Snowmass, 18 July 2007 Impact Studies with Airborne Doppler Lidar Observations: A-TReC to T-PARC Martin Weissmann, Andreas Dörnbrack, Stephan Rahm, Oliver Reitebuch Institut für Physik der Atmosphäre, DLR Oberpfaffenhofen, Germany Carla Cardinali ECMWF, Reading, UK

Snowmass, 18 July 2007 DLR lidar systems scanning coherent 2 µm Doppler lidar: step-and-stare scan with 24 positions  24 LOS observations (~30/54 s)  vertical profile of 3-D wind vector horiz. resolution km vert. resolution 100 m range: km recording of every single shot (500 Hz) correction with ground return Doppler lidar 20° off nadir dropsondes, u, v, t, rh, p new 4 wavelength water vapour DIAL ~ nm, 100 Hz, > 2 W parameter: water vapour molecule number nadir pointing (zenith is possible) horiz. resolution: km vert. resolution: m high spectral resolution DIAL

Snowmass, 18 July flights in "sensitive areas" (targeting) 1 flight for Greenland Tip Jet 1 flight for intercomparison ASAR and lidar 2 transfer flights ======================================= 8 flights, 1600 wind profiles, lidar observations, 49 dropsondes DLR participation in the Atlantic THORPEX Regional Campaign ( November 2003)

Snowmass, 18 July 2007 Iceland Ireland ECMWF sensitivity plot and 500 hPa Observations on 25 November 2003 (A-TReC) 1 scan revolution (res. ~10 km) 25 values per profile (2500 m) coverage = 36% 4 scan revolutions (res. ~40 km) 38 values per profile (~3800 m) coverage = 54%

Snowmass, 18 July 2007 Error lidar (u,v): RMS = m/s Statistical intercomparison of lidar and dropsondes Weissmann et al (JTECH)

Snowmass, 18 July km x 40 km (Isaksen 2005) Dropsonde (2000 times enlarged) Radiosonde/Dropsonde: (most accurate operational wind observation) Observational error <0.5 m/s Assigned error: 2-3 m/s Observational error lidar: m/s Rep. error < 0.5 m/s (Frehlich and Sharman 2004) Assigned error: m/s Assigned error AMV: 2-5 m/s Assigned errors in ECMWF data assimilation

Snowmass, 18 July 2007 Background departure = difference background and observation (Std(bg-dep)) 2 = (Std obs ) 2 + (Std bg ) 2 Background departures

Snowmass, 18 July experiments November 2003 lidar, ~10 km, Std = 1 m/s lidar, ~40 km (2 averaging types), Std = 1 m/s lidar, ~40 km, Std =1.5 m/s ~100 dropsondes (from 10 flights) control run thinning to grid points (40 x 40 km, 60 levels) ~ 80% not used ~ 3000 used measurements 5 million operational measurements used per day lidar = 0.005% additional measurements 4 un-cyled experiments to investigate targeted observations (forecast sensitivity) Experiments with ECMWF T511 global model

Snowmass, 18 July 2007 Lidar u, v Dropsonde u, v Observation influence Number of observations Information content observation influence (Cardinali et al. 2004): 0 --> no influence of observations 1 --> no influence of background Observation influence (22 November 2003) northern hemisphere AMV: 0.15 Raso: 0.3

Snowmass, 18 July 2007 (gpdm) Reduction of forecast error - 48 h

Snowmass, 18 July 2007 (gpdm) Reduction of forecast error - 72 h

Snowmass, 18 July 2007 area: 17 x km 2 (gpdm) Reduction of forecast error - 96 h

Snowmass, 18 July 2007 Mean reduction over Europe, averaged over 29 forecasts (2 weeks) black: experiments with lidar, gray: experiment with 100 dropsondes Reduction of forecast error hPa

Snowmass, 18 July 2007 Reduction of forecast error - 48, 72, 96 h

Snowmass, 18 July 2007  Reduction of u, v, z, rh, and t forecast errors Weissmann and Cardinali 2007, QJ Relative reduction of RH forecast error - 48, 72, 96 h

Snowmass, 18 July 2007 Why do we need more studies? large, significant improvement in a few events, but the judgement for a future satellite mission needs to show: the impact in different areas, flow regimes and for many cases? a reliable quantification of the impact? the impact in different assimilations systems? the sensitivity to accuracy and resolution?

