Physical Oceanography, Vol. 17, No. 4, 2007
ANALYSIS OF OBSERVATIONS AND METHODS FOR CALCULATING
HYDROPHYSICAL FIELDS IN THE OCEAN
PACIFIC DECADAL OSCILLATION AND EUROPEAN CLIMATIC ANOMALIES
M. Yu. Bardin
and E. N. Voskresenskaya
By using the NCEP/NCAR reanalysis data sets for 1951–2001, we study the characteristics of
Pacific cyclones. It is shown that the northeast–southwest direction is predominant in the displa-
cements of cyclones in the North Pacific. We study the variability of the field of surface atmo-
spheric pressure in different phases of the Pacific decadal oscillation characterizing the tempera-
ture anomalies on the surface of the ocean in the region bounded by
60°N. It is shown
that the decadal variations of the North Atlantic Oscillation supported by the large-scale anoma-
lies of the Pacific decadal oscillation is the most important cause of natural decadal oscillations
in the European region. We study and evaluate the regional response to the Pacific decadal os-
cillation by using, as an example, the analysis of variations of the discharge of European rivers.
The investigations carried out for the last
show that the Pacific decadal oscillation (PDO) described
for the first time at the end of the 1990s [1, 2] can be regarded as an indicator of global changes in the climate.
This climatic signal can be briefly described as periodic variations of the ocean–atmosphere system in the north
part of the Pacific Ocean. As a measure of its variability, it is customary to use the so-called PDO index defined
as the average anomaly of the sea-surface temperature (SST) in the North Pacific between
and 60°N. In
1, as an illustration of the scales of variability of the PDO, we present the time dependences of its index for
the last century. It is easy to see that the quasi-20-yr
periods of existence of positive and negative anomalies of
the SST in the general
periodicity are accompanied by noticeable higher-frequency oscillations in the
ocean–atmosphere system, in particular, with periods of
yr. They are characterized by the corresponding
changes in the components of this coupled system. The atmospheric cyclones formed over the water area of the
ocean prove to be important constituent elements of the system because, traveling over the continents, they are,
to a significant extent, responsible for the subsequent formation of weather and climatic anomalies. At present,
there are several hypotheses concerning the causes of decadal variations in different geographical regions and the
influence of PDO is one of these hypotheses [3–5].
In recent publications (see, e.g., [6, 7]), it is shown that the analysis of the influence of PDO is extremely
important for the evaluation of the climatic trends over the territory of North America. Thus, it has been discov-
ered that the period of positive phase of the PDO is characterized by the presence of a trend toward droughts in
the northwest part of North America and a trend toward damping in its northeast part.
Institute of Global Climate and Ecology, Russian Committee on Hydrometeorology and Russian Academy of Sciences, Moscow,
Marine Hydrophysical Institute, Ukrainian Academy of Sciences, Sevastopol.
Translated from Morskoi Gidrofizicheskii Zhurnal, No.
13–23, July–August, 2007. Original article submitted November 29,
2005; revision submitted March 10, 2006.
200 0928-5105/07/1704–0200 © 2007 Springer Science+Business Media, Inc.