Output Data

Last update: June 18, 2001


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Format

    Please write the outputs in netCDF format. A good source of documentation on the netCDF format can be found at http://www.unidata.ucar.edu/packages/netcdf/guidef/. The online users manual is filled with example code blocks. Also, Jan Polcher has written and assembled some general software for reading and writing netCDF format (see http://www.lmd.jussieu.fr/ALMA/alma_bazar.html).

Names and Units

    The variable names and units are to follow the ALMA protocol for Rhone-AGG (see http://www.lmd.jussieu.fr/ALMA/). See Tables 5.1 and 5.2. in the Rhone-AGG description for a list of the output variable names and units.

Naming convention and file content

    We would like the participants to create two netCDF files for each experiment (5 total), and for each year (3 total). The first file should contain the output data requested at a 3-hour time step, and the second with the output data at a daily time step (see Tables 5.1 and 5.2. in the Rhone-AGG description to see which variables are requested at 3-hour or daily time steps).

Please use the following naming convention:

model_expnumber_time stephr_year.nc

where

model acronym for your model. It can be whatever length you choose, but please limit the characters to numbers, letters, - and _.
number experiment number...either 1, 2a, 2b, 2c or 3
time_step in hours, either 3 or 24
year data are to be output using the same starting and ending times as the atmospheric forcing less the first (spin-up) year, i.e. August 1, 1986 (0000) through July 31, 1989 (2100).

As an example, the output file containing the 3-hour variables from ISBA for experiment 2b from August 1, 1987 - July 31, 1988 should be named

ISBA_exp2b_3hr_8788.nc

The total number of files from each group should then be 2 (3 and 24 time steps) * 5 (number of experiments) * 3 (total years to report) = 30.

Please use the Linux/UNIX compress or gzip (GNU zip) to compress the output files. For those using PCs, WinZip is also acceptable.

Array structure

    Please write the outputs using the same array format as the provided input atmospheric data: i.e. 2-D arrays in space and time for which space is to be treated as a 1-D array (1471 points) using the provided masks. The length of the time dimension should be defined using "NF_UNLIMITED". Time should be reported in the same manner as in the inputs: using the number of time steps and the number of seconds since July 31, at 21:00 LST [eg. for the 3hr output, the first reported time step (count) is 1, and the first time at 00:00 is 10800 seconds: the first time step reported is Aug. 1, 00:00 LST]. The daily averages and totals correspond to the values from midnight of the previous day to the last time step of the current day.

Software

    As time goes on, we hope to make some relatively simple software packages/code, which have been developed specificly for Rhone-AGG, available via the web. Currently, there is a Pvwave program available for reading data from the Rhone-AGG data distribution CD, and plotting fields on a rectangular grid.

    Participants should periodically check to see if any new software is posted on the web. Additional software is currently available on the ALMA site (checking model outputs, read/write in netCDF, etc.).

Errors/Problems

    As in previous PILPS exercises and the GSWP, we will notify participants as soon as possible if we detect questionable results. The deadline for submission of results is currently Sept. 1, 2001.

Additional Information

    We would like the participants to send us a concise text summarizing the following by the end of August (we will use this to help us interpret the results):



  1. The most recent/important model reference(s) for their model

  2. A summary of what model parameters were calibrated and how/if they were extrapolated over the domain

  3. What type of sub-grid parameterizations are used by their model (what best describes their model)
    • effective parameters (and which parameters)
    • tile/mosaic approaches (structure: i.e. multiple columns or many surfaces over a single soil, etc.)
    • integration using probability distributions (gamma, normal, etc...and for which variables...)
    • some combination of the above


  • What sub-grid parameterizations they use
    • sub-grid runoff scheme
    • sub-grid precipitation interception
    • sub-grid saturated fraction for evaporation
    • fractional snow cover area parameterization and how it influences the overall surface energy budget
    • other?
        A model might use only a), or all of the above, etc.

      1. which soil parameter model and which aggregation method they used
        • Cosby et al. (provided for all Experiments)
        • Noilhan and Lacarrere (provided for all Experiments)
        • their own parameters derived from the provided soil texture (and possibly surface type also in the case of the wilting point VWC) fields.
            Note that the provided aggregated soil hydraulic parameters for Experiments 2a,b,c and 3 have been calculated using the provided aggregated soil texture. Modelers may choose to calculate the aggregated parameters for Experiments 2a,b,c and 3 by aggregating the parameters themselves. This choice is up to the modelers: we only ask that you tell us which aggregation method you use.

          1. If the aggregated surface/vegetation parameters on the data distribution are not used in favor of different aggregation methods, please explain what method was used and for which parameters.

          2. Surface energy budget structure
            • single soil/snow/vegetation composite surface energy budget
            • distinct canopy and soil with composite snow
            • distinct soil, canopy and snow
            • other


              1. We will post questions (anonymously) and answers on the FAQs page of this web site (as was done in PILPS-2e). We will make every effort to update this site every day (that we receive email) by 1200 GMT.