Status of Societal and Economic Research and Applications (SERA) for weather and climate information in Mexico
J.L. Vazquez-Aguirre and J. Cervantes-Perez

Recent activities by the World Weather Research Programme and THORPEX led to propose a framework for Societal and Economic Research and Applications (SERA) of weather and climate information (Morss et al., 2007, BAMS). Five areas emerged for further research and applications: a) Understanding the use of forecast information in decision-making; b) communication of forecast uncertainty; c) user-relevant verification of forecasts; d) economic valuation of forecasts and e) development of decision support systems and tools. This poster summarizes some aspects related to observed high-impact weather, availability of weather forecasts and the work conducted with user communities, for the case of Mexico. Use and perception of weather forecasts are depicted from an electronic survey conducted at the end of winter 2008-2009 through the National Meteorological Service (SMN) webpage.

Identifying changing climate responses of boreal forest trees in northwestern Canada
J. Barichivich, K. Briffa, K.J. Anchukaitis, D. Sauchyn, and T. Melvin

Tree growth at high northern latitudes has provided a detailed history of extra-tropical Northern Hemisphere temperature variability over most of the last millennium. Contrary to what might have been expected, recent tree growth in some circumpolar locations does not appear to be tracking the strong warming trend of the past few decades. This apparent sensitivity change in tree growth has been described as the "divergence problem". It has important implications for the interpretation of paleoclimatic reconstructions based on treerings and for the global carbon cycle. There is no consensus on the causes or if the problem is real or is just an statistical artifact of tree-ring methods.

Assessment of Atmosphere-Ocean General Circulation Model Simulations of Northern Hemisphere Atmospheric Blocking
J. Vial and T. Osborn

Atmospheric blocking are large-scale, quasi-stationary and persistent anticyclones that block or deflect the progression of transient smaller-scale weather systems. They are often responsible for temperature and rainfall anomalies, and sometimes lead to extreme weather events. In summer 2003, a heat wave developed during a strong and persistent blocking high located over western Europe. This event caused the death of 35.000 people, an economic loss of several million Euros mainly due to a deficit in agricultural production, and severe environmental damage such as forest fires due to extremely high temperatures (De Bono et al., 2004). The ability of six coupled atmosphere-ocean general circulation models (AOGCM) to simulate the frequency and the duration of atmospheric blocking in the Northern Hemisphere is assessed. It will contribute to increase our understanding of the mechanisms responsible for the formation and the maintenance of atmospheric blocking, and its impact on extreme weather events. It will also help to indicate the confidence that we have in future projections of extreme weather events that are often the product of large-scale weather regimes such as blocking.