Peter P. Dodge

The Intensity Forecasting Experiment: A NOAA Multiyear Field Program for Improving Tropical Cyclone Intensity Forecasts

Abstract In 2005, NOAAs Hurricane Research Division (HRD), part of the Atlantic Oceanographic and Meteorological Laboratory, began a multiyear experiment called the Intensity Forecasting Experiment (IFEX). By emphasizing a partnership among NOAAs HRD, Environmental Modeling Center (EMC), National Hurricane Center (NHC), Aircraft Operations Center (AOC), and National Environmental Satellite Data Information Service (NESDIS), IFEX represents a new approach for conducting hurricane field program operations. IFEX is intended to improve the prediction of tropical cyclone (TC) intensity change by 1) collecting observations that span the TC life cycle in a variety of environments; 2) developing and refining measurement technologies that provide improved real-time monitoring of TC intensity, structure, and environment; and 3) improving the understanding of the physical processes important in intensity change for a TC at all stages of its life cycle. This paper presents a summary of the accomplishments of IFEX d...

The landfall of Hurricane Hugo in the Carolinas : surface wind distribution

Abstract Hurricane Hugo struck Charleston, South Carolina, on 22 September 1989 as the most intense hurricane to affect the United States since Camille in 1969. The northeastern eyewall, which contained the maximum winds measured by reconnaissance aircraft shortly before landfall, moved inland over a relatively unpopulated area and there were few fatalities. However, no observations were available to document the surface wind distribution in this part of the storm as it continued inland. To improve specification of surface winds in Hugo, empirically adjusted aircraft winds were combined with coastal, offshore, and inland surface observations and were input to the Ooyama objective analysis algorithm. The wind analysis at landfall was then compared with subsequent analyses at 3 and 6 h after landfall. Reconstruction of the surface wind field at landfall suggests that the maximum (∼13 min mean) surface wind at the coast was 50 m s−1 in the Bulls Bay region, ∼40 km northeast of Charleston. Surface roughness o...

A REANALYSIS OF HURRICANE ANDREW'S INTENSITY

Hurricane Andrew of 1992 caused unprecedented economic devastation along its path through the Bahamas, southeastern Florida, and Louisiana. Damage in the United States was estimated to be

The kinematic structure of a hurricane with sea level pressure less than 900 mb

26 billion (in 1992 dollars), making Andrew one of the most expensive natural disasters in U.S. history. This hurricane struck southeastern Florida with maximum 1-min surface winds estimated in a 1992 poststorm analysis at 125 kt (64 m s−1). This original assessment was primarily based on an adjustment of aircraft reconnaissance flight-level winds to the surface. Based on recent advancements in the understanding of the eyewall wind structure of major hurricanes, the official intensity of Andrew was adjusted upward for five days during its track across the Atlantic Ocean and Gulf of Mexico by the National Hurricane Center Best Track Change Committee. In particular, Andrew is now assessed by the National Hurricane Center to be a Saffir–Simpson Hurricane Scale category-5 hurricane (the highest intensity category possible) ...

Mapping of airborne doppler radar data

Abstract A National Oceanic and Atmospheric Administration aircraft recorded the first Doppler radar data in a tropical cyclone with a minimum sea level pressure (MSLP) 50 m s−1 extended to 12 km, higher than has been reported in previous hurricanes. The inner eyewall contained weak ...

Real-Time Implementation of Single-Doppler Radar Analysis Methods for Tropical Cyclones: Algorithm Improvements and Use with WSR-88D Display Data

Abstract Two sets of equations are derived to 1) map airborne Doppler radar data from an aircraft-relative coordinate system to an earth-relative coordinate system, and 2) remove the platform motion from the observed Doppler velocities. These equations can be applied to data collected by the National Oceanic and Atmospheric Administration WP-3D system, the National Center for Atmospheric Research ELDORA system, and other airborne radar systems.

