October 02, 2003 1st 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

October 02, 2003 1st 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?

October 02, 2003 1st 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

October 02, 2003 1st IHOP_2002 Water Vapor Intercomparison Workshop

DIAL principle

Example: DIAL

October 02, 2003 1st IHOP_2002 Water Vapor Intercomparison Workshop

1

0111

1

1

0111

1

2

0222

2

2

0222

2

1

1

2

2

,

, ,

,

, ,

ln

,

, ,

,

, ,

ln

lnln

,,21

2

R

dRRbRR

R

dRRbRR

R

dRRbRR

R

dRRbRR

RNRN

RNRN

RRRRn

onWV

WVonmol

par

offWV

WVoffmol

par

onWV

WVonmol

par

offWV

WVoffmol

par

on

off

on

off

offonOH

Shotland equation1st guess estimate

Doppler broadening terms

Retrieval

October 02, 2003 1st IHOP_2002 Water Vapor Intercomparison Workshop

zP1

Flow chart of retrieval module

TIME AVERAGE

Single-shotsignals

QUALITYCONTROL

zP1

zP2

-

-

VERTICALAVERAGE

BACKGROUNDDETERMINATION

z1

z2

zP2

CONDITIONALSAMPLING

BACKGROUNDSUBTRACTION

zbk1

zbk2

RATIO

zPzP

2

1

LOGARITHM

zPzP

2

1ln

DIFFERENTIATION

zP

zP

dzd

2

1ln

October 02, 2003 1st 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

October 02, 2003 1st 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, ….

October 02, 2003 1st 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, …

October 02, 2003 1st 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

October 02, 2003 1st 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

October 02, 2003 1st 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

October 02, 2003 1st 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