Difference between revisions of "Control file"

Revision as of 15:41, 7 November 2007

control.nml

This is the main control file and sets up parameters for the experiment. This includes pointers to the following files:

metname

This is the root name for the climate forcing files. Each should be named metname_year.txt where year is the year of the data (e.g., Ny_Alesund_1976.txt). Each file should have 5 columns: year; julian day; mean daily temperature; daily temperature range (maximum – minimum); and daily precipitation (mm). Temperature is in degrees C.

Metelev

This is the elevation (m) of the meteorological station or era data (era data is always interpolated to sea level and therefore set to 0 m) that is provided in the metname file (see above). It is required to calculate the local temperature on the glacier.

geomfile

This is the file that contains the geometry data for the glacier. The structure of the file is:

cellpadding="10" align="center"

Line	Information held in file
Line 1	Number of tributaries (including main)	Total number of data points in all tributaries
Line 2	Label for tributary (1 for main)	Number of data points in this tributaries	Downstream tributary (0 for main)	Junction point on downstream tributary (0 for main)
Line 3 onwards. Geometry data for the tributary. Starting at most up-glacier point. Ordering should be such that downstream tributaries must appear before the current tributary.	Upper surface elevation	Bedrock elevation	Reference thickness	Reference width

Glacname

The glacier’s name that is used as prefix for output files

Aspect

The aspect is required if an energy balance model is being used to calculate the mass balance. Aspect is given in radians / (deg. from N) (?)******

Slope

Only required if energy balance model is used.

Lat

Glacier latitude (degrees. North is positive)

Long

Glacier longitude (degrees. East is positive)

Winterday

start winter mass balance season in julian days

Summerday

start of summer mass balance season in julian days

Weights

These are the weights applied to the various optimisation data being used in model. For each optimisation dataset there needs to be an associated weight. To ignore a dataset, weight is set to 0. To include the data, the weight is set to a positive number that reflects your confidence in the data. The weights can also be used to give optimisation data equal weighting even if the data is of different scales, e.g. length data vs mass balance data. The weights are in the following order; 1. geometry (thickness along the flowline)

  2.3.4. mass balance survey (annual, winter, summer)    
  5. length 
  6.7.8. global mass bass balance (annual, winter, summer)
  9. snowline

Start year

The year at the beginning of the simulation

End Year

The year at the end of the simulation.

Dx

Grid spacing in meters along the flow line.

Mode

This determines how the model is run. 0 – is to use the Genetic Algorithm optimiser to determine the best values for the parameter set. 1 – runs the model across the phase space for the various parameters calculating the various cost function for each combination of parameter values. 2 – runs the model in inverse mode >2 – runs the model in the forward model with no optimisation.

Writeout

This is the flag for which output files are required (T/F). The output files available are; annual values for mass summer, winter and net mass balance; daily values of snow pack composition, melt, climate variables; change in the glacier profile, evolution of ice thickness and width. The format of the output files is shown in Section ??***

Outputcell

The resolution along the flow line of the glacier that the results are outputted at.

optimfile

This file contains information on key parameter values and whether they are to be optimized. The file has the following structure; Logical statement (T/F) as to whether the parameter is to be optimised Minimum value that can be taken by parameter. Maximum value that can be taken by parameter. Initial parameter value. If the parameter is not to be optimised, this is the value used in the model. Currently the model is set up to optimise the following parameters;

lapserateartm – air temperature lapse rate.
lapserateprcp – precipitation lapse rate.
pddfs – degree day factor for snow.
pddfi – degree day for ice.
rainsnowtrans – temperature at which rain becomes snow.
wmax – fraction of precipitation/melt that can refreeze in the ice pack.
fiddle – factor related to the softness of ice.
offsetartm – to account for systematic differences between met and era data for air temp.
offsetprcp – to account for systematic differences between met and era data for precipitation.

The following files contain observations against which the model is optimized.

Lengthfile

Contains the year of observation, glacier length and snowline elevation. Line 1 The number of observations. Line 2 Year of observation;

length of glacier;
snowline elevation.

Globmbfile

Annual values for net, winter and summer mass balance for the whole glacier. Line 1 The number of observations. Line 2 Year of observation;

Net mass balance;
Winter mass balance;
Summer mass balance.

Geomsurvfile

Contains survey data of ice thickness along the flowline. Line 1 The number of observations. Line 2 Year of observation; Distance along the flowline; Ice thickness.

Mbsurvfile

Annual values of net, winter and summer mass balance distributed across the glacier. Line 1 The number of observations. Line 2 Year of observation;

Net mass balance;
Winter mass balance;
Summer mass balance.

whichthck

Logical switch to determine whether flow is incorporated into the thickness calculation, or whether only mass balance changes are included; 0 no calculation; 1 flow incorporated.

whichacab

Determines which method is used to calculate the mass balance; 0 day degree; 1 energy balance. Currently the model is set to work with the degree day model, and a simple energy balance model. To use the energy balance model additional meteorological input data is required. *****

whichrain

Controls whether the air temperature that is used to calculate if precipitation falls as rain or snow is set to the daily average or uses a diurnal temperature cycle. 0 mean daily temps only; 1 using diurnal temp cycle (cosine).

whichdayd

Controls whether the air temperature that is used to calculate the degree day is set to the daily average or uses a diurnal temperature cycle. 0 mean daily temps only; 1 using diurnal temp cycle (cosine).

@@ Line 79: / Line 79: @@
 Logical statement (T/F) as to whether the parameter is to be optimised	Minimum value that can be taken by parameter.	Maximum value that can be taken by parameter.	Initial parameter value. If the parameter is not to be optimised, this is the value used in the model.
 Currently the model is set up to optimise the following parameters;
-/ lapserateartm – air temperature lapse rate.
+# lapserateartm – air temperature lapse rate.
-/ lapserateprcp – precipitation lapse rate.
+# lapserateprcp – precipitation lapse rate.
-/ pddfs – degree day factor for snow.
+# pddfs – degree day factor for snow.
-/ pddfi – degree day for ice.
+# pddfi – degree day for ice.
-/ rainsnowtrans – temperature at which rain becomes snow.
+# rainsnowtrans – temperature at which rain becomes snow.
-/ wmax – fraction of precipitation/melt that can refreeze in the ice pack.
+# wmax – fraction of precipitation/melt that can refreeze in the ice pack.
-/ fiddle – factor related to the softness of ice.
+# fiddle – factor related to the softness of ice.
-/ offsetartm – to account for systematic differences between met and era data for air temp.
+# offsetartm – to account for systematic differences between met and era data for air temp.
-/ offsetprcp – to account for systematic differences between met and era data for precipitation.
+# offsetprcp – to account for systematic differences between met and era data for precipitation.
 '''The following files contain observations against which the model is optimized.'''
 ===Lengthfile===
 Contains the year of observation, glacier length and snowline elevation.