The tenth IMSC, Beijing, China, 2007 - International Meetings on ...

transform the logarithm to reduce the herteroskedasticity, and then to repeat the step (1) until
they pass through ARCH test and stationary test, (3) to determine the component of the prime
period by periodogram analysis, and to put forward three kinds of tests to determine
significance level of the prime period. According to the new model, the naturalized streamflows
from 1784 to 1997, from Alaer and Xinquman gaging Station are analyzed respectively. When
reducing their herteroskedasticity, AR(4) Model and AR(2) Model are developed respectively.
It is concluded that the naturalized streamflows in the two stations have the same cryptic
period of 42.7 years.
Examining the Oceanic Fresh Water Flux in the NCEP Reanalyses and Global Models
Pingping Xie
NOAA Climate Prediction Center
Pingping.Xie@noaa.gov
John E. Janowiak
NOAA Climate Prediction Center
Mingyue Chen
NOAA Climate Prediction Center
C.-L. Shie
UMBC/Goddard Earth Sciences and Technology Center
L. Chiu
GMU / Center for Earth Sciences and Space Research
Seasonal and interannual variations of global oceanic precipitation and evaporation
generated by the NCEP CDAS, CDAS2, GDAS, GFS AMIP runs, and the CFS coupled
simulations have been examined and compared with those of the observations from CMAP
and GSSTF2. In general, large-scale distribution and seasonal variation patterns of global
oceanic precipitation, evaporation and fresh water flux are relatively well re-produced by the
NCEP reanalyses and the climate models. Systematic differences, however, are observed in
the magnitude of the precipitation and evaporation compared to the CMAP and GSSTF2. For
instance, both the precipitation and the evaporation in the CDAS2 are over-produced, while
their differences (fresh water flux) are in general agreement with the observations over tropical
and sub-tropical oceans. Interannual variability of precipitation and evaporation associated
with the ENSO, NAO, AO and PNA is reasonably well captured in the reanalyses and model
simulations examined here. Quantitative agreements between the reanalyses and the
observations, however, are less desirable, especially over tropical oceans. Monthly anomaly
correlation between the NCEP reanalysis 2 (CDAS2) and observation is less than 0.4 for both
precipitation and evaporation over most of the global tropical oceanic regions. Further work is
underway to examine the surface wind, temperature, humidity and other related atmospheric
and oceanic fields to better understand the differences with the observations and among the
reanalyses and model simulations.
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