A Multi-Faceted Examination of the Extratropical Transition of Tropical Cyclones Steve Guimond ONR Intern FSU/COAPS Tuesday, July 19, pm

Overview of Extratropical Transition (ET) symmetric,warm-core,non-frontal,barotropic GOES-12 1 km VIS Hurricane Karl 20 Sep Z 17N Typhoon Sonca 25 Apr Z 16N

Overview of Extratropical Transition (ET) asymmetric,cold-core,frontal,baroclinic GOES-12 1 km VIS GOES-9 4 km IR Hurricane Karl 24 Sep Z 40N Typhoon Sonca 25 Apr Z 21N

Tracking TC Structure: Cyclone Phase Space (Dr. Robert Hart FSU)

Who Cares? Why Is This Important? ET can produce: –Continuation of high winds with wind field expansion –Large ocean swell –Extreme rainfall (intensity and accumulation) –Rapid track accelerations Forecasting Challenges –Predicting track,intensity and rainfall –Warning for high winds,heavy seas and flooding Threat to Naval operations in various sub-tropical ocean basins

How Can I Help Solve The Problem? New Approaches to Analyzing ET Focus: Quantitative Precipitation Forecasting (QPF) (1)Multi-Satellite Blended Precipitation Products (2)Mapping Cyclone Structural Phase from Satellite Perspective (3)Algorithm to Compute CAPE from AMSU/HIRS for Convective Rainfall Predictive Purposes Master’s Thesis (1)Computing Moisture Budget (2)Describing Dynamical Forcings from Phase Space

Model Moisture Evaluation: Hurricane Karl ECMWF 1.125° vs. NOGAPS QUASI 1.0° –Mean hPa Relative Humidities Compared to GOES-12 WV(ch 3) 4 km –Weighting Function Peaks in ~ hPa Layer Purpose: To find model that describes evolution of ET signatures more realistically

ECMWF ° NOGAPS ~1.0 °

ECMWF ° NOGAPS ~1.0 °

Isentropic Ertel Potential Vorticity Hurricane Karl 2004 Explains interaction and response of TC from movement into a baroclinic environment

Isentropic Ertel Potential Vorticity Animation Typhoon Sonca 2005 Early Season Case: Storm Sheared Apart By Sub-Tropical Jet

Multi-Satellite Blended Precipitation Products Buffet of Passive Microwave Sensors (“constellation”) –TRMM TMI/PR –F-13/14/15 DMSP/SSMI –NOAA-15/16/17 AMSU-B –EOS AMSR-E Utilize rapid time capability of geo-IR to calibrate the IR obs between gaps in constellation Result ? High quality precip on dense space and time scales NASA vs. NRL: NRL smaller error!!

Blended Satellite Precipitation NRLB:Hurricane Karl Mean 3 hourly rainrate

Blended Satellite Precipitation NRLB:Typhoon Sonca 2005 Mean 3 hourly rainrate

Precipitation Evolution Analysis Techniques Divide storm into annuli Examine mean precipitation change (intensity and accumulation) vs. time and distance from TC center Serve as risk assessment tool for ET precipitation enhancement and flooding

Mapping Cyclone Structural Phase: Satellite Perspective TRMM PR Bright Band Heights proxy for warm/cold core structure –Bright Band = distinct radar signal created by frozen hydrometeors falling through storm melting layer –Stratiform precipitation typically associated with convective cells –Retrieve melting layer heights along ET track produce satellite derived cyclone phase

Test Case: Typhoon Meari 2004 TRMM PR STATS –4 km horizontal resolution –250 m vertical resolution –220 km swath width –Coverage: 40°N/S –100 along track scans/minute –49 across track rays/scan AMSU

TRMM PR Vertical Cross Section Animation Things to look for: (1)Fluctuations in Convective Cloud Heights Mirrors intensity change (2) Development of Outer Core/Asymmetric Precipitation ET Signature (3) Changes to darker colors Heavy precipitation;Higher dBZ values

Zoomed Snapshots: Two Stages of Typhoon Meari Warm CoreCold Core

A TRMM PR STRUCTURAL TRACK

Features of CAPE algorithm Soundings produced from retrievals of T and Q at each pixel of AMSU/HIRS Mixed layer parcel –100 hPa tropics;50 hPa mid-lats yields more accurate cloud base heights and CAPE (Craven et al. 2002) Virtual temperature correction –Accounts for variable amount of moisture allowing use of dry gas constant when calculating density Accounts for irregular soundings –Unrealistic tropopause levels –Parcel acquiring negative buoyancy

Test Case: Hurricane Karl Examining Convective Precipitation Trough approaching high CAPE Response to CAPE

TEST CASE: Hurricane Karl Potential for convective forecasting over various ocean basins and regions with sparse radiosonde networks TC Genesis Studies

What to Take Away From this Seminar Multi-satellite blended precipitation products useful for QPF studies –Explain ET rainfall enhancement –Blazing Trails: Never been done before with ET Objective satellite cyclone phase –Shown to distinguish ET commencment from warm to cold core –Promise for future work CAPE algorithm useful for convective precipitation forecasting –AMSU/HIRS derived soundings need work in upper levels

MANY,MANY THANKS TO Jeff Hawkins –Support for Internship;Insightful comments;Food and Beverage (pumpkin bread) Joe Turk –Extensive knowledge of satellite precipitation;Making me spend 3+ hours retrieving TRMM data Clay Blankenship and Ben Ruston –Retrievals for CAPE;support for coding issues Kim Richardson –Computer assistance and book loans Rob Wade –NOGAPS and GOES WV data Everyone who made my stay an enjoyable one!

Thanks to Tom Lee for BIG SUR TRIP

ECMWF ° NOGAPS ~1.0 °

ECMWF ° NOGAPS ~1.0 °

ECMWF ° NOGAPS ~1.0 °