Tu3_T03_5_ChangIGARSS2011.pdf
Upcoming SlideShare
Loading in...5
×
 

Tu3_T03_5_ChangIGARSS2011.pdf

on

  • 508 views

 

Statistics

Views

Total Views
508
Views on SlideShare
503
Embed Views
5

Actions

Likes
0
Downloads
0
Comments
0

1 Embed 5

http://www.grss-ieee.org 5

Accessibility

Categories

Upload Details

Uploaded via as Adobe PDF

Usage Rights

© All Rights Reserved

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
    Processing…
Post Comment
Edit your comment

Tu3_T03_5_ChangIGARSS2011.pdf Tu3_T03_5_ChangIGARSS2011.pdf Presentation Transcript

  • Tropical  Cyclone  Observa2ons   with  Aircra7  Passive  and  Ac2ve   Microwave  Instruments   Paul  Chang  and  Zorana  Jelenak,  NOAA/NESDIS/STAR   James  Carswell,  Remote  Sensing  Solu2ons   Stephen  Frasier,  University  of  MassachuseLs   1  IGARSS  2011  -­‐  26  July  2011   !
  • Mo2va2on  Stepped  Frequency  Microwave  Radiometer  (SFMR)  •  Deployed  on  NOAA  research  and  53rd  Air  Force  Reserve  Weather   reconnaissance  aircra7.  •  Provides  cri2cal  wind  speed  observa2ons  of  tropical  cyclone   environment  to  forecasters  for  wind  radii  es2ma2on.  •  Provides  “surface  truth”  for  geophysical  model  func2on  development   and  valida2on.  Problem:  •  SFMR  under  es2mates  precipita2on  rate  within  TCs  …  •  Retrieved  wind  speed  and  rain  rate  errors  correlated  …  •  Thus  wind  speed  error  depends  on  environment  in  field  of  view            (i.e.  precipita2on).   IGARSS  2011  -­‐  26  July  2011   2   !
  • Measurement  Geometry   IWRAP:   •  SFMR                                            Specifica2ons      Simultaneous,  Mul2-­‐Beam     •  Nadir Viewing. Frequency:  C-­‐band  &  Ku-­‐band      Doppler/Reflec2vity   •  C-band – 6 channels. Polariza2on:  VV,  HH      Profiling   •  ~4.7 to 7.2 GHz. Beam  Incidence  Angles:  30,  35,  41.5,  50   SFMR column   (20-28 deg)ange:  • 00  –  8000  m   Al2tude  R 5 IWRAP Range  Resolu2on:  •  5,  30,  60  &  120  m   1 C/Ku-band Doppler Radar.   •  Conical scanning. •  Four beams. •  20 to 55 degrees incidence.Conical  Scan   •  30-m range gates.    (60  rpm)   •  NOAA Tail Doppler Radar •  X-band. SFMR foot print •  Helix scan fore/aft 20 deg. Propor2onally  not  to  scale.   •  75-m range gates. •  Not to scale •  NOAA Lower Fuselage Radar •  NOAA Tail Doppler Radar & Lower Fuselage Radar •  C-band (~5.3 GHz) beams not shown •  Reflectivity. •  Near grazing conical scanning. IGARSS  2011  -­‐  26  July  2011   3   !
  • SFMR  Tb  Geophysical  Model  Func2on  (GMF)   Tb Versus U10N & Frequency Tb Versus Rain Rate & Frequency 3  km  al2tude,  28oC  SST   3  km  al2tude,  28oC  SST  IGARSS  2011  -­‐  26  July  2011   4   !
  • Rain  Rate  Under  Es2mated   IWRAP  derived  aLenua2on  ploLed  versus  SFMR  rain  rate   retrievals.   •  Corrected  SFMR  Rain  Rate  =  2.5  x  SFMR  Rain  Rate  –  5  mm/hr.   •  Figures  from  [Esteban  Fernandez,    2005];  UMass  SFMR  –  2003  flights.  IGARSS  2011  -­‐  26  July  2011   5   !
  • Rain  Rate  Under  Es2mated  by  SFMR   •  SFMR  under  predicts  rain  rate     by  a  factor  of  2.5   •  SFMR  rain  rate  es2mates  are   biased  by  ~  5  mm/hr.   •  Same  results  observed  in   2003  comparison  between   IWRAP  and  UMass  SFMR.   •  Comparisons  with  Tail   Doppler  and  Lower  Fuselage   radars  show  same  5  mm/hr   bias  and  SFMR  under   es2mates  rain  rate.  *  NOAA  Aircra7  Opera2ons  Center  SFMR   IGARSS  2011  -­‐  26  July  2011   6   !
  • New  SFMR  Absorp2on  Model   SFMR Absorption Model Current K =α f ( Rm Rr Fe )(R ) Re r Model Monte-Carlo: Clustered Solutions Re Fe Rm Slope (m) Offset (b) Monte- 0.76 0.0676 2.75 0.947 0.110 Carlo 0.74 0.0696 2.75 0.950 0.138 Solutions 0.74 0.0716 2.8 0.900 0.015 0.72 0.0736 2.8 0.910 -0.109 0.7 0.0756 2.8 0.915 -0.074 * Minimized offset and required slope > .85IGARSS  2011  -­‐  26  July  2011   7   !
  • New  SFMR  Absorp2on  Model   Old SFMR Model New SFMR ModelSFMR Tb data from Uhlhorn, et al, 2007: Hurricane Surface Wind Measurements from an OperationalStepped Frequency Microwave Radiometer. Monthly Weather Review, v.135, pp. 3070–3085.IGARSS  2011  -­‐  26  July  2011   8   !
  • New  SFMR  Absorp2on  Model  –  IWRAP  Comparison   IWRAP Z measurements versus SFMR Rain Rate Retrievals •  IWRAP  C-­‐band   reflec2vity  factor   measurements.   •  SFMR  rain  rate   derived  using  new   absorp2on  model.   •  Solid  black  line  is   opera2onal  Z-­‐R   model  for  tropical   cyclones.   •  Red  line  is  fit  to  data   solving  for  exponent   only.   •  Green  line  is  fit  to   data  solving  for   exponent  and   mul2plier.  *  2008  IWRAP  and  SFMR  measurements  from  hurricane  season.  IGARSS  2011  -­‐  26  July  2011   9   !
  • Wind  Speed  and  Rain  Rate  Retrieval  Errors  IGARSS  2011  -­‐  26  July  2011   10   !
  • Summary  •  SFMR rain rate retrievals have been documented to under predict the rain rate in tropical cyclones.•  New absorption GMF developed for SFMR for 2005 data set.•  SFMR wind speed retrievals compared with GPS drop sondes winds improves with new SFMR absorption model.•  SFMR rain rate – IWRAP reflectivity factor comparison improves with new SFMR absorption model.IGARSS  2011  -­‐  26  July  2011   11   !
  • THANK YOU Ques2ons?  IGARSS  2011  -­‐  26  July  2011   12   !