# Presentation: 716905

## Tropical Cyclones

**by**
***Kristina B. Katsaros***
**for the**
**Atlantic Oceanographic and Meteorological Laboratory (AOML)**
**and**
**Geophysical Fluid Dynamics Laboratory (GFDL)**

**Presentation at NWS/OAR Weather Workshop**

- NWS/OAR Workshop

- March 26-27, 2002

## Two Atlantic hurricanes:  Floyd (1999) and Andrew (1992), seen from the GOES satellite in visible light at the same scale (note the outlines of Florida and Cuba).  Floyd was about 1000 km in diameter, while Andrew was half the size at 500 km.

**Two Atlantic hurricanes:  Floyd (1999) and Andrew (1992), seen from the GOES satellite in visible light at the same scale (note the outlines of Florida and Cuba).  Floyd was about 1000 km in diameter, while Andrew was half the size at 500 km.**

- NWS/OAR Workshop

- March 26-27, 2002

## Hurricane Modeling and Simulation at GFDL

**Plans for the next five years:**
**Year 1: Development of a WRF prototype model**
**Year 2: Experiments commence with increasing resolution to 5 km**
**Year 3: Continue development of modeling system, including the incorporation of both nesting feasibility and ocean coupling**
**Year 4: Run computational intense simulations of all life cycles of hurricane development**
**Year 5: The research model is now ready to be considered for operational use**

- NWS/OAR Workshop

- March 26-27, 2002

## Tropical Cyclone (TC) Research at AOML

**Research involves:**
**Observation targeting strategies to improve hurricane track forecasts**
**Operational five-day tropical cyclone ensemble forecasts with a barotropic model**
**A climatology and persistence baseline model for hurricane rainfall forecasts**
**Operational real-time surface wind analyses**
**Statistical prediction of rapid intensification**
**Deployment of the Stepped-Frequency Microwave Radiometer (SFMR) on all reconnaissance aircraft**

- NWS/OAR Workshop

- March 26-27, 2002

## Four G-IV surveillance missions were flown in Hurricane Michelle (2001).  Forecast track improve-ments in the AVN model were between 40% and 75% at all forecast times except 12 h and     72 h.  This allowed forecasters to correctly predict that Michelle would not strike south Florida as a major hurricane.

**Four G-IV surveillance missions were flown in Hurricane Michelle (2001).  Forecast track improve-ments in the AVN model were between 40% and 75% at all forecast times except 12 h and     72 h.  This allowed forecasters to correctly predict that Michelle would not strike south Florida as a major hurricane.**

**The surveillance missions improved already very good forecasts.  During the first two years of operations (1997-1998), surveillance missions improved track forecasts.**

- NWS/OAR Workshop

- March 26-27, 2002

## 40-member orthonormalized bred-mode VICBAR ensemble.  Note the easternmost ensemble member with a forecast track along the southeastern Florida coast.  This track was not the most likely track, a slight possibility existed that Irene would follow this track.

**40-member orthonormalized bred-mode VICBAR ensemble.  Note the easternmost ensemble member with a forecast track along the southeastern Florida coast.  This track was not the most likely track, a slight possibility existed that Irene would follow this track.**

**Operational forecast models initialized at the same time as the VICBAR ensemble.  Note that none of the operational models forecasted the track up the east coast.  The actual track is “BTRK.” The VICBAR ensemble was able to show the possibility that the actual track would occur, whereas the deterministic models were unable to do so.**

- NWS/OAR Workshop

- March 26-27, 2002

## The average NHC track and intensity forecasts for the period 1993-1997.  Errors were normalized by the average errors from climatology and per-sistence models (CLIPER for track and SHIFOR for intensity). A negative normalized error indicates improvement over climatology and persistence (forecast skill).

**The average NHC track and intensity forecasts for the period 1993-1997.  Errors were normalized by the average errors from climatology and per-sistence models (CLIPER for track and SHIFOR for intensity). A negative normalized error indicates improvement over climatology and persistence (forecast skill).**

- NWS/OAR Workshop

- March 26-27, 2002

## 1997-2000 operational over-water forecast skill relative to the climatological and persistence model (SHIFOR) for all cases with maximum winds  35 kt.

