Recent progress of NCEP OSSE project

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Results from Winter Storm Reconnaissance Program
2007
Yucheng Song IMSG at EMC/NCEP Zoltan
Toth EMC/NCEP/NWS
Sharan Majumdar Univ. of
Miami Mark Shirley
NCO/NCEP/NWS http//www.emc.ncep.noaa.gov/gmb/tar
gobs
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Acknowledgments

• NWS field offices, HPC/NCEP and SDMs
• NOAA G-IV and the USAFR C-130 flight crews
• CARCAH (John Pavone)
• Jack Woollen - EMC
• Russ Treadon - EMC
• Mark Iredell - EMC
• Istvan Szunyogh Univ. of Maryland
• Craig Bishop - NRL
• others who have contributed!

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Winter Storm Reconnaissance Program
Operational since January 2001

• Objective
• Improve Forecasts of Significant Winter Weather
  Events Through Targeted Observations in Data
  Sparse Northeast Pacific Ocean
• Adaptive approach to collection of observational
  data
• 1) Only Prior to Significant Winter Weather
  Events of Interest
• 2) Only in Areas that Influence high impact
  event Forecasts
• Results
• 70 of Targeted Numerical Weather
  Predictions Improve
• 10-20 error reduction for high impact event
  forecasts
• 12-hour gain in predicting high impact events
  earlier warnings possible

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About the Winter Storm Reconnaissance (WSR 2007)
Program

• Took place 20 Jan 13 March 2007
• Dropwinsonde observations taken over the NE
  Pacific by aircraft operated by NOAAs Aircraft
  Operations Center (G-IV) and the US Air Force
  Reserve (C-130s).
• Observations are adaptive
• collected only prior to significant winter
  weather events of interest
• in areas that might influence forecast the most.
• 31 flights, around 478 dropsondes this winter
  which is increased from 342 drops last year
• Several communication problems from C-130s

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About the Winter Storm Reconnaissance (WSR 2007)
Program (continued)

• Evaluation methods
• NCEP Global Forecast System running on T126L28
  resolution
• Three sets of experiments
• A. GFS run with all the WSR dropsondes being
  assimilated
• B. GFS run without WSR dropsondes data rejected
  on all days
• C. GFS run with WSR dropsondes data rejected only
  on the WSR observation day (i.e. the guess files
  are the same as the operational while data file
  is different)
• Experiment Design
• - Experiment C is used for signal
  propagation studies, it can single out the data
  impact due to current dropsondes clearly without
  worrying about the previous drops

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Targeting methods - ETKF
Dropsondes to be made by G-IV
Storm
The ETKF spotted the target area
Expected error reduction propagation
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Forecast verification(Jan 20-22,2007)
500mb height
Sea Level Pressure
Red contours show forecast improvement due to WSR
dropsondes, blue contours show forecast
degradation
250mb height
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Impact of Dropsondes
Surface pressure
Precipitation
Contours are 1000mb geopotential height, shades
are differences in the fields between two
experiments
500mb height
250mb height
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Comparison of ETKF signal and NCEP signal
The ETKF signal
The NCEP signal
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Forecast Verification for Wind (2007)
10-20 rms error reduction in winds
RMS error reduction vs. forecast lead time
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Forecast Verification for Wind (2007)
10-20 rms error reduction in Temperature
60 hr forecast is equivalent to 48hr forecast
RMS error reduction vs. forecast lead time
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Breakdown for cases
Variable cases improved cases neutral cases degraded
Surface pressure 25 0 12
Temperature 24 0 13
Vector Wind 27 0 10
Humidity 24 0 13

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Individual Case Comparison
VR OBSDATE P T V OVERALL REGION
FHOUR AK 20070120 1 1 1 1 130W
,55N 48 C 20070128 1 -1 -1 -1
97W ,33N 72 W 20070207 1 -1 -1 -1
123W ,40N 48 W 20070208 -1 1 1 1
123W ,40N 24 W 20070209 1 1 1
1 122W ,38N 24 W 20070211 1 -1 1
1 110W ,32N 48 E 20070211 1 -1
-1 -1 86W ,36N 72 W 20070212 -1 -1
-1 -1 110W ,32N 36 E 20070212 1
1 1 1 77W ,38N 60 W 20070215 1
-1 1 1 120W ,45N 24 AK 20070216
1 -1 1 1 135W ,60N 48 W 20070217
1 1 1 1 124W ,40N 36 W
20070218 1 1 1 1 117W ,40N 24
C 20070218 1 1 1 1 108W ,37N
48 C 20070218 1 1 1 1 90W ,35N
72 W 20070220 1 1 1 1 122W
,40N 60 W 20070221 1 1 1 1
122W ,40N 36 C 20070221 1 -1 -1 -1
96W ,43N 72 C 20070221 1 1 1 1
93W ,40N 96 W 20070222 1 1 1
1 120W ,37N 24 C 20070222 -1 -1 -1
-1 90W ,40N 72 E 20070222 -1 1
1 1 80W ,36N 96 W 20070223 1 1
1 1 123W ,42N 48 C 20070223 1
-1 1 1 94W ,37N 48 W 20070225 -1
1 1 1 123W ,42N 48 W 20070226
1 1 1 1 123W ,42N 24 W 20070228
1 1 1 1 122W ,43N 36 E
20070228 -1 1 1 1 86W ,35N 48
W 20070302 1 1 1 1 125W ,49N
36 AK 20070306 -1 -1 -1 -1 130W ,55N
36 E 20070308 1 1 1 1 85W
,34N 108 W 20070308 -1 1 -1 -1
124W ,46N 60 W 20070309 1 -1 1 1
124W ,45N 72 C 20070310 -1 -1 1 -1
93W ,37N 48 C 20070311 -1 1 -1
-1 96W ,32N 36 E 20070311 -1 1 -1
-1 81W ,42N 96 E 20070313 -1 1
1 1 81W ,42N 48
1 denotes positive effect 0 denotes
neutral effect -1 denotes negative effect
26 OVERALL POSITIVE
0 OVERALL NEUTRAL 11 OVERALL NEGATIVE
70 improved 30 degraded
OVERALL EFFECT
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ETKF signal vs. NCEP signal (Feb 18-Feb 22)
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Impact of Dropsondes
Surface pressure
Precipitation
Contours are 1000mb geo-potential height, shades
are differences in the fields between two
experiments
500mb height
250mb height
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Impact of Dropsondes
Surface pressure
Precipitation
Contours are 1000mb geo-potential height, shades
are differences in the fields between two
experiments
500mb height
250mb height
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Impact of Dropsondes
250mb height
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Overall results for Surface pressure
Of all cases 25 improved 0 neutral 12
degraded
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Overall results for Temperature
Of all cases 24 improved 0 neutral 13
degraded
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Overall results for Vector wind
Of all cases 27 improved 0 neutral 10
degraded
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Overall results for Humidity
Of all cases 24 improved 0 neutral 13
degraded
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WSR overall statistics (2004-2007)
Variable cases improved cases neutral cases degraded
Surface pressure 2120132579 01001 149141249
Temperature 2422172487 11002 107101340
Vector Wind 2319212790 10001 111161038
Humidity 2219132478 00000 1311141351
25221926 92 OVERALL POSITIVE
CASES. 010 0 1 OVERALL NEUTRAL
CASES. 1078 11 36 OVERALL NEGATIVE
CASES. 71.3 improved
27.9 degraded
OVERALL EFFECT
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Issues with WSR07

• C-130s communication problems
• 6-hr data window requirement
• Some of the dropsondes data were out of the 6-hr
  window surrounding 00Z