Lincoln Laboratory, Massachusetts Institute of Technology, Lexington, MA, USA
A NOAA and MIT Lincoln Laboratory funded program has developed and deployed six Portable Aircraft Derived Weather Observation Systems (PADWOSs) across four states in the southern United States (US). Each system can generate wind and temperature observations from aircraft equipped with a Mode S Enhanced Surveillance (EHS) transponder that fly within 60 NM of an installation. The observations can be taken at a high rate and are available in real-time. The observation rate is configurable and is nominally every 15 seconds for aircraft ascending or descending and every 30 seconds otherwise. This particular effort, which will include a multi-year field campaign, is designed to evaluate and ameliorate the performance of PADWOS and utilize the collected data in data denial experiments to determine potential improvements in short-term weather forecasts by providing dense and timely observations for enhanced data assimilation.
One of the rationales for the development and deployment of PADWOS was the realization that the primary source of upper-air observations used in numerical weather prediction data assimilation comes from a small number of specially equipped aircraft that are unfortunately very sparse spatially and the measurements are temporally delayed. The source of this valuable and beneficial information is the Meteorological Data Collection and Reporting System (MDCRS). Only a small portion of the commercial aircraft fleet are equipped to provide observation data to MDCRS and approximately half of all observations are reported above 20,000 feet while observations below this altitude are concentrated around major airports.
This lateral/vertical sparseness and latency could be significantly addressed by generating observations from aircraft that are equipped with Mode S EHS transponders. Each PADWOS can interrogate such aircraft to estimate in situ wind and temperature. Because more than 95% of commercial aircraft and greater than 50% of general aviation aircraft in the US are equipped with such transponders (and with equipage increasing each year), the density of observations in time and space are significantly increased in the 11,000 sq-miles around each PADWOS installation. These observations are especially valuable in regions away from major airports, at low altitudes where general aviation aircraft fly, as well as from departing and arriving flights at smaller airports. These measurements can partially fill a significant gap in and just above the planetary boundary layer.
In this work, we will describe the deployment of six fielded systems placed in Alabama (x2), Arkansas (x2), Louisiana, and Mississippi, and whose siting and observation area covers a rectangular geographical region of approximately 475 miles wide and 300 miles high. We will report the characteristics of the aircraft environment observed by the systems as that provides important information on the availability of weather observations. The quantity and quality of PADWOS generated observations will be compared to MDCRS provided observations over the same region.
© 2023 Massachusetts Institute of Technology. This material is based upon work supported by the Observations Program within NOAA/OAR Weather Program Office under Award No. NA21OAR4590395.
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