FEATURES OF TEMPERATURE AND HUMIDITY REGIME OVER THE NORTH PACIFIC OCEAN IN THE COLD PERIOD. 700 MB GEOPOTENTIAL HEIGHT

Abstract

Problem Statement and Purpose. Formation of hydrometeorological characteristics at 700 hPa level is governed with the processes of interaction of the underlying surface with the surface layer of air and, at the same time, processes in the middle troposphere. Such processes assume the presence of inhomogeneities in the fields of various hydrometeorological characteristics over the Pacific Ocean basin and the adjoining land area. Clusterization of the average monthly fields of air temperature, mass fraction of water vapor at 700 hPa level, the calculation of the statistical characteristics of the proper homogeneous zones is the goal of this work and, at the same time, part of a more general study related to the determination of regions of intense interaction between the processes that form the hydrometeorological characteristics of the atmosphere and the ocean in Northern Pacific, as analogues of energy-active zones.Data & Methods. As a research object for investigation the fields of mean monthly air temperatures and the mass fraction of water vapor given at nodes of the regular grid of points 2.5º×2.5º in the North Pacific from 1957 to 2003 (November–March ), were taken. In order to identify homogeneous regions in the fields of these hydrometeorological characteristics, the algorithm of the Universal iterative method of data clusterization is used. This method is based on known parametric and nonparametric criteria: Euclidean distance, Fisher criteria, Cramer-Welch criteria and omega-square criteria (Lehmann-Roseblatt).Results. The clusterization schemes proposed are verified from both physical and statistical points of view. The general structure of the obtained homogeneous zones of air temperature and humidity has a latitudinal direction: their dimensions along the latitudinal circle are much higher than the meridional ones. In the fields of temperatures there is a focal zones in the areas of the Bering Sea and the eastern shores of the Northern Pacific. The results of clusterization correspond to processes of turbulent transfer of heat and moisture, circulation patterns in the atmosphere and the ocean. Analysis of the variability of the boundaries of homogeneous regions, the mean values of representative vectors, variances, mean square deviations over subsequent time intervals, will help to determine the features of climate variability by the example of the fields of the hydrometeorological characteristics in question.