Experiments in El Nino analysis and prediction

This software is connected to the Azimuth Code Project Experiments in El Nino analysis and prediction.

R / netcdf-convertor-ludescher.R

This script written by Graham Jones converts netCDF files containing daily mean surface temperature data from NOAA (e.g. air.sig995.1951.nc) into a format more easily readable by other programs in other languages. You need to have installed the package RNetCDF to use this scipt. You can edit it in these ways to meet your requirements:

• change the ranges of latitude and longitude
• change the range of years

As supplied, it converts the data from 1948 to 1949 in a region of the Pacific used in a paper by Ludescher et al. Then start R, and copy and paste the whole file into the R console. (There are other ways of running R scripts but this is simplest for novices.)

More instructions are in the script itself. For even more detailed explanations, see Part 4 and Part 5 of the El Niño Project series on the Azimuth blog.

R / ncdf-convertor.R

This is a modified version of the above script made by Benjamin Antieau, who was unable to get RNetCDF to work on OS 10.9 Mavericks. This uses the R package ncdf instead. For a comparison of these packages, read this.

R / nino3.4-anoms.txt

This is a copy of the monthly Niño 3.4 index from the US National Weather Service; the copy was made in July 2014 and contains data from 1948 to 2013. It has monthly Niño 3.4 data in the column called ANOM.

R / ludescher.R

This program is aimed at replicating the paper by Ludescher et al. To run it, you need to have the files Pacific-1948-1980.txt (created using the above program, netcdf-convertor-ludescher.R) and nino3.4-anoms.txt in your working directory for R.

For detailed explanations of what the program does, see Part 3 and Part 4 of the El Niño Project series.

R / average-link-strength.R

This fie has the average link strength S as computed by ludescher.R at 10-day intervals, starting from day 730 and going until day 12040, where day 1 is the first of January 1948. For an explanation see Part 4 of the El Niño Project series.

R / grj / covariances-basin-vs-rest.R

Makes maps of the Pacific, one per quarter from 1951 to 1979, showing covariances of grid points with the 'Ludescher et al basin'.