Modeling rainfall diurnal variation of Northern American monsoon core using different spatial resolution

By analyzing the North American Monson Experiment (NAME) Enhanced Raingauge Network (NERN) data, Gochis et al (2003) found that monsoon core rainfall timing and intensity varied with the height of elevation over western Mexico. In this study, we use mesoscale model PNN STATE/NCAR MM5 with different spatial resolutions to simulate the observed rainfall diurnal variations. The result from 25- km spatial resolution indicates that the model can reproduce the rainfall diurnal variation over high-elevated area. However, modeled rainfall peak and time has 2-3 hour earlier than that from NERN data. Further, the model under-represented the rainfall diurnal variation over low-elevation area. The result from 3-km resolution shows that the rainfall diurnal variation over low-elevation area was reasonably represented. Finally, using the model output from 3-km resolution, the possible mechanism of the diurnal variation over this area was investigated.