THE INTERANNUAL VARIABILITY OF THE SUMMER MONSOON IN THE ARABIAN SEA (FACTOR ANALYSIS)

Abstract

The paper analyzes the features of the interannual variability of surface waves in the area of action of the summer Indian Ocean monsoon in the period 2010–2017 in the context of the tasks of maritime logistics and navigation safety. The study is based on the generalization of long-term observation series, which made it possible to identify the regularities of the formation of the wave regime in different years and assess the degree of its variability. Based on statistical analysis, it is shown that anomalous wave regimes can be formed both in the form of an increased integral intensity of the process and in the form of seasonal dynamics without pronounced extreme manifestations. This indicates the complex nature of interannual variability, which is not always manifested through obvious storm events, but can significantly affect the general conditions of navigation.

It is established that classical climate indices, in particular ENSO and the Indian Ocean Dipole, do not provide an unambiguous explanation of the actual differences in the wave regime of the Arabian Sea in the indicated years. This indicates the need to expand existing approaches to the interpretation of climate processes and take into account additional factors. To identify the causes of anomalous manifestations of monsoon circulation, the feasibility of including geophysical processes in the well-known list of influential weather-forming factors has been substantiated. As a result of the factor analysis of the interannual variability of the summer monsoon by 4 characteristics (2010, 2013, 2015 and 2017 were highlighted), the influence of the variability of the Earth's angular velocity on the summer monsoon of the Arabian Sea was confirmed at the quantitative level. The dependencies which were formed as the result of the given analyses provide a deeper understanding of the mechanisms of wave regime formation and clarify the role of global geophysical processes in the dynamics of monsoon circulation.

The results obtained can be used to increase the reliability of forecasting wave conditions of the summer monsoon, optimize the planning of maritime transportation and reduce risks for shipping in the Arabian Sea. The practical significance of the study lies in the possibility of taking into account the identified patterns when developing forecasting models and making management decisions in the field of maritime logistics