The El Ni~ no–La Ni~ na asymmetry is evaluated in 14 coupled models from phase 5 of the Coupled Model Intercomparison Project (CMIP5). The results show that an underestimate of ENSO asymmetry, a common problem noted in CMIP3 models, remains a common problem in CMIP5 coupled models. The weaker ENSO asymmetry in the models primarily results from a weaker SST warm anomaly over the eastern Pacific ...

The mid-Pliocene warm period is a recent warm geological period that shares similarities with predictions of future climate. It is generally held the mid-Pliocene Atlantic Meridional Overturning Circulation must have been stronger, to explain a weak Atlantic meridional δ(13)C gradient and large northern high-latitude warming. However, climate models do not simulate such stronger Atlantic Meridi...

The 1998 annual cycle and 1991–98 summer simulations of Greenland ice sheet surface climate are made with the 0.58-horizontal resolution HIRHAM regional climate model of the Arctic. The model output is compared with meteorological and energy balance observations from 15 Greenland Climate Network automatic weather stations. The model reproduces the monthly average surface climate parameters, to ...

The mechanism by which the Gulf Stream sea surface temperature (SST) front anchors a band of precipitation on its warm edge is still a matter of debate, and little is known about how synoptic activity contributes to the mean state. In the present study, the influence of the SST front on precipitation is investigated during the course of a single extratropical cyclone using a regional configurat...

We examine 800-year time series of internally generated variability in both a coupled ocean-atmosphere model where water vapor anomalies are not allowed to interact with longwave radiation and one where they are. The ENSO-like phenomenon in the experiment without water vapor feedback is drastically suppressed both in amplitude and geographic extent relative to the experiment with water vapor fe...

Ocean surface temperatures and wind speeds tend to vary together across ocean basins away from tropical regions. Typically, stronger surface winds are seen over cooler and weaker winds over warmer water, because strong winds cool the ocean surface by evaporation and by stirring up cold subsurface water. But is this always the case? Aside from warm tropical oceans, where moist air ascends high i...

The intertropical convergence zone (ITCZ) is displaced to the south edge of the eastern Pacific warm pool in boreal winter, instead of being collocated. A high-resolution regional climate model is used to investigate the mechanism for this displaced ITCZ. Under the observed sea surface temperature (SST) and lateral boundary forcing, the model reproduces the salient features of eastern Pacific c...

An unusually intense sea surface temperature drop (DSST) of about 10.88C induced by the Typhoon KaiTak is observed in the northern South China Sea (SCS) in July 2000. Observational and high-resolution SCS model analyses were carried out to study the favorable conditions and relevant physical processes that cause the intense surface cooling by Kai-Tak. Upwelling and entrainment induced by Kai-Ta...

The purpose of this paper is to improve the accuracy of the COMFA outdoor thermal comfort model for application to subjects performing physical activity. A sensitivity analysis was performed to identify conditions where the COMFA model produced erroneous estimates of the heat and moisture exchanges between the human body and the ambient environment, based on data from subjects performing modera...

We present the application of interactive threedimensional (3-D) visualization of ensemble weather predictions to forecasting warm conveyor belt situations during aircraft-based atmospheric research campaigns. Motivated by forecast requirements of the T-NAWDEX-Falcon 2012 (THORPEX – North Atlantic Waveguide and Downstream Impact Experiment) campaign, a method to predict 3-D probabilities of the...