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Aerosonde Observations in the Hurricane Boundary Layer Environment

Principal Investigator:
Joseph Cione
Collaborating scientist(s):
Jason Dunion (HRD/CIMAS)
Eric Uhlhorn (HRD/CIMAS)
Brenda Mulac (Aerosonde Corporation)
Greg Holland (NCAR/Mesoscale And Microscale Meteorology Division)
Gary Barnes (University of Hawai'i)
Chris Sisko (NOAA/Tropical Prediction Center)


First hurricane flight story

Power Point presentation on this Project

Aerosonde Corp.

Aerosonde first hurricane flight

NASA's Wallops Flight Facility


Objective:
While the successful utilization of the P-3 Orion and Gulfstream 4 aircraft have made NOAA a global leader in the area of hurricane aircraft surveillance and reconnaissance, detailed observations of the near-surface tropical cyclone (TC) boundary layer environment have been elusive due to the severe safety risks associated with low level TC manned flight missions. The primary objective of this funded project is to address this significant observational shortcoming by utilizing the unique low flying attributes of the (unmanned) Aerosonde observing platform.

It is believed that the payoff for such an effort would be significant and in some cases immediate. These benefits would include detailed documentation of a heretofore unknown region of the TC (Monitor and Observe) and simultaneously provide NOAA's Tropical Prediction Center (TPC) with real-time near surface wind and thermodynamic data within the TC environment. In addition, this effort will enhance our physical understanding of this critically important environment (Understand and Describe) and ultimately, provide improvements to future forecasts of TC intensity change (Assess and Predict).

The primary objective of this project is to utilize the unique capabilities of the Aerosonde platform to document areas of the TC environment that would otherwise be either impossible or impractical to observe. While the main scientific goal of this project is to accurately document and improve our understanding of the rarely-observed TC boundary layer, an important (and immediate) additional benefit would be the real-time transmission of TC surface conditions directly to the TPC. In addition, detailed comparisons between in-situ and satellite-derived observations will also be possible. It is also envisioned that this unique data could ultimately be used to help initialize and verify both operational and research-oriented TC numerical simulations. When combined, these research and operational objectives match NOAA's Weather and Water stated outcome of "Increased accuracy and amount of lead time."


Background:
Simply stated, continuous observation of thermodynamic (temperature and moisture) and kinematic (wind) structure of the near-surface hurricane environment has never been documented in a hurricane. This environment, where the atmosphere meets the sea, is critically important since it is where the ocean's warm water energy is directly transferred to the atmosphere just above it. The TC surface layer is also important because it is where we find the strongest winds in a hurricane and coincidentally, the level at which most of us live (i.e. at/near the surface). As such, observing and ultimately better understanding this region of the storm is crucial if we hope to improve our ability to make accurate forecasts of TC intensity change. Enhancing this predictive capability would not only save our economy billions of dollars but more importantly it would save countless lives.


Method:

The two primary scientific objectives would be to observe and better understand:

  • The surface ocean and atmospheric boundary layer environment ahead of and along the projected TC track

  • The low-level inflow layer associated with a mature hurricane.
Under the first objective, the PI and select key participants plan to investigate Sea Surface Temperature (SST) variability along the predicted storm track as well as the thermodynamic structure of the ambient atmospheric boundary layer ahead of the storm. The motivation for this work is multifold. Findings from Cione and Uhlhorn (2003) show a clear link between SST variability within the TC inner core environment and subsequent changes in storm intensity. In addition, such an experiment would also support recent work by Dunion et al. (2004) that illustrates a relationship between ambient low moisture conditions surrounding the TC and storm intensity change.

This experiment would also be in support of ongoing funded work by Cione under NOAA's 2003-05 Joint Hurricane Testbed (JHT) as well as the scientific foci associated with the African Monsoon Multidisciplinary Analysis (AMMA) field experiment scheduled for 2006.

Under the second objective, the focus would be to document the TC inflow layer out ahead of the storm, through the storm eyewall region and into the eye and compare these findings with recent results from Cione and Uhlhorn (2003), Wroe and Barnes (2003), and Cione et al (2000). As mentioned previously, documenting and improving our understating of this rarely observed high wind storm environment is critical if we are to significantly improve future forecasts of TC intensity change.

This project is funded by the OAR Assistant Administrator's Discretionary Fund (AADF) project, the JHT, and NASA. This includes 75 Aerosonde flight hours as well as travel costs for the PI to the Aerosonde Wallops Island VA launch facility.


Accomplishment:


Key references:

  • Cione, J.J., and E. W. Uhlhorn 2003: Sea surface temperature variability in hurricanes: Implications with respect to intensity change. Mon. Wea. Rev., v.131, pp.1783-1796
  • Wroe, D.R. and G.M. Barnes 2003: Inflow Layer Energetics of Hurricane Bonnie (1998) near Landfall. Mon. Wea. Rev. v.131 pp. 1600-1612
  • Cione, J.J., P. J. Black and S. Houston 2000: Surface observations in the hurricane environment. Mon. Wea. Rev, v.128 pp.1550-1561
  • Dunion, J.P., and C.S. Velden, 2004: The impact of the Saharan Air Layer on Atlantic tropical cyclone activity. Bull. Amer. Meteor. Soc., v.85 no. 3, pp.353-365


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Last modified: 4/04/2005

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