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Creates a new fieldset with all the fields' values replaced by those supplied. If supplied as a single vector, the values are set in all fields; if a list of vectors is supplied then there must be the same number of vectors as there are fields in the fieldset. The default behaviour is to produce an error if the input fieldset and vector have different numbers of values. If, however, a third parameter (set to the string 'resize') is passed to the function, the resulting fieldset will instead be resized to have the same number of values as the input vector - this can be useful when creating a new fieldset from a template. Missing values in the vector(s) are retained as missing values in the fieldset.

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shear_deformation(fx: fieldset, fy: fieldset)

For each field in the input fieldset, this function creates a field where each grid point has the value of the sine of its latitude. For example, the following macro adds the coriolis parameter to each grid point of a field :

# Computes absolute vorticity from vorticity
omega = 2 * pi / 86400
coriolis = 2 * omega * sinlat(vort)
absvort = vort + coriolis

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New in Metview version 5.13.0.

Computes the shear deformation of 2-dimensional vector fields. The computations for a vector field f=(fx,fy) are based on the following formula:

d(f) = \frac{1}{R \ cos\phi}\frac{\partial f_y}{\partial \lambda} + \frac{1}{R}\frac{\partial f_x}{\partial \phi} + \frac{f_x}{R}tan\phi

where

• • R is the radius of the Earth (m)
  • φ is the latitude
  • λ is the longitude.

The derivatives are computed with a second order finite-difference approximation. The resulting fields contain missing values on the poles.  Please note that this function is only implemented for regular latitude-longitude grids.

For each field in the input fieldset, this function creates a field where each grid point has the value of the sine of its latitude. For example, the following macro adds the coriolis parameter to each grid point of a field :

# Computes absolute vorticity from vorticity
omega = 2 * pi / 86400
coriolis = 2 * omega * sinlat(vort)
absvort = vort + coriolis

This function accepts a fieldset as input and returns it sorted according to keys and rules specified in the other input arguments.

Specified with only the fieldset as its single argument, sort() sorts in ascending order the fieldset according to the following MARS keys: date, time, step, number (ensemble member), levelist and param (integer ID).

The second argument allows you to modify the precedence of the sorting keys - e.g. if the second argument is a string "param", then the sorting is done according to the param key. If the second argument is a list you specify a list of sorting keys - e.g. ["param", "date"] sorts on parameter and then date.

The third argument specifies a sorting direction. This can be a string (">" or "<") or a list ([">", "<", ">",...]). If it is a string, the sorting direction it specifies applies to all sorting keys specified in the second argument. If it is a list, then the second argument must also be a list with the same number of elements - the sorting directions apply to each sorting key specified.

Computes the standard deviation of a fieldset. A missing value in any field will result in a missing value in the corresponding place in the output fieldset. With n fields in the input fieldset, if xik is the ith value of the kth input field and yi is the ith value of the resulting field, the formula can be written :

Image Added

Note that the following lines are equivalent :

y = stdev(x)
y = sqrt(mean(x*x)-mean(x)*mean(x))
y = sqrt(var(x))

Computes the standard deviation over a weighted area. The area, if specified, is a list of numbers representing North, West, South, East. If the area is not specified, the whole field will be used in the calculation. The result is a number for a single field, or a list for a multi-field fieldset.

New in Metview version 5.13.0.

Computes the stretch deformation of 2-dimensional vector fields. The computations for a vector field f=(fx,fy) are based on the following formula:

d(f) = \frac{1}{R \ cos\phi}\frac{\partial f_x}{\partial \lambda} - \frac{1}{R}\frac{\partial f_y}{\partial \phi} - \frac{f_y}{R}tan\phi

where

• • R is the radius of the Earth (m)
  • φ is the latitude
  • λ is the longitude.

The derivatives are computed with a second order finite-difference approximation. The resulting fields contain missing values on the poles.  Please note that this function is only implemented for regular latitude-longitude grids

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This function accepts a fieldset as input and returns it sorted according to keys and rules specified in the other input arguments.

Specified with only the fieldset as its single argument, sort() sorts in ascending order the fieldset according to the following MARS keys: date, time, step, number (ensemble member), levelist and param (integer ID).

The second argument allows you to modify the precedence of the sorting keys - e.g. if the second argument is a string "param", then the sorting is done according to the param key. If the second argument is a list you specify a list of sorting keys - e.g. ["param", "date"] sorts on parameter and then date.

The third argument specifies a sorting direction. This can be a string (">" or "<") or a list ([">", "<", ">",...]). If it is a string, the sorting direction it specifies applies to all sorting keys specified in the second argument. If it is a list, then the second argument must also be a list with the same number of elements - the sorting directions apply to each sorting key specified.

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Computes the standard deviation of a fieldset. A missing value in any field will result in a missing value in the corresponding place in the output fieldset. With n fields in the input fieldset, if xik is the ith value of the kth input field and yi is the ith value of the resulting field, the formula can be written :

Image Removed

Note that the following lines are equivalent :

y = stdev(x)
y = sqrt(mean(x*x)-mean(x)*mean(x))
y = sqrt(var(x))

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