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Drivers
THIS PAGE HAS OUTDATED INFORMATION
The header file for the meteorological files are specified by the ED_MET_DRIVER_DB setting in the ED2IN file. The header file, which is in ASCII, then summarizes the content and frequency of various HDF5 met files. The component met files are set up so that different variables can be stored at different frequencies.
The NACP model-data intercomparison met files can be converted to the old ASCII format using the Media:NACP2DRIVER.txt script
The old ascii files can be converted to HDF5 using:
> cd EDBRAMS/ED/src/preproc/ascii2hdf > make > ./convert_ascii <first_year> <last_year> <findir> <foutdir> <frqin> <frqin_rad> VARIABLES: first_year --- first year to process last_year --- last year to process findir --- directory of the input data foutdir --- directory of the output data frqin --- Frequency at which input (non-radiation) data was written out [seconds]. frqin_rad --- Frequency at which the input radiation data was written out [seconds].
The organization of the meteorological data header file
<number of file formats>
{<path and prefix of files> } Repeat n blocks
{<nlon>, <nlat>, <dx>, <dy>, <xmin>, <ymin> }
{<number of variables> }
{<list of variable names> }
{<list of update frequencies (seconds) or scalar values if flag=4> }
{<list of variable flags> }
VARIABLE FLAGS
(0) read gridded data - no time interpolation
(1) read gridded data - with time interpolatation
(2) read gridded data - constant in time, not changing (if this is lat/lon, will overwrite line 3 information)
(3) read one value representing the whole grid - no time interpolation
(4) specify a constant for all polygons, constant in time (most likely reference height)
VARIABLE NAMES FOLLOW NCEP NAMING CONVENTIONS:
nbdsf: near IR beam downward solar radiation [W/m2] nddsf: near IR diffuse downward solar radiation [W/m2] vbdsf: visible beam downward solar radiation [W/m2] vddsf: visible diffuse downward solar radiation [W/m2] prate: precipitation rate [kg_H2O/m2/s] dlwrf: downward long wave radiation [W/m2] pres: pressure [Pa] hgt: geopotential height [m] ugrd: zonal wind [m/s] vgrd: meridional wind [m/s] sh: specific humidity [kg_H2O/kg_air] tmp: temperature [K] co2: surface co2 concentration [ppm] lat: grid of latitude coordinates, if this variable is present line 3 is ignored lon: grid of longitude coordinates, if this variable is present line 3 is ignored
see Meterorological Variables below for further information on each variable
An example met header file for a single flux tower site:
1
/home/mdietze/inputs/fluxnet/blodgett/met/ED_OL_
1 1 1. 1. -121.0 38.0
13
'vbdsf' 'vddsf' 'prate' 'dlwrf' 'pres' 'ugrd' 'vgrd' 'sh' 't
mp' 'hgt' 'co2' 'nbdsf' 'nddsf'
1800.0 1800.0 1800.0 1800.0 1800.0 1800.0 1800.0 1800.0 1800.0 5
0.0 1800.0 1800.0 1800.0
1 1 1 1 1 0 0 1 1
4 3 1 1
The following is a description of the old ASCII met files, but most of the same variables are still used
| Variable | Units | Description |
|---|---|---|
| geoht | m | Geopotential height 1000mb |
| up | m/s | U velocity |
| vp | m/s | V velocity |
| theta | Degrees K | Potential temperature |
| rv | Humidity | |
| pi0 | Exner function | |
| dn0 | Density of air | |
| conprr | Kg/m2/s | Convective precipitation rate |
| pcpg | Resolved precipitation rate | |
| sclp | ppm | CO2 concentration |
| rlong | W/m2 | Downward longwave radiation |
| rshort | W/m2 | Downward shortwave radiation |
A *.dat is written with time as the outer loop, N->S as the intermediate loop, and E->W as the inner loop. The file contains a two line header that specifies: month year #_of_latitude_bins #_of_longitude_bins lat_resolution lon_resolution ll_lat ll_lon
-rad.dat file
Same header as *.dat, two columns of direct and diffuse incident radiation (W/m2), loop is same as *.dat?
