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Physical Oceanography Division Phone: 305/361-4345

4301 Rickenbacker Cswy Fax: 305/361-4412

Miami, Florida 33149-1097

**September 2008**

**[Cruise Plan -- AX7]{.underline}**

**[Ship Name]{.underline}:** ***M/V Hapag Lloyd Rome Express***

**[Project Title]{.underline}:** Atlantic Climate Change Program

Volunteer Observing Ship High Resolution XBT Line AX7

**[Beginning date]{.underline}:** On or about 25 September 2008 from
Barcelona, Spain

**[Ending date]{.underline}:** Arriving Fort Lauderdale, Florida on or
about 7 October 2008

**[Loading date:]{.underline}** 2 September 2008, Port Everglades,
Florida, USA

**[Scientific Ship Rider:]{.underline}** Jim Farrington, NOAA/AOML

**[Description of the Scientific Program]{.underline}**

The volunteer ship, ***M/V ROME EXPRESS***, will be involved in a study
of the upper ocean thermal structure of the subtropical North Atlantic
Ocean within the context of the Atlantic Volunteer Observing Ship
Program. Repeat crossings of the center of the subtropical gyre, every 3
months, will be conducted with the intent of determining and monitoring
the seasonal-to-interannual variability of the upper ocean. This
particular line along nominally 30^0^ N, designated as AX7, is ideal for
monitoring heat flux variability in the Atlantic because it lies near
the center of the subtropical gyre which has been shown to be the
latitude of the maximum heat flux in the ocean. The upper ocean thermal
structure obtained by the voluntary observing ship (VOS) using the
expendable temperature probes (XBTs) will be used to correlate the
subtropical gyre intensity with atmospheric forcing as well as
determining the heat transport. XBT data along this latitude will be
compared and combined with several ongoing and historical studies
including estimates of the Florida Current and Deep Western Boundary
Current Transports and several full water column historical surveys
completed near the same latitude. The new higher resolution for this
line should help determine the correct sampling strategies for lower
resolution XBT lines as well as providing resolution of the eddy
structure so necessary to incorporate into the atmospheric-ocean
forecast models now being implemented at the National Meteorological
Center.

**[Implementation]{.underline}**

The first crossing of this VOS line (designated AX7) began on September
30, 1994 (Figure 1). We have more or less proceeded on the same route
since that time (Figure 2). This VOS line will meet WOCE criterion for
high-resolution deployment providing temperature profiles every 50 km in
the open ocean and between 10-30 km near boundary currents down to a
depth of about 800 m. This section emphasizes consistent horizontal
spacing of XBT probes: clusters in space or time are of little value.

![](media/image2.png){width="5.998611111111111in"
height="6.013888888888889in"}

**Figure 1**: Table of times of all section occupations since the
program began in 1994.

![](media/image3.png){width="6.0in" height="3.6979166666666665in"}

**Figure 2**: Map of station locations of all XBT sections taken along
AX7 since the program began in 1994.

The overall plan for the ship track is as follows:

-   From Barcelona, Spain to 5^0^20'W, 36^0^ N: Set up and test XBT
    launcher as desired. No planned sampling.

-   From near 5^0^20'W, 36^0^ N to near 7^0^ W, 36^0^ N: High resolution
    sampling every 10 km: i.e., 15 probes over 150 km deployed every 22
    minutes.

-   From near 7^0^ W, 36^0^ N to near 70^0^ W, 26^0^30'N: Standard
    sampling every 50 km: i.e., 120 probes over 5990 km deployed every 1
    hour and 48 minutes.

-   From near 70^0^ W, 26^0^30'N to near 76^0^20' W, 26^0^ N: Medium
    resolution every 30 km: i.e., 21 probes over 635 km deployed every 1
    hour and 5 minutes.

-   From (76^0^20' W, 26^0^ N) to Hole in the Wall, Abaco (near 77^0^20'
    W, 25^0^40' N) : High resolution sampling every 10 km: i.e., probes
    over 107 km deployed every 22 minutes.

-   Northwest Providence Channel: From Hole in the Wall, Abaco (near
    77^0^07' W, 25^0^48' N) to the Western end of the Providence Channel
    (near 79^0^05'W, 26^0^10' N): Medium resolution sampling every 30
    km: i.e., 6 probes over 176 km deployed every 1 hour and 5 minutes.

-   Florida Straits: From the end of the Providence Channel (near Great
    Isaccs, Bahamas, 79^0^12'W, 26^0^10' N) to 80^0^00'W, High
    resolution sampling every 12 nautical miles (8 probes), then 1 final
    drop between 80^0^02'W and 80^0^01'W.

The above sampling time-interval time interval estimates are based on a
ship traveling at 15 knots. If the ship is traveling at a different
speed it will be necessary to adjust the launch times (see table 1 as a
quick guide).

![](media/image4.jpeg){width="4.501388888888889in"
height="2.720833333333333in"}

**Table 1**. Time interval between XBT launches based on ship speed and
desired sampling spacing.

If the planned cruise track deviates significantly from the outline
above please notify Molly Baringer at (305)361-4345 or (305)710-9240.

