Version 2.1 IFA-averaged fields for TOGA COARE in support of Single Column Models (v2.0 released 04/26/02, v2.1 released 10/21/02)

About the Dataset Files

The data files have been gzipped and should be transferred as binary files. This should be a setable feature of your Web Browser.

The data are contained in the following four files with version number as part of filename:

All data in these files represent an average over the COARE Intensive Flux Array (IFA) computed using the gridded dataset described below. At the perimeters of the IFA polygon were four Integrated Sounding Sites (ISS): Kapingamarangi, Manus, R/V Shiyan 3 and R/V Kexue 1. The dates when the R/V ships were present are:
cruise 1: 11/10 to 12/10
cruise 2: 12/18 to 01/23
cruise 3: 01/31 to 02/18
One must realize that the representativeness of IFA averaged data is best during these three cruises and should be used with caution at other times.

Fields of geopotential height (z), zonal wind (u), meridional wind (v), temperature (T) and specific humidity (q) were objectively analyzed using multiquadric interpolation (Nuss and Titley 1994) over the Large Scale Array (LSA) of TOGA/COARE at 25 mb resolution from 1000 to 25 mb and at 1 degree resolution in both the latitude and longitude directions. A description of this gridded data product is given in Ciesielski et al. (1997). Surface pressure (see note below) was also analyzed over the LSA. This analyses was done for 480 six hour intervals (00, 06, 12, and 18UTC) during the COARE Intensive Observing Period (IOP - 1 November, 1992 through 28 February, 1993).

Notes:

• Users of the version 2 analysis should reference Ciesielski et. al (2003) listed below in the references.
• The version 2 analysis uses the NCAR/ATD humidity corrected sonde data (Wang et al. 2002).
• Also in version 2 the analysis of the divergence field has been improved using a technique described briefly here.
• Because of issues with sampling errors (see Mapes et al. 2003), IFA timeseries plots have been typically been presented (e.g., as in Johnson and Ciesielski 2000) as filtered (smoothed in time with a 5 day running mean filter) to reduce the high-freuqency noise. However the IFA data on this site represents the actual data with no such smoothing applied.
• Version 2.1 contains a slight correction to the humidity field for temperature below freezing which acts to lower the specific and relative humidities.
• For the surface analyses: data were assumed to be surface data only if the height of the observations were within 10 m of the station height. To remove bad surface humidities (e.q., at Kapinga from 11/17/92 to 01/04/93), surface specific humidities less than 10 g/kg were removed from the analyses. Surface pressure represents pressure reduced to sea level.
• Negative precipitation rates, found occasionally in the file "eopo.data" result from a combination of factors: sampling errors (i.e., the inadequacy of a sounding at a given time and location to represent conditions in a large area and a longer time period), data errors, errors introduced by the objective analyses, and errors in the estimation of surface evaporation.
• To keep updated on any future problems, issues and/or changes to the data, users should register with Paul Ciesielski at paulc@atmos.colostate.edu.

Line 1 contains: [year, month, day, hour]
                  written with format (4i3)
Lines 2-42 contain: [p(mb), z(m), T(C), q(g/kg), rh(%), u(m/s), v(m/s) 
                  written with format (f7.1,1x,6f8.2)

Line 1 contains: [year, month, day, hour]
                  written with format (4i3)
Lines 2-42 contain: [p(mb), divergence(1/s)*10e6, vertical p-velocity (mb/hr),
                     Q1 (K/day), Q2(K/day)]
                  written with format (f7.1,1x,4f8.2)
The apparent heat source, Q1, and moisture sink, Q2 (Yanai et al. 1973)
were computed as:
Q1/cp = [dT/dt + h(T) + (p/po)**kappa * omega * d(theta)/dp]
Q2/cp = -Lv/cp * [dq/dt + h(q) + v(q)]
      where dt = 12 hours
            po = 1000 mb
            cp = 1004
            Lv = 2.5e6
             g = 9.8

Note: The computation of Q1 and Q2 were not done for the first and last 
periods of the IOP because time center differences were used in 
computing these fields and no grids were analyzed before and after the IOP. 

lsf_flds.ifa
File "lsf_flds.ifa" contains 480 periods of six-hourly data. For each six hour period there are 42 lines of data.