NCEP REANALYSIS
NCEP reanalysis can be converted to ED format. Check the RAPP page for further information.
ECMWF
Check with David for code
Eddy Flux Tower
David has code for Harvard Forest ESM tower and Howland Forest tower. Harvard code is located on malthus scratch/dmm2/hf-data/tower. Fills in missing data using the ECMWF. Mike has code for Bartlett, Harvard Forest Hemlock, Harvard Forest met station, and Duke Forest Hardwood tower (new sites added continually). Fills in missing from NCEP reanalysis OR from specified directory of ED input met files (e.g. A local met station already converted into this format). Code is in /home/mcd/inputs/fluxnet as flux2lsm Mike also has code to convert the AMERIFLUX level 3 post-processed flux files to ASCII met drivers, that can then be converted to HDF5
Unless otherwise noted, meteorological variables are taken to be values ABOVE the canopy, since the model estimates conditions IN the canopy and soil. Definitions of input meteorological parameters, flux measurements, and useful conversions to get from flux tower data to the specified inputs are as follows.
Geopotential height – 1000mb (geoht): Height above “gravity adjusted” mean sea level where the air pressure is 1000mb. General defaults to 30m. Wind speed (u,v): Horizontal velocity of wind (m/s) in east (u) and north (v) vector components. Easily calculated from horizontal wind speed and direction. Potential temperature (theta): (from Wikipedia) The potential temperature of a parcel of air at pressure P is the temperature that the parcel would acquire if adiabatically brought to a standard reference pressure P0, usually 1 bar. The special temperature is denoted θ and is often given by , where T is the current temperature of the parcel, R is the gas constant of air, and cp is the specific heat capacity at a constant pressure. Humidity (rv): where rh is relative humidity (proportion) and T is air temperature (Kelvin) Relative humidity is also related to vapor pressure deficit, a common variable in ecosystem models and thus often reported with flux data, as rh = 1-vpd/svp where svp is saturated vapor pressure, which can be estimated based on air temperature (T). Exner function (pi0): where p is pressure (Pascals) and p00 is the reference pressure (1 bar) Air Density (dn0): where p is pressure (Pascals), T is temperature (Kelvin) and rv is humidity (see above) Precipitation (conprr and pcpg): convective (conprr) and resolved (pcpg) precipitation rates (kg/m2/s) Atmospheric CO2 (sclp): Atmospheric carbon dioxide concentration (ppm). Defaults to 370. Radiation (rlong and rshort): Downward solar (rshort) and long-wave (rlong) radiation (W/m2). rshort can be estimated from PAR as: rshort = PAR/(0.45*4.6). Latent heat flux: heat flux from evaporating water (reminder: I need to summarize how is LE mathematically related to evaporation + transpiration)
There are three options to prescribe the phenology in ED:
- 0 – Calculate based on meteorology
- 1 – User prescribed
- 2 – MODIS derived
Clearly there is work to be done on phenology and at a minimum we need to work to generalize cases 1 and 2.
Land use change is driven by a number of files related to rates of land cover change and forestry. All files are assumed to reside within directories referenced from the directory specified by the IOPTINPT setting. Land cover, is driven by 1x1 degree *.lu files in the “lu” directory. The current data is annual and covers 1700-1999 and comes from Hurtt et al 2006 GCB. File format is tab delimited ASCII:
year cp pc pv vp vc cv sc cs sp ps vs shb f_sbh vbh sbh2 f_sbh2 vbh2 f_vbh2
Forestry is driven by 1x1 degree *.fhr files in the “forestrybyage” directory and covers 1700-2050 at a 10 year time step. File format is tab-delimited ASCII:
year harvest_rate secondary_base_f
In addition, state variables are read from the reference.biomass and fraction.plantation files in the “forestry” folder. Files are 1x1 degree ASCII tab-delimeted formats:
reference.biomass: lat lon tagb
fraction.plantation: lat lon fracplant