Impacts of QuikSCAT on Tropical Prediction Center Operations

Richard Knabb, Christopher Hennon, Daniel Brown, James Franklin, Hugh Cobb, Jamie Rhome, and Robert Molleda NOAA/NWS/NCEP/TPC/National Hurricane Center, Miami, FL

TPC/NHC Core Operational Products

• • • • • • • •

Hurricane Specialists

Tropical Cyclone Public Advisory Tropical Cyclone Forecast/Advisory Tropical Cyclone Discussion Tropical Cyclone Strike Probabilities Special Disturbance Statements Tropical Cyclone Updates Tropical Cyclone Position Estimates Tropical cyclone graphics

• • • • • • • • •

Tropical Analysis and Forecast Branch (TAFB)

High Seas Forecasts Offshore Waters Forecasts Tropical Weather Discussions Marine Weather Discussions Tropical surface analysis Graphical marine products Dvorak intensity estimates and satellite position fixes Satellite rainfall forecast guidance Pan-American temperature and precipitation table

TPC/NHC AREAS OF RESPONSIBILITY TPC HURRICANE FORECAST AREA TPC TAFB FORECAST AREA TPC TAFB ADDITIONAL SURFACE ANALYSIS AREA TPC BACKUP AREA FOR OCEAN PREDICTION CENTER (MOSTLY HIDDEN) TPC BACKUP AREA FOR WFO HONOLULU AND CPHC AREAS (PARTIALLY HIDDEN) TPC BACKUP AREA FOR AVIATION WEATHER CENTER (COMPLETELY HIDDEN)

Land, island and marine (ships, buoys) TPC Numerical Weather Prediction Overview 4

QuikSCAT Fills Some Data Gaps However, it has gaps of its own between swaths, which are fairly large in the Tropics

NAWIPS Display of QuikSCAT Data

Ship data still important, esp. in swath gaps

Surface Analysis without QuikSCAT

Surface Analysis without QuikSCAT

Surface Analysis with QuikSCAT

Surface Analysis with QuikSCAT High Seas Forecast

Surface Analysis with QuikSCAT

Central America Gap Winds Rain flag often fails in these events Gulf of Tehuantepec Gulf of Papagayo

Visit the TPC/TAFB Poster on Tehuantepec Events

Funneling of Winds in Atlantic Passages Windward Passage Mona Passage

Intertropical Convergence Zone Including broad/double ITCZ structures 18 March 2004

Edge of Swath Problems Very common in the Caribbean Bad Data

Nov-Dec 2003 TAFB Forecaster Survey Results

•

QuikSCAT data used during forecast shift at least 75% of the time

•

When QuikSCAT led to changes in the wind velocities in analyses and forecasts, the revised winds were higher about 65% of the time

•

Primary reasons for QuikSCAT data not being used on a particular forecast cycle are lack of timeliness and/or lack of data over the feature/area of interest

TAFB Warning Events

Gales/Storms T.S./Hurcn

80

# E v e n t s

60 40 20 0 21 34 1999 32 42 28 40 22 48 32 48 2000 2001 2002

Year

2003 27 46 2004

More than tropical cyclones

QuikSCAT Impacts on TAFB Products

•

Important tool for locating weather features

•

Important for determining the extent of certain wind speeds around a feature, which can affect warnings

•

Data source for verifying forecasts and warnings

•

Assist in determining reliability of ship data

•

Comparison with model analyses and short-term forecasts

•

Forecasters have gained a much better understanding of localized wind events (e.g., terrain gap flows)

•

Increased confidence in forecasting these events

•

Losing scatterometer data, without a viable replacement, would be severely detrimental to TAFB marine analyses, forecasts, and warnings

Hurricane Karl (2004)

Hurricane Karl (2004)

Hurricane Karl (2004)

Hurricane Karl (2004)

Hurricane Karl (2004)

Hurricane Karl (2004)

Hurricane Karl (2004)

Wind radii in N semicircle expanded from 120 to 175 nm However, uncertainty is high since rain contamination a significant problem in tropical cyclones

Manual Directional Ambiguity Analysis

Formation of Tropical Depression #2 3 Aug 2004 Northerly and northwesterly ambiguities suggest possible closed circulation

Visit the TPC/NHC Poster on Ambiguity Analysis

Normalized Radar Cross Section Imagery

Concentric Eyewalls of Hurricane Isabel 11 Sep 2003

QuikSCAT Impacts on NHC Products

•

Sometimes useful for estimating 34 kt wind radii

•

Not as useful for 50 and 64 kt radii due to rain contamination

•

Sometimes useful in estimating the intensity of tropical depressions and weak tropical storms, but not for hurricanes

•

Automated solutions not very useful in TC center fixing

•

Directional ambiguities sometimes analyzed to help determine if and where a surface circulation exists

•

NRCS imagery occasionally useful in TC location fixing and in discerning concentric eyewalls

•

Slight positive impact on NWP forecasts of TC track

•

QuikSCAT explicitly mentioned during 2004 in 47 Tropical Cyclone Discussions (TCDs) for the Atlantic basin and in 43 TCDs for the eastern North Pacific basin

Looking Ahead

•

Continued operational availability of scatterometer data is greatly needed in TPC operations

•

TPC forecasters have gained substantial experience with scatterometer data and have learned to extract much useful information… hopefully an investment in the future

•

More than one instrument is needed due to large gaps between swaths in the Tropics and due to infrequent passes over a feature of interest

•

Improvements needed to address challenges of rain contamination and directional ambiguities

•

Ideally, if the passive radiometer is to be the future platform for retrieving ocean surface vector winds in operational tropical meteorology, it must be as accurate as the scatterometer

•

Highly applied research with both platforms ongoing at TPC

TPC/NHC Branch Responsibilities

•

Hurricane Specialists (NHC) Develop, coordinate (domestically and abroad), and issue tropical

•

cyclone warnings, forecasts, and outlooks Provide "off season” training to emergency managers, meteorologists,

• •

and the media Conduct applied research and interact with research community Conduct public awareness programs

•

Tropical Analysis and Forecast Branch (TAFB)

Develops, coordinates, and issues marine analyses, forecasts, and

• •

warnings

•

Provides satellite-based position and intensity estimates for tropical cyclones and other disturbances Conducts public outreach to mariners Augments operational support staffing to Specialists

•

Technical Support Branch (TSB)

•

Provides computer systems support 24x7, applications development, training, and technology infusion Emergency operational support staffing to other branches

140 °W 30 °N EQ 18.5

°S 31 °N 7 °N 35 °W

Surface Analysis in Hurricane Season

Another Mona Passage Example

Quikscat from 0050 UTC 25 January. Surface observations from 0400 UTC SSTs in Red

20 and 34 kt Wind Radii Estimation

15.0

10.0

5.0

0.0

-5.0

-10.0

-15.0

-20.0

12

QuikSCAT Impact on Model TC Track Forecasts

Impact of Removing AMSU, HIRS, GOES Wind, Quikscat Surface Wind Data on Hurricane Track Forecasts in the Atlantic Basin - 2003 (34 cases) NOAMSU NOHIRS NOGOESW NOQuikscat 24 36 48 Forecast Hour 72 96 120 Satellite data ~ 10-15% impact Jung and Zapotocny JCSDA work funded by NPOESS IPO