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Holm, E., R. Forbes, S. Lang, L. Magnusson, and S. Malardel, 2016:
New model cycle brings higher resolution. Newsletter No. 147 -
Spring 2016, ECMWF, 6 pp., URL:
http://www.ecmwf.int/sites/default/files/elibrary/2016/16299-newsletter-no147-spring-2016.pdf.
Siemen, S., I. Russell, T. Quintino, and D. Varela Santoalla, 2015:
Software updates in preparation for model cycle 41r2. Newsletter No.
146 - Winter 2015/16, ECMWF, 1 pp., URL:
http://www.ecmwf.int/sites/default/files/elibrary/2016/15041-newsletter-no-146-winter-201516.pdf.
Malardel, S., N. Wedi, W. Deconinck, M. Diamantakis, C. Kuhnlein, G.
Mozdzynski, M. Hamrud, and P. Smolarkiewicz, 2015: A new grid for
the IFS. Newsletter No. 146 - Winter 2015/16, ECMWF, 6 pp., URL:
http://www.ecmwf.int/sites/default/files/elibrary/2016/15041-newsletter-no-146-winter-201516.pdf.
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ECMWF has implemented a significant resolution upgrade and
methodology for high-resolution forecasts (HRES) and ensemble
forecasts (ENS) beginning January of 2016. HRES is now performed via
a transform grid with a nominal grid point spacing of 9 kilometers
(0.08 degrees), and is carried out with IFS (Integrated Forecast
System) model cycle CY41r2. Improvements in computational efficiency
and effective resolution have been brought about by implementing a
triangular cubic octahedral reduced Gaussian grid in which the
shortest spatial wavelength is represented by at least four grid
points anywhere on the globe, as opposed to the former linear
arrangement whereby the shortest wavelength was represented by two
grid points, while at the same time retaining the same number of
spherical harmonics and triangular truncation. (The term "cubic" is
due to the ability of the grid to represent cubic products in the
dynamical equations.) In addition, the reduction of grid points
along latitude circles as one approaches the poles is achieved using
a triangular to octahedral mapping which corresponds to a poleward
reduction of four points per latitude circle and an optimization of
the total number of grid points and their local mesh resolution.
Based on IFS CY41r2, ECMWF has documented superior filtering
properties at higher resolution, an improved representation of
orography, improved global mass conservation properties, substantial
efficiency gains, and more scalable locally compact computations of
derivatives and other properties that depend on nearest-neighbor
information only. More details may be found in the publications
cited below and the documentation tab at the top of the dataset home
page (to be added).
NCAR's Data Support Section (DSS) is performing and supplying a
grid transformed version of ERA-Interim, in which variables
originally represented as spectral coefficients or archived on a
reduced Gaussian grid are transformed to a regular 5120 longitude by
2560 latitude N1280 Gaussian grid. In addition, DSS is also
computing horizontal winds (u-component, v-component) from spectral
vorticity and divergence where these are available.
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