Snowmass, 18 July 2007 NOAA DLR at 18 Step at 18 Step at 18 Step at 18 Step30 Cut off low; heavy precipitation in SE-Spain Heavy rain/strong wind in Portugal and NW-Spain Strong winds –northwest Europe Heavy rain, Scotland and Norway A-TReC targeting campaigns

Snowmass, 18 July 2007 The influence of targeted observations ­ + ­ + main conclusion: we need more cases A-TReC cases were not ideal: planning needs to be improved maximum of sensitive area out of reach for the aircraft period with no high impact weather event and without low forecast error

Snowmass, 18 July 2007 evaluate targeted observations and determine impact in different flow regimes larger data set is needed for sensitivity studies to determine the optimal configuration of future satellite Doppler lidar (e.g. reduce to LOS or resolution) investigate the value of future operational observation targeting (e.g. with satellite lidar) test targeting strategies derive parameters for the simulation of future satellite systems (observations in cloud gaps, correlation of backscatter and humidity, ground return over the sea etc.) What we could do with more data

Snowmass, 18 July 2007 airport base: Yokota, Japan flight time: 120 h including transfer period: 7 weeks costs: M$ 1.7 (80% funded) funding agencies: DLR, NSF, JMA, ESA, FZK/IMK, Canada, EUCOS, Korea (?) range of DLR Falcon aircraft THORPEX Pacific Asian Regional Campaign (T-PARC), autumn 2008

Snowmass, 18 July 2007 Nida(2004) Megi(2004) Conson(2004) Mindulle(2004) Nanmadol(2004) Aere(2004) Meari(2004) Nockten(2004) Wu et al. (2006)

Snowmass, 18 July 2007 Tetsuo Nakazawa

Snowmass, 18 July 2007 Impact studies with DIAL water vapour data Germany Iceland Greenland North America WV mixing ratio [mg/kg] 13 May May May 2002 Studies with Elias Holm, ECMWF

Snowmass, 18 July analysis with lidar data (11 down, 6 upward looking) lidar observations ongoing: new quality control sensitivity studies (e.g. no coupling with wind)

Snowmass, 18 July 2007 no correlation found between key analysis errors and lidar analysis departures or analysis diff. -neither statistical correlation nor qualitative similarity -same for B-matrix norm and total energy norm -this confirms that results of Isaaksen et al 2005 that KAEs draw the analysis away from obs., but now it is also shown for data sparse regions -raises the question what KAEs describe -results submitted to Meteorologische Zeitschrift (Koch, Ehrendorfer and Weissmann 2007) Comparison of key analysis errors and lidar analysis departures

Snowmass, 18 July 2007 significant improvement of ECMWF forecasts fields (wind, temperature, and humidity) (~3% for 2-4 day forecasts over Europe) lower assigned error than all other current wind observations --> higher observation influence more data is needed for sensitivity studies, a more accurate quantification of the improvement, and the evaluation of observation targeting some targeted lidar observations during COPS/E-TReC (ongoing at the moment) and THORPEX-IPY in spring 2008 what we need is a large consistent data set for statistically reliable conclusions  T-PARC, 20% funding missing, preparation needs to start soon (decision in September)  evaluate the impact in different assimilation systems: ECMWF, JMA, NRL, Canada...  additionally observations with TODWL on P-3? ground campaign with the ADM demonstrator ongoing at the moment: much stronger signal than before; flight campaign possibly 2008 Summary

Snowmass, 18 July 2007

range=0-2.5km range=2.5-5km range=5-7.5km range=7.5-12km Correlation of backscatter and humidity