Dr Joanne Williams

Group: 
Marine Physics and Ocean Climate
Email: 
joll@noc.ac.uk
Location: 
Liverpool
Telephone: 
+44 (0)151 795 4856

Research interests:

As part of the Sea Level group at NOC, I'm currently working on global tide and surge reanalysis, seeking to improve the understanding of coastal flood-risk around the world. I'm working with Kevin Horsburgh on the Atlantos project.

Storm surge refers to the excess sea-level that is caused by weather systems. In the UK, where we have very large tidal range, one of the effects of a storm can be to change the timing of high tide as well as the maximum water level. In analysing past events from tide-gauge records we have to be very careful how we separate these effects. Rather than just take the difference between continuously measured water level and predicted tide (the non-tidal residual) we sometimes use "skew-surge", the difference between peak observation and prediction, even if these are at a different time.

Previously, with Chris Hughes and Mark Tamisiea, I've studied bottom pressure records and their use in measuring sea-level, mass changes in the ocean, and ocean circulation. We extended the Weighing the Oceans calculation to incorporate more records and to analyse errors. You can watch some animations explaining the mass changes in the ocean.

The work on weighing the ocean has highlighted to us again that bottom pressure recorders are subject to non-linear drift that can be at least as great as annual cycles or long-term trends. We have found that this drift can be better characterised by proper accounting of known annual cycles, and are working on techniques to improve this. We are also interested in alternative techniques to measure bottom pressure, such as combining thermosteric moorings and satellite altimetry.

I'm also interested in using global ocean model data, from for example the NEMO or OCCAM models, to analyse bottom pressure and sea-level where no records exist. This has led to some interesting findings about the comparison of tide-gauge records (necessarily at the shore) and altimetry (usually some distance away). We have found that whether it is valid to use these inter-changeably is dependant on latitude and the time-scales of interest. More details can be found here

Career:

I have worked at the National Oceanography Centre (formerly the Proudman Oceanographic Laboratory) since 2008, mostly part-time. My PhD, in Thin-film Rimming Flows was from the University of Nottingham, with David Riley, Stephen Hibberd and Henry Power. Prior to that I was employed at Malvern in research on aircraft communication systems, and have a maths MSc from Bristol and BA from Oxford.

 

Publications

Article

Hughes, Chris W.; Williams, Joanne; Hibbert, Angela; Boening, Carmen; Oram, James. 2016 A Rossby whistle: a resonant basin mode observed in the Caribbean Sea. Geophysical Research Letters, 43 (13). 7036-7043.10.1002/2016GL069573
Williams, Joanne; Horsburgh, Kevin; Williams, Jane; Proctor, Robert. 2016 Tide and skew surge independence: new insights for flood risk. Geophysical Research Letters, 43 (12). 6410-6417.10.1002/2016GL069522
Hughes, Chris W.; Bingham, Rory J.; Roussenov, Vassil; Williams, Joanne; Woodworth, Philip L.. 2015 The effect of Mediterranean exchange flow on European time mean sea level. Geophysical Research Letters, 42 (2). 466-474.10.1002/2014GL062654
Williams, Joanne; Hughes, Chris W.; Tamisiea, Mark. 2015 Detecting trends in bottom pressure measured using a tall mooring and altimetry. Journal of Geophysical Research: Oceans, 120 (7). 5216-5232.10.1002/2015JC010955
Williams, J.; Hughes, C.W.; Tamisiea, M.E.; Williams, S.D.P.. 2014 Weighing the ocean with bottom-pressure sensors: robustness of the ocean mass annual cycle estimate. Ocean Science, 10 (4). 701-718.10.5194/os-10-701-2014
Hughes, C.W.; Williams, Joanne; Coward, A.C.; de Cuevas, B.A.. 2014 Antarctic circumpolar transport and the southern mode: a model investigation of interannual to decadal timescales. Ocean Science, 10 (2). 215-225.10.5194/os-10-215-2014
Williams, Joanne; Hughes, Christopher W.. 2013 The coherence of small island sea-level with the wider ocean: a model study. Ocean Science, 9. 111-119.10.5194/os-9-111-2013
Hughes, Christopher W.; Tamisiea, Mark E.; Bingham, Rory J.; Williams, Joanne. 2012 Weighing the ocean: Using a single mooring to measure changes in the mass of the ocean. Geophysical Research Letters, 39 (17). L17602.10.1029/2012GL052935

Conference item

Hughes, Chris W.; Tamisiea, Mark E.; Bingham, Rory J.; Williams, Joanne. 2012 Weighing the ocean: How a single mooring in the mid-Pacific can monitor changes in ocean mass. In: European Geosciences Union General Assembly 2012, Vienna, 22-27 Apr 2012. (Unpublished)
Williams, Joanne; Hughes, Chris W.. 2012 Coherence of off-shore steric height and island sea level. In: European Geosciences Union General Assembly 2012, Vienna, 22-27 Apr 2012.
Williams, Joanne; Hughes, Christopher. 2011 Sea-level spectral maps. In: British Applied Mathematics Colloquium, Birmingham, April 2011. (Unpublished)
Williams, Joanne; Hughes, Christopher; Bingham, Rory. 2009 North Atlantic circulation in a 1000 year climate model. [Poster] In: European Geosciences Union General Assembly 2009, Vienna, 19-24 April 2009. (Unpublished)