The Rapid Intensification of Hurricane Karl (2010): Insights from New Remote Sensing Measurements 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 Simulated and flight-level data from HS3/NOAA coord. (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 HAMSR From 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 Retrievals Guimond et al. (2014) J. Atmos. Oceanic Technol., 31,

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

HS3 Coordinated Flight

 Quality controlled  Keep data with time offset 5  N = ~ 5000  Ka band retrievals have slightly lower mean errors  Recommendation: use Ku band retrievals where dBZ > ~ 20 – 25 and Ka below All science results in this work use this partitioning

HIWRAP on Global Hawk Detects Karl (2010) Rapid Intensification 9/16 ~ 19 UTC – 9/17 08 UTC 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

HIWRAP on Global Hawk Detects Karl (2010) Rapid Intensification 9/16 ~ 19 UTC – 9/17 08 UTC From NHC

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 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 km Strongest 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 suspect ~ 40 m/s

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

Structure of Inner-Core: ~2040 & 2042 UTC HIWRAP NOAA TA Reflectivity comparison

HIWRAP NOAA TA outflow inflow Storm relative radial wind comparison Structure of Inner-Core: ~2040 & 2042 UTC

HIWRAP NOAA TA Edge downdraft Vertical wind comparison Structure of Inner-Core: ~2040 & 2042 UTC

HIWRAP NOAA TA Edge downdraft Structure of Inner-Core: ~2040 & 2042 UTC

Convective Towers HIWRAP Time Series

HAMSR 54 GHz 750 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)Symmetric 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 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 sfc, ~ 1 15 km height FREE PARAMETERS HIWRAP: Atmospheric Wind Retrievals