The Rapid Intensification of Hurricane Karl (2010): Insights from New Remote Sensing

Measurements

Collaborators:Anthony Didlake (NPP/GSFC) ,Gerry Heymsfield (GSFC), Paul

Reasor (HRD)

Steve Guimond (UMD/GSFC)

Outline

• Brief background on datasets used (HIWRAP, HAMSR, P3 TA) and Karl case.

• HIWRAP processing– 3DVAR wind retrieval algorithm– Error characteristics

• flight-level data comparisons from HS3/NOAA coordination (2013)

• Understanding of Karl’s RI with remote sensing data– Answers to questions from HS3 inner-core part of proposal

• What is role of convective bursts in intensification? • How do convective bursts form?• Does warm-core development depend on bursts?

Remote Sensing Instruments

600 – 700 m (along-track) 150 m (gate spacing)

1 km retrieval products

HIWRAP HAMSRFrom JPL

NOAA P3 TA Radar

Sensitive to Temp & Precipitation ~ 2 km resolution, ~ 60 km swath width

From NOAA

X-band large coverage area

2 km retrieval products

3D Least Squares and Variational Methods:

Values of coefficients found by tuning to simulated and in situ data.

Nonlinear minimization

HIWRAP: Atmospheric Wind RetrievalsGuimond et al. (2014) J. Atmos. Oceanic Technol., 31, 1189-1215.

HS3 Coordinated Flight with P3 (2013)

Quality controlled Keep data with time offset < 10 min, space offset < 1 km, dBZ > 5 N = ~ 5000 Ka band retrievals have slightly lower mean errors

Recommendation: use Ku band retrievals where dBZ > ~ 20 – 25 and Ka belowAll science results in this work use this partitioning

HS3 Coordinated Flight with P3 (2013)

HIWRAP on Global Hawk Detects Karl (2010) Rapid Intensification

9/16 ~ 19 UTC – 9/17 08 UTC

From NHC…16 / 18 UTC 982 hPa 36 m/s hurricane

17 / 00 UTC 971 hPa 44 m/s 17 / 06 UTC 966 hPa 49 m/s 17 / 12 UTC 956 hPa 57 m/s

HIWRAP on Global Hawk Detects Karl (2010) Rapid Intensification

9/16 ~ 19 UTC – 9/17 08 UTC

From NHC Global Hawk Observations

Warm SSTs

Low wind shear

1845 Z 2215 Z

0145 Z 0600 Z

NRL

HIWRAP Time Mean Structure Ku Band Time Mean (12 – 13 h) Reflectivity and Wind Vectors

Only inner beam functional (~ 20 km swath width @ surface)

Deep convective towers down shear to down shear left (well known). Very active pulsing for ~ 6 h between (~ 1800 – 0000 UTC).

~ 5 m/s

2 km 8 kmStrongest Winds

Structure of Inner-Core: Pass 1 (1853–1919 UTC) 2 km height in down-shear left quadrant

30 – 40 m/s

10 – 20 m/s

Structure of Inner-Core: Pass 1 (1853–1919 UTC) 2 km Height

Attenuation from bursts

Structure of Inner-Core: Pass 1 (1853–1919 UTC)

Eye-Eyewall Interaction

10 – 15 m/s radial flow~ 10 m/s updraft

Structure of Inner-Core: Pass 2 (1938–1957 UTC) 2 km height in down/up-shear left quadrant

Structure of Inner-Core: Pass 2 (1938–1957 UTC)

Ku band reflectivity at nadir

center

Structure of Inner-Core: Pass 2 (1938–1957 UTC)

Storm-relative radial wind at nadir

Structure of Inner-Core: Pass 2 (1938–1957 UTC)

Vertical wind at nadir

Convective induced descent

Structure of Inner-Core: Pass 3 (2009–2055 UTC)

30 – 40 m/s

10 – 20 m/s

2 km height in down-shear direction

20 – 30 m/s

~ 40 m/s

Structure of Inner-Core: ~2040 & 2042 UTC

HIWRAP

NOAA TA

Reflectivity comparison

HIWRAP

NOAA TA

outflow

outflowinflow

inflow

Storm relative radial wind comparison

Structure of Inner-Core: ~2040 & 2042 UTC

HIWRAP

NOAA TAEdge downdraft

Edge downdraft

Vertical wind comparison

Structure of Inner-Core: ~2040 & 2042 UTC

HIWRAP

NOAA TASpin-up

Spin-up

Tangential wind comparison

Structure of Inner-Core: ~2040 & 2042 UTC

Convective TowersHIWRAP Time Series

HAMSR54 GHz750 hPa

Courtesy of JPL GRIP PORTAL

Science Discussion• GRIP inner-core data indicates…1) Convective bursts forming through transport & converg. of

warm anomaly air from eye to eyewall.2) Turbulent mixing between eye/eyewall and convective

descent responsible for carving out eye and intensifying warm core locally (large asymmetric component).

3) Axisymmetric and asymmetric projection of burst heating leads to symmetric vortex response, which includes symmetric intensification of warm core at later times.

4) Convective bursts are important for RI Builds on prior work (Heymsfield et al.,Reasor et al., Molinari et

al., Guimond et al., Rogers et al., Montgomery et al., Braun et al., etc…)

Guimond et al. (2015) JAS, in preparation.

Acknowledgements• Thanks to HIWRAP engineers– Matt McLinden, Lihua Li, Martin Perrine, Ed Zenker,

Jaime Cervantes, Michael Coon• Thanks to HAMSR engineers for L1 data• Thanks to HS3 PIs (Scott Braun/Paul Newman)

HS3 Coordinated Flight Quality controlled

Keep data with time offset < 10 min, space offset < 1 km, dBZ > 5 N = ~ 5000 Ka band retrievals have slightly lower mean errors

Recommendation: use Ku band retrievals where dBZ > ~ 20 – 25 and Ka below

HIWRAP: Atmospheric Wind Retrievals

Traditional Least Squares Method (Guimond et al. 2014):

min

γ = 0.75, β = 6 For HIWRAP δ = ~ 3 – 4 km @ sfc, ~ 1 km @ 15 km height

FREE PARAMETERS

HIWRAP: Atmospheric Wind Retrievals

HIWRAP on Global Hawk Detects Karl (2010) Rapid Intensification

9/16 ~ 19 UTC – 9/17 08 UTC

From NHC

Error Characteristics Simulated errors:

~ 2.0 m/s for horizontal winds, ~ 1.0 m/s or less for vertical winds Function of cross-track location: best at nadir.

In situ (NOAA P3 flight-level winds) errors: IWRAP data (~ 7 % for horizontal winds, ~ 2.0 m/s for vertical winds) HIWRAP data (9/25/2013 coordinated flight with NOAA43 during HS3)

See Guimond et al. (2014) for simulated and in situ (IWRAP) error characteristics

Structure of Inner-Core: Pass 3 (2009–2055 UTC)

center

Ku band reflectivity at nadir

Structure of Inner-Core: Pass 3 (2009–2055 UTC)

Convective descent weaker burst in “blow up” stage

Vertical wind at nadir

Structure of Inner-Core: Pass 3 (2009–2055 UTC)

Storm-relative radial wind at nadir

Warm anomaly air

Significant eye-eyewall interaction

Strong outflow