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Just a quick message that we’ve revised our manuscript for Reviews of Geophysics, Model hierarchies for understanding atmospheric circulation. In particular, I like our new figure illustrating the web of models around state-of-the-art Atmospheric General Circulation Models (AGCMs). These hierarchies of simpler models enables us to understand and improve our weather and climate prediction systems. 
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While Rome and New York receive the same amount of energy from the sun (being situated at the same latitude), the former experiences a much warmer climate, particularly in the winter months. This is due to large variations in the atmospheric flow with longitude, known as “stationary waves”. It has long been known that these variations are generated by differences between land and sea, topography, and variations in sea surface temperatures. But just how do these different components add up to produce our climate?
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The whole group is hitting the road. Check out talks in Boulder, Palo Alto, and uptown, to be helf over the next couple weeks!
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Coming to the AMS Annual Meeting in Phoenix next week (6-10 January)? Check out these presentations!
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Please see our paper Quantifying the variability of the annular modes: Reanalysis uncertainty vs. sampling uncertainty, just accepted in Atmospheric Chemistry and Physics. Patrick Martineau and I show that reanalyses have gotten quite good, and we are chiefly limited by the finite length of the observational records. In this sense, we are starved for data, not model physics!
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Deterministic weather forecast are only possible for one to two weeks. (Or in other words, we just can’t predict whether it will be sunny or rainy 14 days from now.) But can we say something about the weather over the next few weeks, for example, will it be warmer and drier than average, even if we can’t say exactly which days will be sunny?
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Why do some Sudden Stratospheric Warmings appear to influence the troposphere, shifting the jet stream equatorward over the next 2-3 months, while others don’t? Much of the issue is tropospheric variability, which can overwhelm the influence of the stratosphere. However, our recent study, The Downward Influence of Sudden Stratospheric Warmings: Association with Tropospheric Precursors shows that there are regional patterns that can help us predict whether a Sudden Warming is more likely to have an influence on the troposphere!
