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Tropical Cyclone Formation, Structure, and Longevity during HS3

Tropical Cyclone Formation, Structure, and Longevity during HS3. Mike Montgomery and Mark Boothe Naval Postgraduate School Tim Dunkerton and Blake Rutherford NorthWest Research Associates Sponsored by NSF. 2010. 2012-2014. Overarching NASA-HS3 Science Questions :.

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Tropical Cyclone Formation, Structure, and Longevity during HS3

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  1. Tropical CycloneFormation, Structure, and Longevity during HS3 Mike Montgomery and Mark Boothe Naval Postgraduate School Tim Dunkerton and Blake Rutherford NorthWest Research Associates Sponsored by NSF 2010 2012-2014

  2. Overarching NASA-HS3 Science Questions: How do hurricanes form? What causes rapid intensity change? What is the role of deep convection in intensification? What is the role of Saharan Air Layer (SAL) on intensity change? What determines storm resilience and longevity, such as Nadine (2012)?

  3. Understanding Nadine Scientific Questions Formation How did it form? (Is there a pouch?) Structure How does the wind field evolve? Longevity Why so resilient? (Was Nadine always in a favorable environment OR was it able to protect itself from an occasionally hostile environment?)

  4. Understanding Nadine Approach Conduct Lagrangian analyses within the marsupial framework Review genesis sequence Examine dropsonde data to study change in circulation Examine dividing streamlines to document structure change with the ECMWF model analyses Examine ECMWF theta-e tracer field for possible interaction with environmental dry air

  5. Animations of Nadine

  6. Animations of Nadine

  7. Formation of Nadine 0000 UTC 4 September Initial time of pouch designation ~ 13N, 4W 700 hPa ECMWF Streamlines and Okubo-Weiss Comoving Phase speed: -7.3 m/s Earth-relative Phase speed: 0 m/s

  8. Formation of Nadine 700 hPa ECMWF Streamlines and Okubo-Weiss P25L frame of reference P23L 0000 UTC 4 September 2012 0000 UTC 5 September 2012 P23L P24L P24L P25L P25L 0000 UTC 6 September 2012 1200 UTC 6 September 2012 P23L P23L P24L P24L P25L P25L P25L initially arrests P24L/pre-Nadine westward motion, but growing P24L/pre-Nadine then absorbs P25L on 7 September

  9. Formation of Nadine 700 hPa ECMWF Streamlines and Okubo-Weiss (P24L/pre-Nadine frame of reference) 0000 UTC 8 September 2012 1200 UTC 8 September 2012 P23L P24L P23L P24L 700 hPa ECMWF Ozone Tracer (P24L/pre-Nadine frame of reference) 1200 UTC 8 September 2012 0000 UTC 10 September 2012 P23L tracks along blue manifold around P24L Stretched P23L is then absorbed into the outer portion of P24L/pre-Nadine

  10. Track of Nadine RF4 50 kt RF5 RF6 RF3 50 kt 50 kt 65-70 kt RF2 ~30-35 kt

  11. NHC HURDAT2 Intensities 65-70 kt 30-35 kt 50 kt RF2 RF3 RF4 Circulation -10.3 Average tangential cyclonic wind C / perimeter

  12. 50 kt 50 kt 50 kt RF4 RF5 RF6 50 kt

  13. Understanding Nadine: Dividing Streamlines RF03 ECMWF Dividing Streamline Analysis 2012091500 Drops: 1701Z Sept 14 – 0808Z Sept 15 (-6:59…+8:08) 1728 1756 1715 1743 1824 1809 1848 1701 1833 1901 0808 0756 2113 2045 2003 1947 2032 2058 1935 2018 1921 2126 0745 2228 2339 2256 2313 2328 2241 0729 0728 0015 2200 0725 0808 2211 0724 0000 2146 0031 0722 0721 0000 0719 0708 1701 0050 0256 0104 0241 0213 0145 0117 0131 0228 0159 0657 0646 0316 0518 0448 0502 0346 0332 0403 0416 0430 0633 0623 0538 0611 0557 Courtesy Michael Riemer, NRC postdoc • Small, vertically aligned (925-700 hPa) pouch • High TPW • Saddle point to the southwest

  14. Understanding Nadine: Dividing Streamlines RF04 ECMWF Dividing Streamline Analysis 2012092012 Drops: 0107Z – 1235Z Sept 20 (-10:53…+00:35) 1152 1144 1135 1201 1235 1210 1218 1226 1128 0938 0947 1101 0956 1005 1014 1023 1032 1050 1041 1108 0931 0821 0848 0852 0842 0837 0832 0827 0816 0919 0732 0910 0739 0748 0758 0901 0807 0107 1200 0529 0633 0547 0537 0556 0642 0650 0604 0659 0606 0609 0611 0614 0616 0619 0623 0518 0505 0345 0426 0454 0416 0435 0357 0445 0313 0407 0304 0107 0255 0146 0214 0126 0155 0116 0205 0136 0243 • Larger, with a saddle point to the northeast • TPW decreased • Vertically aligned

  15. Understanding Nadine: Dividing Streamlines RF06 ECMWF Dividing Streamline Analysis 2012092700 Drops: 1638Z Sept 26 – 0428Z Sept 27 (-7:22…+4:28) 1638 1648 1658 1708 1718 1728 1738 1748 1758 1810 0428 0418 1822 1855 1845 1905 1915 1927 1936 1946 1956 1835 2012 0344 0401 2111 2114 2117 2120 2123 2127 2130 2022 2042 2052 2140 2101 2149 2034 2201 } 1638 0132-0330 0000 2209 0428 0122 2220 2351 2228 2238 2248 2258 2328 2338 2304 2308 2313 2318 0112 0000 0105 0012 0058 0021 0031 0040 0051 • Has shrunk • TPW had continued to decrease, now increasing again • Still vertically aligned

  16. Simple Kinematic Model of Point Vortex in Uniform Flow with Mass Sink

  17. Understanding Nadine: Theta-e tracer field

  18. Understanding Nadine Scientific Questions Answered Formation How did it form? (Is there a pouch?) Yes. Merged with P25L (east) and P23L (west). Structure How does the wind field evolve? Grows in extent, then declines (presumably grew again when it reintensified to a hurricane on 28 September) Longevity Why so resilient? (Was Nadine always in a favorable environment OR was it able to protect itself from an occasionally hostile environment?) Size growth contributes to extensive pouch and shear sheltering from hostile intrusions in lower troposphere

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