FS2004 – 50 North Simulations 737-30 [CRACKED]


FS2004 – 50 North Simulations 737-30

the seasonal evolution of the water yield for the reference condition of the cmip5 models and from nldas-uw are examined for the 11 nam models. as the cmip5 models more closely resemble observations in both the mean and spread, we also include nldas-uw (hofstra et al. 2013) for context (fig. 15). the water yield from nldas-uw is concentrated in may and june in the southwestern united states, whereas the models overpredict the daily and monthly water yields by roughly 2%20% (fig. 16 and table 12). the models overpredict the water yield in winter and, to a lesser extent, in spring. the winter overprediction in the nldas-uw water yield is not clear from the figure, but the mean model overprediction in fig. 16 is estimated to be ~50%70% (table 12). using a standard z-score scaling (table 12), the models have mean values of z-score of zspi6-uw=-0.06, zswb-uw=-0.00. while the z-scores for the nam water yield (nldas-uw) imply substantial overprediction, the values for the great plains are more modest and suggest a slight underprediction of the models. the positive z-scores for swb and spi6 are consistent with the wide spread of cpc-unified water yields (fig. 16a). the canesm2, hadcm3, and hadgem2-es models are relatively closer to observations (table 12). however, both of these models have been tested with limited spatiotemporal resolution and may result in enhanced model behavior for climatology when trying to apply to global models.

the relationship of water yield to surface evapotation is examined for figure 16 and nam models (fig. 15). the cmip5 models and nldas-uw overpredict the nam water yields, and the nam models tend to reflect nldas-uw. the reason for overprediction is examined in fig.

figure 17 shows the same results as fig. 16 but for the cmip5 high-resolution simulations (1000-m resolution). the mean meridional wind at the equator is only slightly weaker in the simulations compared to the reanalysis ( fig. 17a ), but there is a significant difference in the meridional wind at the poles ( figs. 17b, 17c ). these differences are likely related to the differences between the models and the reanalysis noted above. models tend to have peak wind at higher latitudes, which may be related to either the poor representation of the dynamical system along with poor grid resolution, or the different parameterizations. this is the first time that the divergent nature of the wind is shown by examining multiple model results, which is also related to the dynamical system of the atmosphere. the cmip5 simulations again show strong southerly wind in the great plains in early july, but from mid-may to late july, the circulation is anticyclonic. this is in contrast to the reanalysis result, which shows an example of a cyclonic summer circulation in the great plains.
we use data from multiple model simulations of the historical scenario from the cmip5 database. the cmip5 experiments were carried out by 20 modeling groups representing more than 50 climate models with the aim of further understanding past and future climate change in key areas of uncertainty ( taylor et al. 2012 ). in particular, experiments have been focused on understanding model differences in clouds and carbon feedbacks, quantifying decadal climate predictability and why models give different answers when driven by the same forcings. the cmip5 builds on the previous phase [phase 3 of cmip (cmip3)] experiments in several ways. first, a greater number of modeling centers and models have participated. second, the models are more comprehensive in terms of the processes that they represent and are run at higher spatial resolution, therefore hopefully resulting in better skill in representing current climate conditions and reducing uncertainty in future projections. table 1 provides an overview of the models used. the specific models used vary for each individual analysis because of data availability at the time of this study, and so the model names are provided within the results section where appropriate.



Posted by benqui