Circulations in the Atlantic Basin Philippe P Papin Ryan D Torn Lance F Bosart Department of Atmospheric and Environmental Sciences University at Albany State University of New York Funding provided by NSF grant ATM0849491 ID: 239076
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Slide1
Tropical Cyclone Interactions Within Gyre Circulations in the Atlantic Basin
Philippe P. Papin, Ryan D. Torn, Lance F. Bosart
Department of Atmospheric and Environmental SciencesUniversity at Albany, State University of New York
Funding provided by NSF grant ATM-0849491
Research Roundtable 2-17-2015Slide2
Motivation
Gyre circulations are rarely studied in the Atlantic basin
Sometimes associated with Tropical Cyclones (TCs)Frequently result in significant societal impact (flooding)Track uncertainty resulting from gyre – tropical cyclone (TC) interactionsTC Stan (2005)
5-day total precipitation and average 850-hPa windsSlide3
CAG Climatology
42 Cases over a 31 year period (1980-2010)Case of CAG that occurred in October 2005 (large blue dot)
CAG 1: Oct 3 – Oct 6Slide4
CAG Climatology
42 Cases over a 31 year period (1980-2010)Case of CAG that occurred in October 2005 (large blue dot)
CAG 1: Oct 3 – Oct 6Slide5
Synoptic EvolutionSlide6
Quantifying Role of CAG of TC Stan MotionSlide7
Piecewise Vorticity Inversion
Want to quantify what impact the CAG wind field has on the track of TC Stan
Invert the vorticity field only over the CAGRemove TC Stan vortex to obtain steering flowAlso look at steering flow without CAG circulationSteering layer flow 925 – 500-hPa layer meanSlide8
Invert Vorticity over 7
o
Circle
Invert
the vorticity field only over the CAGRemove TC Stan vortex to obtain steering flowAlso look at steering flow without CAG circulationSteering layer flow 925 – 500-hPa layer meanPiecewise Vorticity Inversion
Want to quantify what impact the CAG wind field has on the track of TC StanSlide9
Want to quantify impact of the CAG wind field on the track of TC Stan
Remove Vorticity over TC Stan (2.5
o
)
Invert
the vorticity field only over the
CAG
Remove
TC Stan vortex to obtain steering
flow
Also look at steering flow without CAG circulation
Steering layer
f
low 925 – 500-hPa layer mean
Piecewise Vorticity InversionSlide10
Want to quantify impact of the CAG wind field on the track of TC Stan
Remove CAG and TC to see Environmental Flow
Invert the vorticity field only over the CAGRemove TC Stan vortex to obtain steering flowAlso look at steering flow without CAG circulationSteering layer flow 925 – 500-hPa layer mean
Piecewise Vorticity InversionSlide11
Want to quantify impact of the CAG wind field on the track of TC Stan
Invert the vorticity field only over the
CAGRemove TC Stan vortex to obtain steering flowAlso look at steering flow without CAG circulationSteering layer flow 925 – 500-hPa layer mean
Remove CAG and TC to see Environmental Flow
Piecewise Vorticity InversionSlide12
Vorticity Inversion
Actual TC motion: 270
o at 9 kt1200 UTC 3 Oct 2005Winds associated with CAG (rgyre ≤ 7o)Winds associated with CAG (without TC Stan) (rgyre ≤ 7o) and (rstan ≥ 2.5o)
Wind associated with the environmental flow (removal of CAG) (renv ≥ 7o)Slide13
Vorticity Inversion
Actual TC motion: 270
o at 9 kt1200 UTC 3 Oct 2005Winds associated with CAG (rgyre ≤ 7o)Winds associated with CAG (without TC Stan) (rgyre ≤ 7o) and (rstan ≥ 2.5o)Wind associated with the environmental flow (removal of CAG) (r
env ≥ 7o)Slide14
Vorticity Inversion
Actual TC motion: 270
o at 9 kt1200 UTC 3 Oct 2005Winds associated with CAG (rgyre ≤ 7o)Winds associated with CAG (without TC Stan) (rgyre ≤ 7o) and (rstan ≥ 2.5o)
Wind associated with the environmental flow (removal of CAG) (renv ≥ 7o)Slide15
Vorticity Inversion
1200 UTC
4 Oct 2005Winds associated with CAG (rgyre ≤ 7o)Winds associated with CAG (without TC Stan) (rgyre ≤ 7o) and (rstan ≥ 2.5o)Wind associated with the environmental flow (removal of CAG) (renv
≥ 7o)Actual TC motion: 235o at 10 ktSlide16
Vorticity Inversion
1200 UTC
4 Oct 2005Winds associated with CAG (rgyre ≤ 7o)Winds associated with CAG (without TC Stan) (rgyre ≤ 7o) and (rstan ≥ 2.5o)Wind associated with the environmental flow (removal of CAG) (renv ≥ 7o
)Actual TC motion: 235o at 10 ktSlide17
Vorticity Inversion
1200 UTC
4 Oct 2005Winds associated with CAG (rgyre ≤ 7o)Winds associated with CAG (without TC Stan) (rgyre ≤ 7o) and (rstan ≥ 2.5o)Wind associated with the environmental flow (removal of CAG) (renv ≥ 7
o)Actual TC motion: 235o at 10 ktSlide18
Conclusions
Investigated a TC that appeared to interact with a CAG
Lead to poor track verification by the NHCTC Stan likely moved cyclonically around CAG via barotropic binary interactionPiecewise inversion of vorticity strongly suggests TC motion driven by CAG circulationFlow attributed to CAG matched track of TC StanEnvironmental flow did not match track of TC StanGFS track error likely due to initial position error and failure to develop CAGSlide19
QUESTIONS?