Changes between Version 4 and Version 5 of Branches/Driver_Improvements
- Timestamp:
- 2012-09-13T10:49:55+02:00 (12 years ago)
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Branches/Driver_Improvements
v4 v5 7 7 The driver of ORCHIDEE is expected to read forcing files with a very specific temporal structure. 8 8 All time information are defined on UTC time. 9 10 the instantaneous value at t+1 for Temperature, Wind Speed, Air Pressure and Specific Humidity.11 the mean value between t and t+1 for Long and Short Wave Incomming Radiation and the Precipitation.9 The fields read at a certain time step t in the Netcdf file correspond to: 10 * the instantaneous value at t+1 for Temperature, Wind Speed, Air Pressure and Specific Humidity. 11 * the mean value between t and t+1 for Long and Short Wave Incomming Radiation and the Precipitation. 12 12 13 *Interpolation13 Interpolation 14 14 * Instantaneous fields and the Long-Wave Radiation are then linearly interpolated for each t:t+1 time period in order to calculate half-hourly value. 15 * The Precipitation field is downscaled to half-hourly resolution using a step distribution function with one parameter (nb_spread, that is the number of half-hourly time steps over which we spread the precipitation). nb_spread can vary from 1 (all precipitations over a forcing time period (3 ou 6 hours) are put on the first time step) to SPLIT_DT (number of integration time steps with a forcing time period, in that case, the precipitation are distributed uniformely). By default, nb_spread is set to 1. 15 * The Precipitation field is downscaled to half-hourly resolution using a step distribution function with one parameter (nb_spread, that is the number of half-hourly time steps over which we spread the precipitation). nb_spread can vary from 1 (all precipitations over a forcing time period (3 ou 6 hours) are put on the first time step) to SPLIT_DT (number of integration time steps with a forcing time period, in that case, the precipitation are distributed uniformely). By default, nb_spread is set to 1. We may wonder if it is the most appropriate default value. I (Nicolas Vuichard) would recommend to set nb_spread to SPLIT_DT, by default. 16 16 * The Short-Wave radiation is interpolated using a function distribution that corresponds to the solar angle distribution over a forcing time period. 17 17 … … 26 26 27 27 == Restart the last forcing time step read == 28 As the driver is built now, the first time step read (for the Temperature for instance) is valid for t+1. This means that for a yearly file at a 6-hourly time resolution, the first temperature read is for "1-JAN 06:00". For a simulation starting from scratch (no restart), the driver uses the first value for the second day ("2-JAN 00:00") in order to interpolate with the first one readed (and to calculate half-hourly values between "1-JAN 00:00" and "1-JAN 06:00". At the end of a simulation, the last forcing file read is not written in the restart file of the driver. When we perform monthly runs using a yearly forcing file, it is managed within the driver to use the appropriate time step in the forcing file but when we perform yearly runs using a yearly file, we process as for a run starting from scratch (while we could use the last values read during the last run). We suggest to restart the last time step read of the meteorological variables in order to be make possible this. 28 As the driver is built now, the first time step read (for the Temperature for instance) is valid for t+1. This means that for a yearly file at a 6-hourly time resolution, the first temperature read is for "1-JAN 06:00". [[BR]] 29 For a simulation starting from scratch (no restart), the driver uses the first value for the second day ("2-JAN 00:00") in order to interpolate with the first one readed (and to calculate half-hourly values between "1-JAN 00:00" and "1-JAN 06:00". 30 At the end of a simulation, the last forcing file read is not written in the restart file of the driver. [[BR]] 31 When we perform monthly runs using a yearly forcing file, it is managed within the driver to use the appropriate time step in the forcing file but when we perform yearly runs using a yearly file, we process as for a run starting from scratch (while we could use the last values read during the last run). [[BR]] 32 We suggest to restart the last time step read of the meteorological variables in order to be make possible this. 29 33 30 34 == Remove the reading of the watchout files == 31 In ORCHIDEE, there is the possibility to write in an output file, the meteorological fields used during the simulation. It is a feature useful when doing a coupled simulation (ORCHIDEE coupled to LMDz) in order to be capable to re-use this 'forcing' in off-line mode. These output files are named WATCHOUT files. These WATCHOUT files are not based on the same template than the standard forcing files read by ORCHIDEE. Consequently, there are specific reading for these WATCHOUT files. We suggest to : 35 In ORCHIDEE, there is the possibility to write in an output file, the meteorological fields used during the simulation. It is a feature useful when doing a coupled simulation (ORCHIDEE coupled to LMDz) in order to be capable to re-use this 'forcing' in off-line mode. These output files are named WATCHOUT files. These WATCHOUT files are not based on the same template than the standard forcing files read by ORCHIDEE.[[BR]] 36 Consequently, there are specific reading for these WATCHOUT files.[[BR]] 37 We suggest to : 32 38 * either generate the WATCHOUT files in ORCHIDEE under the format than a standard forcing file 33 39 * or, develop a specific tool that convert the WATCHOUT file into the same format than a standard forcing file. This tool will be launch as a pre-treatment.