**1997-2000 operational over-water forecast skill relative to the climatological and persistence model (SHIFOR) for all cases with maximum winds ******** 35 kt.**

- NWS/OAR Workshop

- March 26-27, 2002

## 24 h tracks of the 1989-2000 cases of rapid intensification

**24 h tracks of the 1989-2000 cases of rapid intensification**
**(maximum wind speed increase of 30 kt or greater over 24 hr)**

- NWS/OAR Workshop

- March 26-27, 2002

## The predictors and rapid intensification (RI) thresholds used in the SHIPS RI index. The SHIPS RI index was made available operationally at the NHC on 2 August 2001.

- NWS/OAR Workshop

- March 26-27, 2002

## Precipitation estimates: R-CLIPER (CLImatology and PERsistence) cases.  Statistical estimate of rain amount as a function of storm intensity and integrated along the track (color contours denote storm total rain (inches).

**Best Track (6 h)**

**Precipitation estimates: R-CLIPER (CLImatology and PERsistence) cases.  Statistical estimate of rain amount as a function of storm intensity and integrated along the track (color contours denote storm total rain (inches).**

**Andrew 92**

**Danny 97**

**Floyd 99**

**Allison 01**

- NWS/OAR Workshop

- March 26-27, 2002

## Operational Support to TC Forecasting

**Hold daily weather briefings**
**Perform aircraft surveillance missions on the WP-3D and G-IV aircraft for hurricanes near Cuba and at landfall**
**Prepare flight plans for and participate in surveillance G-IV missions**
**All year they:**
**Interact with the Aircraft Operations Center**
**Acquire expendable probes**
**Develop real time data analysis and communication software**
**Off-hurricane season, they:**
**Participate in national conferences: *****NOAA Hurricane Conference, Interdepart-mental Hurricane Conference, AMS Tropical Meteorology Conferences *****(biannually)*****, the Governor’s Conference***** (Florida), etc.**
**Participate in the international *****Workshop on Tropical Cyclones***** (WMO annual meeting on tropical cyclones) and in other venues**

**Operational Support to TC Forecasting**

- NWS/OAR Workshop

- March 26-27, 2002

## View of low-level clouds swirling in the center of Hurricane Floyd (1999) as seen from the window of one of NOAA’s WP-3D reconnaissance aircraft.  The WP-3D’s wingtip appears in the upper left corner.  The eyewall rises up in the far right corner another 10 km or so above the aircraft flight level which is at 4 km elevation.

**View of low-level clouds swirling in the center of Hurricane Floyd (1999) as seen from the window of one of NOAA’s WP-3D reconnaissance aircraft.  The WP-3D’s wingtip appears in the upper left corner.  The eyewall rises up in the far right corner another 10 km or so above the aircraft flight level which is at 4 km elevation.**

- NWS/OAR Workshop

- March 26-27, 2002

## Wind speed data collected by the aircraft’s Stepped-Frequency Microwave Radiometer (SFMR) during a transect through Hurricane Floyd.  Flight level winds at 4 km are higher, as expected.  Yellow symbols are from dropsonde data: squares represent the highest wind speeds measured; inverted triangles represent 100-m winds; and circles represent the last measured winds, i.e., surface wind speeds below 10-m height. The bottom trace is the rain rate.

**Wind speed data collected by the aircraft’s Stepped-Frequency Microwave Radiometer (SFMR) during a transect through Hurricane Floyd.  Flight level winds at 4 km are higher, as expected.  Yellow symbols are from dropsonde data: squares represent the highest wind speeds measured; inverted triangles represent 100-m winds; and circles represent the last measured winds, i.e., surface wind speeds below 10-m height. The bottom trace is the rain rate.**

- NWS/OAR Workshop

- March 26-27, 2002

## Surface wind analysis plot for Hurricane Michelle (November 4, 2001).  Wind analyses are used for determining the intensity and radial extent of the maximum sustained wind in tropical systems.

**Surface wind analysis plot for Hurricane Michelle (November 4, 2001).  Wind analyses are used for determining the intensity and radial extent of the maximum sustained wind in tropical systems.**

- NWS/OAR Workshop

- March 26-27, 2002

## In cooperation with NAVOCEANO, AOML annually deploys an array of buoys in the tropical Atlantic prior to the hurricane season that measure sea surface temperature, barometric pressure, wind speed, and wind direction. Data from these buoys are available in real time through the GTS system and aid researchers in the prediction and forecasting of hurricanes.

