Tropical Cyclone Reconnaissance with the Global Hawk: Opera9onal Requirements, Benefits, and Feasibility Patrick Harr, Department of Meteorology, Naval Postgraduate School NASA Global Hawk flight tracks over Hurricane Nadine in September 2012
Uncertainty in forecasts of tropical cyclone tracks Defined by ensemble prediction systems at global operational weather centers Represents the chaotic nature of the atmosphere and sensitivity to initial conditions ECMWF/UKMO Ensemble track predictions for TY Sinlaku in 2008 Forecasts obtained from the THORPEX Interactive Global Grand Ensemble (TIGGE) database
Western Pacific: Active Area of Maneuverability 1.4M sq miles of area lost to error swath at 72 hours. A 50% reduction in error would add up to 21M sq miles of sea maneuver per year. Current uncertainty Desired uncertainty PACOM Goal: Increase US/Coalition Sea Maneuver Space Naval Oceanography
JTWC TRACK ERRORS (Western North Pacific - 24-72 Hours) Annual errors are at all time low values But 5 yr averages are not decreasing Naval Oceanography
JTWC TRACK ERRORS (Western North Pacific - 24-72 Hours) Annual errors are at Trends in forecast accuracy: all time low values Natural variability certain tracks may be But 5 yr averages are not decreasing more difficult to predict Availability of data to assess initial conditions Storm structure o Remote sensing data o In situ data Large-scale environment Limits to predictability Naval Oceanography
Extratropical Transi@on Downstream Impacts TC Intensifica@on. structure change, track uncertainty Recurvature, ini9a9on of ET Forma@on Large- scale circula9on, deep convec9on, monsoon depressions, tropical waves, TC forma9on
Simultaneous observations of TY-core, TY-environment and distant sensitive region associated with TY Sinlaku Joint mission of: Falcon (yellow) C-130 (black) DOTSTAR (red) Inner core Immediate vicinity Remote sensitivity region From M. Weissmann
Weissmann et al. Mon. Wea. Rev. 2010 Differences in 72- h DROP and NODROP track forecast errors Sinlaku Forecast degrada@on arer recurvature Recurvature @me Incorpora@on of aircrar observa@ons improve forecasts prior to recurvature The tropical regions are rela@vely data- void compared to midla@tude regions over which the storm moves following recurvature Forecasts that are very accurate without aircrar data are degraded by the use of aircrar data
Western North Pacific Tropical Cyclone Reconnaissance: Andersen AB, Guam Andersen AFB, Guam
Current NASA Global Hawk Instrument Design
Global Hawk Instrumenta@on Dropwindsondes Basic sensor that provides numerous profiles of the en@re typhoon environment Intended to improve weather models used to forecast TC loca@on and intensity
Remote Sensing Instrumenta9on Measures hurricane surface wind speeds and rain rates over a wideswath: Swath Width ~ 80 km Resolution ~ 1-5 km Wind speed ~10 85 m/s Rain rate ~ 5 100 mm/hr Key Feature: Near-instantaneous mapping of entire inner-core hurricane surface wind field and rain structure. Operational advantages: Surface wind and rain swath will complement SFMR and airborne Doppler radar mapping of innercore structure for improved shortterm advisories and numerical model initialization. HIRAD Swath Geometry NASA HS3 Global Hawk configura9on for 2012-2014
Tropical Cyclone Structure Environmental Interac@ons are oren concentrated in the ouvlow layer, which is above 45,000 feet. Upper Level OuSlow
WPAC Global Hawk Demo: concept of operations Height (km) 15 10 5 Radar Outflow Air Force WC-130J SFMR: Surface winds / intensity Radar: Precipitation structure Flight level instruments SFMR Global Hawks Suite of remote sensing Ø Environmental Ø Over-Storm Dropsondes Ø YES sondes 0 100 300 600 radius (nm)
Some numbers: Global Hawk tropical cyclone reconnaissance demonstra@on 2 months of opera@on from Andersen AB, Guam Workshop 6-8 November to coordinate USAF, USN, and NOAA