The impact of PCW satellite winds filling the gap at high latitudesL. Garand, J. Feng, Y. Rochon, S. Heilliette, EC, and A. P. Trishchenko,CCRS

Satellite Applications for Arctic Weather and SAR Operations (SAAWSO) WorkshopSt-Johns, NFLD, 22-24 April, 2013

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OutlineAdvantage of Highly Elliptical Orbit for polar regionsMotivation for a specific AMV impact studyOSSE definitionImpact results of real and simulated AMVs Conclusion

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Polar Communications and Weather (PCW) mission in a few words2-satellite constellation in highly elliptical orbit Core meteo instrument similar to ABI (GOES-R)Extends GEO applications to the pole, 15 min imagery 16-h 3-apogee (TAP) ground track spatio-temporal coverage vs latitude Apogee 43,000 km, at 30 N, 30,000 km

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16-h three apogee (TAP) orbit path over two days SAT-1 would be 8-h ahead of SAT-2, and follows same path each satellite would image +/- 5-h to apogeePositions represent 1-h intervals

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Motivation here: impact on NWP of filling the AMV gap in the northern polar regionCurrent AMV coverageAfter quality controland thinning4 HEO satellites wouldBe needed to fill both N and S gapsAMVs would be produced from 15 min imageryAt latitudes 45o-90o

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HEO (2-sats) vs LEO (2, 4, 7 sats) coveragebased on May 2011 average Ref: Trishchenko and Garand, 2012, Canadian J. Remose Sensing

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Simulation and assimilation setups

Assimilation model and system:Operational Global Environmental Multi-scale model (GEM)801x600 (~35 km), 80 levels, top 0.1 hPa 3D-VAR assimilation, FGAT (First Guess at Appropriate Time) Cycle starts from 5-day forecast from NR

ECMWF Nature Run serves as truth (~40 km resolution) interpolated to GEM grid for validation purposes

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OSSE definition

Period covered in test cycles (2.5 months):15 December 2005 to 28 February 2006Simulated from NR all data types assimilated. Positions are those at the same dates in 2008-2009, to include recent types (GPSRO, IASI) not available in 2005-2006. All-sky (cloudy) IR radiances were simulated from NR. Clear radiances were selected as done operationally (residual cloud contamination is possible).Background check done once for all (same data assimilated in all cycles).

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Non-radiance observations assimilated

Observing networkAtmosphericVariablesApplied resolution Data densityRadiosondes anddropsondesWind, temp, hum, Ps28 vertical levels~750 stations, twice per day Surface reports, ships and buoysWind, temp, hum, Ps1 report / 6h~6 000 stations, hourlyWind profilers Wind750 m vert. resol.35 US sites, hourlyAircrafts Wind, temp., hum.100 - 1025 hPa~14 000 to 22 000 per 6-hGPS RO (COSMIC (6), GRACE, METOP, CHAMP)Temp, hum~1 km to 40 km vert. range, 830 m vert. resol. ~600 profiles/6hScatterometer winds from Quikscat Ocean surface wind100 km thinning ~10 000/6hPolar AMVsWind180km thinning~2500 per 6-h,from TERRA/AQUAGEO AMVs Wind150 km thinning ~14 000 to 26 000 per 6-h

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Radiance observations assimilated

InstrumentPlatformNumber per day (~)Channels usedAMSU-A NOAA-15338 000Ch. 3-14 over oceanCh. 6-14 over landNOAA-18472 000AQUA332 000AMSU-B NOAA-1541 000Ch. 2-5 over oceanCh. 3-4 over landNOAA-1684 000NOAA-1793 000MHS NOAA-1896 000SSMIDMSP-1361 000Ch. 1-7 SSMISDMSP-1639 000AIRSAQUA660 00087 channels IASIMETOP-A501 00062 channels GOES imagersGOES-1135 000Water vapor ~6.7 mmChannel onlyGOES-1242 000MVIRIMETEOSAT-769 000SEVIRIMETEOSAT-9 42 000MTSAT-01METSAT-1R21 000

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Observation perturbationsPerturbations applied to the simulated observations using Gaussian-distributed random errors

No applied spatial or inter-channel error correlations.

