Version 3.1 EBA-averaged fields for NAME in support of Single Column Models
(v3.1 released 08/29/08)

Users of the version 3.1 datasets should reference Johnson et al. (2007) and Ciesielski et al. (2009) listed below.

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

• T1A basic fields as a function of pressure, basic_v3p1.t1a
• T1A large-scale forcing fields as a function of pressure, lsf_v3p1.t1a
• T1A Q1 and Q2 fields as a function of pressure, q1q2_v3p1.t1a
• EBA basic fields as a function of pressure, basic_v3p1.eba
• EBA large-scale forcing fields as a function of pressure, lsf_v3p1.eba
• EBA Q1 and Q2 fields as a function of pressure, q1q2_v3p1.eba

All data in these files represent an average over the land portion of the NAME Enhanced Budget Array (EBA) computed using the gridded dataset described below. At the perimeters of the EBA polygon were five sounding sites. Near the mouth of the Gulf of California (GoC) was the R\V Altair which also released soundings. Dates when the Altair was present are:

• cruise 1: 07/07 to 07/22
• cruise 2: 07/26 to 08/11

One should realize that the representativeness of EBA averaged data better during these cruises.

• t1a files are for 40 days, 4x daily
• eba files are for ~18 IOP days, 6x daily

One should the note that at pressure levels below 750 hPa that some points are below the surface. The first line of data for each time period gives the values at the surface. In the example below, the mean surface pressure averaged over the Land-EBA is 867.77 hPa which is at a mean geopotential height of 1347 meters. The last number in each line lists the number of 1-degree resolution points that went into this average. In the example below there were only 3 points at 1000 hPa that were above the surface. Therefore the data values at a 1000 hPa are only representative of the land-EBA areas that are above the surface at this level.

   867.77  1347.17    -1.17     0.43     0.73    18.15   303.74    12.09    79.35    -0.35    -1.09 22
  1000.00    88.61    -3.22    -0.23     1.31    24.82   297.97    14.60    73.17   -16.86     0.49  3

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 Tier 1 Array (T1A) of NAME 25 mb resolution from 1000 to 50 mb and at 1 degree resolution in both the latitude and longitude directions. A description of this gridded data product is given in Johnson et al. (2007). Surface pressure (see note below) was also analyzed over the T1A. This analyses was done for 160 six hour intervals (00, 06, 12, and 18UTC) during the NAME Enhanced Observing Period (EOP) from 07 July to 15 August, 2004).

During ~18 days (Intensive Observing Periods or IOPs) sondes in the EBA were launched every 4 hours. For these 18 days the objective analysis was done at 4-hour intervals (00, 04, 08, 12, 16, 18, 20) over a region slighty larger than the EBA.

• Users of the version 3.1 analysis should reference Johnson et. al (2007) listed below in the references.
• Version 3.1 used humidity corrected sounding as described in Ciesielski et al. (2009)
• In producing the gridded analyses upon which the EBA averages are based, no reanalysis data were used in the far field. This makes the large-scale forcing data independent of any models and parameterizations.
• The version 3.1 analysis uses data from the NAME pibal network as well as v2.4 of the surface data (described in Ciesielski and Johnson 2008) which includes non-zero vertical motion at the surface resulting from flow over the sloped terrain of Mexico.
• Because of issues with sampling errors (see Mapes et al. 2003), EBA timeseries plots have been typically been presented (e.g., as in Johnson et al. 2007) as filtered (smoothed in time with a 5 day running mean filter) to reduce the high-freuqency noise. However the EBA data on this site represents the actual data with no such smoothing applied.
• At pressure levels below 750 hPa, some of the grid point in the EBA are actually below the surface. The EBA average at pressure levels which intersect the ground represent the average of all above-ground grid points. The number of grid points in the EBA average is listed in these files.
• 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 2-41 contain: [p(mb), z(m), u(m/s), v(m/s), omega(mb/hr),
                     T(C), theta(K), r(g/kg), RH(%), 
                     div(1.e6 1/s), vor(1.e5 1/s), np 
                  written with format (11f9.2,i5) 
        where p - pressure from surface to 50 mb
              z - geopotential height
              u - zonal wind
              v - meridional wind
              omega - vertical p-velocity
              T - temperature
              theta - potential temperature
              r - water vapor mixing ratio
              RH - relative humidity
              div - horizontal divergence
              vor - horizontal component of vorticity
              np  - number of point in EBA average 

Line 1 contains: [year, month, day, hour]
                  written with format (4i3)
Lines 2-41 contain: [p(mb), Q1 (K/day), Q2(K/day), np]
                  written with format (3f8.2,i5)
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

Omega is computed using O'Brien's (1970) method with an isovalue adjustment. Omega at surface comes from surface dataset, omega at tropopause was computed assuming adiabatic flow.

Line 1 contains: [year, month, day, hour]
                 written with format (4i3)
Lines 2-41 contain: [p(mb), hT(C/s), vT(C/s), hq(gr/(gr*s)), vq(gr/(gr*s)), np]
                          written with format (f8.2,1p,8e11.3)
                          where hT - horizontal advection of T
                                vT -   vertical advection of T
                                hq - horizontal advection of q
                                vq -   vertical advection of q
                                np - number of points in EBA average

These horizontal and vertical advection terms were computed using centered differences as follows:

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

q1q2_v3p1.eba
Similar to file "q1q2_v3.t1a" but contains 107 periods of four-hourly data for NAME IOP days.

lsf_v3p1.eba
Similar to file "lsf_v3.t1a" but contains 107 periods of four-hourly data for NAME IOP days.

REFERENCES

Ciesielski P.E. and R. H. Johnson, 2008: Diurnal cycle of surface flows during the 2004 NAME and comparison to model reanalysis. J. Climate 21, 3890-3913.