1. Highlights of studies at DLR and LMU based on aircraft observations during T‑PARC
Martin Weissmann1,2, Florian Harnisch1,2 and Kathrin Folger1
Hans-Ertel-Centre for Weather Research, DA Branch, LMU München, Germany
Formerly: DLR Oberpfaffenhofen
Collaborators:
C. Cardinali, ECMWF, Reading, United Kingdom
R. Langland and P. Pauley, NRL, Monterey, USA
T. Nakazawa, WMO, Geneva, Switzerland
M. Wirth, S. Rahm, DLR Oberpfaffenhofen, Germany
Y. Ohta and K. Yamashita, JMA, Japan
C.-C. Wu, K.-H. Chou and P.-H. Lin, NTU, Taiwan
Y. Kim and E.-H. Yeon, NIMR, Korea
S. Aberson, NOAA/AOML/HRD, USA
Falcon funding
Picture taken by Yomiuri Shimbun on 11 Sept. 2008

2. THORPEX Pacific Asian Regional Campaign (T-PARC, Aug – Oct 2008)
DLR Falcon:
25 flights
Dropsondes
Wind lidar
Water vapour lidar
Atsugi:
DLR Falcon
Taiwan:
DOTSTAR
Astra Jet
Guam:
US AirForce WC-130
NRL P-3

3. Dropsonde observations
Evaluation of dropsonde impact
Period: Three weeks in September 2008
Typhoons: Sinlaku and Jangmi
Models:
ECMWF (global)
JMA GSM (global)
NCEP GFS (global)
WRF-ARW (regional)
>1000 dropsondes
Campaign objectives:
TC genesis and structure
Targeted observations for NWP
ET transition

4. Model set-up used for the evaluation of dropsonde impact
ECMWF IFS
JMA GSM
Japan
KMA WRF NIMR KOREA
NCEP GFS
Resolution
TL799L91
(~25 km)
TL959L60
(~20 km)
30 km
T382L64
(~38 km)
DA-method
12h 4D-VAR
6h 4D-VAR
6h 3D-Var
Domain
Globe
190*190 grid points
Bogus NO
(YES in oper. version)
vortex relocation, bogus if no vortex in first guess (rare)
Use of TC
core and eyewall observations
YES
Denied observations
Pacific dropsondes
driftsondes
JMA ship SYNOP
JMA ship TEMP
JMA special TEMP
Atlantic dropsondes
Atlantic and Pacific dropsondes
ECMWF, JMA and NCEP systems from 2008/2009/2010 (no hybrid DA)
(Weissmann, Harnisch, Wu, Lin, Ohta, Yamashita, Kim, Jeon, Nakazawa and Aberson, 2011, MWR)

5. Influence of T-PARC dropsondes on typhoon track forecasts
JMA GSM
4D-Var
NCEP GFS
3D-Var
Different scales!
All models show some reduction of typhoon track forecast errors with dropsondes, but impact strongly depends on DA system
KMA WRF
3D-VAR
ECMWF
4D-VAR
(Weissmann, Harnisch, Wu, Lin, Ohta, Yamashita, Kim, Jeon, Nakazawa and Aberson, 2011, MWR) 5

6. Influence of T-PARC dropsondes on typhoon track forecasts
Large improvement in NCEP-GFS and WRF (models with 3D-Var, less other obs., larger errors)
Lower impact in JMA and ECMWF (4D-Var, more satellite observations, lower errors)
Best forecast both with and without dropsondes by ECMWF
GFS with dropsondes comparable to ECMWF despite 3D-Var and less satellite observations
(Weissmann, Harnisch, Wu, Lin, Ohta, Yamashita, Kim, Jeon, Nakazawa and Aberson, 2011, MWR)

7. Dropsonde impact for individual forecasts
Low mean impact of JMA due to two deteriorating forecasts, whereas majority of forecasts improves
(both deteriorating forecasts contain observations in typhoon core and eyewall region)
All models show more improving than deteriorating forecasts
deterioration improvement
SINLAKU
JANGMI
(Weissmann, Harnisch, Wu, Lin, Ohta, Yamashita, Kim, Jeon, Nakazawa and Aberson, 2011, MWR)

8. Comparison of dropsonde targeting strategiesSV
Japan
China
ETKF
Concept for ideal mission and sensitivity experiments: Joint mission on 11 September
Falcon obs. in sensitive area highlighted by e.g. SV, ETKF (red)
DOTSTAR observations in typhoon surrounding (blue)
WC-130 observations in typhoon center (green)
Evaluation of targeting strategies in ECMWF system
(Harnisch and Weissmann, 2010, MWR)

9. Which dropsonde observations are most beneficial?
Remote sensitive regions:
small positive to neutral impact
Typhoon vicinity:
improvement of the track forecast
Typhoon center and core:
overall neutral impact
Possible reasons:
SV resolution
Insufficient sampling of region
Low analysis error
Possible reasons:
Model resolution
Static B-matrix
Observation error, QC
ECMWF Integrated Forecast System
(Harnisch and Weissmann, 2010, MWR)

