Climate Dynamics

Researchers at Atmospheric and Environmental Research (AER) are advancing the worldwide scientific community’s understanding of large-scale climate dynamics on seasonal to interannual time scales and the application of this research for climate prediction.

Climate variability

AER efforts to diagnose the general circulation are concerned with quantifying the changing heating processes that drive the atmosphere' s energy cycle. We study signals in the large-scale atmosphere, like the role of climate modes on timescales from subseasonal to interannual. Diagnosing climate fluctuations extends to extracting signals in atmospheric variability driven by forcings like snow cover variability, volcanic aerosol loading, urban warming, and greenhouse gas increases. We’re studying how the climate is becoming more variable and why.

Regional climate fluctuations

We analyze the climate of specific regions and determine how a variety of models best describe those regional climate fluctuations including hydrological variability. For example, we’ve determined which climate models best describe the hydrology of the Southwest U.S. and the convergence of moisture that increases midsummer rainfall, a climate signal known as the North American monsoon.

Climate dynamics impacting weather forecasting

We are also interested in the dynamic workings of the atmosphere, for example, relating seasonal precipitation to the internal structure of the atmosphere that might change from year to year. Applying these concepts to seasonal forecasting, we’ve shown how large-scale climate signals affect weather over specific regions, particularly during extreme periods, such as drought.

Seasonal forecast innovations improve accuracy

Our research has enabled us to develop, and confirm through peer review, the most accurate winter seasonal forecast in the world. Our scientists improved the accuracy of winter seasonal forecasts for the Northern Hemisphere by introducing a new predictor for winter climate in the temperate regions: autumn snow cover. Our Ph.D. meteorologists demonstrated the high correlation between autumn snow cover in northern Asia (Siberia) with winter temperatures across the North America, Northern Europe and Asia. The robustness of our methods has been confirmed through peer reviewed numerical experiments as well as observational analysis. The method is being tested by leading forecast organizations.

As a result, our model can predict the phase and amplitude of the Arctic Oscillation (AO), also called North Atlantic Oscillation (NAO), which is the dominant predictor of Northern Hemisphere winter climate variability. Because the AO/NAO is the single most highly correlated atmospheric index with winter surface temperatures across the North Hemisphere, AER’s successful prediction of the AO/NAO is possibly the most important recent achievement in worldwide climate prediction.

For well over ten years, models based on our research have been used to provide real-time long range and seasonal forecasts to commercial markets. Our seasonal forecasts have performed considerably better than those forecasts that are solely dependent on ocean temperatures.

In recognition of the contribution to improved understanding of climate variability and the success of the seasonal forecasts, National Science Foundation (NSF) has highlighted our accomplishments in the “Predicting Seasonal Weather” special report on their website.

Hurricane forecasting and analysis

AER experts in tropical meteorology have extensive experience developing and applying numerical modeling and data assimilation codes to simulations and forecasting of tropical cyclones. Some recent examples include mesoscale hurricane simulations, and the use of scatterometer data in the ECMWF’s forecasts of tropical cyclones.

Our hurricane research coupled with operational services conducted for governments and businesses include an array of tropical cyclone probabilistic forecasts, improving early warning timeframes to reduce hurricane risk and speed response, and support for decision-making and best practices.

Climate dynamics, ocean surface and sea ice

AER scientists are studying other elements of the climate system, including the oceans and sea-ice and how air-sea fluxes can impact our climate. As part of several ocean research projects, AER investigators are contributing to the understanding of the oceanic meridional overturning circulation variability and its influence on the Earth's heat balance, the relation between the oceanic heat transports and sea surface temperature acting as a boundary forcing for the atmosphere, and the effects of sea ice on surface salinity and climate dynamics of the North Atlantic sector.

Climate change research

We continue to study hemispheric, and even global, climate trends and climate change. AER’s studies are particularly relevant to the debate on the role of natural variability versus anthropogenic forcing in global warming. If global warming can be shown to be strongly dependent on a natural mode of the atmosphere, it obscures its attribution to anthropogenic forcing. AER results to date do not support claims that the major mode of atmospheric variability is in a robust positive trend, or that it is contributing in a consistent manner to the global warming trend.

To learn more about AER's Climate Dynamics expertise, please contact us.