oct 20081 october 2008 an update provided by thomas nehrkorn atmospheric & environmental...
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Oct 2008 1
October 2008
An update provided by
Thomas Nehrkorn
Atmospheric & Environmental Research, Inc.131 Hartwell Ave
Lexington, Massachusetts 02421www.aer.com
High-resolution WRF runs for NACP
Atmospheric and Environmental Research, Inc.
Introduction
Provide overview of available WRF fieldsGenerated at NASA Columbia supercomputer facilityFunding provided by NASA and NOAA
Provide overview of verification procedure and sample verification resultsDiscuss future plans
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Atmospheric and Environmental Research, Inc.
Overview of Time periods and Domains
2004 and 2006:5-domain setup: 40km, 10km, 3@2km resolution
2005:2-domain setup: 40km and 10km
2007:2-domain setup: 40km and 10km (extended further west)
Oct 20083
Atmospheric and Environmental Research, Inc.
WRF domains used for 2004 and 2006
40km: 207x19210km: 349x357 (encloses d03-d05)2km: 251x251 (Moody, WLEF, and Argyle)
Oct 20084
Atmospheric and Environmental Research, Inc.
WRF domains used for 2005
40km: 207x19210km: 393x357 (extended W for OK/CO sites)
Oct 20085
Atmospheric and Environmental Research, Inc.
WRF domains used for 2007
40km: 207x19210km: 521x357 (extended W to CA)
Oct 20086
Atmospheric and Environmental Research, Inc.
WRF runs setup
Using WRF v2.2Customized to provide:
Time-averaged mass-coupled winds, convective fluxes
NARR input used for I.C. and B.C.30-hr Forecasts, initialized every 24 hr (00 UTC)
Use hours 7-30 from each forecast (avoid spin-up)
Outer domain uses analysis nudging to NARRInner domains use 1-way nestingHourly output
Netcdf (WRF native format), all fields archivedARL (compressed, STILT-compatible)
Oct 20087
Atmospheric and Environmental Research, Inc.
WRF runs verification
Winds: using WRF/STILT to colocate:WRF winds as determined from short-term trajectory computationRaob winds at selected pressure levels
925, 850, 700, 500, 400, 300 hPa
PBL heights:Profilers: TEXAQS (2006) and ICARTT (2004)Raobs: derived from T,q,u,vusing WRF/STILT to colocate:
PBL heights computed by STILT from WRF T,q,u,vPBL heights computed by WRF
Oct 20088
Atmospheric and Environmental Research, Inc.
Raob winds results: effects of nudging
For May-Aug 2004, compare:
WRF v2.2 fields with nudging (case06, 40km)WRF v2.1.2 fields without nudging (case09, 40km)
Fields generated during earlier work for Argyle tower simulations
Result show effectiveness of nudging in limiting error growth
Oct 20089
Atmospheric and Environmental Research, Inc.
Raob winds results: outer / inner domains
Results shown for June-July-August 2004:d01 and d02 compared against identical Raobs
Oct 200810
Atmospheric and Environmental Research, Inc.
Raob winds results: outer / inner domains
Results shown for June-July-August 2004:d03-d05 have 1-3 Raobs inside domain
Oct 200811
Atmospheric and Environmental Research, Inc.
Raob winds results: outer / inner domains
Wind errors generally larger in nested domains
Nudging only through B.C. from outer domainSmaller scales get penalized by point statisticsError growth from 12-24 hours evident (viz. jja_d04 in previous slide), but not uniformly at all seasons/domains/levels
Colocations have been performed for all domains, and all years:
2004 and 2006: subsampled forecasts (~1/3)2005 and 2007: all forecasts
Oct 200812
Atmospheric and Environmental Research, Inc.
PBL height verification
Ongoing. Preliminary results:WRF/STILT PBL heights tend to be overestimatesErrors are comparable for d01, d02, and d03
Oct 200813
Atmospheric and Environmental Research, Inc.
PBL height verification
Sample time series of simulated/observed:Simulated values only shown for hours with obs
Oct 200814
Atmospheric and Environmental Research, Inc.
Future Plans
Characterization of uncertaintiesCharacterize transport uncertainties based on Raob wind-colocation error statisticsCharacterize PBL height bias and random errorsExtend PBL height verification:
Extend to ICARTT 2004 profiler dataCross-compare against Raob-derived PBL heights
Extend WRF runs to additional time periodsUse existing setup
Oct 200815
Atmospheric and Environmental Research, Inc.
Future Plans - continued
Pending NSF project:Upgrade to WRF v3, explore different physics options, evaluate impact on WRF fieldsOutstanding issue: Handling of nested domains in STILT
A single particle exiting inner-most domain causes switching to coarser domain for all particlesWe will evaluate the feasibility of importing relevant upgrades from HYSPLIT to STILT
Oct 200816