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Miami, February 29, 2008

Captain

M/V Safmarine Gonubie

Dear Captain:

On behalf of the United States Department of Commerce\'s Atlantic
Oceanographic and Atmospheric Administration, I would like to thank you
and your Company for your help and cooperation in providing us with the
opportunity to use your ships to deploy oceanographic instrumentation.
Mr. James Farrington of AOML/NOAA will be the scientific party in this
operation.

The Atlantic Oceanographic and Atmospheric Laboratory is located in
Miami, Florida, and is one of twelve laboratories of the National
Oceanographic and Atmospheric Administration (NOAA). You may be familiar
with one of our sister organizations, the U.S. National Weather Service.

The Physical Oceanography Division of this laboratory has the mission to
investigate the effect of the ocean on climate. To accomplish this we
maintain an oceanographic and climate observing system to, for example,
measure the upper ocean thermal structure and currents. Several data
sets are obtained and developed by our laboratory\'s staff of scientific
and technical support personnel to investigate the ocean processes and
their link to climate variability and environmental changes.

Some of these observations are made by hydrographic measurements
including the acquisition of temperature sections across long oceanic
sections. The ship tracks used to deploy eXpendable BathyThermographs
(XBTs) to obtain these temperature sections are usually referred as
lines. The line between Cape Town and Newark is known as line AX08. The
ships your company has made available run along this line. Moreover,
other instruments such as drifters and floats are sometimes also
deployed to help investigate ocean currents. Remote sensing procedures
are also used, including satellite observations to monitor surface ocean
currents, wind fields and sea surface temperatures.

Many of the results obtained from our research can be viewed in real or
near-real time on our laboratory\'s web pages. As we obtain the data, we
place updates on the progress of our research, which can be accessed
through our web pages. This information can be accessed by navigating
our laboratory (www.aoml.noaa.gov) or divisional
(www.aoml.noaa.gov/phod) web pages. Of special interest to you could be
the web pages where we show results obtained from high density
(www.aoml.noaa.gov/phod/hdenxbt) or low density
(www.aoml.noaa.gov/phod/uot/seasxbt.html) deployments, done from ships
that join the Voluntary Observing System. Moreover, results from
satellite-derived ocean surface currents (www.cwcaribbean.aoml.noaa.gov,
click in \'Access CoastWatch Data\', and then in \'Altimeter and GTS
Data\') and surface winds (www.cwcaribbean.aoml.noaa.gov, click in
\'Access CoastWatch Data\', and then click in \'Near Real-Time Wind
Data') can also be accessed through our web pages.

Results obtained from observations and instrument deployments from
volunteer ships are transmitted in real-time to our laboratory and then
used by the National Weather Service to produce their marine and
atmospheric forecast. Shipping companies such as yours then use their
information as an aid for their operations.

Please feel free to contact us in case you have any question regarding
our activities or results, or if you are further interested in using our
ocean currents and wind products. We sincerely appreciate the
opportunity you give us to do our research and enhance the current ocean
observing system.

Thank you very much for your time, consideration and attention.

##### Dr. Gustavo Jorge Goni

##### United States Department of Commerce

National Oceanic and Atmospheric Administration

Atlantic Oceanographic and Meteorological Laboratory

Physical Oceanography Division

4301 Rickenbacker Causeway

Miami, FL 33149

305-361-4339 (voice)

305-361-4412 (fax)

email: gustavo.goni@noaa.gov

web: www.aoml.noaa.gov/phod

![](media/image2.png)

![](media/image3.png)**Cruise Plan**

**Implementation of High-Density XBT Line AX08.**

National Oceanic and Atmospheric Administration

Atlantic Oceanographic and Meteorological Laboratory

Physical Oceanography Division

4301 Rickenbacker Causeway

Miami, Florida 33149

Principal Investigators:

Gustavo Goni and Molly Baringer

**Date**: Departing Cape Town, South Africa approximately March 28,
2008; arriving in Newark, New Jersey approximately April 15, 2008.

**Ship Name**: M/V Safmarine Gonubie

**Scientific Party**: Mr. James Farrington (AOML/NOAA)

**Description of the Program:**

The Atlantic Ocean plays an important role within the global ocean
thermohaline circulation, through the interocean and interhemispheric
exchanges of water, heat, salt and vorticity. The Meridional Overturning
Circulation (MOC) in the subpolar North Atlantic is driven by the
formation of the North Atlantic Deep Water (NADW), with a formation rate
and properties that are highly influenced by climate changes on the
decadal and interdecadal time scales. These climate changes affect the
air-sea buoyancy flux in the subpolar basin, where warm-to-cold water
transformation processes take place. Recent results indicate that the
formation of the NADW is the cause of strong traces of the North
Atlantic Oscillation (NAO), a leading signal in decadal time scale
climate changes in the Atlantic. The MOC in the subtropical North
Atlantic is mostly affected by changes in momentum, air-sea fluxes and
salinity. However, the processes by which they cause changes in the
ocean dynamics are not completely known, particularly at decadal and
longer time scales.

