simulating a dual technology dwl at 833km
DESCRIPTION
Simulating a Dual Technology DWL at 833km. G. D. Emmitt and S. A. Wood, SWA M. J. Kavaya, NASA/LaRC B.Gentry, NASA/GSFC Working Group on Space-based Lidar Winds June 28- July 1, 2005 Welches, Oregon. Proposed NPOESS DWL Mission Concept. Acquire useful data - PowerPoint PPT PresentationTRANSCRIPT
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Simulating a Dual Technology DWL at 833km
G. D. Emmitt and S. A. Wood, SWAM. J. Kavaya, NASA/LaRC
B.Gentry, NASA/GSFC
Working Group on Space-based Lidar WindsJune 28- July 1, 2005
Welches, Oregon
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Proposed NPOESS DWL Mission Concept
• Acquire useful data• Demonstrate instrument architecture
– Hybrid DWL • Direct detection for molecular backscatter• Coherent detection for aerosol backscatter
– NASA SHADOE scanner– 2 tracks, biperspective– 3 m/s wind accuracy– 0-20 km altitude
• Adaptive targeting – < 100% duty cycle to maintain NPOESS P3I margins – Select high impact targets
• Hurricanes/typhoons (DoD, DOC)• Air quality “episodes” (DoD, DOC)• Mid and high latitude cyclones (DoD, DOC)• Civilian and military aircraft operations (DoD, DOT)• Stratospheric/Tropospheric Exchange (NASA, DoD, IPO)
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The Hybrid DWL Approach• First proposed in 1995 as WOS/H (Wind Observing
Satellite/Hybrid)– Capitalize on the strengths of both technologies– Coherent detection for probing lower troposphere with high
velocity accuracy below clouds and in regions of enhanced aerosols
– Direct detection for broad coverage of the mid/upper troposphere (+ stratosphere) with modest accuracy
– Lower total mission costs by reducing investment in “very big” individual lidars; sharing a launch; sharing a platform; sharing pointing control, data collection, mission management and science team, etc.
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Science Synergies for the Hybrid DWL Approach
• The hybrid approach will provide full tropospheric wind observations sooner, with much of the accuracy, resolution and coverage needed by tomorrows global and regional models
• The direct detection molecular DWL sub-system would, in its first mission, provide useful wind observations in cloud free regions of the mid/upper troposphere and lower stratosphere
• The coherent DWL sub-system would immediately meet the science and operational IORD requirements throughout the troposphere in regions of high aerosol backscatter (dust layers, clouds, PBL aerosols)
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Parameter Coherent Directmol
Wavelength (microns) 2.05 .355
Energy/pulse (Joules) .250 .2 (@.355)
PRF (design) (Hz) 10 100
Optical Efficiency (total) .7 .3
Mixing Efficiency .4 N/A
Detector Efficiency .8 .8
Collector Diameter (meters)
.2 1.0 (HOE)
Integration Time (sec) 12 12
Wallplug Efficiency .03 .07 (@ 1.064)
Weight TBD TBD
Total Power (watts)
(w/o scanner)
82 (peak and average)
850 Peak
(250 average)
NPOESS Hybrid DWL
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The Hybrid Instrument
• Uses two lidar subsystems– One direct detection, the other coherent– Subsystems have complementary measurement
properties• Direct detection subsystem
– Detects doppler shift from atmospheric molecules– Operates everywhere, 0 to 20 km altitude– Provide useful wind observations in cloud free regions
• Coherent DWL subsystem– Meets requirements in regions of high aerosol
backscatter (dust layers, clouds, PBL aerosols)
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The Adaptive Targeting Mission• Adaptive targeting of tropospheric wind profiles for high impact weather
situations– Hurricanes/typhoons (Navy)– Air quality “episodes” (Army)– Mid and high latitude cyclones (DoD)– Civilian and military aircraft operations (DoD)– Stratospheric/Tropospheric Exchange (USAF)
• 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– Depth of PBL– Initial Condition Adaptive Targeting (ICAT) for managing direct detection
• Direct detection (molecular) sub-system (using HOE)– 10-15% duty cycle (aperiodic, i.e. adaptively targeted)– Cloud free mid-upper tropospheric/ lower stratospheric winds
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Primary Targets for Hybrid/AT*
• Significant Shear regions– Requires contiguous observations in the vertical. Thus both
direct and coherent detection technologies are needed.
