1 Global Observing Systems Simulation Experiments at NCEP Michiko Masutani

2 1 NOAA/NWS/NCEP/EMC, Camp Springs, MD 2 NOAA/NESDIS, Camp Springs, MD 3 Simpson Weather Associates, Charlottesville, VA 4 Joint Center for Satellite Data Assimilation 5 NASA/GSFC, Greenbelt, MD # RS Information Systems + Science Applications International Corporation % QSS Group, Inc. Authors and Contributors OSSEs: Observing Systems Simulation Experiments Michiko Masutani 1#, John S. Woollen 1 +, Zoltan Toth 1, G. David Emmitt 3, John LeMarshal 4, Stephen J. Lord 1, Russ Treadon 1, Thomas J. Kleespies 2, Haibing Sun 2 %, Yucheng Song 1+, Sidney A. Wood 3, Steven Greco 3, Chris O’Handley 3, Joseph Terry 5, Weiyu Yang 1+, John C. Derber 1,Paul VanDelst 1+, Bert Katz 1+ Many other people of EMC, SWA, NESDIS, NASA/GSFC, JCSDA, and ECMWF

3 Nature Run Withdraw or Add data for existing instruments Data assimilation Forecast impact test Control data Real observed data Simulation Real Control data + Simulated data for future instruments Forecast Calibration Analysis Analysis impact test Forecast impact test Analysis impact test Analysis Forecast Data assimilation Analysis and forecast are evaluate against analysis of control Simulation of data Nature Run Evaluation of New Instruments Simulated analysis and forecast are also evaluate against the Nature Run Experimental data Real observed data Simulated data

4 NCEP Winter time Nature run (1 month) NR by ECMWF model T213 (~0.5 deg) NCEP data assimilation T62 ~ 2.5 deg 1993 data distribution Simulate and assimilate satellite 1B radiance Use line-of- sight wind for DWL Evaluation and adjustment of cloud Calibration performed Effects of observational error tested Scale decomposition of anomaly correlation skill Summer time Nature run (4 month) including hurricanes. NR by NASA FVCCM model with 0.5 deg Use NASA DAO GEOS-3 data assimilation with deg 1999 data distribution Use interpolated temperature for radiance data Use U and V wind for DWL data Impact on hurricane forecast Evaluate cyclone tracks and Jet streak locations NASA/GLA Two OSSEs

5 The realistic cloud cover of NR is important. However, three observations are very different.

6 Underestimation of Low level stratocumulus over ocean. Over estimation of low level cloud over snow were evident. Adjustment based on ground based observation was performed.

7 OSSE Calibration Compare real data sensitivity to sensitivity with simulated data – Relative order of impacts should be same for the same instruments – Magnitudes need not be the same but should be proportional – Quality control (rejection statistics) – Error characteristics (fits of background to Obs) Data impact depends on Data assimilation (DA) system Choice of the nature run. Observational error assignment.

8 Initial condition from reanalysis with OP93 OSE (real data) Nature Run (known) Spin up period Feb.5Feb.13March 7 Provide initial condition OSSEs Real analysis with OP99 Switch to OP2005 model on Feb 5th Spin up period Control experiment Simulation of observation Known observational error Real Atmosphere (unknown) Observation (unknown observational error) Add or subtract data

9 OSSE Calibration Compare real data sensitivity to sensitivity with simulated data Impact of withdrawing RAOB winds Real Simulated Analysis 72 hour forecast 500hPa U

10 SH NH 500 hPa Height Anomaly Correlation 72 hour forecasts Calibration of Simulated Data Impacts Vs Real

11 Anomalous warm localized SST in SH Pacific in REAL SST. In simulation experiment constant SST is used. Four analyses are performed with real SST, constant SST, with and w/o TOVS. With TOVS data the difference is small in mid troposphere but without TOVS data, large differences appear and propagate. Four experiments are repeated for simulated data. This atmospheric response to SST is reproduced by simulated experiments. With variable SST TOVS radiance become much more important. Impact of TOVS is much stronger in real atmosphere. SST and Impact of TOVS

12 Impact Assessment of a DWL using OSSEs All levels (Best-DWL): Ultimate DWL that provides full tropospheric LOS soundings, clouds permitting. DWL-Upper: An instrument that provides mid and upper tropospheric winds only down to the levels of significant cloud coverage. DWL-PBL: An instrument that provides only wind observations from clouds and the PBL. Non-Scan DWL : A non-scanning instrument that provides full tropospheric LOS soundings, clouds permitting, along a single line that parallels the ground track. Bracketing experiments were performed The real DWL will be somewhere among these.

