A Comparison of Ensemble Spread, ETKF and Singular Vector Targeting Guidance for Tropical Cyclones

Dr Sharanya J. Majumdar (UM/RSMAS/MPO), Dr Melinda S. Peng (NRL Monterey), Dr Carolyn A. Reynolds (NRL Monterey), Dr Roberto Buizza (ECMWF), Dr Craig H. Bishop (NRL Monterey), Dr Sim D. Aberson (NOAA/AOML/HRD)

Introduction

While the ETKF and Singular Vector targeted observing strategies have been demonstrated to be effective for 1-3 day weather forecasts in the mid-latitudes, they have not yet been tested for tropical cyclone forecasts. The aim of this collaborative project is to identify and understand similarities and differences between the respective techniques, in the target regions that they recommend for guidance. They will also be compared against the present operational strategies of uniform sampling and ensemble spread, used by the NOAA National Hurricane Center and Hurricane Research Division to design flight tracks for the NOAA Gulfstream G-IV Jet aircraft.

Comparisons are performed for all Atlantic Basic cases, in which the aim is to improve a 2-day forecast
Targeting time = Initialization time + 48/60h
Verification time = Targeting time + 48h

Singular Vector, ETKF and Ensemble Spread targeting maps (78 cases)

Interpretation of these maps:

ETKF Summary Maps : maps of the vertically averaged "signal variance" within the verification region, as a function of the hypothetical observing location.
Ensemble Spread : maps of the ensemble variance or "spread" of the wind fields, valid at the targeted observing time.
Singular Vectors : initial-time singular vectors, from which errors are predicted to grow most rapidly into the verification region.

NEW (added Jan 31, 2005)
Maps on large scale (140-0W, 0-70N)
Maps on synoptic surveillance scale (within 15^o of storm center)

On the following table: click on the storm's name to access the NHC Advisory Archive.
Click on the corresponding observing dates (all 1 link) to access the directory of targeting plots for that storm.
G: G-IV flew on that date, C: C-130 flight. (Some G-IV and C-130 flights also flew on 12Z.)
Date in filename corresponds to ensemble initialization date, which is 48-h prior to the targeted observing date.
nc: 20-member NCEP ensemble (00Z, 12Z), ec: 50-member ECMWF ensemble (12Z)

Alex	Charley	Danielle	Earl	Frances	Gaston	Ivan	Jeanne	Karl	Lisa
2004080300 2004080400 2004080600	2004081200G 2004081300G 2004081400 2004081500	2004081600 2004081700 2004081800 2004081900 2004082000 2004082100 2004082200 2004082300	2004081600 2004081700 2004081800	2004082700 2004082800 2004082900 2004083000GC 2004083100GC 2004090100 2004090200GC 2004090300G 2004090400G 2004090500 2004090600 2004090700 2004090800	2004083000 2004083100	2004090500 2004090600 2004090700G 2004090800G 2004090900G 2004091000G 2004091100G 2004091200G 2004091300G 2004091400 2004091500G 2004091600G 2004091700 2004091800	2004091600 2004091700 2004091800C 2004091900 2004092000 2004092100 2004092200 2004092300 2004092400G 2004092500G 2004092600 2004092700 2004092800 2004092900	2004091900 2004092000 2004092100 2004092200 2004092300 2004092400 2004092500	2004092200 2004092300 2004092400 2004092500 2004092600 2004092700 2004092800 2004092900 2004093000 2004100100

Additional links:
NOAA/AOML Hurricane Research Division	National Hurricane Center	NRL Monterey Tropical Cyclones	CIMSS Wisconsin	Unisys Hurricane Archive

A Comparison of Ensemble Spread, ETKF and Singular Vector Targeting Guidance for Tropical Cyclones

Dr Sharanya J. Majumdar (UM/RSMAS/MPO), Dr Melinda S. Peng (NRL Monterey), Dr Carolyn A. Reynolds (NRL Monterey), Dr Roberto Buizza (ECMWF), Dr Craig H. Bishop (NRL Monterey), Dr Sim D. Aberson (NOAA/AOML/HRD)

Introduction

Singular Vector, ETKF and Ensemble Spread targeting maps (78 cases)

Interpretation of these maps:

Additional links: