1. Status of Bracketing OSSEs at NCEP for Several DWL Notional Concepts
G. D. Emmitt
M. Masutani, S. Lord
WG on Space-based Lidar Winds
Oxnard, CA
7-9 February, 2001

2. General Status “Current” (i.e.1993) data simulation complete
RAOBs, ACARS, CTW(?), TOVS(1B), Surface
All simulated DWL observations complete
bracketing concepts with m << 1 m/s
Calibration of OSSE nearly complete
Temperature bias still unresolved
Initial DWL impact on analyses being assessed for bracketing concepts

3. Key Calibration Issues
Are the statistics of the simulated data similar to those of the real data?
Are the impacts of individual data sets on analyses similar in both “real” OSEs and “simulated” OSEs?

4. Relative importance of tropospheric wind observations in OSE segment
RAOB winds in the NH
impact on model wind field
impact on derived temperature
CTWs in SH & NH
impact on winds
impact on temperature

5. Review of bracketing OSSE strategy
Technology neutral but with realistic observational coverage
4 basic coverage concepts plus an OSSE reference data set
Three series of impact experiments
Coverage (m = 0 m/s ; s = 2 m/s)
Accuracy (m = 2 or 5 m/s ; s = 2 m/s)
Systematic Errors (m = 2 or 5 m/s ; s = 2 m/s; plus correlated errors)

6. Figure of merit o2 = m2/Ns + s2/Ne
o2 is total observation error for use in the SSI cost function (assigned a value if necessary).
m2 is the instrument’s observation error for the target motion within the illuminated volume
s2 is the variance of the winds within the effective resolution grid of the assimilating model
Ns is the number of independent samples that are effective in reducing the LOS measurement error
Ne is the number of independent samples that are effective in reducing the error in estimating the average LOS within the sampled area.

7. Example m = 10 m/s (Sqrt(m2/Ns) = 1 m/s) s = 3 m/s N = 100
o2 = m2/Ns + s2/Ne
m = 10 m/s (Sqrt(m2/Ns) = 1 m/s)
s = 3 m/s
N = 100
Cluster: o = 3.2 m/s
Distributed: o = 1.4 m/s