Climate and Hydrology in Taiwan Province Strait

In Taiwan Province Province, the cross-strait monsoon alternates obviously, and the frequent northerly wind is very strong. From 10 to April every year, the northeast wind is dominant; Southwest winds predominate from June to August.

Every year, strong typhoons accompanied by heavy rains will lead to drastic changes in tidal levels and strong coastal erosion.

Taiwan Province Strait belongs to the south subtropical and north tropical monsoon climate. The average highest temperature in Central China is 28. 1℃, and the lowest is 15.9℃. Affected by the mainland, the annual temperature difference in northwest China is large; The southeast is affected by the ocean, and there is little difference between year and day. From June 65438 to March of the following year, there were many northeast monsoons, and the wind force reached 4 ~ 5, sometimes more than 6; There is a southwest monsoon from May to September, and the wind force is about 3. From July to September, there are many tropical cyclones, which are affected by tropical storms and typhoons 5-6 times a year on average, and the center passes twice on average. There are more rainy days, but the precipitation is less than that on both banks, with an annual precipitation of 800 ~ 1500mm. Northeast monsoon period and southwest monsoon period are more, and autumn is less. There are few foggy days in the Strait, and the Penghu Islands average 3-4 days a year. There are more foggy days along the coast. Dongshan Island, Mazu Islands and Kaohsiung have more than 30 days a year, and the rest have less than 20 days.

Affected by the Kuroshio, the water temperature is higher, and the salinity and transparency are also higher. The annual average temperature of surface water is 17 ~ 23℃, the lowest is1~ March, and the average is 12 ~ 22℃. It is the highest in July, with an average temperature of 26 ~ 29℃ and an average salinity of 33‰, 30 ‰ ~ 3 1 ‰ in the northwest and 33 ‰ ~ 34 ‰ in the southeast. The transparency in the east is greater than that in the west, with an average of 3 ~15m. The water color is blue in the east, blue-green in the west, and green-yellow in the estuary or in bad weather.

There are regular semidiurnal tides along the coast of Fujian, the Penghu Islands, the west coast of Taiwan Province Province and the north of Haikou berth. The west coast of Taiwan Province Province, south of Haikou berth, is an irregular semidiurnal tide; Okayama to Fangliao is an irregular diurnal tide. The tidal range in the west is greater than that in the east, reaching 4-6 meters to the north of Jinmen Island in the west and decreasing significantly to the south. The middle of the east is larger than both ends, with Houlonggang reaching 4.2 meters, Haikou berth and Danshui port 2.6 meters, Haikou berth 0.6 meters south, and Penghu Islands 1.2 ~ 2.2 meters. North of the line from Houlonggang to Haitan Island, the high tide flows to the southwest and the low tide flows to the northeast, with a velocity of 0.5 ~ 2 knots; The south flow direction is opposite to the above. The current near Penghu Islands is relatively large, reaching 3.5 knots in the southeast.

The Strait is a stormy area in the East China Sea. Surge is more than wind and waves, with 4-level waves accounting for 42% of all waves, 5-level waves accounting for 28%, and waves larger than 5-level waves accounting for 8%. The northeast monsoon season is dominated by northeast-north waves. The southwest monsoon season is dominated by southwest-south waves. Affected by cold waves in winter and tropical cyclones in summer, 8 ~ 9 waves can be formed. The current is controlled by the Kuroshio west branch and the South current in the north, and the Zhejiang-Fujian coastal current in the south, and influenced by the monsoon. In summer, the coastal current stops going south, and the whole strait is a northeast current combining the southwest monsoon current and the west branch of Kuroshio, with a velocity of 0.6 knots and 2.3 knots in Penghu waterway. In winter, the coastal flow affected by the northeast monsoon flows south, and the western and central parts flow southwest, with a velocity of about 0.5 knots; The northeast airflow in the east is weakened, and when the northeast wind is strong, the surface layer even turns to southwest airflow.