地球惑星科学専攻 地球科学輻合部特別講演会
 
日時: 2011年6月17日(金) 16:00〜18:00
場所: 京都大学理学部1号館5階563号室
 
【１】
講演１題名：
The Experimental Regional Seasonal Ensemble Forecast at NCEP
 
講演者１：
Dr. Hann-Ming Henry Juang (Environmental Modeling Center, NOAA/NCEP)
 
講演１要旨：
For the past years, the experimental regional seasonal ensemble forecast
(RSEF) at NCEP by using regional spectral model has been conducted under the
support from NOAA funds. The main idea is to downscale from the NCEP CFS
(Couple climate forecast system) over USA to examine the capability of the
regional ensemble forecast for seasonal predictions, at the same time to
provide downscaling data for fire danger seasonal prediction. Due to the
resources limitation, a reduced set of model run with limited ensemble size
and domain coverage only over CONUS is performed once in a month since 2003.

Using this data set from this single model RSEF, including hindcast since
1982 up to now, we can have preliminary idea of possible capability and/or
predictability of RSEF over CONUS. The statistical results from this
long-term data set will be presented. The predictabilities of season,
initial condition, diurnal cycle and different regions over CONUS will be
investigated.  In addition to present the results from the experimental
monthly RSEF, several sensitivities of limited sets of RSEF have performed
to examine the predictabilities of single model RSEF, such as boundary
conditions, bias correction, and ensemble sizes. Finally, all other
possibilities of configuration to improve RSEF will be discussed. Some
results from most current project will be presented as well.

 
【２】
講演２題名：
Advection of smooth and non-smooth tracers with spectral bicubic interpolation
 
講演者２：
Dr. Takeshi Enomoto (Disaster Prevention Research Institute, Kyoto U.)
 
講演２要旨：
Spectral bicubic interpolation (Enomoto 2008) is a simple and accurate
scheme that uses the derivatives calculated from spectral coefficients in
bicubic interpolation. It is intended for applications in spectral models
traditionally used in general circulation models for numerical weather
prediction (NWP) and climate simulations. In such models the derivatives are
trivially obtained. The longitudinal, latitudinal and cross derivatives are
used in addition to the grid point values at the four corners of the cell.
Since bicubic interpolation is local, no halo points are required for
interpolation except for grid points beyond the poles. Dissipation, inherent
in semi-Lagrangian advection, is very small with this scheme.

Enomoto (2008) has shown excellent accuracy of the scheme for smooth tracers
by performing the test of Ritchie (1987). In this study the scheme is
validated by the challenging tests that include non-smooth fields (Lauritzen
and Skamarock 2010). The proposed scheme is compared with the quasi-cubic
interpolation, which is a combination of one-dimensional linear and cubic
interpolation (Ritchie et al. 1995) commonly used in NWP. In general
spectral bicubic interpolation produces smaller error than quasi cubic
interpolation. For example, the edge of the slotted cylinders is sharper and
overshoots around the correlated cosine bells are reduced. The selective
quasi-monotone filter (Sun et al. 1996) effectively removes most of
short-wave noise.
The fixer of Sun and Sun (2004) is used to conserve global mass. The filter
and fixer degrade the accuracy very little and require negligible
computational cost.

References :
      Enomoto, T., 2008: SOLA, 4, 5--8, doi: 10.2151/sola.2008-002.
      Lauritzen, P. H. and W. Skamarock, 2010: available from
http://www.cgd.ucar.edu/cms/pel/tracer-workshop.html
      Ritchie, H., 1987: MWR, 115, 608--619.
      Ritchie, H. et al., 1995: MWR, 123, 489--514.
      Sun W.-Y. and Sun M.-T., 2004: MWR, 132, 975--984
      Sun W.-Y. et al., 1996: QJRMS, 122, 1211--1226. 
 
 
問い合わせ先：
余田 成男