13 Results from OSSEs for Doppler Wind Lidar (DWL) All levels (Best-DWL): Ultimate DWL that provides full tropospheric LOS soundings, clouds permitting. DWL-Upper : An instrument that provides mid and upper tropospheric winds only down to the levels of significant cloud coverage. DWL-PBL: An instrument that provides only wind observations from clouds and the PBL. Non-Scan DWL : A non-scanning instrument that provides full tropospheric LOS soundings, clouds permitting, along a single line that parallels the ground track. All levels (Best-DWL DWL-Upper: DWL-PBL Non-Scan DWL Number of DWL LOS Winds 2/12/93

14 Non scan Note: In order to measure U and V from non scan DWL, two satellite or DWL sample for two directions are required Clustered-Sample Distributed Sample Clustered-Sample

15 Highlight of the Results from DWL OSSEs Scanning significantly increases the impact In NH, DWL with scanning is required to produce significant additional skill over existing data. Non-scan DWL may produce significant impacts in SH similar to 1993 radiance data.

16 Using 1999 version of NCEP DA DWL with scan: 12 hour improvement DWL non scan: 4 hour improvement Forecast hours % The diagram is anomaly correlations with nature run for 200mb V. Improvement in forecast skill with respect to forecasts with RAOB and surface data only. Skill for Northern Hemisphere synoptic scale events are presented. The resolution of DA is T62.x NH synoptic scale

17 Other finding through DWL OSSEs Upper level data become more important after 3 days even at lower levels Impact of DWL is more significant at smaller scales In tropics large analysis impacts diminish rapidly – Need more model improvement to achieve forecast impact – DWL will be useful in evaluating analysis Systematic large scale error added to the simulated data increase the data impact at large scale There are evidence that even non-scan lidar will produce an almost similar amount of impact as RAOB wind in NH average. – RAOB wind has more impact over land. Non-scan lidar has more impact over ocean and tropics. Scanning is more important in upper troposphere than in lower troposphere

18 Doppler Wind Lidar (DWL) Impact in Synoptic Scale Time averaged anomaly correlations between forecast and NR for meridional wind (V) fields at 200 hPa and 850 hPa. Anomaly correlation are computed for zonal wave number from 10 to 20 components. Differences from anomaly correlation for the control run (conventional data only) are plotted. Forecast hour Non Scan Scan Lidar Upper lidar become more important in low level 8 8

19 Effect of Observational Error on DWL Impact Percent improvement over Control Forecast (without DWL) Open circles: RAOBs simulated with systematic representation error Closed circles: RAOBs simulated with random error Orange: Best DWL Purple: Non- Scan DWL Total Wave Forecast length Significant impact in large scale by adding systematic large scale observational error DWL with large scale error

20 Impact of DWL with Scanning T170 vs. T62 Analysis 48 hr T170 T62 T170T NOAA 11, 12 TOVS were not ready for T170 experiments

21 T62 and T170 CTL (Conventional data only) Data Impact in T62 vs. T170 Total scaleSynoptic Scale T62 CTLwith Non Scan DWL T62 CTL with Scan DWL T170 CTL with Non Scan DWL T170 CTL with Scan DWL 200 mb V -T62 CTL -T170 CTL Differences in anomaly correlation ◊ CTL ● Non-ScanDWL X Scan DWL Impact with T170 model look less than with T62 model T62 T170

22 T62 CTL (refernece) (Conventional data only) Data Impact of scan DWL vs. T170 T62 CTL with Scan DWL T170 CTL T170 CTL with Scan DWL ◊ CTL X CTL+Scan DWL - CTL Differences in anomaly correlation Synoptic ScaleTotal scale 200 mb V T170 is better than adding DWL with scan Adding DWL with scan is more important than T170 model Impact of T170 model Impact of DWL

23 Impact of DWL T170 vs. T62 (Cont) Apparent data impact is less in a high resolution model (T170 or better model) because the guess is already good. However, improvement from the new data becomes more robust in high resolution model. Much of the apparent improvement in a low resolution model diminishes in the forecast fields.