- NWS/OAR Workshop

- March 26-27, 2002

## Global Ocean Observations Support TC Prediction

**Drifting buoys**
**Expendable bathythermograph (XBT) lines**
**Argo**
**SEAS (Shipboard Environmental data Acquisition System) work: Voluntary observing ship data from certain ships (350 ships), approximately half of NOAA’s observing ships**
**Organization of and quality control of data furnished to GTS network and NWS**

**AOML collects data and operates data centers for weather and longer-range forecasts, as well as for climate studies:**

- NWS/OAR Workshop

- March 26-27, 2002

## New Thrusts

**Ozone measurements in hurricanes (since 1997 by AOML chemists).  Ozone is a tracer for vertical motion.**
**Saharan dust observations from satellites during 2001. The dust is a tracer for dry air from Africa and may be important for TC weakening.**
**Synthetic aperture radar from RADARSAT shows secondary flows and structure in surface wind around eyes.**
**Wave spectra work with surface contour radar (Ed Walsh, NASA/ETL).**

- NWS/OAR Workshop

- March 26-27, 2002

## Chemistry measurements gathered during Hurricane Floyd, September 1999. (a) Floyd near maximum intensity (category 4), aircraft heading southwest; (b) Aircraft heading westward over Eleuthera, Bahamas; and (c) aircraft heading northeast, just prior to landfall near Cape Fear, North Carolina at 06:30 z on September 16, 1999.

- NWS/OAR Workshop

- March 26-27, 2002

## Hurricane Erin/SAL Time Series:  2/5/9 September 2001

**Hurricane Erin/SAL Time Series:  2/5/9 September 2001**

**Yellows and oranges represent the thermal emission from Saharan dust at ~700 mb.  Dust is a tracer for dry air and low level wind surge, characteristic of the Saharan air layer.**

- NWS/OAR Workshop

- March 26-27, 2002

## Hurricane Erin Intensity

**Hurricane Erin Intensity**
**05 September - 15 September 2001**

- Intensity (kt)

- NWS/OAR Workshop

- March 26-27, 2002

## RADARSAT-1 SAR (left) and TRMM (right) images from Hurricane Mitch on 27 October 1998.  The SAR image at 1133 UT covers 184 x 322 km.  The TRMM image at 0837 UT has the same orientation as the SAR image and is 1060 x 1100 km.  The red box outlines the SAR swath.  The color scale is TRMM rainfall in mm/h.  Green = 10 mm/h; red = 20 mm/h.

**RADARSAT-1 SAR (left) and TRMM (right) images from Hurricane Mitch on 27 October 1998.  The SAR image at 1133 UT covers 184 x 322 km.  The TRMM image at 0837 UT has the same orientation as the SAR image and is 1060 x 1100 km.  The red box outlines the SAR swath.  The color scale is TRMM rainfall in mm/h.  Green = 10 mm/h; red = 20 mm/h.**

- NWS/OAR Workshop

- March 26-27, 2002

## RADARSAT-1 SAR images of five hurricane “eyes” from the 1998-1999 hurricane season.

**RADARSAT-1 SAR images of five hurricane “eyes” from the 1998-1999 hurricane season.**

- NWS/OAR Workshop

- March 26-27, 2002

## Research has its own Goals and Requirements

**The requirements for new research can be formulated, prioritized, and put on a “sort-of” schedule**
**For instance, for hurricane intensification, there are known influences whose relative importance are not well understood:**
**Wind shear in the environment**
**Source of fuel in terms of deep warm oceanic upper layer and speed of movement of storm over a warm eddy**
**Upper level vorticity impulses**
**Vortex dynamics, size (stability, contracting eyewalls)**

**Research has its own Goals and Requirements**

- NWS/OAR Workshop

- March 26-27, 2002

## Objectively analyzed heat content (color: KJ cm-2) and the depth of the 26C isotherm (contour in meters) for a) pre-hurricane Gordon, and b) tropical storm Helene. Data derived from the NOAA WP-3D research flights in late September 2000 based on a combination of AXCPs (star), AXCTDs (diamond), and AXBTs (circle) relative to the storm track and intensity (wind speed).

**Objectively analyzed heat content (color: KJ cm****-2****) and the depth of the 26********C isotherm (contour in meters) for a) pre-hurricane Gordon, and b) tropical storm Helene. Data derived from the NOAA WP-3D research flights in late September 2000 based on a combination of AXCPs (star), AXCTDs (diamond), and AXBTs (circle) relative to the storm track and intensity (wind speed).**

- NWS/OAR Workshop

- March 26-27, 2002