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Modeling North American Extreme Temperature Events and Patterns

Paper Reviewed
Grotjahn, R., Black, R., Leung, R., Wehner, M.F., Barlow, M, Bosilovich, M., Gershunov, M.F., Barlow, M., Bosilovich, M., Gershunov, A., Gutowski Jr., W.J., Gyakum, J.R., Katz, R.W., Lee, Y.-Y., Lim, Y.-K. and Prabhat. 2016. North American extreme temperature events and related large scale meteorological patterns: a review of statistical methods, dynamics, modeling, and trends. Climate Dynamics 46: 1151-1184./

The chief objective of the ten authors of this Climate Dynamics paper (Grotjahn et al., 2016) was "to review statistical methods, dynamics, modeling efforts, and trends related to temperature extremes, with a focus upon extreme events of short duration that affect parts of North America" and that are also "associated with large scale meteorological patterns (LSMPs)." So how have the world's climate modelers fared in this regard?

Grotjahn et al. report that "generally, climate models capture observed properties of heat waves and cold air outbreaks with some fidelity," but they add that they (1) "overestimate warm wave frequency" and (2) "underestimate cold air outbreak frequency," as well as (3) "the collective influence of low-frequency modes on temperature extremes." And they go on to add that (4) "even though LSMPs are resolvable by global and regional climate models, they are not necessarily well simulated."

In concluding their report, therefore, the 13 researchers note that "the studies that form the basis of the IPCC AR5 reports and the 3rd U.S. National Climate Assessment do not consider the role of LSMPs in the [5] magnitude and [6] trends of extreme temperatures," while also adding that future such assessments, particularly at the regional scale, "must include the connection between LSMPs and extreme temperature events [ETEs]." And having not yet made this connection, they conclude that (7) "much work" remains to be done in order "to understand better past and future occurrences of ETEs and their underlying physical causes."

So hope for the best, folks. But don't hold your breath!

Posted 8 September 2016