Dear Dick, and COARE colleagues:

We can all agree that the issue of accurately estimating surface and low level moisture from COARE data is most important, but also most frustrating.

We are also handicapped by being forced to examine and evaluate the data in so many separate groups. It is inevitable that we are (and have been) forced to rely on our individual best judgments on what we believe to be the closest estimates to the "truth". At this critical time in the analysis, many of us want desperately to believe that the archived data (plus a few agreed-to

biases that are well-publicized) can at last be used uncritically. This communication is about some differences we have in our professional judgments about the "agreed-to-biases", and they are, sadly, too profound to ignore. [Nothing herein should be taken as criticism of the super job, and super patience in dealing with the problems, that Hal, Erik, and their colleagues exhibited. The fact that their end-product cannot be taken at face value by some of us is probably no surprise to them!]

I believe that we must evaluate the properties of the sea surface, surface" meteorological measurements, and atmospheric boundary layer profiles as a coupled problem. As promised, here are some comparisons of surface statistics that help convince me that despite all efforts at

correction, the Kapinga, PRC5, and Wave soundings are too dry, while the surface moisture measurements are approximately correct:

*******************************************************************

CHRIS LUCAS SENDS THE FOLLOWING:

Values are averaged temperature/specific humidity of the surface points as reported in the 5mb interpolated ISS Final sounding data set for the times indicated.

Science 1

time	cru 1	cru 2 cru 3

23z 28.49/17.91 28.02/18.53 28.44/18.91

5z 28.78/17.67 28.47/18.59 28.62/18.54

11z 28.58/17.83 27.99/18.79 28.14/19.12

17z 28.13/17.82 27.50/18.71 28.12/19.07

10Nov-11Dec 18Dec-22Jan 28Jan-19Feb

Moana Wave [These q's are "as is"; they DO NOT have any correction applied. To correct, one would add 1.04 g/kg if precisely 6.0% is the right number.]

time cru 1	cru 2 cru 3

23z 28.80/17.88 27.66/17.29 28.35/17.35

5z 28.72/17.73 27.89/17.60 27.88/17.24

11z 28.28/17.40 27.76/17.59 28.16/17.30

17z 27.96/17.43 27.67/17.55 27.53/17.35

10Nov-3Dec 16Dec-11Jan 28Jan-13Feb

Exp 3

time cru 1	cru 2 cru 3

23z 28.62/17.36 28.07/18.66 28.15/18.56

5z 28.76/17.45 28.22/18.54 28.68/18.74

11z 28.12/17.43 27.82/18.57 27.74/18.59

17z 27.73/17.38 27.50/18.86 27.74/18.90

10Nov-11Dec 18Dec-22Jan 28Jan-19Feb

PRC 5

time cru 1 cru 2 cru 3

23z */* 28.34/18.61 28.44/18.23

5z */* 28.20/18.84 28.40/18.56

11z */* 27.79/18.97 28.39/18.55

17z */* 27.48/19.08 27.91/18.65

15Dec-8Jan 24Jan-18Feb

Kapinga, for some analagous times

time cru 1 cru 2 cru 3

23z 28.95/19.10 28.69/19.44 28.84/18.95

5z 29.46/19.28 28.88/19.42 28.76/18.92

11z 27.66/18.54 27.65/18.96 27.07/18.53

17z 27.24/17.74 27.33/18.86 26.84/18.42

10Nov-9Dec 20Dec-19Jan 30Jan-19Feb

Notes:

1. No correction applied to Moana Wave data

2. Not many soundings during cruise 1 of prc5, so no means.

3. Kavieng not included because of large diurnal variations. Not really

suitable for comparison.

Conclusion: Some difference in the sounding data surface points, but not enough

to explain the disparity between boundary layer averages and surface points. The soundings are bad, not the surface points. Uncorrected Moana wave points especially low during Cruises 2 & 3.

**********************************************************************

DAN CECIL SENDS THE FOLLOWING: Here are some averages for the surface data to compare with what Chris sent out. These are for Cruise 3, using all times available (not just sounding times).

Science 1: T/q=3D 28.2278/18.6059

standard dev=3D2.02348/0.810197

Moana Wave: T/q=3D 27.6409/18.1544 [These INCLUDE the correctionfor q]

standard dev=3D0.688133/0.767203

PRC #5: T/q=3D 28.2322/18.4249

standard dev=3D0.645672/0.651249

Vickers: T/q=3D 27.9738/19.2133

0.773828/0.901169 (Jan 27 - Feb 26)

Imet: T/q=3D 28.1507/18.4457

1.04318/0.750254 (Jan 28. - Feb 13...same as Wave)

The Science 1 data is 1 minute, Moana Wave ~10 minutes, PRC 3 hours,

Vickers is 5 minutes, and Imet is 7.5 minutes.

**********************************************************************

(Back to EZ talking) In the absence of large differences in mean SST or wind speeds across the IFA, one would not expect large differences in surface temperature or specific humidity, and with relatively minor exceptions the surface data are therefore quite believable. What is not

believable (to me) are large differences in vertical gradients of q in the mixed layer within

the IFA. And they are large.

Chris Lucas has prepared scatter diagrams, for all of COARE, for surface q vs average q in a fixed interval above the surface (approx. 40 mb or 400 m, I forget which). If anyone has any doubt that there is a major dry bias in the soundings, I will have Chris send them these diagrams. The exceptions are Science 1 (which has its own peculiar moist bias) and Vickers, which

looks very good, albeit possibly up to 0.5 g/kg high both at the surface and in the mixed layer.

What shall we do about this situation?

Chris has done an extensive "cluster analysis" of all COARE soundings. Our

initial motivation, aside from doing some simple comparisons of CAPE and

CIN with other tropical regions, was to have input data we could trust for

initialization of cloud models. In parallel we are working with Peggy LeMone to produce specific input data for aircraft case studies. We have put so much effort into his analysis that we will obviously submit a paper for publication, but that will take time. Should we make our "best

estimate" to an informal peer review of interested COARE folks, and then distribute that to the TCDM list???

Comments and advice earnestly solicited.

Ed

------------------------- =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D ------=

----------------------------

Ed Zipser || Internet: zipser@ariel.tamu.e=

du

Dept. of Meteorology ||

Texas A&M University /\ || |\/| Telephone (409)-862-4171

College Station, TX | | || | | (409)-845-7671 (De=

pt.)

77843-3150 |--| || | | Fax Number (409)-862-4466

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zipser@ariel.tamu.edu

Subject: Surface humidities in COARE

To: "Richard H. Johnson" <rhj@vortex.atmos.colostate.edu>

Cc: zipser@ariel.tamu.edu

Cc: lucas@ariel.tamu.edu

Cc: dcecil@ariel.tamu.edu

Cc: fairall@disco.pmel.noaa.gov

Cc: cwf@etl.noaa.gov

Cc: cpaulson@oce.orst.edu

Cc: rweller@whoi.edu

Cc: bradley@enmech.csiro.au

Cc: chinman@tcdm.coare.ucar.edu

Cc: jdickey@squall.atmos.colostate.edu

Cc: paulc@tornado.atmos.colostate.edu

Cc: rutledge@olympic.atmos.colostate.edu

Cc: lin@swirl.atmos.colostate.edu

Cc: millere@ncar.ucar.edu

Cc: cole@ncar.ucar.edu

Cc: lemone@ncar.ucar.edu