file format: PISTON_MeansNFluxes_LEGi_rj.mat and PISTON_MeansNFluxes_LEGi_rj.txt 10-min met and flux results from final processing col var description 1 yday Decimal yearday (UTC) 2 U Wind speed (m/s) relative to earth measured at 16.59m 3 Ur Wind speed (m/s) relative to water measured at 16.59m 4 wdir Wind direction (deg) from relative to earth 5 wdirR Wind direction (deg) from relative to water 6 tair Air temperature (C) measured at 15.34m 7 pair Sealevel atmospheric pressure, mbar 8 rh Relative humidity(%) measured at 15.34m 9 tsea Sea temperature (C) from Seasnake at 5cm depth 10 Rain Precipitation rate (mm/hr) 11 salinity Salinity from ship thermosalinograph at 4m depth 12 Lat Latitude (deg) 13 Lon Longitude (deg) 14 heading Ship's heading (deg) 15 SOG Speed over ground (m/s) 16 COG Course over ground (deg) 17 cspd Current speed (m/s) 18 cdir Current direction (deg) from 19 Hs Significant wave height (m) 20 Cp Phase speed of dominant waves (m/s) 21 U10 Wind speed (m/s) relative to earth adjusted to 10 m 22 Ur10 Wind speed (m/s) relative to water adjusted to 10 m 23 T10 Air temperature (C) adjusted to 10 m 24 SST Sea surface temperature (C) from tsea minus cool skin 25 RH10 Relative humidity(%) adjusted to 10 m 26 Q10 Specific humidity (g/Kg) adjusted to 10 m 27 SSQ Sea surface specific humidity (g/Kg) from Qsea minus cool skin 28 Qsea Specific humidity (g/Kg) 'near' ocean surface from sea snake 29 taub Bulk surface stress (N/m2) relative to water 30 Solardn Measured downwelling solar (W/m2) 31 Solarup Reflected solar (W/m2) estimated from Payne (1972) 32 IRdn Measured downwelling IR (W/m2) 33 IRup Upwelling IR (W/m2) computed from SST 34 hlb Bulk latent heat flux (W/m2) 35 hsb Bulk sensible heat flux (W/m2) 36 rhf Sensible heat flux from rain (W/m2) 37 Evap Evaporation rate (mm/hr) 38 U_flag Wind data corrected due to poor relative winds (0=no correction, 1=data corrected) 39 ta_flag Temperature data corrected due to poor relative winds (0=no correction, 1=data corrected) 40 reldir Relative wind direction, 0-360 deg from bow 41 taucx Streamwise stress, covariance, N/m2 42 taucy Cross-stream stress, covariance, N/m2 43 hsc Sensible heat flux, covariance, W/m2 44 hlc Latent heat flux, covariance, W/m2 45 covflag Covariance contamination index (1=bad, 0=good) Notes: Fluxes are defined as negative downward and positive upwards. For example, the net heat flux is defined as: Qnet = Solarup+Solardn+IRup+IRdn+hlb+hsb+rhf Qnet<0 is heating ocean The wind and current directions are in meteorological convention (i.e., direction from). Wind speed and direction come from the NOAA sonic anemometer on the bow mast. Flow distortion correction were applied based on similarity with a sister ship, the Ronald H Brown. The wind speed was corrected for flow blockage when wind was from the stern. For this, the ship propvanes on top of the bridge were used and height adjusted to correct the NOAA sonic measurement. Only 8% of data for leg 2 were affected, about 30% on leg3. For reference, U_flag indicates the corrected wind periods. Tair is taken from the NOAA aspirated air temperature sensors on the bow mast. This was least affected by solar heating. The air temperature was however corrected for island heating effects due to poor relative wind direction. A correction was computed based on a period when Tsea-Tair was relatively constant. For reference, ta_flag indicates the corrected air temperature values. Because of issues with NOAA humidity sensor during leg 2 (salty probe), we reconstruct the humidity signal from the ship SCS instrument (also at the bow). The SCS T/RH sensor is greatly affected by solar heating, but the quantity Qa is less sensitive to solar heating as long as the temperature and RH are measured simultaneously. Thus we first correct Qa SCS for bias compared to the NOAA sensor for leg 3. We then reconstruct RH from the corrected Qa SCS, aspirated and corrected NOAA Tair and SCS Pair measurements to remove the effects of solar heating. tsea is measured by the sea snake. SST is estimated after correction for cool skin and this accounts for the difference between tsea and SST. Similar corrections are applied to SSQ from Qsea. Rain represent a mean rainrate computed as the average of several rain gauges, the NOAA and OSU optical raingauge, the APL disdrometer and the ship's bucket raingauge. Each sensors were QC'd for noise spikes and other contamination. The ship bucket raingauge was corrected for undersampling associated with the horizontal relative wind. A mean rainrate time series was computed and a gain corrected for each gauge was determined. A new mean was computed by averaging the gain-corrected time series for all gauges. Solardn and IRdn is provided by NOAA's radiometer and represent an average of two collocated pyranometers and pyrgeometer respectively. Some values of Solardn are provided by the ship radiometer for periods of shadowing on the NOAA instruments. A solar offset correction at night was also applied on Solardn. Solarup is taken from a commonly used parameterization for surface albedo of the ocean (Payne, 1972). IRup was derived from the SST measurements using the COARE 3.6 algorithm. The bulk fluxes of stress (momentum), sensible heat, latent heat and sensible heat due to rain were provided by the COARE 3.6 algorithm. The COARE 3.6 algorithm was also used to compute the 10-m values of wind speed, temperature and humidity. SOG, COG and Gyro were taken from the ship GPS compass. These were used to compute the wind speed relative to earth. Surface currents are measured by the ship's ADCP and have been QCed compared to a side mounted ADCP operated by OSU. These were used to compute the wind speed relative to water. The wind speed relative to water are used to compute the fluxes. Finally the significant wave height Hs and phase speed come primarily from the NOAA laser distance meter. Some values were corrected with the WAMOS system and the WaveWatchIII model hindcasts. NOTICE TO USERS The data is intended for use by PISTON investigators. Although the data has been through some quality control, it should be considered as preliminary data and users should expect revisions. Revisions will be posted on this site and changes to the data will be documented in the readme files. Questions about the data and its use in publications should be addressed to: Chris Fairall (NOAA/PSD/ESRL, chris.fairall@noaa.gov) Ludovic Bariteau (NOAA/PSD/ESRL, ludovic.bariteau@noaa.gov)