1. October 02, 20031 st IHOP_2002 Water Vapor Intercomparison Workshop Status of intercomparisons and the next steps  Characterize moisture measuring techniques  Identify missing specifications  Suggest additional efforts such as further intercomparisons to close knowledge with respect to instrument performance

2. October 02, 20031 st IHOP_2002 Water Vapor Intercomparison Workshop Instruments considered 1)DIAL and Raman lidar 2)S-Pol refractivity 3)GPS and microwave radiometer 4)In-situ sensors (reference radiosondes, dropsondes, standard radiosondes, aircraft sensors) 5)AERI? 6)NAST? 7)Satellites? 8)Complete?

3. October 02, 20031 st IHOP_2002 Water Vapor Intercomparison Workshop Suggestion for providing information about instrument performance  Performance analysis web page (status, intercomparisons, etc.)  Specific web page for each instrument: - Methodology (references) - Retrieval technique (flow chart), expected errors (references) - Approaches applied for error analysis (analytical, ACOV, intercomparisons including lessons learned, …) - Most important errors sources, critical components (important for future campaigns) - Spec table (continuously updated), goals? - Future efforts and suggestions to close remaining gaps

4. October 02, 20031 st IHOP_2002 Water Vapor Intercomparison Workshop DIAL principle Example: DIAL

5. October 02, 20031 st IHOP_2002 Water Vapor Intercomparison Workshop Shotland equation 1st guess estimate Doppler broadening terms Retrieval

6. October 02, 20031 st IHOP_2002 Water Vapor Intercomparison Workshop Flow chart of retrieval module TIME AVERAGE Single-shot signals QUALITY CONTROL - - VERTICAL AVERAGE BACKGROUND DETERMINATION CONDITIONAL SAMPLING BACKGROUND SUBTRACTION RATIO LOGARITHM DIFFERENTIATION

7. October 02, 20031 st IHOP_2002 Water Vapor Intercomparison Workshop Error analysis  Systematic errors: - Analytical error propagation - Forward performance model - Intercomparisons (LASE validation campaigns: 6%) - Rms error or mean difference?  Noise errors: - Poisson statistics - Autocovariance technique - Spectral technique  Representativeness error: IHOP data

8. October 02, 20031 st IHOP_2002 Water Vapor Intercomparison Workshop 1) DIAL and Raman lidar specifications  Horizontal or time resolution (weighting function)  Vertical resolution (weighting function)  Systematic error profile (bias)  Noise error profile (precision) in dependence of resolutions  Errors at boundaries (special attention, e.g. Rayleigh Doppler)  Representativeness error  Overall accuracy including covariance matrix for each profile, if required, for all missions  Suggestions: Cross section at 930 nm, investigate spectral purity, ….

9. October 02, 20031 st IHOP_2002 Water Vapor Intercomparison Workshop 2) S-Pol refractivity specifications  Height above ground including weighting function  Horizontal and range resolution (weighting function)  Time resolution  Systematic error map (bias)  Noise error map (precision)  Errors at boundaries?  Representativeness error?  Overall accuracy matrix Suggestions: further comparisons: radiosondes, lidar data, …

10. October 02, 20031 st IHOP_2002 Water Vapor Intercomparison Workshop 3) GPS and microwave  Pointing direction  GPS: ZPD, slant path, tomography  Time resolution, spatial resolution (tomography)  Systematic error (bias)  Noise error (precision)  Representativeness error?  Further comparisons: lidar, radiosondes

11. October 02, 20031 st IHOP_2002 Water Vapor Intercomparison Workshop 4) In-situ sensors specifications  Vertical resolution (weighting function)  Systematic error profile (bias)  Noise error profile (precision)  Errors at boundaries (special attention, e.g. drop sondes)  Representativeness error  Overall accuracy including covariance matrix for each profile, if required

12. October 02, 20031 st IHOP_2002 Water Vapor Intercomparison Workshop 5) AERI and others  Vertical resolution (weighting function)  Systematic error profile (bias)  Noise error profile (precision)  Errors at boundaries  Representativeness error  Overall accuracy including covariance matrix for each profile, if required

13. October 02, 20031 st IHOP_2002 Water Vapor Intercomparison Workshop 6. Expectations  Coordination of intercomparison efforts  Identify missing, important comparisons  Access to results (Web page?)  REPRODUCIBLE PROCEDURES: - Flow chart of data analysis (DIAL and others) - Clear definition and characterization of all errors  Representativeness error  Blind test