Distribution features of the weather conditions in Nha Trang Bay (The South China Sea)

Nha Trang Bay is a semi-envelop coastal basin. It is located on the west coast of the South China Sea as well as in the south of the central part of the Vietnamese coast. The climate of the bay belongs to the sub-equatorial zone or to the zone of equatorial-tropical monsoons. Determination of the meteorological characteristics of an ocean region, especially for nearshore bay waters, plays a very important role in the sustainable development of the social-economical system of Vietnam. This paper presents a spatial and temporal long-term analysis of several meteorological characteristics in Nha Trang Bay, such as wind, tropical cyclones, air temperature, air humidity, and rainfall. The meteorological data were collected from the Nha Trang meteorological station during 1977–2015 (wind data until 2020). The data for typhoons were extracted from the National Weather Service (USA) and the Japan Meteorological Agency during 1945–2015. Statistical methods for collecting and analyzing data to estimate the statistical parameters of meteorological characteristics were used in the study. A study of results shows that the meteorological characteristics in the Nha Trang Bay are a seasonal variation of the East Asian monsoon (northeastern-NE and southwestern-SW monsoons). The winds in Nha Trang Bay are the seasonal change, influenced by the NE monsoon from October to April and the SW monsoon from June to August. May and September are the transition periods. Nha Trang Bay has a temperate tropical climate because the temperature regime of the bay ranges from less than 25°C in the winter and more than 28°C in the summer. Extreme conditions, including typhoon activity and heavy rainfall (coinciding with high humidity), occurred in October, November, and December.