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The various Climatologies to compute PIRATA anomalies
and to grid PIRATA data are briefly described below.
For information on how we grid PIRATA data, see the
Latitude-Time Gridding
and
Time-Logitude Gridding
web pages.
Reynolds and Smith AOI SST Climatology (1971 - 2000)
The AOI SST climatology is an optimum interpolation analysis of
Sea Surface Temperature with an adjusted base period of 1971 to 2000,
on a global 1 degree by 1 degree by 1 month grid. As of July 23 2002
we have begun using the latest version of the Reynolds and Smith
climatology, which formerly had a base period of 1961-1990.
Differences between these climatologies are generally small in
the tropics, usually below 0.2°C.
For further information, please see:
Smith, T. M. and R. W. Reynolds, 1998: A high resolution global sea
surface temperature climatology for the 1961-90 base period. J.
Climate, 11, 3320-3323.
Xue, Y., T.M. Smith and R.W. Reynolds, 2002: A new SST
climatology for the 1971-2000 base period and interdecadal
changes of 30-year SST normals. J. Climate in revision.
World Ocean Atlas Subsurface Temperature Climatology
The World Ocean Atlas (See Conkright et al 2002:
"World Ocean Atlas 2001: Objective Analyses, Data Statistics,
and Figures, CD Rom Documentation", US Dept. of Commerce) temperature
climatology is used to compute temperature anomalies in the Tropical
Atlantic.
COADS Winds (1946 - 1989)
The COADS climatologies of Zonal and Meridional Wind,
Scalar Wind Speed, and Wind Direction,
are used for computing Wind anomalies, and for gridding
Zonal and Meridional Winds and Scalar Wind Speed in the
Latitude-Time section plots. For example plots of
TAO Winds and their anomalies see the
TAO/TRITON Data Display page.
COADS Relative Humidity (1946 - 1989)
The Relative Humidity (RH)
climatology was derived from the COADS Specific
Humidity (SH) climatology.
The SH climatology was
converted to RH using a routine written by Ms.
Margie McCarty at NOAA/PMEL, which takes as input
SH, pressure, and Air Temperature.
This climatology is used for computing RH
anomalies, and for gridding RH
in the Latitude-Longitude Maps and Latitude-Time section plots. For example plots
of RH see the "Assorted Plots" on the
TAO/TRITON Data Display page.
COADS Sea Level Barometric Pressure (1946 - 1989)
The Sea Level Pressure (SLP) climatology is used for computing SLP
anomalies, and for gridding SLP in the Latitude-Time section
plots.
20°C Isotherm Depth
The 20°C Isotherm Depth climatology was computed from the
World Ocean Atlas subsurface temperature climatology (see above),
by linear interpolation of depth versus temperature.
This climatology is used for computing 20 degree C Isotherm depth
anomalies, and for gridding 20 C depths
in the Latitude-Longitude Maps and Latitude-Time section plots. For example plots
of 20C Depth see the
TAO/TRITON Data Display page.
Dynamic Height
The Dynamic Height climatology was computed from the
World Ocean Atlas subsurface temperature climatology (see above), by
vertically integrating the specific volume anomaly
using a set of long-term mean temperature-salinity
relations, one for each grid location, derived from
the "World Ocean Atlas 2001" (See Conkright et al 2002:
"World Ocean Atlas 2001: Objective Analyses, Data Statistics,
and Figures, CD Rom Documentation", US Dept. of Commerce)
This climatology is used to compute Dynamic Height
anomalies, and for gridding Dynamic Heights
in the Latitude-Longitude Maps and Latitude-Time section plots. For example plots
of Dynamic Height see the
TAO/TRITON Data Display page.
Salinity and Sigma-Theta
The World Ocean Atlas climatologies (See Conkright et al 2002:
"World Ocean Atlas 2001: Objective Analyses, Data Statistics,
and Figures, CD Rom Documentation", US Dept. of Commerce)
include salinity and temperature. The salinity climatology is used
to compute salinity anomalies. The salinity and temperature
climatologies are used to compute a climatology of sigma-theta,
which is used to compute sigma-theta anomalies. Sigma-theta is
computed as follows:
Salinity is combined with potential temperature computed
from the World Ocean Atlas temperature climatology
to compute the potential density anomaly (sigma-theta)
defined as sigma-theta = 1/V(S,Theta,P) -1000 kg m-3
where V is specific volume, S is salinity, Theta is potential
temperature and P is set to zero. The algorithms used in these
calculations are from "Algorithms for computation of fundamental
properties of seawater" by Fofonoff and Millard (UNESCO technical
papers in marine science, 44, 1983).
Shortwave Radiation (1945-1989)
The shortwave solar radiation climatology from the "ATLAS of
Surface Marine Data" (da Silva et al, 1994) is used to
compute anomalies.
Longwave Radiation (1945-1989)
The outgoing longwave radiation climatology from the "ATLAS of
Surface Marine Data" (da Silva et al, 1994) is used to
compute anomalies.
Xie and Arkin Precipitation Climatology (1979 - 1995)
The precipitation climatology from Xie and Arkin (1997)
is used to compute anomalies.
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