Aerosonde Observations in the Hurricane Boundary Layer Environment

Principal Investigator: Joseph J. Cione, Ph.D
National Oceanic and Atmospheric Administration
Atlantic Oceanographic and Meteorological Laboratories
Hurricane Research Division
Miami, FL

Key Participants: Jason Dunion*, Eric Uhlhorn*, Brenda Mulac^, Greg Holland#, Chris Sisko+
* University of Miami/Rosenstiel School of Marine and Atmospheric Science
^ Aerosonde Corporation
# National Center for Atmospheric Research/Mesoscale and Microscale Meteorology Division
+ NOAA/Tropical Prediction Center

1. Introduction

Hurricanes, and other severe weather events cause several deaths and an average of $11 billion in damages each year 
to the U.S. economy. Three strategies that have been identified by NOAA that would help address and ultimately 
mitigate these major concerns are outlined in NOAAÕs stated mission goal of Weather and Water.  These strategies 
are to:

Monitor and Observe  To meet societyÕs diverse and expanding needs for weather-related  information, we will 
work with our international and domestic partners to cost-effectively increase  the number, breadth, accuracy, and 
availability of observation systems. 

Understand and Describe  We will invest in new technologies, techniques, and weather and water forecast 
modeling to improve the accuracy and timeliness of our prediction capabilities and services.  

Assess and Predict  To reduce uncertainty and increase the economic benefits to the Nation from our forecast and 
warning capabilities, we will improve the performance of our suite of weather and water, air quality, and space 
weather prediction capabilities.   

These three strategies, when combined, fit very well with the overall goals of this funded OAR Assistant 
AdministratorÕs Discretionary Fund (AADF) project.

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 NOAAÕs 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).

2. Statement of the problem

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 
ocean meets the sea, is critically important since it is where the oceanÕs 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.  

3. Proposed solution and science objectives

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 NOAAÕs Weather and Water stated outcome of "Increased accuracy and amount of lead time."

Specifically, the two primary scientific objectives would be to observe and better understand:

_ The surface ocean and atmospheric boundary layer environment ~24h ahead of the TC along the projected 
storm track and;

_ 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 
 (http://www.joss.ucar.edu/amma).

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 composite storm results recently found by 
Cione et al. (2000) and Cione and Uhlhorn (2003).  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. 

4. FY2005 Budget 

Current funding for this project is $25,000.  This represents the total (NASA partially-subsidized) cost for 75 
Aerosonde flight hours as well as travel costs for the PI to the Aerosonde Wallops Island VA launch facility.

Direct Aerosonde Flight Hours Cost for FY05						$23,000
(25h for a pre-storm module and 50h for two in-storm modules; 75h total)
Travel Costs for Cione to Wallops VA 							$2,000
(Coordinate/plan/conduct the 2 day Aerosonde flight plan)	
									--------------------------------	
									Total		$25,000

5. References

Cione, J.J., and E. W. Uhlhorn 2003: Sea surface temperature variability in hurricanes: Implications with respect to 
intensity change.  Mon. Wea. Rev. 131, 1783-1796.
Cione, J.J., P. J. Black and S. Houston 2000:  Surface observations in the hurricane environment.  Mon. Wea. Rev, 
128 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., 85 no. 3, 353-365.