The last major modifications to the algorithm were made at the COARE Air-Sea Interaction (Flux) Group Workshop in Honolulu, 2-4 August 1995 (Bradley and Weller, 1995). Transfer coefficients were adjusted by six percent to give better average agreement with covariance latent heat fluxes from several COARE ships. This produced version 2.5b, which has been used successfully on various ocean-atmosphere field campaigns by members of the Flux Group, at various locations and from a variety of platforms. At the Woods Hole workshop, 9-11 October 1996 (Bradley and Weller, 1997) it was agreed that no further development would be attempted to the community version of the COARE Bulk Flux Algorithm, and that a version 2.5b bulk algorithm "package" would be made available, consisting of the fortran source code and a test data set. This was released at a meeting of the Flux Group at NCAR, 14-16 May 1997 (Bradley, Moncrieff and Weller, 1997):
coar2_5b.f 33K (Fortran source code)
test2_5b.dat 12K (Test data set)
test2_5b.out 14K (Output file from test data)
1. The input "read" statement is set up for the test data file test2_5b.dat . This consists of four days of Moana Wave COARE data, 26-29 Nov 1992, prepared from Chris Fairall's hourly data file wavhr2_5.asc dated 31/10/96. A full description of the Moana Wave operations, instruments and data set is given at: http://www.ncdc.noaa.gov/coare/catalog/data/air_sea_fluxes/moana_flux.html
2. Only those observations required by the flux algorithm were extracted from Chris' lines of data, excepting that his independently calculated bulk fluxes are included for comparison.
3. Some parameters are not input, but must be redefined in the code if necessary (e.g., the height of sensors (hum, htm), the bulk temperature sensor depth (ts_depth), needed for calculation of the warm layer effect, and pressure and mixed layer height (pp and zi) if available).
4. Because Chris' Tsea was measured at only 0.05m depth, we have added Ts at 6m depth from Mike Gregg's Advanced Microstructure Profiler (AMP, but called MSP in the file) to demonstrate the warm layer code. The Profiler was operated from the Moana Wave during leg 1, and the data was kindly provided in suitable form for the test file by Hemantha Wijesekera (Oceanography Dept., Oregon State University).
5. The warm layer and/or cool skin code may be bypassed by setting jwarm and/or jcool to zero in the code.
6. To demonstrate the warm layer and cool skin, we output the respective delta-temperatures and the warm layer thickness. Note that dt_warm is the warming across the entire warm layer--only if tk_pwp is less than the sensor depth (ts_depth = 6m in the test case) will T0=ts-dt_cool+dt_warm. Otherwise, a linear profile is assumed, and the appropriate fraction of warming above the bulk sensor calculated. Chris' Tsea at 0.05m depth will generally include most of the warm layer but not the cool skin effect.
7. The Webb correction to latent heat flux and the sensible heat flux due to rainfall are NOT added to these fluxes internally in the code. They are output separately, and may be accounted for at the user's discretion.
Date: YYMMDDHHmmss, YY=year, MM=month, DD=day, HH=hour, mm=minute,ss=sec U: true wind speed at 15-m height m/s Tsea: sea surface temp (at about 0.05m depth) deg.C Tair: Vaisala air temperature (about 15 m) deg.C qair: Vaisala air specific humidity (about 15 m) g/kg Hsb: Fairall's bulk sensible heat flux W/m2 Hlb: Fairall's bulk latent heat flux W/m2 Taub: Fairall's bulk surface stress N/m2 Rs: solar irradiance W/m2 Rl: downwelling longwave irradiance W/m2 Rain: precipitation mm/hr Lat: Latitude Lon: Longitude MSP: AMP temperature at 6m depth deg.C
index: data line number xtime: YYMMDDHHmmss, date and time as read in hsb: Fairall's bulk sensible heat flux as read in W/m2 hlb: Fairall's bulk latent heat flux as read in W/m2 taub: Fairall's bulk surface stress as read in N/m2 ts: AMP temperature at 6m depth as read in (rounded) deg.C HF: calculated sensible heat flux W/m2 EF: calculated latent heat flux W/m2 TAU: calculated surface stress N/m2 T0: calculated sea skin temperature deg.C Webb: correction to latent heat flux (to be added) W/m2 RainF: sensible heat flux due to precipitation W/m2 rain: precipitation mm/hr as read in dt_cool: cool skin effect deg.C dt_warm: total warming across warm layer thickness deg.C tk_pwp: warm layer thickness m
Bradley, E.F., and R.A. Weller, 1997: Fourth Workshop of the TOGA COARE Air-Sea Interaction (Flux) Working Group. Woods Hole, 9-11 Oct 1996. UCAR/TCIPO. UCAR Communications, PO Box 3000, Boulder CO 80307-3000 USA.
Bradley, E.F, M.W. Moncrieff and R.A. Weller, 1997: Joint workshop of the TOGA COARE Flux and Oceans Working Groups, and the GEWEX GCSS Working Group 4. Boulder, Colorado, 14-16 May 1997. NCAR/MMM, PO Box 3000, Boulder CO 80307-3000 USA.
Caldwell, D.R. and W.H. Elliott, 1971: Surface stresses produced by rainfall, J. Phys. Oceanog. 1, 145-148.
Fairall, C.W., E.F. Bradley, J.S. Godfrey, G.A. Wick, J.B. Edson, and G.S. Young, 1996a: The cool skin and the warm layer in bulk flux calculations. J. Geophys. Res. 101, 1295-1308.
Fairall, C.W., E.F. Bradley, D.P. Rogers, J.B. Edson, G.S. Young, 1996b: Bulk parameterization of air-sea fluxes for TOGA COARE. J. Geophys. Res. 101, 3747-3764.
Godfrey, J.S., and Beljaars, 1991: J. Geophys. Res. 96, 22043-22048.
Gosnell, R., C.W. Fairall, and P.J. Webster, 1995: The sensible heat flux of rainfall in the tropical ocean. J. Geophys. Res. 100, 18437-18442.
Liu, W.T, K.B. Katsaros and J.A. Businger, 1979: Bulk parameterization of the air-sea exchange of heat and water vapor including the molecular constraints at the interface, J. Atmos. Sci. 36, 1722-1735.
Price, J.F., R.A. Weller and R. Pinkel, 1986: Diurnal cycling: Observations and models of the upper ocean response to diurnal heating, cooling, and wind mixing, J. Geophys. Res. 91, 8411-8427.
Saunders, P.M., 1967: The temperature at the ocean-air interface, J. Atmos. Sci. 24, 269-273.
Smith, 1988: J. Geophys. Res. 93, 15467-15472.
Webb, E.K., G.I. Pearman and R. Leuning, 1980: Correction of flux measurements for density effects due to heat and water vapour transfer, Q.J.R. Meteorol. Soc. 106, 85-100.
Boulder, CO 80303 USA
E. Frank Bradley
Centre for Environmental Mechanics
GPO Box 821
Canberra, ACT 2601 AUSTRALIA
Phone: (61) 62 46 5575
Fax: (61) 62 46 5560
David P. Rogers
Scripps Institution of Oceanography
La Jolla, CA 92093-0230 USA
Phone: (619) 534-6412
Fax: (619) 534-7452