6C.7 Use of Reconnaissance Aircraft Data in Estimating Hurricane Intensity

Saturday, 14 November 2009: 10:00 AM
Nipun Aggarwal, NOAA, New York, NY; and J. Jeyaratnam and Z. J. Luo

The importance of accurate estimate of hurricane intensity can hardly be overstated. At present, almost all estimates are made from satellites (except for the Atlantic basin where reconnaissance aircraft are regularly dispatched to survey these deadly storms). Current satellite operational methods contain some large uncertainties at certain conditions. It is therefore of interest to develop new alternative techniques. The Emanuel method, as developed by Prof. Kerry Emanuel of MIT, is such a method. It can be briefly summarized as:

Vm^2 = (heyewall - ho) (Ts – To) / To

Vm = Peak hurricane wind speed

Ts = Sea Surface Temp.

To = Cloud-top Temperature

h* = Moist Static Energy (MSE)

h = CpT + gZ + Lvq

T = Air Temperature in Kelvin

g = Gravitational Force

Z = Height

q = Specific Humidity

Lv= Latent Heat

Cp= Isoboric Specific Humidity Capacity of dry air

Specific Humidity is found using the following equations:

Clausius-clapeyron equation

Pe = 6.612 e (17.67 * tdew / (tdew + 243.5))

Specific Humidity

Q = 0.622 * pe / static pressure

The purpose of this research is to use reconnaissance aircraft data to calculate the defining parameters (in particular MSE) and to test the Emanuel method. The estimated wind speed based on the equation above will be evaluated against observations of true wind speed. Our REU research of this past summer focused on analyzing aircraft reconnaissance data to estimate the distribution of MSE for a few hurricane cases. Preliminary results will be presented.

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