Thread by @Lijing_Cheng

[THREAD,1/9] Pleased to inform that our paper “Improved estimates of changes in upper ocean salinity and the hydrological cycle.” published. A new ocean salinity product is available and enables a new estimate on water cycle change. doi.org/10.1175/JCLI-D… @MichaelEMann @jfasullo

[2/9] The new IAP ocean salinity product covers global ocean (0~2000m, 41 levels; 1 deg. spatial resolution, monthly from 1960 to present). The spatial interpolation method is the same to our temperature data, uses the spatio-temporal co-variability of salinity from CMIP5 models.

[3/9] The new product is clearly more reliable for examining long-term salinity changes, as we show that this new salinity reconstruction has much better continuity through changes in the observing-system (from altimeters on satellites and profiling floats (Argo) in the ocean.

[4/9] The new data show ‘fresh gets fresher, salty gets saltier’ salinity trends. The 0-2000m salinity trend indicates freshening in most Pacific Ocean; broad salinification within 40S-40N Atlantic, freshening in N Atlantic, and contrasts between N and S Indian ocean

[5/9] A simple index is used to synthesize the spatially complicated changes, named the Salinity-Contrast index, defined as the difference between the salinity averaged over high-salinity and low-salinity regions. S2000 pattern has amplified by 1.6% and SSS has amplified by 7.5%.

[6/9] CMIP5 historical simulations are able to capture the observed trends, i.e., they reveal that the salinification and freshening trends occur in the saltier and fresher regions, respectively. However, CMIP5-Natural simulations show distinctly different spatial pattern

[7/9] The increase of salinity-contrast is due to human influence, and this anthropogenic signal has exceeded the natural background variability (>2-sigma). It takes a little more than a decade to isolate the climate change signal from background noise in this particular metric.

[8/9] We use salinity change to estimate water cycle change, as it reveals the surface freshwater exchanges: evaporation takes freshwater from the ocean into the atmosphere and increases the ocean salinity, precipitation puts more freshwater into ocean and reduces salinity

[9/9] An improved estimate of the global water cycle change has been compiled based on the new salinity data, salinity-contrast metrics and model simulations. It shows that the water cycle has been already amplified by 2~4 % per degree Celsius since 1960

Find data here: http://159.226.119.60/cheng/