10. Doppler wind lidar (DWL) assimilation in ECMWF and NOGAPS
Impact of 1 DWL similar to dropsondes from 4 aircraft
Low impact on TC forecasts, likely due to bogus that “competes“ with other observations near TC
Airborne scanning DWL:
Coherent 2 µm Doppler lidar
Profiles of horizontal wind
Horiz. resolution ~5 km
Vert. resolution 100 m
Accuracy: m/s
Representative observations
(Weissmann, Langland, Pauley, Rahm and Cardinali, 2012, QJRMS)

11. FSO impact per observation (area 20-50N, 120-160W)
ECMWF
NOGAPS
TPW
SCAT
bogus
buoys
AMVs
SYNOP
radiosonde
SCAT
DWL
DWL
aircraft
Relative reduction of global 24-h forecast error by different observations:
Overall, significant impact of DWL in both systems
NOGAPS: DWL impact largest after TPW, bogus and scatterometer
ECMWF: DWL impact similar to aircraft observations
Larger total (accumulated) impact of DWL in NOGAPS although small impact on TC tracks (likely due to bogus near TC, but less other satellite observations elsewhere)
(Weissmann, Langland, Pauley, Rahm and Cardinali, 2012, QJRMS)

12. Water vapour lidar (DIAL) assimilation at ECMWF
Forecast impact
S-Korea
Japan
Okinawa
Improvement
Observations from 8 flights assimilated in ECMWF system
Verification with independent dropsondes shows analysis improvement
Weak forecast impact in most cases, but improvement in two events with modified downstream development
(Harnisch, Weissmann, Cardinali and Wirth, 2011, QJRMS)

13. Height correction of AMVs with lidar cloud top observations
Layer beneath lidar cloud top
Atmospheric motion vectors (AMVs) are the only available wind information in many regions of the globe, but:
Height assignment errors lead to significant wind errors
These errors are correlated over several hundred km  only a small fraction of AMVs is used for NWP
T-PARC offered a unique data set to test the potential of correcting AMVs with lidar information
Availablility of collocated lidar observations and independent dropsonde winds for verification
Best results were achieved for assigning AMVs to a 100 hPa layer beneath lidar cloud tops
On average, AMV wind errors were reduced by 14% with lidar correction
(Weissmann, Folger and Lange, 2013, JAMC)

14. Application of the correction with CALIPSO lidar observations
error for lidar layers
error for AMV level
error for layer 25% above, 75% beneath
Results:
12-17% lower AMV wind error
Lower bias
Lower error correlation
(further details on poster)
~1200 collocated MSG-AMVs/CALIPSO observations per day
(Folger and Weissmann , 2014, JAMC)

15. Conclusions Dropsonde impact in different models:
Some benefit of dropsonde observations in all systems
Large impact in NCEP GFS and KMA WRF (models with 3D-Var, less satellite observations and larger errors)
 Overall, targeted dropsondes are beneficial for TC forecasts, whereas results for mid-latitude targeting are neutral or small (latter not shown)
Specific ECMWF results:
Largest impact from dropsondes in typhoon vicinity
Low impact from dropsondes in remote “sensitive areas” indicated by singular vectors or ETKF
Neutral impact from core/eyewall dropsondes
Doppler wind lidar (DWL)
Overall significant and comparably large impact
Emphasizes high expectations for ADM-Aeolus satellite (despite some differences of the systems)
DIAL assimilation:
Improved humidity analysis, but weak forecast impact in most cases
Forecast impact when humidity is transported in mid-latitudes and downstream development is modified
AMV height correction with lidar cloud top observations:
Significant reduction of AMV wind errors (12-17%)
Lower bias and lower error correlation

16. Thanks to the T-PARC Falcon team!
Organisation: Martin Weissmann (DLR), Ulrich Schumann (DLR), Sarah Jones (KIT, DWD), Pat Harr (NPS), Tetsuo Nakazawa (JMA MRI, WMO), Dave Parsons (WMO, U. Oklahoma), Jim Moore (NCAR)
US Naval Air Facility Atsugi
Atsugi support team: Stephan Rahm (DLR), Rudolf Simmet (DLR), Oliver Reitebuch (DLR), Christian Lemmerz (DLR), Benjamin Witschas (DLR), Martin Wirth (DLR), Andreas Fix (DLR), Axel Amediek (DLR), Michael Esselborn (DLR), Gerhard Ehret (DLR), Felix Steinebach (DLR), Peter Mahnke (DLR), Reinhold Busen (DLR), Florian Harnisch (DLR), Johannes Dahl (DLR), Andreas Schäfler (DLR), Lisa Klanner (DLR), Kotaro Bessho (JMA), Sarah Jones (KIT, DWD), Doris Anwender (KIT), Simon Lang (KIT)
Aircraft team: Andrea Hausold (DLR), Frank Probst (DLR), Stefan Grillenbeck (DLR), Philipp Weber (DLR), Roland Welser (DLR), Michael Grossrubatscher (DLR), Christian Hinz (DLR), Wolfgang Meier (DLR), Josef Wiesmiller (DLR), Alexander Wolf (DLR), Christian Mallaun (DLR), Martin Zöger (DLR)
Falcon funding