1
STMAS:Space-Time Mesoscale Analysis System
Steve Koch, John McGinley, Yuanfu Xie, Steve Albers, Ning Wang, Patty Miller
2
• Create a mesoscale analysis that:• Assimilates all available surface data at high time
frequency• Performs data quality control • Has a very rapid product cycle (< 15 minutes)• Can sustain features with typical mesoscale structure (gust
fronts, gravity waves, bores, sea breezes, etc)• Can be used for boundary identification and monitoring
(SPC)• Candidate for automated processing
• Is compatible with current workstation technology
STMAS Goal
3
• Surface Observations• Meteorological Aviation Reports (METARs)• Coastal Marine Automated Network (C-MAN)• Surface Aviation Observations (SAOs)• Modernized Cooperative Observer Program (COOP)• Many mesonetworks (constantly growing)
• MADIS offers automated Quality Control• Gross validity checks• Temporal consistency checks• Internal (physical) consistency checks• Spatial (“buddy”) checks
• MADIS Home Page: www-sdd.fsl.noaa.gov/MADIS
• Real-Time Display: www-frd.fsl.noaa.gov/mesonet/
STMAS utilizes surface data available through the FSL Meteorological Assimilation Data Ingest System (MADIS)
4
MADIS Mesonet Providers 5/1/2004
Mesonet Description Provider Name No. of Sites Coverage
Total = 13,748
U.S. Army Aberdeen Proving GroundsCitizen Weather Observers ProgramAWS Convergence Technologies, Inc.Anything Weather NetworkColorado Department of TransportationFlorida MesonetFt. Collins UtilitiesGoodland WFO MiscellaneousGulf of Maine Ocean Observing SystemFSL Ground-Based GPSHydrometeorological Automated Data SystemIowa Department of TransportationIowa Environmental MesonetBoulder WFO MiscellaneousKansas Department of TransportationMulti-Agency Profiler Surface ObservationsCooperative Mesonets in the Western U.S.Minnesota Department of TransportationNational Ocean Service Physical Oceanographic Real-Time SystemNational Weather Service Cooperative Observer ProgramOklahoma MesonetRemote Automated Weather StationsRadiometerDenver Urban Drainage & Flood Control Dist.Weather for You
APGAPRSWXNETAWSAWXCODOTFL - MesoFTCOLLINSGLDNWSGoMOOSGPSMETHADSIADOTIEMINTERNETKSDOTMAPMesoWestMNDOTNOS – PORTSNWS – COOPOK - MesoRAWSRDMTRUDFCDWXforYou
MarylandGlobalU.S.CONUSColoradoFloridaColoradoCO/KS/NEGulf of MaineU.S.New EnglandIowaIowaColoradoKansasCONUSWest CONUSMinnesotaCONUSNew EnglandOklahomaU.S.U.S.ColoradoU.S.
521955600
64107395
1510
340605088134112
25529234
100116
17772
17414
5
MADIS collects data from over 13,000 sites presently (and still growing). Still, the data are
largely distributed like “oases and deserts”.
6
Why conventional objective analysis schemes are inadequate to deal with the desert-oasis problem
Successive correction (SC) schemes (e.g., Barnes used in LAPS) and optimum interpolation (OI) schemes (e.g., as used in MADIS RSAS/MSAS) suffer from common problems:
1. Inhomogeneous station distributions cause problems for a fixed value of the final weighting function or the covariance function scale
2. SC and OI schemes will introduce noise in the deserts if forced to try to show details that are resolvable in the data oases everywhere
3. None of the SC or OI schemes include the high-resolution time information explicitly, with the exception of the modified Barnes scheme of Koch and Saleeby (2001), which required assumptions about the advection vectors in time-to-space conversion approach
7
STMAS solution: Multi-scale space and time analysis capability
• Ability to represent large scales resolvable by the data distribution characteristic of the desert regions
• Two schemes tested: telescopic recursive filter and wavelet fitting• Recursive filter uses residual remaining after removal of the large-
scale component for telescopic analysis:– Compute residual reduce the filter scale do analysis of residuals at
this next smaller scale repeat N times until analysis error falls below the expected error in observations (N = 3-6)
– Include temporal weight in similar manner for the recursive filter– Variational cost function assures fit to observations
• Wavelet fitting technique provides for locally variable levels of detail, non-isotropic searching, and temporal weighting (still under development, though tested on analytic functions)
8
For a 1D grid function u = ui{ } , rightward pass through the data is expressed as:
FαR : yi =αyi−1 + 1−α( )ui
where α ∈ 0,1( ) is the smoothing parameter.
Similarly, a leftward pass through the data is expressed as:
FαL : yi =αyi+1 + 1−α( )ui
A recursive filter for n passes through the data is given as
Fαn = Fα
L ×FαR( )
n
For a 3D grid function u= ui, j ,k{ } in x,y,and t :
F =Fαt
nt ×Fαx
nx ×Fαy
ny .
The procedure, given τ=∈ 12 ,1( ) and large values of αx,αy,αt( ) :
• Solve the data assimilation with αx,αy,αt( )
• Save the analysis fields and compute the residuals
• Set αx,αy,αt( ) =τ αx,αy,αt( )
• Repeat the above steps using the residuals
• Finally, add the saved intermediate results together to yield the final analysis.
Multi-scale Analysis using a Recursive Filter
9
Comparisons of hourly analyses of temperature and winds using
LAPS and STMAS to surface and radar observations
Hourly analyses: 1900 - 2200 UTC
19
Improvements to STMAS
• Use of Spline Wavelets– Accommodate common meteorological structures– Improve analysis in data rich and data sparse
areas
• Data Quality Control Using a Kalman Scheme– Operate in observation space– Provide data projections for future cycles– Optimum model for each station
20
Scattered data fitting using Spline Wavelets
• Basis functions: second order spline wavelets on bounded interval (by Chui and Quak)
• Penalty function in variational formulation: a weighted combination of least square error and magnitude of the high order derivatives
• Inner scaling functions control dilation and translation of the cardinal B-splines:
• Boundary scaling functions control dilation of the cardinal B-spline with multiple knots at the endpoints
21
• Inner wavelet functions: dilation and translation of the cardinal B-wavelets
• Boundary wavelet functions: dilation of the special B-wavelets derived from cardinal B-splines and boundary scaling functions
Wavelet functions
23
Comparison of four different analysis techniques
Barnes Analysis Standard Recursive filter
Telescopic Recursive filter Wavelet fitting
25
Kalman Filter for Surface Data
Provides a continuous station estimate of observation based on how a forecaster would perform observation projection: self trend, buddy trends, and NWP – use for quality checking
With missing obs – maintain constant station count
Time
Station value
Kalman ob
Kalman continuousmodel
Allowable Obserror
Possible bad ob
Producttime
26
Simulated Temp Traces
Station 1-regularStation 2-occasionalStation 3-synopticStation 4-mesonetStation 5-data burstsStation 6-QC problem
Needed Analysis Product TimeTime
27
Aurora, Nebraska
1 3 5 7 9 11 13 15 17
GMT Hour
Deg F
TT-KalTDTD-Kal
0
3
No data
Temperature and Dewpoint observations and as derived from Kalman Filter for 22 Mar 2001
Enid, Oklahoma
13 15 17 19 21 23 1
GMT Hour
Deg F
TT-KalTDTD-Kal
70
60
50
40No data
28
Kalman Forecast Errors (F)(based on stations reappearing after not reporting for a time interval on x-axis)
0123456789
10
0 hour2 hour4 hour6 hour8 hour10 hour12 hour
FallWinterSpringSummer
Temperature
0123456789
10
0 hour2 hour4 hour6 hour8 hour10 hour12 hour
FallWinterSpringSummer
Dewpoint
29
More about STMAS
• Ability to use background fields from a model (e.g., RUC) or a previous analysis (these features were adapted from LAPS and are important to have in the data-void desert regions)
• Background fields are modified to account for very detailed terrain (another useful feature borrowed from LAPS)
• Background field includes lake and sea surface temperatures and a land-weighting scheme to prevent situations such as warm land grid points having an influence on cooler water areas (via LAPS)
• Currently, STMAS compares observations to background for its QC method. Kalman filter will provide both a much more sophisticated QC and the ability to fully utilize temporal detail in the data.
• Reduced pressure calculation for a given reference height, as in LAPS (may see perturbation pressure sometime in the future)
• Value of STMAS is being measured relative to the LAPS analysis• Analyses currently conducted over CIWS domain every 15 minutes
on a 5-km grid (a variety of grid product fields are computed)
72
Recusive Analysis- Moist Convergence and Wind : 2300 - 0100
Zoomed-in analysis of moisture convergence2300GMT
81
Summary
• STMAS is capable of high time and space resolution of important parameters for mesoscale weather
• Shows good time continuity• Features correlate well with independent
observations such as radar• Need to enhance analysis with wavelet
scheme• Need to get robust Kalman QC into scheme
82
Future
• Ensure compatibility with AWIPS• Work in more model background options
(RUC and Eta)• Utilize STMAS fields for automated boundary
diagnostics• Work toward a spatial 3-D scheme
86
Comparisons of hourly analyses of temperature and winds using
LAPS and STMAS to surface and radar observations
Hourly analyses: 1900 - 2200 UTC
109
Relation of analyzed equivalent potential temperature and moisture convergence fields to radar echoes
2100 UTC 27 May - 0200 UTC 28 May
115
• Inner scaling functions: dilation and translation of the cardinal B-splines:
• Boundary scaling functions: dilation of the cardinal B-spline with multiple knots at the endpoints
Scaling functions
φinner
=N3(x),N
m(x) = N
m−10
1
∫ (x−t)dt
N1(x) =χ
[0,1)(x)
116
• Inner wavelet functions: dilation and translation of the cardinal B-wavelets:
• Boundary wavelet functions: dilation of the special B-wavelets derived from cardinal B-splines and boundary scaling functions
Wavelet functions
ψinner
= qn
n∑ N
m(2x−n),
qn=(−1)n
2m−1
ml
⎛
⎝⎜⎞
⎠⎟l=0
m
∑ N2m(n +1−l),n =0,..., 3m−2