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Analyses of hurricane outflow layer structure u sing dropsonde observations deployed from a NASA Global Hawk AUV during HS3. Peter G. Black 1 , Jon Moskaitis 2 , James Doyle 2 , Chris Velden 3 and Scott Braun 4

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Presentation Transcript
slide1

Analyses of hurricane outflow layer structure

using dropsonde observations

deployed from a NASA Global Hawk AUV

during HS3

Peter G. Black1,

Jon Moskaitis2, James Doyle2, Chris Velden3 and Scott Braun4

(With special thanks to Michael Black, NOAA/AOML/HRD for sonde processing)

1Naval Research Laboratory and SAIC, Inc., Monterey, CA

2Naval Research Laboratory, Monterey, CA

3U. Wisconsin/ Cooperative Institute for Meteorological Satellite Studies, Madison, WI

4NASA Goddard Space Flight Center, Greenbelt, MD

slide2

Key Science Issue

  • Understand the coupling between the inflow and outflow branches of the secondary circulation (and the relationship of this coupling to intensity changes):
    • Upper-level outflow changes lead to increased convection and intensification.
      • Active Outflow
      • Interaction of environment with TC
    • Upper-level outflow changes result from increased convection/ low level forcing
      • Passive Outflow
      • Interaction of TC with environment
    • Dependencies on boundary layer characteristics
    • Secondary eyewall cycles
slide3

Strategy: 1) Global Hawks to observe the outflow layer and environment

2) WC-130Js to observe the inflow layer structure and intensity

Upper-Level Outflow

Upper-Level Outflow

CPL

HIRAD

HIWRAP

GPS

Dropsonde

GPS

Sonde

Radar

Low-Level Inflow

SFMR

Secondary Circulation: IN, UP & OUT

Background schematic courtesy of NASA

observational strategy
Observational Strategy
  • Global Hawk:
  • AV-1 remote sensors
    • HIRAD
    • HIWRAP
    • HAMSR?
  • AV-6 Remote Sensors
    • CPL
    • S-HIS
    • AVAPS Dropsondes
    • Outflow layer vertical
    • structure

15

Outflow

10

Height (km)

  • Air Force WC-130J:
  • SFMR: Surface winds/ intensity
  • Radar: Precipitation structure
  • AVAPS Dropsondes: Inflow layer vertical structure

5

Radar

SFMR

0

Strategy:i) Global Hawks to observe the outflow layer and environment

ii) WC-130J to observe inflow layer and inner-core intensity

300

600

100

radius (nm)

slide5

Lifecycle Hypothesis

  • Schematic of Outflow Channel Morphology from 7 case studies:
    • WPAC: Roke and Songda
    • ATL: Earl and Irene
    • GOM: Charlie, Katrina, and Opal
  • Led to hypothesis relating TC outflow morphology changes to TC intensity changes:

II.

I.

III.

HYPOTHESIS: There is a characteristic evolution of the outflow as the storm interacts with the environment that corresponds to changes in intensity and structure.

Phase I- TC development

Phase II- RI

Phase III- Mature & decay

slide6

Leslie (7 Sept, 2012):

Divergent outflow jets resulting from environmental interaction

force inner-core convection?

ACTIVE OUTFLOW

Nadine (14-15 Sept, 2012):

Outflow forced by Supercell Convection?

PASSIVE OUTFLOW

OR

slide7

NASA HS3 Observations

of Leslie and Nadine

76 Drops

80 kts

55 kts

NASA HS3 Global Hawk Flight Tracks

Nadine: 11 Sep – 04 Oct 2012

50 kts

70 kts

58 Drops

65 kts

65 kts

75 Drops

70 Drops

35 kts

34 Drops

30 Drops

  • Nadine was the 5thlongest-lived Atlantic hurricane on record.
  • Nadine intensity varied from a 35 knot tropical storm to 80 knot hurricane.
  • NASA HS3 Global Hawk deployed over 300 dropsondesduring 5 flights in Nadine and 30 dropsondes in Leslie.
slide9

HS3 Observations of Leslie’s Outflow (150 mb)

Leslie CAT1

80

60

Vmax (kt)

