SPURS-MIDAS Cruise Plan v3
The SPURS-MIDAS cruise (Las Palmas de
Gran Canaria 16 March 2013 – Ponta Delgada, Açores 13 April) on
board the Spanish R/V Sarmiento de Gamboa is a contribution to the
SPURS experiment (Salinity Processes in the Upper ocean Regional
Study, http://spurs.jpl. nasa.gov/SPURS/) aimed at understanding the
processes that drive the upper ocean dynamics and the role that
salinity plays on them in the area of maximum salinity in the center
of the North Atlantic subtropical gyre. The experiment is coordinated
by WHOI (R. Schmitt) and sponsored by NASA (E. Lindstrom), and
includes intensive field work with a large variety of
state-of-the-art instrumentation, the use of satellite remotely
sensed salinity information (Aquarius and SMOS), as well as dedicated
numerical modeling.
The cruise is a component of the
ICM-CSIC subproject of the MIDAS-6 project (SMOS ocean salinity and
soil moisture products. Improvements and applications demonstration)
funded by the Spanish R+D National Plan (grant AYA2010-22062-C05, PI
J. Font) that encompasses also processing and mapping SMOS salinity
data as well as numerical modeling work.
The Sarmiento will be in the SPURS site
together with the US R/V Endeavor in a coordinated program to
continue the SPURS field work initiated by the French R/V Thalassa
(STRASSE cruise, August-September 2012) and US R/V Knorr
(September-October 2012). The main role of our cruise is to run first
a general survey for mesoscale mapping of the area by means of TSG,
ADCP and undulating CTD (SeaSoar), and on the same time to deploy a
total of 48 surface salinity drifters in a 15 nm grid around WHOI
mooring. After this initial survey the Sarmiento will participate in
submesoscale high resolution specific samplings, as well as
performing turbulence (ASIP profiler) and other mixed-layer
measurements. Additional opportunity measurements will be done to
collect water and plankton samples for objectives from Spanish
researchers not belonging to the MIDAS team (ICM, U. Vigo, U.
Autònoma Barcelona). We may also pick-up a Mixed Layer Float (MLF)
from U. Washington drifting in the area.
The cruise plan can be drafted as
follows:
March 8: Equipment loaded in Vigo (NW
Spain mainland)
March 10 or 11: Sarmiento de Gamboa
leaves Vigo to Las Palmas
March 16 (approx. 18h GMT): Sarmiento
leaves Las Palmas (28N, 15.3W) steaming at 10 knt heading 25.25N,
36.5W. Nighttime plankton haul (Neuston, daily while in transit).
During the first two hours a zig-zag track at 8 knt will be done for
ADCP alignment calibration
March 17 morning (time always GMT): 18W
approx., CTD test@500m, SeaSoar deployment test (navigation at 8 knt
for 3 h)
March 18 morning: 22W, CTD@2000m,
plankton haul (Bongo, when daytime), Apex floats tests (total 6 h)
(note: CTD always means + LADCP +
rossette water samples at 0, 5, 10, 50, 100, 125,
150, 200, 300, 400, 500, 600, 700, 800, 900, 1000, 1100, 1200, 1400,
1600, 1800 and 2000 m & Deep Chlorophyll Maximum)
March 19 morning/afternoon: 25.5
oW, CTD@2000m, plankton haul, ASIP float tests (6 h)
March 20: steaming
March 21 after midnight: 31oW,
CTD@2000m, plankton haul
LEG 1
March 22 morning: 15 nm N of point a
(see figure 1), CTD@2000m (symbol +),
plankton haul. SeaSoar mesoscale survey (SPURS-MIDAS leg 1) starts
heading South (some 80 nm East of WHOI mooring 24o
34.867’N, 38o 0.0’W)
The survey will proceed at 8 knt
following the N-S 75 nm tracks spaced 15 nm (letters a-r)
March 25 early afternoon: interruption
of survey along track 7 (line m-n) to approach the WHOI mooring and
deploy several buoys (ASIP, Surpact, Apex), CTD@2000m. Survey resumed
after 4-5 h
LEG 2
March 26 evening: Survey ends at point
r. Starts deployment of surface drifters in a squared box
(SPURS-MIDAS leg 2). CTD casts@2000m at each corner (see figure 2).
18 out of the total 48 drifters will be released in triplets. This
will be done to study the dispersion near features such as fronts
that should be revealed by the SeaSoar survey. Otherwise the triplets
will be just deployed at the four corners and two near the center of
the box, at either two of the four center nodes
March 27: During the release of
drifters along the line p-o (between 3rd and 4th
points) we will go to the WHOI mooring area to recover the buoys
deployed two days before
March 28: At each release point along
the line n-m a CTD cast will be done down to 700 m to get information
on the surface and subduction waters, as well as to take water
samples for comparison with measurements taken in a S-N transect
along 28.5W by R/V Hesperides in early May for the FICARAM project
LEG 3
May 29: Once the drifters deployment is
finished we will continue the SeaSoar mesoscale survey in the
southern part of the area, starting at point g (see figure 3). Three
2000 m CTD casts will be done to complete the sampling below the
surface layer.
April 3: Southern survey ends at point
r. Shallow CTD cast for SeaSoar calibration
LEG 4
April 3-8: Targeted submesoscale
measurements on specific sites identified during the mesoscale survey
(1-2 days duration each). One of the samplings will be ASIP profiling
close to a WHOI turbulence glider now in operation in the area.
When/if possible plankton hauls and CTD stations will also be done.
The final strategy for all these measurements will be fixed by joint
data analysis with the Endeavor team and will be performed in an
optimized way by the two vessels
April 8: End of operations in the SPURS
site. Transit to Azores with some CTD casts and plankton hauls as in
the transit from Las Palmas
April 13: End of SPURS-MIDAS cruise in
Ponta Delgada (Azores). Sarmiento returns to Vigo, where equipment
and samples will be downloaded
Figure 1.
Figure 2
Figure 3
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