Dr Scott Osprey FRMetS

Abstract:

rcp45 is an experiment of the CMIP5 - Coupled Model Intercomparison Project Phase 5 (http://cmip-pcmdi.llnl.gov/cmip5/). CMIP5 is meant to provide a framework for coordinated climate change experiments for the next five years and thus includes simulations for assessment in the AR5 as well as others that extend beyond the AR5.

4.1 rcp45 (4.1 RCP4.5): Future projection (2006-2100) forced by RCP4.5. RCP4.5 is a representative concentration pathway which approximately results in a radiative forcing of 4.5 W m-2 at year 2100, relative to pre-industrial conditions. RCPs are time-dependent, consistent projections of emissions and concentrations of radiatively active gases and particles.

Experiment design is described in detail in http://cmip-pcmdi.llnl.gov/cmip5/docs/Taylor_CMIP5_design.pdf and the list of output variables and their temporal resolutions are given in http://cmip-pcmdi.llnl.gov/cmip5/docs/standard_output.pdf .
The output is stored in netCDF format as time series per variable in model grid spatial resolution. For more information on the Earth System model and the simulation please refer to the CIM repository.

Abstract:

Project: IPCC Assessment Report 5 and Coupled Model Intercomparison Project data sets - These data belong to two projects:1) to the Assessment Report No 5 of the International Panel on Climate Change (IPCC-AR5) and2) to the Coupled Model Intercomparison Project No 5 (CMIP5).CMIP5 is executed by the Program for Climate Model Diagnosis and Intercomparison (PCMDI) on behalf of the World Climate Research Programme (WCRP). Most of the data is replicated between the three data nodes at the World Data Centre for Climate (WDCC), the British Atmospheric Data Centre (BADC), and the PCMDI.The project embraces the simulations with about 30 climate models of about 20 institutes worldwide.

Abstract:

The surface response to 11 year solar cycle variations is investigated by analyzing the long-term mean sea level pressure and sea surface temperature observations for the period 1870-2010. The analysis reveals a statistically significant 11 year solar signal over Europe, and the North Atlantic provided that the data are lagged by a few years. The delayed signal resembles the positive phase of the North Atlantic Oscillation (NAO) following a solar maximum. The corresponding sea surface temperature response is consistent with this. A similar analysis is performed on long-term climate simulations from a coupled ocean-atmosphere version of the Hadley Centre model that has an extended upper lid so that influences of solar variability via the stratosphere are well resolved. The model reproduces the positive NAO signal over the Atlantic/European sector, but the lag of the surface response is not well reproduced. Possible mechanisms for the lagged nature of the observed response are discussed. Key Points 11-year solar signal detected over N. Atlantic/Europe Signal is evident if data are lagged by ~3 years HadGEM climate model simulates signal but not the lag ©2013. The Authors.

Abstract:

Three years of gravity wave observations from the High Resolution Dynamics Limb Sounder instrument on NASA's Aura satellite are examined. We produce estimates of the global distribution of gravity wave momentum flux as a function of individual observed wave packets. The observed distribution at the 25 km altitude level is dominated by the small proportion of wave packets with momentum fluxes greater than ∼0.5 mPa. Depending on latitude and season, these wave packets only comprise ∼7-25% of observations, but are shown to be almost entirely responsible for the morphology of the observed global momentum flux distribution. Large-amplitude wave packets are found to be more important over orographic regions than over flat ocean regions, and to be especially high in regions poleward of 40°S during austral winter. The momentum flux carried by the largest packets relative to the distribution mean is observed to decrease with height over orographic wave generation regions, but to increase with height at tropical latitudes; the mesospheric intermittency resulting is broadly equivalent in both cases. Consistent with previous studies, waves in the top 10% of the extratropical distribution are observed to carry momentum fluxes more than twice the mean and waves in the top 1% more than 10× the mean, and the Gini coefficient is found to characterize the observed distributions well. These results have significant implications for gravity wave modeling. Key Points Observed GW distribution dominated by wave packets with MF>0.5 mPa Intermittency higher over orography Gini coefficient confirmed as a good metric for wave intermittency ©2013. American Geophysical Union. All Rights Reserved.