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.
Please do not ask for 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 (archived copy of notice), this will affect derived products such as the 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.
When using the MOI, please cite:
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. When using the SaOI, please cite:
More information about the Western MOI data (WeMOi) may be found here.
Users of WeMOi should cite:
| Filename | Description |
|---|---|
| MOI | |
| moi1.output.dat | MOI: Algiers and Cairo 1948 to 2022, one line per day, format (f5.0, 2f3.0, f7.3) year, month, day, value Missing values represented by -99.99 |
| moi2.output.dat | MOI: Israel and Gibraltar 1948 to 2022, one line per day, format (f5.0, 2f3.0, f7.3) year, month, day, value Missing values represented by -99.99 |
| SaOI | |
| SaOI(1950-2022).txt | SaOI: Azores and Niamey one line per day, with year, month, day SaOI (separated by tabs). 1 header line. Missing values represented by -99.99 |
| SaOI(2013-2016).txt | SaOI: Azores and Niamey one line per day, with year, month, day SaOI (separated by tabs). 1 header line. Missing values represented by -99.99 |
| WeMOI | |
| Web_WeMOi-2020.txt | WeMOi: Padua and Cadiz, monthly one line per year, with year plus 12 monthly values (tab-separated). 11 header lines. Missing values represented by -999 |
The previous monthly index is still available to allow comparisons to be made:
| Filename | Description |
|---|---|
| Monthly MOI (deprecated) | |
| moac.dat | MOI: Algiers and Cairo, 1958-2000 one line per month, format (i4,i3,f7.2) year, month, value Missing values represented by -99.99 |
| moig.dat | MOI: Israel and Gibraltar, 1958-2000 one line per month, format (i4,i3,f7.2) year, month, value Missing values represented by -99.99 |
These datasets are made available under the Open Database License. Any rights in individual contents of the datasets are licensed under the Database Contents License under the conditions of Attribution and Share-Alike.
Updated: November 2023, Ian Harris