• Divergent regions– Requires some cross track coverage. Identified by NCEP
adaptive targeting scheme(s)
• Partly cloudy regions– Requires measurement accuracy weakly dependent upon shot
integration (i.e., coherent detection).
• Tropics– Tropical cyclones (in particular, hurricanes & typhoons).
Requires penetration of high clouds and partly cloudy scenes.
*AT: Adaptive Targeting
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Locations for current wind profiles from rawinsondes
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Global coverage of lower tropospheric wind profiles, clouds and elevated aerosol layers using 100% duty cycle of coherent subsystem.
Coherent sub-system coverage
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Full tropospheric/lower stratospheric wind soundings, 10% duty cycle with direct detection subsystem combined with
coherent detection coverage of lower troposphere
Direct sub-system coverage
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Example Adaptive Targeting coverage
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Example of AT coverage with CONUS interests only
Red: direct detection coverage; Blue: coherent detection coverage
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Example of vertical AT coverage
With backgroundaerosol distribution
With convectivelypumped aerosoldistribution
Red: < 4 m/s errorBlue: < 1.5 m/s error
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Adaptive Targeting OSSE(performed at NASA/GSFC)EXAMPLE TARGETED LOCATIONS FOR DWL OSSE
( White symbols: full lidar coverage; Red symbols: targeted cove rage)
1999
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Forecast impact of 10% duty cycle AT
Model: GEOS -2 Recon. Verification: ECMWF Nature Run
Control: - Conventional Data + Perfect TOVSCTW - Control + Cloud Tracked Winds1 m/s Wind - Control + Doppler Wind Lidar (RMSE = 1 m/s)Adaptive Targeting - Control + Adaptive Targeting of DWL Observations (~10% duty cyc le)
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Current wind profiles for NWP P3I coherent 100% duty
P3I direct 10% duty Full potential for an NPOESS orbit
Blue indicates percent of 300 x 300 km areasnot sampled by observing system
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Evaluation of adaptive targeting of DWL observations
• IPO-funded studies at NOAA/NCEP and NASA/GSFC show adaptive targeting (10-15% duty cycles) products can rival 100% duty cycle
• IPO and THORPEX funded OSSEs at NCEP and GSFC – Quantify AT impacts – Evaluate methods of identifying targets
• Field programs (NASA’s CAMEX and NOAA’s WSR) demonstrated the value of adaptive targeting
• Many military needs would be met with targeted wind observations.
* OSSE: Observing System Simulation Experiment
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Backup slides
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IPO funded Hybrid feasibility study
• 1999-2001 Developed “reference systems” which could be used in trade studies.
• Defined a common data product as target• Scaled each technology to obtain the same
data product. (yielded very large systems)• Defined a hybrid system that would yield
the same data products; in some respects better.
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Potential Impact of new space-based observations on Hurricane Track Prediction
Based on OSSEs at NASA Laboratory for Atmospheres
• Tracks• Green: actual track• Red: forecast beginning 63 hours
before landfall with current data• Blue: improved forecast for same
time period with simulated wind lidar
• Lidar in this one case• Reduces landfall prediction error by
66%
DWLs greatly improvehurricane track predictions
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Potential Impact of new space-based observations on Hurricane Track Prediction
Based on OSSEs at NASA Laboratory for Atmospheres
• Tracks• Green: actual track• Red: forecast• Blue: improved forecast for same
time period with simulated wind lidar
• Lidar in this one case• Indicates the hurricane will make
landfall
DWLs greatly improvehurricane track predictions