Wet gets wetter, salty gets saltier: using ocean observations to measure global water cycle change

Abstract: 

I will start by asking how we can detect changes in the global water cycle from changes in ocean salinity. The water cycle transports over 2.5x109 litres of fresh water from high salinity regions to low salinity regions of the ocean every second. This makes saline regions more saline and fresh regions more fresh, widening the distribution of water masses in salinity coordinates and is balanced by the collapsing effect of mixing. Using this framework a physical model is developed describing the link between changes in the salinity distribution and changes in the water cycle. From observations we find that the water cycle is increasing at 3±2% per Kelvin of global warming, an amplification consistent with climate model projections and less dramatic than previous estimates based on surface salinity alone.

I will then introduce the use of thermodynamic diagrams more generally in both oceanographic and atmospheric contexts with emphasis on understanding the movement of heat, fresh water and energy in the climate system and its response to climate change.

This is a joint Fluid Dynamics / Applied Mathematics seminar.

More info:

Zika, J. D., N. Skliris, G. Nurser, L. Mudryk, F. Laliberté, S. Josey, R. Marsh: Maintenance and broadening of the ocean's salinity distribution by the water cycle. Journal of Climate. In press.

Zika, J. D., F. Laliberté, L. Mudryk, W. P. Sijp, G. Nurser: Changes in ocean vertical heat transport with global warming. Geophysical Research Letters, 42, 1-9.

2015 Laliberté, F., J. D. Zika, L. Mudryk, P. Kushner, J. Kjellsson, K. Döös: Constrained work output of the moist atmospheric heat engine in a warming climate. Science, 347, 540-543.