Welcome to the Rhubarb talks website
Upcoming seminars are posted below and cover a whole range of scientific exploits. Talks are held every other Monday afternoon at 4.30pm in the postgrad lounge (node 086) and are accompanied by nibbles and refreshments.
For more info or to volunteer for a talk, please contact The Rhubarb Team: Liz (E.Sargent@noc.soton.ac.uk), Rosanna (R.Greenop@noc.soton.ac.uk), Maike (email@example.com) or Sara (Sara.Cregeen@noc.soton.ac.uk)
Wednesday, February 22, 2012
Monday, February 20, 2012
Want to know more about a particular method of collection or analysis? Or perhaps you have experience with a technique not known to many?
Rhubarb talks are expanding to include a Rhubarb Methods session.
We are looking for speakers willing to give ≥5 minute talks about any method they are familiar with that others might like to know more about. These talks would be grouped in 3 or 4 to fill a 30 minute Rhubarb slot.
Possible topics include, but are not limited to: Electron microscopy, qPCR, elemental analysis, field collections/sampling techniques, biogeochemical models, etc.
Please get in touch if you are interested in speaking or have other ideas for topics.
The Rhubarb Team
Monday, February 13, 2012
In preparation for an upcoming conference, Maike Sonnewald will present a Rhubarb talk next Monday, 20.2.12 at 4:30pm in the PG lounge.
Oceanic dominance of interannual subtropical North Atlantic heat content variability
Ocean heat content varies on a range of timescales, with significant impact on the local climate through interactions with the atmosphere. This variability can be driven either by oceanic or atmospheric heat transport for a local body of water. To diagnose the relative contributions and respective timescales, this study uses a box model forced with GCM output to investigate the heat content variability of the upper 800 m of the subtropical North Atlantic from 26oN to 36oN. The ocean and air-sea heat flux data needed to force the box model is taken from a 19 year (1985 to
2006) simulation performed with the 1/12o version of OCCAM. The box model heat content is compared to the corresponding heat content in OCCAM for verification. The main goal of the study is to identify to what extent the interannual to subannual ocean heat content variability is of atmospheric or oceanic origin. To this end, the box model was subject to a range of scenarios forced either with the full (detrended) ocean and air-sea fluxes, or their deseasoned counterparts. This revealed that in all cases, the seasonal variability was dominated by the subannual component of the air-sea flux, which produced a seasonal range of ~0.41oC. However, on longer timescales the interannual oceanic heat transport dominates, with changes of up to ~0.16oC.
The technique is subsequently appplied to observational data. For the ocean heat fluxes, we use data from the RAPID programme at 26oN, and at 36oN heat transport is inferred using a linear regression model from the oceanic low-frequency transport in OCCAM. The air-sea flux from OCCAM is used for the period 2004 to 2006 when the RAPID timeseries and the OCCAM simulation overlap, and a climatology is used for the air-sea flux from
2006 onwards. The results confirm that on longer (>2 years) timescales the ocean dominates the ocean heat content variability. This work illustrates that oceanic divergence significantly impacts the ocean heat content variability on timescales relevant for applications such as hurricane forecasts, and thus that understanding the underlying mechanisms is of great socioeconomic importance.
Harriet Cole will be presenting a practice talk for the ASLO conference this week.
INTERANNUAL VARIABILITY IN GLOBAL PHYTOPLANKTON PHENOLOGY
Harriet Cole, Stephanie Henson, Adrian Martin & Andrew Yool
Large areas of the world's oceans experience a significant seasonal cycle in phytoplankton biomass. The timing of the bloom affects ecosystem dynamics with implications for biogeochemical cycles and higher trophic levels. Phenological changes may additionally indicate climate change, as the physical processes that control timing alter in a warming world.
However, to understand future phenological changes we must first determine variability in timing and what drives it.
Here, phytoplankton phenology metrics such as bloom initiation and peak are calculated globally using satellite ocean colour data. The impact of gaps in the time-series is investigated using a global biogeochemical model that assimilates SeaWiFS data. We find that the missing data significantly alter estimations of bloom timing. This uncertainty is seen to vary spatially and between different methods of calculating the same metric.
We choose the most reliable metric based on this analysis to explore the relationships between interannual variability in phenology and underlying physical drivers, such as mixed layer depth and climate oscillation indices. Relating phenology to indicators of ocean variability offers new insights on the mechanisms that control bloom dynamics.