If the planned sampling is interrupted for any reason (such as an
autolauncher failure) the procedure will be to drop another probe as
close as possible to the planned drop and continue with the desired
spacing of the XBTs for that section of the cruise track (according to
the above guide). If a serious malfunction of the autolauncher occurs
then manually deploy the XBTs from the stern of the ship using the hand
launcher.

The ship-rider will work as needed around the clock to:

> 1\) Check and load the auto-launcher;
>
> 2\) Check that the system is logging data correctly; and
>
> 3\) Deploy ARGO profiling floats and surface drifting buoys as
> necessary.

In addition to the above, four (4) surface drifting buoys were loaded
aboard the ship. Deployment positions for the floats will be determined
at a later date.

**[Summary]{.underline}**

This high resolution XBT line will require 240 probes plus an
anticipated 10% failure rate of 24 probes for each Atlantic crossing.
This requires a total of 264 probes per crossing. Drifting buoys will
also be deployed during the cruise. ARGO floats will not be deployed
during this cruise.

![](media/image5.png){width="5.9944444444444445in"
height="4.291666666666667in"}

***Figure 3***. This figure shows a temperature section of a typical
crossing along the AX7 *route.*

> Temperature contours shown on the figure are in ^0^C. This section was
> taken aboard the
>
> ***BARCELONA EXPRESS*** in September of 2007.

Figure 3 shows a typical temperature section across the subtropical
Atlantic. Some features in these sections include:

-   Increase depth of isotherms (constant temperature surfaces) towards
    the west (e.g., 15^0^C isotherm starts near 100m in the east and
    deepens to over 650m in the west).

-   A rapid decrease in the depth of isotherms near the western boundary
    (where the Florida Current and Azores current bring warm water
    northward).

-   Warmest surface water is found in the west (near the Gulf
    Stream/Florida Current and the subtropical gyre recirculation).

-   Large fluctuations in the depth of temperature surfaces between
    20-30^0^ W where the Azores current crosses the section.

Typical currents expected in the region are shown in Figure 4. The XBTs
deployed will identify the vertical structure of the mesoscale features
present in the region.

![](media/image6.png){width="5.0in" height="3.4791666666666665in"}

![](media/image7.png){width="3.9375in" height="2.8229166666666665in"}

**Figure 3.** Satellite altimetry-derived surface currents and dynamic
height in the North Atlantic for 12 September 2007.

**[Available Data Products]{.underline}**

Temperature sections and information on XBT deployments can be found on
the following web page:
<http://www.aoml.noaa.gov/phod/hdenxbt/high_density_home.html>

![](media/image9.png){width="4.279861111111111in"
height="3.658333333333333in"}

Real-time surface winds and ocean surface currents can be found at:

<http://www.aoml.noaa.gov/phod/dataphod/work/trinanes/INTERFACE/index.html>

![](media/image10.jpeg){width="4.133333333333334in"
height="3.4097222222222223in"}

**[High Density Check-out list for the Ship Rider]{.underline}** **[Date
Completed]{.underline}**

***Data to be copied to CD or other means of transportable memory***
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

1\. All XBT data in .BIN, .NDC and electronic XBT drop log sheet.

2\. HistoryAllAttempts.txt -- found at
c:\\ProgramFiles\\AMVERSEAS\\XBT\\ARCHIVE

3\. Cruise webpage summary, cruise report, drifting buoy log sheet and
ARGO float log sheet

***XBT data and HistoryAllAttempts.txt CD to each of the following:***

Molly Baringer \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

Robert Roddy \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

Qi Yao \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

Juan Delgado \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

***Argo deployment information while underway***:

e-mailed to: [**aoml.argo@noaa.gov** and
**robert.j.roddy@noaa.gov**](mailto:aoml.argo@noaa.gov and robert.j.roddy@noaa.gov)
**\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_**

***Drifting buoy deployment information while underway***:

**<shaun.dolk@noaa.gov>** \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

***Cruise webpage summary***. This information goes on the webpage
including number XBTs dropped, drifters/floats deployed, any data
affecting issues. Send an email to each of the following:

Gustavo Goni [**gustavo.goni@noaa.gov**](mailto:gustavo.goni@noaa.gov)
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

Molly Baringer
[**molly.baringer@noaa.gov**](mailto:molly.baringer@noaa.gov)
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

Qi Yao (XBTs) [**qi.yao@noaa.gov**](mailto:qi.yao@noaa.gov)
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

Silvia Garzoli **<silvia.garzoli@noaa.gov>**
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

Shaun Dolk [**shaun.dolk@noaa.gov**](mailto:shaun.dolk@noaa.gov)
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

Juan Delgado (GTS)
[**juan.delgado@noaa.gov**](mailto:juan.delgado@noaa.gov)
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_

***Please email a Cruise Report to Molly Baringer, Silvia Garzoli and
Gustavo Goni stating the following:***

-   XBTs deployed

-   Drifters deployed (ID, date, time, latitude, longitude)

-   Profiling floats deployed (start time, deployment time, latitude,
    longitude)

-   GTS transmission (Real-time, twice a day, problems)

-   Additional equipment, tools, supplies needed

-   Problems

-   Recommendations

-   Other narrative

***At the end of the cruise please send an e-mail to Sommyr Pochan
<sommyr.pochan@noaa.gov> notifying her that cruise is over so that a
thank you note can be forwarded to the captain and crew. List any
special thanks or comments that you would like included in the note.***