To access these data files, click on the above hyperlinked filenames.
This figure shows an inventory of sounding data during the SCSMEX IOPs. A completely filled circle indicates that soundings were available 152 times out of a possible 152 (4 soundings per day for 38 days). The red circles indicate the nominal positions of the research vessels located within the enhanced sounding arrays. The grid over the NESA shows the analysis domain for our gridded data product.
Data in the above files represent an average of gridded data fields over the SCSMEX Northern Enhanced Sounding Array (NESA), that is, the northern polygon in the above figure. Fields of 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 a rectangular grid slightly larger than the NESA at 25 mb resolution from 1000 to 25 mb and at 1 degree resolution in both the latitude and longitude directions (see grid in above figure). Surface pressure was also analyzed over this grid. These analyses were done for 244 periods (61 days at 00, 06, 12, and 18 UTC) during May and June of 1998.
Data used in this analyses included quality-controlled sounding data from 53 sounding sites around and over the South China Sea and the JMA reanalysis in data sparse regions (i.e., at every 5 degree grid intersection no observations within a 3 degree radius). During SCSMEX the ships were on site during the following periods:
Notes:
Line 1 contains: [year, month, day, hour] written with format (4i3) Lines 2-42 contain: [p(mb), z(m), u(m/s), v(m/s), omega(mb/hr), T(C), theta(K), specific humidity(gr/kg) and divergence(1/s)*10e6] written with format (9f.2)Omega is computed using O'Brien's (1970) method with an isovalue divergence adjustment. Omega is set to zero at the surface and at 100 mb.
advect.nesa
File "advect.nesa" contains 244 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), hu(m/s**2), vu(m/s**2), hv(m/s**2), vv(m/s**2), hT(C/s), vT(C/s), hq(gr/(gr*s)), vq(gr/(gr*s))] written with format (f8.2,1p,8e11.3) where hu - horizontal advection of u where vu - vertical advection of u where hv - horizontal advection of v where vv - vertical advection of v where hT - horizontal advection of T where vT - vertical advection of T where hq - horizontal advection of q where vq - vertical advection of qThese 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/dpq1q2.nesa
Line 1 contains: [year, month, day, hour] written with format (4i3) Lines 2-42 contain: [p(mb), Q1(C/day), Q2(C/day)] written with format (3f.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 = 9.8eopo.nesa
p_0 = e_0 + 1./(g*Lv) * [integral(Q2*dp) from 1000mb to 100mb] Line 1-244 contains: [year, month, day, hour, e_0(mm/day), p_0(mm/day)] written with format (4i3,2f8.2)References
O'Brien J.J., 1970: Alternative solutions to the classical vertical velocity problem. J. Appl. Meteor., 9, 197-203.
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.