Data
This contribution is mainly based on the daily data (digital maps) of the SLA
(DT-Global-MSLA-Upd product) with a grid of 1
◦
̸ 4 × 1
◦
̸ 4, which is produced by
the French CLS (Collected Localization Satellites) agency using satellite altimetry
observations. The data are available in the Internet (DT Global-MADT-Upd product, http://www.aviso.altimetry.fr). Each daily map corresponds to 00:00 GMT. In
addition to these data, the data on the Formal Mapping Error (FME) and Absolute
Dynamic Topography (ADT) (DT-Global-MADT-Upd product) published by the
CLS agency with the same resolution were also used. The FME characterizes the
accuracy of satellite measurements and the mathematical self-evaluation of
the procedure for interpolating data from satellite tracks onto the ocean surface in
space and time. The ADT data are the sum of the SLA and the mean ADT version
of CNES-CLS13 produced by the CLS Space Oceanography Division and distributed by AVISO, with support from CNES (http://www.aviso.altimetry.fr/) [15].
The data on ADT, SLA, and FME are given in centimeters.
The analysis was carried out for the tracks of a number of hydrographic sections
occupied from one continental slope to the other in the era of the altimetric
observations of the ocean surface. These are quasi-zonal sections AR05 and A05 in
the North Atlantic, the tracks of which pass nominally along 60° N and 25° N,
sections P02 along 30° N in the Pacific, as well as sections carried out in the
Southern Hemisphere, nominally along 30° S: A10 in the Atlantic, I05 in the
Indian, and P06 in the Pacific. In the Southern Ocean the following tracks of
quasi-meridional sections in different sectors of the ocean were analyzed: SR01,
A21 and a series of the Russian sections in the Drake Passage, SR02 and I06 in the
region south of Africa, I09, SR03, P11A south of Australia, and P19 in the
southeastern sector of the Pacific Ocean. More detailed information about these
sections and their locations are given in Table 1 and Fig. 1. The WOCE and
CLIVAR data are available at https://cchdo.ucsd.edu.
The bottom relief along the hydrographic section lines was determined from the
data of the digital array of the bottom topography [17], V.18.1 (http://topex.ucsd.
edu/cgi-bin/get_data.cgi). The resolution of the array is 1/cosφ of angular minutes
by latitude and 1 minute by longitude; φ is the latitude.
Method of Processing
The nonstationarity of the current field in combination with the non-simultaneity of
measurements over the section leads to a distorted pattern of the field of currents
recovered from these data. The ADCP-measurements of instantaneous velocity
profiles at the ocean surface at specific points are actually equivalent to the measuring of instantaneous sea level gradients at these points. The level difference thus
accumulated along the line of the section differs from the real one because of the
Influence of the Current Field Non-stationarity …
363
This contribution is mainly based on the daily data (digital maps) of the SLA
(DT-Global-MSLA-Upd product) with a grid of 1
◦
̸ 4 × 1
◦
̸ 4, which is produced by
the French CLS (Collected Localization Satellites) agency using satellite altimetry
observations. The data are available in the Internet (DT Global-MADT-Upd product, http://www.aviso.altimetry.fr). Each daily map corresponds to 00:00 GMT. In
addition to these data, the data on the Formal Mapping Error (FME) and Absolute
Dynamic Topography (ADT) (DT-Global-MADT-Upd product) published by the
CLS agency with the same resolution were also used. The FME characterizes the
accuracy of satellite measurements and the mathematical self-evaluation of
the procedure for interpolating data from satellite tracks onto the ocean surface in
space and time. The ADT data are the sum of the SLA and the mean ADT version
of CNES-CLS13 produced by the CLS Space Oceanography Division and distributed by AVISO, with support from CNES (http://www.aviso.altimetry.fr/) [15].
The data on ADT, SLA, and FME are given in centimeters.
The analysis was carried out for the tracks of a number of hydrographic sections
occupied from one continental slope to the other in the era of the altimetric
observations of the ocean surface. These are quasi-zonal sections AR05 and A05 in
the North Atlantic, the tracks of which pass nominally along 60° N and 25° N,
sections P02 along 30° N in the Pacific, as well as sections carried out in the
Southern Hemisphere, nominally along 30° S: A10 in the Atlantic, I05 in the
Indian, and P06 in the Pacific. In the Southern Ocean the following tracks of
quasi-meridional sections in different sectors of the ocean were analyzed: SR01,
A21 and a series of the Russian sections in the Drake Passage, SR02 and I06 in the
region south of Africa, I09, SR03, P11A south of Australia, and P19 in the
southeastern sector of the Pacific Ocean. More detailed information about these
sections and their locations are given in Table 1 and Fig. 1. The WOCE and
CLIVAR data are available at https://cchdo.ucsd.edu.
The bottom relief along the hydrographic section lines was determined from the
data of the digital array of the bottom topography [17], V.18.1 (http://topex.ucsd.
edu/cgi-bin/get_data.cgi). The resolution of the array is 1/cosφ of angular minutes
by latitude and 1 minute by longitude; φ is the latitude.
Method of Processing
The nonstationarity of the current field in combination with the non-simultaneity of
measurements over the section leads to a distorted pattern of the field of currents
recovered from these data. The ADCP-measurements of instantaneous velocity
profiles at the ocean surface at specific points are actually equivalent to the measuring of instantaneous sea level gradients at these points. The level difference thus
accumulated along the line of the section differs from the real one because of the
Influence of the Current Field Non-stationarity …
363