Tropical Cyclone studies in France

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Tropical Cyclone studies in France

• CETP (N Viltard) satellite data (MW radiometry
  radar)
• Météo-France / CRC (S Westrelin, D Barbary, S
  Jolivet) operational (RSMC SW Indian), modeling
  (large-scale ARPEGE, ALADIN, mesoscale MésoNH
  )
• LA (F Roux) Doppler radar data, modeling with
  MésoNH
• LPA (F Chane-Ming, A Rechou) radar data,
  gravity waves, meso-synoptic interactions
• Météo-France / CNRM / RETIC (E Pesin, JL Ricard,
  ... ) applied studies (TCs impact in DOM-TOM)

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Intense Tropical Cyclone Dina (16-28 January 2002)
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GB-EVTD analysis of Doppler observations Roux et
al. 2004 JAOT, 21, 1501-1518
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At 2 km altitude, the location intensity of the
maximum wind changed with time from 68 m s-1 to
the east at 1052 to 62 m s-1 to the south at
1352. The wind asymmetry decreased significantly
with time (at 50 km radius, it was 20 m s-1 at
1052, 10 m s-1 at 1222, 5 m s-1 at
1352). At 6 km altitude, similar though weaker
features were found  with time, the tangential
wind maximum moved from SE to SSE while
decreasing slightly and the wind field became
more symmetric
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• Sketch of the interaction between tropical
  cyclone Dina and La Réunion island
• the light arrows denote the low-level airflow,
• the dotted line contour indicates probable
  location of the orographically induced
  convergence,
• the contoured arrows represent Dinas motion.

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• Non-hydrostatic numerical simulation with Meso-NH
  
• 2-way nested model (36 km / 12 km / 4 km / 1 km)
• stretched vertical grid (50 levels between 0 and
  25 km)
• parameterized convection in A B, explicit in C
  D
• initialized with ECMWF analysis on 22 Jan 02 at
  00 UTC
• bogus vortex deduced from Doppler radar
  observations
• (Nuissier et al. 2005 QJRMS, 131, 155-194)

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• A bogus vortex derived from Doppler radar
  observations

GB-EVTD analysis of Doppler radar data ?
symmetric tangential wind T0(r,z)
Analytic wind VT(r,z) from Holland 80
Thermal-wind relation
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Initial field 850 hPa wind on 22 Jan 02 at 00
UTC
ECMWF analysis
ECMWF analysis with bogus
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( Domain C 4 km )Horizontal wind at 850 hPa
22 Jan 02 09-21 UTC / 30 min
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( Domain C - 4 km) accumulatedprecipitation22
Jan 00-21 UTC
Observed
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Domain D (1 km) 22 Jan 02 at 1710,1720,1730
UTC 1 km
Radar reflectivity (dBZ)
Relative vorticity (10-3s-1)
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• Island orographic influence on Dinas evolution
  (dynamics of the eye the eyewall, storm motion
  ...) Samuel Jolivet PhD 2004-2007 (Coll.
  LPA-CRC-LA, Funding Région Réunion)
• AMS Conference, Albuquerque Oct 2005.
• Influence of the vertical grid resolution on
  storm intensification (Dougherty et Kimball - AMS
  2004) Méso-NH users meeting 2005.
• Impact of a humidity bogus to limit duration of
  Méso-NH spin-up (coll. MF/RETIC applied TC
  studies).
• Collaboration with CNRM/MEMO for a new
  parameterization of the exchange coefficients (OA
  fluxes of momentum, sensible latent heat) incl.
  saturation for wind speeds gt30 m s-1. Proposed
  for 2006

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CRC 3D-VAR ALADIN in SW Indian

• Improving analysis forecast spatial resolutions
  
• Determining structure functions over this region
• Using high-density non-conventional satellite
  observations
• ? cyclone BENTO (20-30 nov. 2004)

Ph.D. 2005-2008 R. Montroty (GMAP-CRC-LA, EGIDE
funding) Impact of a mesoscale assimilation on
TC forecast.
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CETP Estimate of the diabatic source QH from
satellite data

• From the retrieved profiles of rain, snow
  graupel
• equations for conservation of water
  thermodynamique equation
• horizontal transport terms are neglected
• parameterized melting layer (Font)
• précipitation production function F(qp)
• d0 in unsaturated air (F(qp)lt0)
• ?1 in saturated air (F(qp)gt0)
• We have

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Bret 1999
Brightness temperature
Precipitation content profile
Correlation with storm evolution
QH
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Evolution of QH 21 orbits for Alberto (2000)
intensification
weakening
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Conclusions

• Coherence between évolution intensity of QH
• Similar results for other case studies

Perspectives

• Improving ice phase retrieval
• 3D structure of QH
• Horizontal transports
• Comparisons with Méso-NH radars

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LPACRCLA Rossby wave breaking tropical
cyclones
RWB in the southern hemisphere
Forte relation RWB nombre de jours cyclones
Les RWB repoussent la cyclogénèse ( o ) vers
l'équateur
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LPA gravity waves generated by a cyclone
Chane-Ming et al., 2002 GRL, 29, 1094, 18
Wavelet analysis of the vertical profiles of
u,v,T at Tromelin Island during the passage of
the intense tropical cyclone Hudah (April 2000)
? Inertia-gravity waves in the upper troposphere
and the lower stratosphere with vertical
wavelengths of 1.53 km, horizontal wavelengths
lt2000 km and periods of 0.61.6 days. GW
associated with Dina (2002), coll. Z. Chen (Chin.
Acad. Sci.)
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LPA comparison MF Doppler radar - TRMM
2 January 2002 (before Dina !)
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Conclusions

• TCs impact on Martinique Guadeloupe (Caribbean
  sea), La Réunion (Indian ocean), Nlle-Calédonie
  (Pacific ocean) operational (Météo-France)
  research
• Improve coordination between (ground-based and
  airborne) radar observations, satellite data,
  (global and mesoscale) numerical modeling
  assimilation, initialization, control,
  mod-to-sat,
• Scientific issues TC genesis, interactions with
  terrain / orography , TC synoptic environement,
  extratropical transition
• Instrumented aircraft Falcon-20 with dropsondes
  
• Megha-Tropiques very high time resolution vs.
  numerical model control and verification