System-defined monhly time series
As the roots of the Climate Explorer are in ENSO teleconnections, the
following monthly time series are always available to correlate when
the time scale is monthly. For other time scales only time is
available at the moment.
- NINO1+2, NINO3, NINO3.4, NINO4: SST anomaly indices by A. Kaplan 1856-1949, CPC/NOAA 1950-now. Niño indices based on
ERSST and HadSST can be selected via monthly indices.
NINO1+2 is the SST anomaly over 10°S-EQ, 80°-90°W; NINO3
over 5°S-5°N, 90°-150°W; NINO4 covers
5°S-5°N, 160°E-150°W. The NINO3.4 index is between
NINO3 and NINO4 at 5°S-5°W, 120°-170°W.
NINO1+2 is an indicator for coastal El Niño, which influences
the coasts of Ecuador and northern Peru. NINO3 is an indicator of
variability in the cold tongue, whereas NINO4 sits on the edge of
the warm pool. NINO3.4 combines both ENSO mechanisms and often is
the best overall indicator of the strength of the basin El
Niño or La Niña. Note that these series are not very
homogeneous. As SST observations have become much better over
time the variability has increased, particularly since the 1970s.
- SOI: the Southern Oscillation Index from CRU 1866-2006 is an atmospheric indicator for the
strength of El Niño or La Niña. It is defined as the
normalised pressure difference between Darwin and Tahiti. As these
pressures are also influenced by more local weather it contains more
noise than the SST-based indices. However, it is also more
homogeneous: the observation method has not changed much since the
middle of the 19th century. Unfortunately CRU does not seem to
update the series any more. The CPC pattern-based SOI runs over
1948-now and can be selected under monthly indices.
- NAO: the North Atlantic Oscillation index from CRU, based on the pressure difference between
Iceland and Gibraltar. The latter point is not in the center of
action, but has a much longer time series. This time series is
updated irregularly by CRU. The CPC pattern-based NAO index
1948-now can be selected under monthly indices.
- Time: centered on 1-jan-2000. Very useful to do trend analyses; the
regression against time is the trend.
You can also correlate with a user-defined
, which is generated by selecting it. If it is of type
"index" it will atomatically be added to the list, otherwise add it to the list explicitly