Please do not ask me to produce monthly MOI data: it is ambiguous, as it can be calculated in different ways. If you need monthly MOI then feel free to calculate it from the daily data presented here.
Note that early NCEP data (1948-1967) has a problem relating to SLP, this will affect derived products such as these MOI indices.
Note that the previous versions (1958 to 2010) did not include leap year days (29/02) for 2004 and 2008 due to a fault in the programs. This has been corrected for the updated files.
The MOI is defined by Palutikof et al. (1996) and Conte et al. (1989) as the normalized pressure difference between Algiers (36.4°N, 3.1°E) and Cairo (30.1°N, 31.4°E) A second version of the index can be calculated from Gibraltar's Northern Frontier (36.1°N, 5.3°W) and Lod Airport in Israel (32.0°N, 34.5°E) (Palutikof et al., 2003). Here data is presented for both variants, using pressure interpolated (16 point Bessel) from NCEP/NCAR reanalysis data.
More information about the Western MOI data (WeMOi) may be found here. Users of WeMOi should also reference:
The Saharan Oscillation Index (SaOI) is defined by Khomsi et al. (2020) as the difference between the normalized pressures at the Azores (37.79° N, -25.5° E) and Niamey (13.51° N, 2.10° E). It is calculated based on the sea level pressure data provided by the ERA5 reanalysis accessible in the Climate Data Store from the European Centre for Medium-Range Weather Forecasts (ECMWF) (CDS; https://cds.climate.copernicus.eu/#!/search?text=ERA5&type=dataset). We present two sets of the SaOI data: - Daily data as used in (Khomsi et al., 2020) between 2013 and 2016; - Daily data calculated between 1950 and 2021.
|New Daily File format (MOI only)|
for year = 1948 to 2021 for month = 1 to 12 format(F5.0, 2F3.0, F7.3) year, month, day, value
|Missing values represented by -99.99 (MOI)|
WeMOi format is one line per year, with year plus 12 monthly values (tab-separated). 11 header lines. Missing values represented by -999
SaOI format is one line per day, with year, month, day SaOI (separated by tabs). 1 header line. Missing values represented by -99.99
|moi1.output.dat||506 kilobytes||MOI: Algiers and Cairo|
|moi2.output.dat||506 kilobytes||MOI: Israel and Gibraltar|
|Web_WeMOi-2020.txt||29 kilobytes||WeMOi: Padua and Cadiz, monthly|
|SaOI(1950-2021).txt||29 kilobytes||SaOI: Azores and Niamey|
|SaOI(2013-2016).txt||29 kilobytes||SaOI: Azores and Niamey|
June 2022: updates to 2021
April 2021: Updated to 2020
July 2020: Updated to 2019
November 2018: Added WeMOi; Updated to 2017
February 2017: Updated to 2016
August 2015: Updated to 2014
November 2014: Updated to 2013
October 2013: Updated to 2012
May 2011: Indices are now daily. Initial data files run from 1958 to 2010
Thanks to Andrew Harding for updating the index. Future updates are planned. Please contact me (email@example.com) if you wish to access the software routines that calculate the MOI indices from the NCAR Reanalysis Data.
The previous monthly index is still available to allow comparisons to be made:
|Old Monthly File format (MOI)|
for year = 1958 to 2000 for month = 1 to 12 format(i4,i3,f7.2) year, month, value
|Missing values represented by -99.99|
|moac.dat||8 kilobytes||MOI: Algiers and Cairo|
|moig.dat||8 kilobytes||MOI: Israel and Gibraltar|