Feasibility Comparison of Reanalysis Data from NCEP-Ⅰand NCEP-Ⅱ in the Himalayas

Mt. Everest is often referred to as the earth's 'third' pole. As such it is relatively inaccessible and little is known about its meteorology. In 2005, an automatic weather station was operated at North Col (28°01' 0.95" N, 86°57' 48.4" E, 6523 m a.s.l.) of Mt. Everest. Based on the observational data, this paper compares the reanalysis data from NCEP/NCAR (hereafter NCEP-Ⅰ) and NCEP-DOE AMIP-Ⅱ (NCEP-Ⅱ), in order to understand which reanalysis data are more suitable for the high Himalayas with Mt. Everest region. When comparing with those from the other levels, pressure interpolated from 500 hPa level is closer to the observation and can capture more synoptic-scale variability, which may be due to the very complex topography around Mr. Everest and the intricately complicated orographic land-atmosphere-ocean interactions. The interpolation from both NCEP-Ⅰ and NCEP-Ⅱ daily minimum temperature and daily mean pressure can capture most synoptic-scale variability (r>0.82, n=83, p<0.001). However,there is difference between NCEP-Ⅰ and NCEP-Ⅱ reanalysis data because of different model parameterization. Comparing with the observation, the magnitude of variability was underestimated by 34.1%, 28.5 % and 27.1% for NCEP-Ⅰ temperature and pressure, and NCEP-Ⅱ pressure, respectively, while overestimated by 44.5 % for NCEP-Ⅱ temperature. For weather events interpolated from the reanalyzed data, NCEP-Ⅰ and NCEP-Ⅱ show the same features that weather events interpolated from pressure appear at the same day as those from the observation, and some events occur one day ahead, while most weather events interpolated from NCEP-Ⅰ and NCEP-Ⅱ temperature happen one day ahead of those from the observation, which is much important for the study on meteorology and climate changes in the region, and is very valuable from the view of improving the safety of climbers who attempt to climb Mt. Everest.