U23A-01
The North American Monsoon Experiment (NAME): Past Progress and Future Endeavors
In 2007, the North American Monsoon Experiment (NAME) entered into its seventh year of coordinated research and modeling activities. Through intensive observational efforts, diagnostic analyses and modeling research much has been learned regarding the structure evolution and variability of the North American Monsoon system. This overview talk will summarize the major programmatic milestones that have been accomplished to date. These milestones include the design and execution of a large, coordinated field program during the summer of 2004, a multi-institutional model assessment project, and the enhancement of the regional climate observing system in southwestern North America. An outline of new programmatic goals and activities will also be presented.
U23A-02
A 2100-Year Reconstruction of July Rainfall Over Westcentral New Mexico
We have developed a new 2,141-year long tree-ring chronology of latewood (LW) width from ancient Douglas-fir (Pseudotsuga menziesii) and ponderosa pine (Pinus ponderosae) at El Malpais National Monument, New Mexico. This is one of the longest precipitation-sensitive tree-ring chronologies yet constructed for the American Southwest and has been used to develop the first continuous multi-millennial tree-ring reconstruction of July precipitation in the region of the North American Monsoon System (NAMS). Monthly average precipitation increases sharply in July over western New Mexico, marking the dramatic onset to the summer monsoon season. The LW chronology explains 44 percent of the interannual variability of July precipitation in the instrumental record for New Mexico climate divisions 1 and 4 (1960-2004), after removal of the linear dependence of LW width on earlywood width following Meko and Baisan (2001), and has passed statistical tests of verification on independent July precipitation data (1895-1959). The instrumental and tree-ring reconstructed July precipitation data are correlated with the concurrent 500 mb height field over western North America and with the sea surface temperature gradient from the central to eastern North Pacific. The reconstruction exhibits several severe sustained July droughts that exceed any witnessed during the instrumental era, and has significant spectral power at periods near 3-5, 20, and 70 years.
U23A-03
Climate Effects due to Vegetation Changes in Northwest Mexico Under a 2xCO2 Scenario.
Recently IPCC confirmed with a very high confidence level that the global average net effect of anthropogenic activities since preindustrial times has been one of warming. Nonetheless, the anthropogenic activity has not only increased greenhouse gases levels but also that increment is very likely to produce changes in vegetation due to the close relationship between biota and CO2. Thus, this study tries to estimate the climate impact of vegetation changes caused by a 2xCO2 scenario, by looking at 10-yr simulations carried on with the NCAR- CAM3 model. The vegetation changes are calculated based on a USGS report under 2xCO2 conditions, and those changes are introduced into the scheme of CLM3, which is the land model already coupled to CAM3. By performing climate simulations with and without vegetation changes included, this study deduced the climate effects due to the change of vegetation caused by the increasing of CO2. Statistical analyses (with a 95% confidence level) show an increase in winter precipitation of northwest Mexico due to the vegetation changes under 2xCO2 conditions. On the other hand, model simulations show an increase in summer temperatures for the southwestern US due to the same changes in vegetation.
U23A-04
Simulations of the 2004 NAME Field Season by Regional and Global Atmospheric Models: The NAMAP-2 Assessment
The second phase of the NAME Model Assessment Project (NAMAP2) is a coordinated set of atmospheric
simulations of the 2004 North American Monsoon season, associated with the NAME field campaign.
Simulations using prescribed, time-varying SST fields were carried out last year by 6 global models and 4
regional models, implementing a variety of model resolutions and physical parameterizations. Output was saved
in the form of both (a) subdaily time series of horizontal fields of standard meteorological and surface variables in
order to examine the simulated hydroclimatology of Southwest North America, resolving the diurnal cycle; (b) high
resolution time series of full model output in vertical columns colocated with NAME field sites where soundings
were taken, for more detailed analysis of convective processes. An online atlas of NAMAP2 results can be
accessed at: http:rsmas.miami.edu/personal/pkelly/Research.html.
In this presentation we will summarize the results obtained to date and frame what appear to be outstanding
issues in simulating warm season precipitation in complex terrain. NAMAP2 analyses confirm significant
inconsistency among model simulations of the diurnal cycle of precipitation. The biggest component of model
disagreement, especially among the regional models, seems to be in the amount of resolved precipitation
generated by the models. A related disparity among the simulations is the amount of radiatively active cloudiness
generated. The frequency of days with significant precipitation amounts (0.1" or greater) varies widely among
models and available operational precipitation analyses. Special NAME precipitation observations are being
used to provide additional detail on the actual precipitation rates and frequencies in the core monsoon domain.
Model simulations of monsoon onset and analysis of surface flux, surface radiation and soil moisture fields are
being analyzed at present.
http:rsmas.miami.edu/personal/pkelly/Research.html
U23A-05
Impact of Soundings Over Mexico on Regional Analyses
Data impact experiments were carried out to quantify the impact of soundings over Mexico on regional analyses using the Regional Climate Data Assimilation System (RCDAS) for the 2004 NAME Enhanced Observation Period (EOP). The period was chosen because the extensive set of observations and value added products are available for verification. Two experiments were performed and both withheld all soundings over Mexico. The experiment RCDASwt(p) assimilates observed precipitation, and the second experiment RCDASwt(no P) does not assimilate observed precipitation. Results from these experiments are compared with the operational RCDAS during the NAME 2004 EOP. The soundings in general improve the analyses over the areas where the assimilation system has the largest uncertainties and errors. Overall, the biggest impact of soundings can be found over Mexico. While differences at upper levels are small, the differences at lower levels are substantial. The impacts are larger if no precipitation is assimilated. The surface temperature is warmer over the central Mexico without soundings. The difference can be as large as about 1.5 C. Without soundings, there are more vertically integrated moisture convergence anomalies over Mexico. Without P assimilation to correct P, there are large differences in P. Overall, soundings over Mexico improve the quality of analysis over Mexico.
U23A-06
Evolving the linkages between North American Monsoon Experiment research and services in the binational monsoon region
Multi-year drought, high interannual precipitation variability, and rapid population growth present major challenges to water resources and land managers in the U.S. Southwest and binational monsoon region. The NAME strategy to improve warm season precipitation forecasts is paying off in the understanding of the system and its potential predictability, illustrated by a special issue of the Journal of Climate with about 25 articles and numerous other published papers (e.g. Higgins and Gochis et al. 2006; Gutzler et al. 2004, Higgins et al. 2003). NOAA now has set a goal to NAME and other initiatives also have the potential to provide key insights, such as historic information regarding onset and overall strength of the monsoon as it affects stakeholder interests in flooding, soil moisture, vegetation health, and summer water demand. However, the usual avenues for scientific output, such as peer-reviewed publications and web sites designed for use by climate and weather experts, do not adequately support the flow of knowledge to operational decisionmakers. A recent workshop on Monsoon Region climate Applications in Guaymas, Sonora identified several areas in which monsoon science might contribute to reducing societal vulnerability, as well as some research findings that are suited to transition into model development and operations at service providers including NOAA and SMN. They recommended that products are needed that interpret climate forecasts for water resource management applications, and developing new regionally-tailored climate information products. This presentation will discuss how to enhance the flow of monsoon information and predictions to stakeholders by linking user-oriented perspectives with research results from NAME and other programs, including a new effort for a North American Monsoon Forecast Forum which plans to develop periodic consolidated North American Monsoon outlooks.