40

Leslie

Center

CIMSS SATCON

20

X

9

8

7

5

4

6

Sept

Cross Section

6 sondes

slide10

HS3 Observations of Leslie’s Outflow

7 Sep 2012

1041-1111Z

Black, Red, Blue and Pink lines:

Global Hawk observed

wind speed and

temperature profiles

along jet maximum

from dropsondes

Green line: COAMPS-TC model

wind speed profile

Red line: Satellite wind speed

vertical average

Solid black:Tropopause

Dashed: Cirrus top / jet max

Dotted: Cirrus cloud base

Yellow shading: Cloud Physics

Lidar (CPL) domain

slide11

Tropopause

Total Wind Speed

Isotachs every 2.5 m/s

Cloud Physics LIDAR (CPL): Outflow layer cloud image

North

South

  • HS3 dropsondes reveal unprecedented detail in depiction of outflow jet
  • Sharp shear zone just above the sloping tropopause (~14 km) and below outflow jet
  • Top of outflow jet coincident with top of cirrus deck from CPL
  • Detailed cirrus fine structure suggestive of multiple turbulent mixing mechanisms
slide12

Nadine

CIMSS shear: 0-20 kt

SHIPS/CIRA shear: 0-50 kt

SHIPS/CIRA SST: 20-30 C

RSS MW-OI SST: 20-30 C

30

25

20

15

10

GH AV-6 Flight

5

slide13

Outflow jet in Nadine, 14-15 Sept, sampled by multiple dropsondes (triangles- left)

  • and Atmospheric Motion Vectors (AMVs- right).
  • Outflow originates with active supercell west of center
slide14

Outflow forced by

SUPERCELL

Convection:

PASSIVEOUTFLOW?

OR:

Supercell forced by

divergent outflow

as a result of

environmental

interaction:

ACTIVE OUTFLOW

slide15

Double jet max below tropopause

  • (dashed line)
  • Main jet max decreases in height,
  • becomes stronger and thinner with
  • increasing radial distance.
  • Structures repeatable in 6 sondes
  • along jet max.
  • Double wind max and constant
  • wind layers are not observable with
  • satellite AMVs over layer average
  • (green dashed line) and may reflect
  • physical processes not presently
  • understood.
slide16

Green is CIMSS mean upper

wind at sonde location.

slide17

Dramatic Upper-Level Outflow Change during Hurricane Sandy

  • Jet streak associated with upper-level trough (thick blue arrow) approaches Sandy, creating expanded outflow structure (white arrows) toward the north and east.
  • Intensity decreases slightly, but the size of the storm increases dramatically.
  • Strong anticyclonic outflow displaced east of the center (pink dot): supports asymmetric deep convection.

10/27/06z: Sandy intensity = 60 kt

  • Strong outflow displaced west and north, intensifying and expanding (jet max of 100–140 kt), with dramatic change forced by intensifying ridge northeast of Sandy (blue arrows) .
  • Sandy intensifies, further expands and accelerates just prior to landfall.

10/29/12z: Sandy intensity = 80 kt

resulting hurricane sandy landfall impact
Resulting Hurricane Sandy Landfall Impact
  • Landfall of larger, more intense storm 12-hours earlier than expected.
  • Devastating storm surge superimposed on high tide rather than weaker storm surge superimposed on low tide 12-hours later.
  • Driven by Active Outfow?
slide19

Key Results

  • Fine scale outflow layer features and vertical outflow jet structures were recently observed in
  • Hurricanes Leslie and Nadine (2012) by dropsondes deployed from high-altitude Global Hawk AUV
  • They provide a new and more accurate representation of TC outflow layers that complement time
  • evolution provided by AMV’s only.

Recommendations and Future Plans

  • Focus 2013-14 flight plans on more detailed dropsonde observation of outflow jet vertical structure (see following final slide).
  • Obtain observation of magnitude and phasing of low-level mass inflow with respect upper mass outflow and jet structure evolution, i.e. secondary circulation development.
  • Extend Global Hawk outflow layer studies to WPAC monsoon depression TCs and interaction with WPAC TUTT cells.
slide20

Outflow Jet Racetrack pattern

Outflow Jet Fan pattern