Ocean Circulation and Climate: Chapter 28. Long-term Salinity Changes and Implications for the Global Water CycleLong-term global ocean salinity variation provides an insight into water cycle change. This connection reflects changes to the evaporation and precipitation (E–P) fields along with terrestrial runoff, which comprises the global water cycle and sets the spatial pattern of salinity on the ocean surface. The dynamic nature of the global ocean ensures that along with E–P, temperature and circulation changes also play a role in driving patterns of salinity change. This chapter provides an introduction to the global water cycle, briefly outlines the history of ocean salinity observation, and introduces results that relate resolved salinity change to water cycle change. Because of sparse observational coverage, the use of climate models are necessary to investigate these relationships. Long-term changes to global ocean salinity suggest that an unambiguous and coherent water cycle change has occurred over the twentieth and early twenty-first centuries. Climate model simulations project that such changes will intensify in the twenty-first century in response to continued greenhouse gas emissions. |
Common terms and phrases
accuracy Analysis period annual mean Arabian Sea Argo assessments Atlantic Basin atmospheric Bay of Bengal chlorinity climate models climatological mean CMIP5 compared Delcroix density depthintegrated dominated drift Durack and Wijffels E–P changes E–P forcing ENSO evaporation Figure freshening freshwater flux Geophys Res Lett global water cycle gradients Griffies Grodsky highlatitude Hosoda IAPSO Intercomparison Knudsen largescale Levitus Lewis and Perkin longterm changes McPhaden mean SSS measurements model simulations North Atlantic ocean climate ocean models ocean observations ocean surface Oceanogr oceanographic Pacific PCMDI precipitation rainfall regions resolved response Roemmich and Gilson salinity anomalies salinity observations salinity pattern salinity variability salinometers saltier satellite sea surface salinity seasonal seawater Southern Hemisphere spatial patterns SSS changes standard seawater studies subsurface salinity changes suggested temporal thermohaline circulation timescales titration tropical twentyfirst century variability and change warming water cycle change WOCE World Ocean World Ocean Atlas World Ocean Database zonal zonalmean