UGAMP
GROUP NEWS
Oxford News
Welcome to Michael Palmer, a DPhil student on a UGAMP studentship. His project, "Modelling the Little Ice Age", has started by setting up and running a control run of the Hadley Centre model, forced with climatological SSTs and observations from December 1994. He has begun analysis of the data and comparison with observational precipitation datasets. Comparison is also being made with a separate 50-year control run of the same model which did not include a plant transpiration term. A perturbed run of the model in which the solar constant has been reduced by roughly 0.2% is under way: this includes changes to 6 individual spectral bands.
Sophia Oliver continues modelling the diurnal and semidiurnal migrating tides, using the Met Office Unified Model version 4.0, with a mechanistic set-up which involves removing all the physics routines and leaving just a dynamics core. Heating rates taken from the UGAMP model are used to force the model, and UGAMP background winds and temperatures are entered in the initialisation the simple set-up enables clear identification of features relating to the tides. The simulations obtained from this mechanistic approach are being compared with tides extracted from simulations using the Unified Model with full HADAM-3 physics, with a view to ascertaining the features which most affect tidal behaviour.
Maisa Rojas Corradi has been analysing travelling planetary waves in the stratosphere and mesosphere in the Extended UGAMP GCM (EUGCM). The data show a strong 2-day wave during the summer months. To understand the forcing mechanisms of this 2-day wave a linear instability calculation using zonal background fields from the EUGCM was performed. To examine the nonlinear evolution of the waves, the same zonally symmetric state as in the instability calculation was used to initialize a mechanistic model. Runs without and with the radiation scheme have been performed. The former shows the growth to finite amplitude of the waves, including vortex merger and decay: a 'baroclinic lifecycle' in the middle atmosphere. The latter is in process of being analyzed.
Abdel Hannachi has been investigating the atmospheric response to ENSO using a set of multi-decadal GCM runs of the Hadley Centre model HADAM1 with observed SST boundary conditions (see article elsewhere in this issue). Alan Iwi has completed his DPhil, and is working as a post-doc with Warwick Norton on the EU-funded TOPOZ II project (see article elsewhere in this issue).
David Andrews
University of Oxford
andrews@atm.ox.ac.uk
