Is the reduction in moist stability over the Atlantic over the past few decades, with which the model is forced, an artifact?
The data with which we force this model during the control simulations – both through the boundary conditions and through the large-scale interior nudging – comes from the NCEP/NCAR reanalysis. It contains a substantial trend towards reduced stability over the 1980-2006 period: the upper troposphere does not warm enough to maintain the moist stability. This could be a real trend or it could be an artifact. Trends in tropical and global mean stability have been the topic of extensive analysis and discussion in recent years, as summarized in CCSP report 1.1. Trends over the Atlantic share in the uncertainty in the tropics-wide stability trends, but there is an additional factor: the stability in the Atlantic is expected to be reduced (enhanced) when the Atlantic Ocean surface temperatures warm more (less) than the rest of the tropical oceans. The moist stability over the Atlantic is not determined by Atlantic surface temperatures alone. One can think of tropical tropospheric temperature,
Related Questions
- To what extent is the models increase in activity in the past few decades due to a destabilization of the atmosphere over the Atlantic?
- Is the reduction in moist stability over the Atlantic over the past few decades, with which the model is forced, an artifact?
- Are we confident in the projections by global models of future changes in moist stability and shear over the Atlantic?
