Available statistical routines for EXTRA format

This document provides basic information about a set of statistical routines designed to process data in EXTRA format. Files of this type may be used to store climate variability related data. For example, maps of sea level pressure may be stored as grids (vectors) in an EXTRA file. Such a file contains not only the grided values but also supplemental information for each map, like the level code, the grid's number of point etc.

Thus, in an EXTRA format file each vector (record, map) of real values is preceded by four integer values.

These last values represent, in order:

- the current record number;

- the variable's code;

- the variable's level;

- the vector (record, map) length.

More information about the routines may be obtained by typing just the routine name, without parameters.

List of available routines

- By categories

1. Preliminary data processing

1.1 ANMEAN - calculates annual means based on monthly values

1.2 ANOMAL - calculate anomalies based on long term means

1.3 ANORM - calculate anomalies and normalizes the data

1.4 AVG - calculate average over all records

1.5 DECAMEAN - calculates means for every ten consecutive values

1.6 DETREND - subtracts the linear trend

1.7 EDGE - eliminates 'special' values

1.8 LMEAN - calculate long term means

1.9 NRMSTDV - normalizes with standard deviation

2. Mathematical operations with a constant value

2.1 SADD - adds a constant value to data

2.2 SDIV - divides the data with a constant value

2.3 SMULT - multiplies the data with a constant value

2.4 SSUB - subtracts a constant value from data

3. Mathematical operations with a constant field

3.1 CADD - adds a constant field to data

3.2 CDIV - divides with a constant field

3.3 CMULT - multiplies with a constant field

3.4 CSUB - subtracts a constant field from data

4. Mathematical operations with files contents

4.1 ADD - add the contents of two files

4.2 MULT - multiplies the contents of two files

4.3 SUB - subtract the contents of two files

5. Change file’s structure

5.1 APPEND - appends one file to other

5.2 BOXAVG - calculates boxes averages

5.3 CHANOSO - reverses the North-South axis

5.4 COARSE - eliminates each second point from a grid

5.5 GGSTAT - provides statistical information’s about a file' contents

5.6 MERGEF - merge two files

5.7 SELBOX - selects a specific box

5.8 SELMON - selects a specific month from a file

5.9 SELVAR - selects a specific variable from a file

5.10 SPLITF - splits one file in other two files

5.11 TP - transposes a file

6. Changing file’s formats

6.1 DFORM - transforms an EXTRA file to a TEXT file

6.2 EXT2GAD - transforms an EXTRA file to a GRADS file

6.3 EXT1LTEXT2C - transforms an EXTRA file (1 line) to a TEXT file (2 columns)

6.4 FORMINV - transforms a TEXT file to an EXTRA file

6.5 GAD2EXT - transforms a GRADS file to an EXTRA file

6.6 TEXT1CEXT1C - transforms a TEXT file (1 column) to an EXTRA file (1 column)

6.7 TEXT2CEXT1C - transforms a TEXT file (1 column) to an EXTRA file (1 column)

7. Statistical operations

7.1 COMPOZ - calculates composite maps

7.2 COMPOZALL - calculates composite maps and the ´positive´ and ´negative´ maps

7.3 COMPOZCONT - calculates continuous composite maps

7.4 COMPZLAG - calculates composite maps with a specific lag

7.5 CORWINDOW - performs window correlations.

7.6 CROSSCOR - calculates the cross-correlation function between two time series

7.7 CRSRHRT - calculate correlation maps

7.8 PARTIAL-CORWINDOW - performs window correlations

7.9 PROJECTION - projects a vector on a field

8. Filtering the data

8.1 FOUFIL - Fourier filters the data

8.2 RUNNING MEANS - calculates running means

9. Multivariate techniques

9.1 CANCOR - performs canonical correlation analysis

9.2 MKEOF - performs EOF analysis