256
JOURNAL OF PHYSICAL OCEANOGRAPHY
VOLUME 50
TABLE 1. Occupations of the 22 Lätrabjarg transects with velocity measurements used in the study. VMADCP: vessel-mounted ADCP;
LADCP: lowered ADCP. The 11 occupations marked with an asterisk (*) denote the sections added to the Mastropole et al. (2017)
dataset.
Cruise Ship Year
WOCE-93* R/V Aranda
MSMO5-4 R/V Maria S. Merian
KN194 R/V Knorr
BS010 R/V Bjarni Saemundsson
M82-1 R/V Meteor
BS001 R/V Bjarni Saemundsson
M85-2 R/V Meteor
KN203 R/V Knorr
BS002 R/V Bjarni Saemundsson
MSM21-1b R/V Maria S. Merian
‚R267 R/V James Clark Ross
P437 R/V Poseidon
BS013* R/V Bjarni Saemundsson
P471-2* R/V Poseidon
P486* R/V Poseidon
BS015* R/V Bjarni Saemundsson
PS03* R/V Poseidon
BS017* R/V Bjarni Saemundsson
54PE426* R/V Pelagid
ALLO118* NRV Alliance
MSM76* R/V Maria S. Merian
AR306* R/V Armstrong
are uncorrelated, it represents a conservative estimate. The
gridded absolute geostrophic velocities are used for all calcula-
(‚ons presented in this study.
b. Reanalysis wind data
Wind fields from ERAS were obtained from the European
Centre for Medium-Range Weather Forecasts (ECMWF,
attps://www.ecmwf.int/). This is the fifth generation reanalysis,
which uses ECMWF’s Integrated Forecast System (IFS).
Previous studies have shown good agreement between IFS
products and observations (Harden et al. 2016). The spatial
resolution of ERAS is 0.25°. Here we used the 3-hourly product
from 1990 to 2018.
averages which use roughly a thousand crossings each, which
substantially reduces this error (see section 4).
3. Basic characteristics
a. Mean state
We first present the mean Lätrabjarg sections of hydrogra-
phy and absolute geostrophic velocity using the 22 realizations
:hat include velocity data (Fig. 4). We do not consider the re-
zions on the east and west side of the strait where the number
of occupations is less than five. Encouragingly, the mean dis-
cıributions of potential temperature and salinity from the 22
5ccupations are consistent with the analogous means presented
ın Mastropole et al. (2017) using 111 occupations. It indicates
c. Satellite absolute dynamic topography
The along-track absolute dynamic topography (ADT)
data used in the study were provided by the Copernicus
Marine and Environment Monitoring Service (CMEMS,
http://www.marine.copernicus.eu). The product is processed
by the Data Unification and Altimeter Combination System
(DUACS) which applies to multimission altimeter data. The
data are comprised from the TOPEX/POSEDON mission,
:;ogether with the Jason-I, Jason-2, and Jason-3 missions. Since
Denmark Strait is close to the northern turning point of the
orbits, the along-track data have spatial and temporal reso-
utions of roughly 12km and 2 days, respectively. The time
veriod of data coverage used here is 1993-2018. The error
in the along-track ADT measurement is 0.7-1.3 cm, which
:ranslates to an uncertainty of 0.05-0.10 ms! in the surface
geostrophic velocity (http://marine.copernicus.eu/documents/
QUID/CMEMS-SL-QUID-008-032-051.pdf). We make composite
———
——
dec <
Nov .° @8 Min
SL ae pt so
in > 5atfö@n £ 60099)
ak ° ®
Wr eo ofe‘
day
Apr a
‚an
> & SS SPS STH
OO E
FIG. 3. Temporal distribution of the 122 Lätrabjarg hydrographic
sections. Those occupations that include velocity measurements
are colored red (for vessel-mounted ADCP data) and magenta (for
;owered ADCP). The blue circles correspond to hydrographic
measurements only.
3rancht to van hy RBUNDFSAMT FÜR SPFPESCHIFEFT AHPR"
| Inanthenticatern ! Dawnlaadern 01/1272
NA-
”
\AA Ta
