields are passive tracers is problematic on timescales of three hours or more, especially for rapidly developing weather systems, and the inevitable delay with respect to real time pushes the delivery time of the MODIS winds beyond the cut-off of many operational data assimilation systems. The Molniya orbit is a very attractive alternative to LEO for the purpose of high-latitude satellite winds. The orbital elements are chosen such that the orbit is stable with two fixed alternating apogee locations over the high northern latitudes. Due to the eccentricity of the orbit, the satellite will spend about two thirds of the time near its apogee, and during this time continuous imaging of the middle and high northern latitudes can be provided at high horizontal and temporal resolution. A mission proposal for a meteorological imaging mission in Molniya orbit is currently under development at the Goddard Space Flight Center. The main mission goals are to demonstrate the feasibility of extending geostationary-type imaging and derived products to the entire globe via a small constellation of Molniya orbiting satellites. The mission concept will be presented and feedback from potential users and other interested parties will be invited. .
Session 6, Building the Earth Information System
Wednesday, 12 January 2005, 8:30 AM-9:30 AM
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