What is the standard of average sea level used in China?

The average sea level used in China is based on the water level data of the Yellow Sea.

In view of the fact that the average depth of the Yellow Sea is 44 meters, the seabed is relatively flat and not bumpy. Compared with the other three shallow seas, it is less affected by climate and current, and the water surface is relatively stable. Therefore, our country has made it clear in 1956 that the average sea level observed by Qingdao tide gauge station is the national unified height starting surface.

Mean sea level refers to the arithmetic average of sea level per hour in a certain period, and it is the starting surface of elevation in geodetic survey and hydrological survey. The change of average sea level is closely related to the influence of astronomy, meteorology, seawater density, basic circulation structure and geographical conditions. Mean sea level and its change can provide valuable information for the study of oceanography and solid geophysics (such as the shape of the earth).

Extended data:

The Blue Book of China Climate Change Ocean (2020) shows that the global average sea surface temperature has an obvious upward trend from 1870 to 20 19, and the average value in recent ten years (20 10-20 19) is higher than1877. In 20 19, the global average sea level was 8.5 mm higher than that in 20 18, which is the highest value since satellite observation records.

From 1980 to 20 19, the sea level changes along the coast of China showed a fluctuating upward trend, with an increase rate of 3.4 mm/year, which was higher than the global average level in the same period. In 20 19, the coastal sea level in China was the third highest since 1980, which was 72 mm higher than the annual average of1993 ~ 2010 and 24 mm higher than that in 20 18.

Baidu Encyclopedia-Average Sea Level of Yellow Sea