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(approximately by 0
.
5
◦
C) is noted. Violation of the daily course of temperature can
be explained by intensification of the vertical exchange. Satellite images (GMS-5)
show that during the period of interest the sky was never completely covered with
clouds, which could have restricted the arrival of solar radiation.
Earlier, in Sect. 7.1.2, the assumed peculiarities of atmospheric circulation due
to the formation of cold SST anomalies were already described. Over the region
of reduced temperature, cooling and thickening of the air should take place, and,
consequently, a 'cold wind' should start blowing from the region of the anomaly.
From Fig. 7.2 it is seen that in the second half of April 29 (i.e. immediately after
the earthquake) the temperature of the air fell sharply. A significant drop in the air
temperature is also noticeable in the period from May 4 to 6, when the most pro-
nounced SST anomaly was observed.
In a recent work [Levin et al. (2006)], a description is given of several cases of
the transformation of vertical temperature profiles in the ocean, which took place
after strong underwater earthquakes. To reveal events of this type the authors of
the work indicated created an integrated database (IDB), that includes vertical pro-
files of oceanographical observations in the World Ocean and seismic catalogues.
Several sources were made use of in filling up the IDB with data. The database
of the World Ocean, version of year 2001 (DB WO-01) [Conkright et al. (2002)],
served as the main source, precisely it made up the main volume of the informa-
tional base. The database of the World Ocean of 2001 presents a further develop-
ment of a series of products concerning oceanographic data in the World Ocean,
published earlier—the 1994 Atlas of the World Ocean and the 1998 database of
the World Ocean. The database contains oceanographic observations at standard
and measured horizons in the form of vertical profiles. It includes practically all
observations available for the time period of observation, which involved 7 037 213
stations. Since the data in the DB WO-01 are limited to the year 2001, in order to
supplement the IDB with the most recent data it turned out to be necessary to take
advantage of the Global Temperature-Salinity Profile Program—GTSPP.
Samples of data of the National Earthquake Information Centre (NEIC) of
the USA were used as initial data. The first set of data comprises historical earth-
quakes of magnitudes above
M
= 6
.
5 during the period from 1900 to 2004, and
the second set includes all significant historical earthquakes starting from 1973 up
to the current day.
In analysis of events, information was sought on measurements made near
the epicentre of an underwater earthquake before and after the seismic event.
Besides, climatic characteristics were calculated: the average temperature profiles
over many years and the respective root-mean-square deviations.
Figure 7.3 presents a case of the vertical thermal structure of the ocean chang-
ing after the underwater earthquake of magnitude
M
= 7
.
7, which took place on
December 4, 1972. The earthquake epicentre was to the south of Honshu Island at
the point with coordinates 33.0
◦
N and 140.7
◦
E. The sites, at which measurements
of the temperature profiles were made before and after the event, were located at
distances of approximately 40-50 km from the epicentre. The dates of temperature
profile measurements made before the event were November 19-20 and after the