An Observational Study of Hurricane Boundary Layer Small-Scale Coherent Structures

Abstract The NOAA/NWS/NCEP/Tropical Prediction Center/National Hurricane Center has sought techniques that use single-Doppler radar data to estimate the tropical cyclone wind field. A cooperative effort with NOAA/Atlantic Oceanographic and Meteorological Laboratory/Hurricane Research Division and NCAR has resulted in significant progress in developing a method whereby radar display data are used as a proxy for a full-resolution base data and in improving and implementing existing wind retrieval and center-finding techniques. These techniques include the ground-based velocity track display (GBVTD), tracking radar echoes by correlation (TREC), GBVTD- simplex, and the principal component analysis (PCA) methods. The GBVTD and TREC algorithms are successfully applied to the Weather Surveillance Radar-1988 Doppler (WSR-88D) display data of Hurricane Bret (1999) and Tropical Storm Barry (2001). GBVTD analyses utilized circulation center estimates provided by the GBVTD-simplex and PCA methods, whereas TREC analys...

Intercomparison of Ground-Based Velocity Track Display (GBVTD)-Retrieved Circulation Centers and Structures of Hurricane Danny (1997) from Two Coastal WSR-88Ds

Abstract Data with high temporal and spatial resolution from Hurricanes Isabel (2003) and Frances (2004) were analyzed to provide a detailed study of near-surface linear structures with subkilometer wavelengths of the hurricane boundary layer (HBL). The analysis showed that the features were omnipresent throughout the data collection, displayed a horizontal and vertical coherency, and maintained an average orientation of 7° left of the low-level wind. A unique objective wavelength analysis was conducted, where wavelength was defined as the distance between two wind maxima or minima perpendicular to the features’ long axis, and revealed that although wavelengths as large as 1400 m were observed, the majority of the features had wavelengths between 200 and 650 m. The assessed wavelengths differ from those documented in a recent observational study. To evaluate the correlation between the features and the underlying near-surface wind field, time and spectral analyses were completed and ground-relative freque...

Characteristics of Rainbands, Radar Echoes, and Lightning near the North Carolina Coast during GALE

Abstract A plausible primary circulation and circulation center of a tropical cyclone (TC) can be deduced from a coastal Doppler radar using the ground-based velocity track display (GBVTD) technique and the GBVTD-simplex algorithm. The quality of the retrieved primary circulation is highly sensitive to the accuracy of the circulation center that can only be estimated from the degree of scattering of all possible centers obtained in GBVTD-simplex analyses from a single radar in real TCs. This study extends previous work to examine the uncertainties in the GBVTD-simplex-derived circulation centers and the GBVTD-derived primary circulations in Hurricane Danny (1997) sampled simultaneously from two Doppler radars [Weather Surveillance Radar-1988 Dopplers (WSR-88Ds) in Mobile, Alabama, and Slidell, Louisiana] for 5 h. It is found that the mean difference between the individually computed GBVTD-simplex-derived centers is 2.13 km, similar to the estimates in previous studies. This value can be improved to 1.59 k...

Reconstruction of Hurricane Katrina's wind fields for storm surge and wave hindcasting

Abstract Characteristics of mesoscale rainbands and echoes in radar reflectivity data recorded during the field phase of the Genesis of Atlantic Lows Experiment (GALE) are presented. The primary sources of data were radar microfilm and manually digitized radar (MDR) reports from the operational National Weather Service (NWS) radars at Cape Hatteras (HAT) and Wilmington (ILM), North Carolina. The dataset also included cloud-to-ground lightning flashes that were recorded by the network operated by the State University of New York at Albany. The analyses included rainbands of at least 90-km length with lifetimes of at least 2 h. Nearly all of the rainbands were within 400 km of synoptic-scale or coastal fronts. Warm-sector rainbands predominated. Rain-bands were clarified by the location of their initial detection relative to the land. coastal shelf, and Gulf Stream. Rainbands were initially identified more frequently over the Gulf Stream and ten often over the coastal shelf than the corresponding fractional...