24 Analysis 48 hr Non-scan Lidar over CTL Non-scan Lidar vs. RAOB Wind Red: DWL has more impact Blue: RAOB Wind has more impact CTL: Conventional Data no Satellite data Red: DWL has positive impact Blue: DWL has negative impact Non-Scan Lidar vs. RAOB Wind T170 (Feb13- Feb20) Non scan lidar showed minimum impact over RAOB wind Non scan lidar has more impact over ocean and RAOB has mode impact over land Impact increase in forecast fields

25 Non scan lidar showed minimum impact over RAOB wind Non scan lidar has more impact over ocean and RAOB has mode impact over land Impact increase in forecast fields Non-Scan Lidar vs. RAOB Wind

26 On going work and plans Targeted DWL for NPOESS Including CMV – CMV with estimated error – CMV enhanced by DWL AQUA data – With and without cloud to test QC – Combined impact with DWL Participating development of DA system for new instruments – Test and find out various potential problems.

27 OSSE with TOVS and AIRS December 2003 version of NCEP DA system : AIRS showed minimum impact. Very little data were assimilated. NOAA 11, 12 data ( available in 1993 and can be used for calibration ) Prepared for new 2005 version of DAS and tested. Need some tuning Progress: Updated simulation and assimilation code. AQUA data has been produced with and without cloud condition to allow to test new QC. CrIS and ATMS have been simulated Need to develop DA system NESDIS is working on simulation of CMIS

28 Adaptive Targeting Mission for NPOESS Hybrid DWL Coherent detection sub-system (wedge scanner or HOE) – 100% duty cycle – Lower tropospheric and enhanced aerosol/cloud winds – CMV height assignment Reduce DAS observation error by ~2-3 m/s (per Chris Velden) – Depth of PBL – ICAT for direct detection + target identification by LEKF (e.g.) Direct detection (molecular) sub-system (HOE) – 10-15% duty cycle (aperiodic, i.e. adaptively targeted) – Cloud free mid-upper tropospheric/ lower stratospheric winds

29 Experiments for Thinned Hybrid DWL Testing 10% use of Upper level DWL 100 %PBL 100%PBL+ 100% Upper 100%PBL +10% Upper (10min on 90 min off) 100%PBL+ 50%Upper also tested Experiments with and without NOAA 11,12 radiance data Quick look of impact in analysis for low resolution (T62) experiments showed that impact of Upper DWL is proportional to amount of data included. 10% upper: 20% impact 50% upper: 80% impact

30 Targeted Hybrid DWL (10% of upper DWL) Proposed strategies for targeting Random selection. Uniformly choose 10% Select the area of target based on (obs-ges) Select area based on interest Avoid area which does not produce much impact. (Example: Cloudy area) Further evaluation to be performed higher resolution model (T170) forecast experiments (up to 72hr) More discussion on evaluation strategies will be continued

31 CROSS-CUTTING ACTIVITIES TIP – “OBSERVING SYSTEM” GEOSS TIP – “DATA ASSIMILATION…” TIP – “PREDICTABILITY & DYNAMICAL PROCESSES” TIP – “SOCIAL & ECONOMIC APPLICATIONS” TIP NTSIP DIRECT LINK BETWEEN NOAA THORPEX SCIENCE AND IMPLEMENTATION PLAN (NTSIP) AND THORPEX INTERNATIONAL SCIENCE PLAN & THORPEX IMPLEMENTATION PLAN (TIP) SYSTEM THORPEX GLOBAL ENSEMBLE (TIGGE) THORPEX OSSE is recognized as a major cross cutting activity.

