DYCOMS-II Model: ECMWF DDH (Diagnostique des Domaines Horizontaux) 72 Hour Forecast Data (.tar.gz) 1.0 General Information The ECMWF DDH (Diagnostique des Domaines Horizontaux) 72 Hour Forecast Data is one of several model data sets collected by the University Corporation for Atmospheric Research/Joint Office for Science Support (UCAR/JOSS) as part of the Dynamics and Chemistry of Marine Stratocumulus Phase II: Entrainment Studies (DYCOMS-II) project. The data include ECMWF DDH (Diagnostique des Domaines Horizontaux) 72 hour forecast averaged values over the target region corresponding to the box spanning 236.5-240.0 E, 30.0-32.5 N and point values which locate at 238.4 E and 31.08 N. The data cover the period from 1 - 31 July 2001 and are available once per day at 00 UTC. The data were acquired from the European Centre for Medium Range Weather Forecasting (ECMWF). These are gzipped tar files containing ASCII data files. 2.0 Data Contact Bjorn Stevens, UCLA (bstevens@atmos.ucla.edu) Martin Koehler, ECMWF (martin.koehler@ecmwf.int) 3.0 Data and Format Information 3.1 File Types The ECMWF data files come in six flavors all in ascii format: DYCOMA_200107DD_var_32 DYCOMA_200107DD_sfc_32 DYCOMA_200107DD_sfce_32 these are bundeled in gzipped tar files of the form DYCOMa_200107DD.tar.gz DYCOMP_200107DD_var_7 DYCOMP_200107DD_sfc_7 DYCOMP_200107DD_sfce_7 these are bundeled in gzipped tar files of the form DYCOMp_200107DD.tar.gz The DD stands for Day in July, i.e., 01-31. The DYCOMA files denote averaged values over the target region corresponding to the box spanning 236.5-240.0 E, 30.0-32.5 N. The DYCOMP files denote point values which locate at 238.4 E and 31.08 N. 3.1 VAR files The var files are 4323 lines long. The first 3 lines are header information, the remaining 4320 lines corresponds to field values at 60 levels at 72 times. On each of these lines there are 15 values corresponding to: initialization date initialization time validation date validation time model level (1-60) Pressure at level [Pa] Zonal wind, u [m/s] Meridional wind, v [m/s] Temperature [K] Specific humidity [kg/kg] Liquid water specific humidity [kg/kg] Ice water specific humidity [kg/kg] Cloud fraction [fraction] Relative Humidity [fraction] Omega [Pa/s] the lines loop first through model level and then through time, with a timestep of one hour. 3.2 SFC Files The SFC files give surface, or near surface values of fields at each hour. They are 75 lines long with a three line header. On each line there are 16 values corresponding to : initialization date initialization time validation date validation time model level (always 1) 2m Temperature [K] 2m Specific Humidity [K] 10m Zonal Winds [m/s] 10m Meridional Winds [m/s] Surface Skin Temperature [K] Momentum Roughness Height [m] Thermal Roughness Height [m] Boundary Layer Depth [m] Wind Gusts [m/s] Large Scale Precipitation Fraction Sea Level Pressure [Pa] 3.3 SFCE Files The SFCE files give surface, or near surface fluxes of fields at each hour. They are 75 lines long with a three line header. On each line there are 20 values corresponding to : initialization date initialization time validation date validation time model level (always 1) Total cloud cover [fraction] Low cloud cover [fraction] Mid-level cloud cover [fraction] High cloud cover [fraction] Downward Solar Radiation [W/m^2] Downward Thermal Radiation [W/m^2] Large-scale rainfall [kg/m^2] Convective rainfall [kg/m^2] Surface Sensible Heat Flux [W/m^2] Surface Latent Heat Flux [W/m^2] Surface Solar Radiation [W/m^2] Surface Thermal Radiation [W/m^2] Surface Evaporation [kg/m^2] Surface Clear Sky Solar Radiation [W/m^2] Surface Clear Sky Thermal Radiation [W/m^2] 4.0 Quality Control Procedures UCAR/JOSS conducted no quality checks on these data. 5.0 File Naming Convention The file names are structured as follows: DYCOMp_yyyymmdd.tar.gz Where DYCOMp is the data type (also could be DYCOMa) yyyy is the four digit year mm is the two digit month dd is the two digit day 6.0 References None.