No applied biases

Calibration of OSSE:

Perturbation is simple multiplier of assigned observation error STD for each data type to get (O-A), (O-F) statistics similar to real corresponding statisticsRef: Rochon et al., 2012, Workshop on Impact of observations, Sedona, AZ

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Wind errors assigned in assimilationin comparison to AMV MVD errors AMV error inflated in relation to (O-F) polar MDV lower than extratropics MVD perturbation is 0.28 AMV obs error

Level hPaRaob m/sAMDARm/sAMVm/s(O-F) AMV MVD60-90N 20-60N (m/s)10001.62.63.0---- --- 9251.72.63.0---- 1.88501.72.63.0---- 1.87001.82.63.52.7 3.25002.02.64.52.7 3.24002.23.15.03.2 3.23002.63.15.53.2 3.62502.63.16.03.2 3.62002.33.16.03.2 3.61502.13.16.03.2 3.61001.93.16.03.2 3.6

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Simulated AMV: NR wind at NR cloud top 11m BTFrom NRCloud topPressureWhere TOA tau(cloud)=0.9Cloud fraction1- tau(cloud)

AMVNR windAt cloudtopRef: Garand et al, Atmosphere-Ocean, 2011.

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PCW AMV used in assimilation thinning at 180 km no data where cloud free 50-90 N/S coverage allowed range 100-925 hPa every 6-h same obs error (by level) for all AMVs

Conditions similar to operational AMVs except +-3-hwindow for OPE and range 100-700 hPa

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Definition of OSSE cycles (3dvar)

Experiment name DescriptionREAL_CNTLCorresponds to the operational real data assimilation system REAL_NOAMVSame as REAL_CNTL but without AMV assimilationSIM_CNTLEmulates REAL_CNTL but with simulated dataSIM_NOAMVSame as SIM_CNTL,but without AMV assimilationSIM_PCW1Same as SIM_CNTL but with the addition of HEO AMVs in the 500-900 N regionSIM_ PCW2Same as SIM_NOAMV but with the addition of HEO AMVs in both the 500-900 N and 500-900 S regions Operational GEO and LEO AMVs are not assimilated in that cycle.

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Impact of real and simulated AMVs REAL_CNTL REAL_NOAMV SIM_CNTL SIM_NOAMV

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500 hPa temperatureSTD Differerence w.r.t.Own analyses:REAL_CNTL minusREAL_NO_AMV (left)

SIM_CNTL minusSIM_NO_AMV (right)

Grey: 95% confidenceComparing AMV impactIn real and simulatedData assimilationsystems

REALOSSE

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Impact of adding PCW AMVs in region 50-90 Nin comparison to control (vs NR)SIM_CNTL SIM_PCW1Note: very similar results vs own analyses beyond day 2

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Adding PCW AMVs in regions 50-90 N/S:impact comparison vs no AMVvs own analyses vs Nature Run24-h

120-h

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Comparing impact at 72-h in regions 50-90 N and 50-90 S (vs NR)SIM_PCW2 SIM_NOAMVLarger impact in SH

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500 hPa GZ anomaly correlation vs NRSIM_PCW2 SIM_NOAMVPredictability gain at days 3-5: ~2-h in NH, ~4-h in SH, accounting for50% too optimistic results from OSSE

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ConclusionA comprehensive OSSE setup was developed Real AMVs have a consistent positive impac up to day 4.OSSE AMV impact tends to be higher than real impact, especially in the TropicsAdding 50-90 N PCW AMVs has a significant positive impact in that region up to day 3, but not significant further south Gain of predictability of order 1-3h at day 3 in region 50-90 N. Gain is twice larger in region 50-90 S, and extends to 30 S.Validation vs NR or own analysis consistant after day 2OSSE set-up could be used to infer other impacts, e.g. assimilation of PCW radiances at high temporal resolutionThis work soon to be published in JCAM

*****Surface conditions from the corresponding GEM 2005-06 operational analysis instead of the Nature Run.Perturbed initial state files: Created by producing a 5 day forecasts with GEM starting from the above and re-assigned to the start dates.

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