Ocean Mixing Inverse Model Postdoc - CSIRO, Australia

[wilkin]

Ocean Mixing Inverse Model Postdoctoral Position
with
Dr. Trevor McDougall (Trevor.McDougall@csiro.au) and
Dr. Bernadette Sloyan (Bernadette.Sloyan@csiro.au),
CSIRO Marine and Atmospheric Research, Hobart, Australia.

Short Description

The aim of this project is to exploit a very new mathematical technique that can deduce the strength of ocean mixing processes from modern ocean observations. The strength of ocean mixing that arises from this project will then be used in coupled climate models to better predict climate change.

Longer description

A prominent use of ocean models is to predict future climate change under various greenhouse gas scenarios. This is done using coupled ocean-atmosphere-ice models and widely publicized through the Intergovernmental Panel of Climate Change (IPCC). A key parameter in such models is the strength of ocean mixing. Ocean mixing controls the rate at which heat and CO2 are absorbed by the ocean. These IPCC models need the strength of ocean mixing processes to be prescribed. As ocean models have improved over past decades, their ability to accurately model the present ocean is being more obviously limited by the realism of the imposed mixing coefficients. For example, vertical mixing is commonly set as a constant, or near constant parameter despite it being known to be highly spatially variable. What are lacking are global estimates of rates of vertical and lateral mixing.

To overcome the lack of direct mixing observations we have recently developed a new inverse method; the Tracer-Contour Inverse Method, which is able to deduce the strength of both the vertical and lateral mixing in the ocean, as well as giving superior estimates of the mean ocean circulation. The quest for these parameters from ocean hydrography has been a major goal of oceanographic research for decades, and we have shown that the Tracer-Contour Inverse Model is much more skillful in this regard than the three prior inverse methods that have been used in oceanography since 1978.

This novel inverse method uses the hydrographic data that is becoming available from the Argo floats; autonomous floats that are providing oceanographers with more data than has been available to date from research ships (although the traditional ship-derived data is vital below 2000m depth).

This 2-year post-doctoral position will develop the Tracer-Contour Inverse Method
(TCIM) so that it can be applied on a regular grid without the user having to manually select individual tracer contours on density surfaces. The method will then be applied to an isopycnally averaged hydrographic climatology. This global application of the TCIM will provide an understanding of the spatial variation of the vertical and lateral ocean mixing coefficients that are appropriate to be used in coarse-resolution ocean models.

Location: Hobart, Tasmania, Australia.

Background papers

Papers describing the Tracer-Contour Inverse Method may be found at (as accepted by JPO)
http://www.marine.csiro.au/~zik003/TT_Zika081223.pdf
and as submitted to JPO:
http://www.marine.csiro.au/~zik003/Zika ... 090907.pdf

Salary is around A$72,000 per year plus an additional 15% that is contributed to the employee’s superannuation.