32  As a result a key program element for the Center is to conduct OSSEs for advanced satellite sensors to be used for weather and climate (environmental ) analysis and prediction.  Instruments being currently assessed for such experiments are the CrIS, ATMS, GOES-R/GIFTS and the HyMS* – P and G %. * HyMS Hyperspectral Microwave Sounder % P- Polar, G Geostationary The Role of JCSDA in OSSEs Joint Center for Satellite Data Assimilation (JCSDA) Mission Accelerate and improve the quantitative use of research and operational satellite data in weather and climate analysis and prediction models

33 Search for the New Nature Run Preparation of the nature run consume significant resources. One or two good nature runs for many OSSEs Possible other candidate: Earth Simulator, fv GCM from NASA ECMWF will be able to provide a Nature run. The detail need to be defined. Data would be made available via existing MARS service. Current plans are: -one 13-month long run at T511L91 with detailed output every 3h -for selected periods of the previous one (few weeks duration, totaling two months): T799L91 run with output every 30 minutes

34 New Nature Run (ECMWF proposal) Low resolution Nature Run (L-NR) One year (13month) low resolution (T511) with more vertical levels in stratosphere. 91 levels and 3 hourly dump. Remove the drift. (Discard the first month) Daily SST and ICE (Provided by NCEP) Select two or three most interesting periods Regional NR with high temporal and high horizontal resolution T799L91 30 min dump Get initial condition from L-NR High horizontal resolution NR T799, 91 levels 3 hourly dump High temporal resolution NR T511L91 30 min dump Archived in MARS system Need more discussion and consider various interests

35 Summary OSSE is critical tool for : – Designing future observing systems – Improving DA and ensemble systems Current NCEP system showed OSSEs are capable to provide critical information for assessing observational data impact Future developments at NCEP will be under JCSDA and coordinated with THORPEX and other international scientific community. Need new nature run which will be used by many OSSEs. Extended international collaboration within Meteorological community is essential for timely and reliable OSSEs Operational Test Center OTC – Joint THORPEX/JCSDA JCSDA (NCEP, NESDIS,NASA), ESA, EUMETSAT THORPEX, NPOESS

36 Challenges in OSSE Research The concept of OSSE is simple. However, there are many details in achieving a reliable OSSE – Short cuts will degrade OSSE – It is not possible to reproduce the real system perfectly Evaluate the consequences of a shortcut and present with results OSSE is a very labour intensive project. – Collaboration is very important Require many experts in many fields. – Involve all elements of NWP – Small amounts of time from many people needed There are limitations from the nature run provided – The limitations need to be evaluated Results keep changing as DA system develops – OSSEs need to be repeated over and over again with different systems in various NWP centres.

37 Lessons from OSSEs valuation against truth (NR)● OSSE can evaluate data impact against truth (NR) - Negative impact can be evaluated ● Many findings are different from (theoretical?) expectation. - Worth trying even if not so perfect. ● Coordination is very important. - Missing elements hold back whole project ● Interpretation has to be done very carefully -Apparent impact depends on CTL -The different between NR and real atmosphere Difference in Observational errors ● Work involved -Check NR -Data simulation -Check the simulated data -Preparation of fix files -Assimilation -Evaluation -Diagnostics -Presentation

38 Lessons from OSSEs (cont.) Simulation of observation – Need Orbit simulator – Need to be flexible. Frequent dump of NR and simulate data after ward instead of the time of NR generation. – OSSE with BUFR formatted data Speed up implementation Software for the interface – BUFR decoder etc. – Interpolation for the NR OSSEs are easy to get last priority – Need involvement of operational staffs, who are already overloaded by implementation of existing data – Keep reminding community and instrument community about the benefit of OSSEs in long run.

39 Joint Center for Satellite Data Assimilation (JCSDA) recognized OSSE as a key program element. Observing Systems Simulation Experiments at NOAA National Centers for Environmental Prediction NCEP leads an expanding national and international collaboration in OSSE effort Extended collaboration within the THORPEX community is essential for timely and reliable OSSEs. JCSDA, NCEP, NESDIS,NASA, ECMWF,ESA, EUMETSAT ECMWF agreed to do the next Nature Run (OSSE ground truth). Proposal: A 13 month T511 run archived every 3 hours & T799 runs archived every 30 minutes for selected periods. NCEP collaborates with GMAO/GSFC/NASA to study error characteristics in Data Assimilation using OSSE. The current NCEP system has shown that OSSEs can provide critical information for assessing observational data impacts. The results also showed that theoretical naive explanations will not be satisfactory when designing future observing systems. Results from OSSE with a high resolution model Apparent data impact is less in a high resolution model (T170 or better model) because the guess is already good. However, improvement from the new data becomes more robust in high resolution model. Much of the apparent improvement in a low resolution model diminishes in the forecast fields. Impact of a space based Doppler Wind Lidar with scanning on 200hPa V-component fields.

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