Surface Energy Budget of Springtime Leads Date data posted: 09-01-99 Date last modified: 09-01-99 Data prepared by: James Pinto Data collected by: James Pinto and James Maslanik Data has been compiled from Mobile Radiometric Platform (MRP) measurements and observations from the "Atlanta" and "Baltimore" NCAR flux-PAM stations. Observations were also made in situ and visually as reported in the logs file: ice_thkmmddyy.dat Variable Description Units fjday.........fractional Julian Day.....UTC hi............Ice thickness.............cm file: lead_sebmmddyy.dat Variable Description Units fjday.........fractional Julian Day.....UTC Hs............Sensible heat flux........W m-2 Hl............Latent heat flux..........W m-2 ULWR..........Upward Longwave flux......W m-2 DLWR..........Downward Longwave flux....W m-2 USWR..........Upward Shortwave flux.....W m-2 DSWR..........Downward Shortwave flux...W m-2 Hs is determined from bulk aerodynamic formula using Hs = rhoa*cp*ce*U*(Ts - Ta) where Ta is the surface air temperature measured at a remote flux PAM site "Baltimore", Ts is the surface skin temperature of the new ice forming at the edge of the lead measured with a downward-looking KT-19 radiometer extended by 1.5 m boom from the MRP, U is the wind speed measured at the "Atlanta" flux-PAM site, ce is assumed to be 0.001 as is used for long fetches (Andreas and Murphy, 1986). Hl is determined in a similar manner, Hl = rhoa*lv*ce*U(qs - qa) where qs is determined from the surface skin temperature assuming the surface is saturated with respect to liquid. This assumption is sufficient for slushy ice conditions that were observed particularly for ice thicknesses less than 8 cm. This assumption breaks down at greater ice thicknesses and snow-covered ice and lv should be replaced by ls. For consistency lv and sat. w/r/to liquid is used in all calculations of Hl. A factor of 0.98 is used in the calculation of qs to account for salinity effects. ULWR is determined from e*sigma*Ts^4 where e, the surface emissivity, is set to 0.98. DLWR is observed at the "Atlanta" flux-PAM station. USWR is obsered with the downward-looking LICOR pyranometer mounted on the 1.5 m boom extended from the MRP. DSWR is observed at the "Atlanta" flux-PAM station. Flux-PAM data were stored as 5-min averages. 5-min averages of the MRP data have been calculated from 10-sec data.