2.1.2 Wind
The wind used for this study is a climatology computed from the CFSR,
the same wind used to force the HyCOM simulations described in 2.1.1.
This reanalysis is a fully coupled model representing the interaction
between the atmosphere, oceans, land, and sea ice, described by Saha et
al. (2010). The CFSR assimilates in situ and satellite
observations using sigma–pressure hybrid vertical coordinates, a
simplified Arakawa–Schubert convection scheme with momentum mixing
(Hong & Pan, 1996, 1998; Pan & Wu, 1995), and orographic gravity wave
drag (Alpert et al., 1988, 1996; Young-Joon Kim & Arakawa, 1995). The
land surface model is based on the two-layer OSU land model (H. L. Pan
& Mahrt, 1987), the SW radiation is parameterized following the NASA
approach (Chou et al., 1998; Hou et al., 2002), and the LW radiation
following the GFDL approach (Fels & Schwarzkopf, 1975; Schwarzkopf &
Fels, 1991), based on the RRTM developed at AER (Taubman et al., 1997).
CFSR is coupled to a four-layer Noah land surface model (Ek et al.,
2003) and a two-layer sea ice model (Wu et al., 2005). The temporal data
resolution is 1 hour, with a spatial resolution of 0.5°. We used the
zonal (u -component) and meridional (v -component) wind 10 m
above the surface from the CFSRv1 and CFSRv2 reanalysis data. To ensure
consistency, we also calculated daily means for the wind data and
interpolated them onto the current data grid to create the 25-year
climatology. For interpolation, we employed the Modified Akima cubic
Hermite interpolation method. This approach utilizes a piecewise
function of polynomials, with a maximum degree of three, to interpolate
the values of neighboring grid points in each dimension. Specifically,
the method employs local data information to generate a continuous curve
that passes through the given data points while minimizing the curvature
in the resulting interpolated function.