Line 1 contains: [year, month, day, hour]
                 written with format (4i3)
Lines 2-42 contain: [p(mb), hT(C/s), vT(C/s), hq(gr/(gr*s)), vq(gr/(gr*s))]
                          written with format (f8.2,1p,8e11.3)
                          where hT - horizontal advection of T
                          where vT -   vertical advection of T
                          where hq - horizontal advection of q
                          where vq -   vertical advection of q

horizontal advection of "f": h(f) = u*df/dx + v*df/dy
                      where: dx = a cos(phi)*d(lambda)
                             dy = a d(phi)
                             phi    - latitiude
                             lambda - longitude
vertical advection of "f": v(f) = omega*df/dp

po = eo + 1./(g*Lv) * [integral(Q2*dp) from 1000mb to 100mb]

Line 1-478 contains: [year, month, day, hour, IFA average brightness temp (C), 
IFA average SST(C), IFA average sensible and latent heat flux (mm/day), 
rainfall (mm/day), net radiative heating rate (mm/day)]
                     written with format (4i3,6f8.2)

          omega = u*d(psfc)/dx + v*d(psfc)/dy
     to                                  
          omega = 0.

06/18/96 Surface winds were corrected at R/V Shiyan 3 and R/V Kexue 1. Previous winds were off by about 12 degrees.

The 06/18/96 changes resulted in omega changes from the previous version of the analyses that were greater than 50% from the surface to 975 mb (where omegas are quite small), decreasing to less than 10% above 800 mb and to less than 1% above 500 mb.

07/06/96 Surface fields were corrected in files fields.ifa and advect.ifa on 11/09/92 at 12UTC due to some bad data that made it into the surface analyses on this day.

09/23/96 Date information was corrected in file misc.ifa. In the original version of the file the date associated with data at 00 UTC was incorrect.

11/13/96 Improved surface analyses by assuming that data were from surface only if the height of the observations were within 10 m of station height. Also, bad surface humidities were removed (i.e., specific humidities less than 10 g/kg). The impact of this latter improvement will be most noteable from 11/17/92 to 01/04/93 when surface humidities at Kapinga were often considered bad (i.e., too low). The main effect of these changes, of course, are to the surface data themselves. The overall effect was to increase the IOP IFA daily averaged rainfall (estimated from the Q2 budget) from 8.166 mm/day to 8.207 mm/day (or an increase of 0.041 mm/day).

04/16/02 The version 2.0 analysis uses the NCAR/ATD humidity corrected sonde data (Wang et al. 2002). Also, we employed a spurious divergence correction (Haertel et al. 2002). The overall effect of these corrections was to increase the IOP IFA daily averaged rainfall (estimated from the Q2 budget) to 8.40 mm/day and decreases to -.50 K/day.

10/21/02 The version 2.1 analysis corrects the humidity variables for temperatures below freezing.

References

Ciesielski, P.E., R.H. Johnson, P.T. Haertel and J. Wang: 2003: Corrected TOGA COARE sounding humidity data: Impact on diagnosed properties of convection and climate over the warm pool. J. Clim., 16, 2370-2384. [ PDF]

Ciesielski, P.E., L.M. Hartten, and R.H. Johnson, 1997: Impacts of merging profiler and rawinsonde winds on Toga COARE analyses. J. of Atmos. Oceanic Tech., 14, 1264-1279.

Johnson, R.H., and P.E. Ciesielski, 2000: Rainfall and Radiative Heating Rate Estimates from TOGA-COARE Atmospheric Budgets. J. Atmos. Sci. 57, 1497-1514. [PDF]

Miller E.R. and A.C. Riddle, 1994. TOGA COARE integrated sounding system data report - Volume IA Revised Edition. Available from the TOGA-COARE International Project Office, UCAR, P.O. Box 3000, Boulder, CO 80307.

Nuss W.A. and D.W. Titley, 1994: Use of multiquadric interpolation for meteorological objective analysis. Mon. Wea. Rev., 22, 1611-1631.

O'Brien J.J., 1970: Alternative solutions to the classical vertical velocity problem. J. Appl. Meteor., 9, 197-203.

Wang, J., H.L. Cole, D.J. Carlson, E.R. Miller and K. Beierle, 2002: Corrections of humidity measurements errors from the Vaisala RS80 radiosonde -- application to TOGA COARE data. J. of Atmos. Oceanic Tech. (In press)

Weller, R.A., and S.P.,Anderson, 1996: Surface meteorology and air-sea fluxes in the western Pacific during the TOGA COARE. J. Climate. 9, 1959-1990.

Yanai, M.S., S. Esbensen and J.H. Chu, 1973: Determination of bulk properties of tropical cloud clusters form large-scale heat and moisture budgets. J. Atmos. Sci., 30, 611-627.