Southward spreading of the Changjiang Diluted Water in the La Nina spring of 2008

The La Nina of 2007/2008 was particularly strong, so was the southward flow of the cold, nutrient-rich Changjiang (Yangtze River) Diluted Water (CDW) when the winter monsoon started to blow in the fall. Here we use shipboard data in 2008 in two transects, one in the southwestern East China Sea and one in the southern Taiwan Strait, to show that as late as April in 2008 the CDW was still clearly identifiable when the winter monsoon had weakened. Waters as cold as 16 degrees C with a salinity lower than 30 still occupied the southwestern East China Sea. Waters of 17 degrees C and S<32 could also be found off the coast of China in the central Taiwan Strait. The concentration of NO3+NO2 was higher than 18 mu mol L-1 at both places, which was as much as 40 times higher than the northward moving South China Sea (SCS) water to the east. As a result, the Changjiang River plume may be a significant source of nutrients, particularly N, to the oligotrophic, N-poor SCS, especially in the La Nina years. Indeed, colder and more turbid CDW was more intense and went farther south in 2008 compared with the normal springs of 2006, 2007 and 2009.

Automated summary

The strong La Nina phenomenon in 2007/2008 caused the cold, nutrient-rich Changjiang Diluted Water to flow southwards in the fall, providing a significant source of nutrients, especially nitrogen, to the South China Sea. By April 2008, even when the winter monsoon had weakened, the presence of the Changjiang Diluted Water was still clearly visible.