The upper limb of the MOC carries warm waters from the South Atlantic
into the North Atlantic subtropical gyre through pathways and mechanisms
that are not completely understood and need to be investigated further.
This connection between the upper limbs of the gyres in the southern and
northern hemispheres in the tropical Atlantic is primarily composed by
zonal currents, which are forced by the wind field, primarily by the
position and intensity of the Inter-Tropical Convergence Zone (ITCZ).
Therefore, the tropical Atlantic is of critical interest for the
large-scale ocean circulation since it is where strong western boundary
currents contribute to inter-hemispheric transport of properties. The
MOC carries warm water from the South Atlantic to the North Atlantic off
the coast of Brazil within a western boundary current, the North Brazil
Current (NBC). Below the NBC, colder, fresher Antarctic Intermediate
water flows north in the North Brazil Undercurrent. In addition to the
northward flow of the NBC a shallow Subtropical Cell (STC) carries
subducted surface water from the southern subtropics to the equator,
where it is upwelled to the surface.

While time scales of decades or more characterize the deep flows, the
time scales of the boundary currents and STCs are of months to several
years. Monitoring water mass properties as well as the velocity
structure of the hypothesized pathways between the subtropics and the
tropics provides the tools to characterize both the mean and the
time-dependent properties of the tropical portion of the MOC and the
Atlantic STC. The role of the South Atlantic in the Meridional
Overturning Circulation (MOC) can be better understood by reducing the
uncertainty in the meridional heat flux through the subtropical band.

This program is designed to measure the upper ocean thermal structure in
key regions of the Atlantic Ocean. The seasonal to interannual
variability in upper ocean heat content and transport is monitored to
understand how the ocean responds to changes in atmospheric and oceanic
conditions and how the ocean response may feedback to the important
climate fluctuations such as the NAO. This increased understanding is
crucial to improving climate prediction models. Within this context,
four XBT lines have been chosen to monitor properties in the upper
layers of the Atlantic Ocean.

The key objective of this program is to implement the high density XBT
line AX08 to improve the existing climate observing system in the
tropical Atlantic. These observations will allow improving our knowledge
of the spatial and temporal variability of the surface currents in the
South and tropical Atlantic and to estimate the meridional heat
transport in the South Atlantic

This will be the 27th realization of a five-year program to survey this
line four times a year (Figure 1). Additional information on this
project may be obtained from **http://www.aoml.noaa.gov/phod/hdenxbt/**

![](media/image4.png){width="4.749305555555556in"
height="4.413194444444445in"}

**Figure 1.** Deployment schedule for AX08.

![](media/image5.png){width="3.747916666666667in"
height="3.2416666666666667in"}

**Figure 2.** The location of XBT deployments for the previous AX08 XBT
transects. The key objective of this project is to improve the existing
climate observing system in the tropical Atlantic.

Based on recommendations from the Climate Observing System for the
Tropical Atlantic (COSTA) Workshop (Miami, May 1999) this program will
increase data collection on the AX08 low density XBT VOS line between
Cape Town and New York City traversing key regions in the tropical
Atlantic four times a year. These observations will allow to improve our
knowledge of the spatial and temporal variability of the zonal surface
currents in the tropical Atlantic Ocean.

**Implementation:**

Three types of instruments will be deployed:

**(a) EXpendable BathyThermographs, XBTs.**

> The XBTs were already loaded in the ship. The XBT launches will be
> performed between Cape Town and the Eastern coast of North America,
> along the line, deploying:
>
> **1. Intermediate Density**: one XBT every 40 km between 32^o^S and
> 10^o^S (approximately 90 XBTs),
>
> **2. High Density:** one XBT every 30 km between 10^o^S and 10^o^N
> (approximately 115 XBTs), and
>
> **3. Intermediate Density:** one XBT every 40 km between 10^o^N and
> 20^o^N (approximately 38 XBTs).
>
> The time spacing between drops will be determined by the ship speed
> (Table I). The low-density deployment of XBTs, north of 20^o^N, will
> be done during the rest of the cruise, 4 times a day regardless of the
> speed of the ship.

**(b) Profiling Floats.**

Eight (8) Profiling Floats will be deployed :

> \(2\) South Atlantic: 22°S, 18°S
>
> \(6\) Tropical Atlantic: 4°S, 3°N, 8°N, 11°N, 13°N, 16°N

**(c) Surface Drifters.**

> ***Please remove magnets from all drifters upon leaving Cape Town to
> ensure that the buoys are activated.***

Twelve (12) Tropical Atlantic surface drifters will be deployed:

> 14°S, 11°S (cluster of 4 buoys -- Annual Buoy Manufacturer
> Comparison), 09°S, 07°S, 05°S, 03°N, 06°N, 08°N, 11°N.

![](media/image6.jpeg){width="3.75in" height="2.9034722222222222in"}

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

**Temperature sections and surface conditions:**

The two temperature sections obtained during the September 2001 and
August 2002 transects reveal the main surface currents in the region
that can be detected from the slope of the isotherms (Figure 3).

![](media/image7.png){width="3.247916666666667in"
height="2.325in"}![](media/image8.png){width="3.247916666666667in"
height="2.325in"}

**Figure 3**. Temperature sections obtained from the September 2001 and
August 2002 transects.

The satellite altimetry derived surface currents (Figure 4) in the
region indicate that there is a warm ring centered approximately 10E
34S.

![](media/image9.png){width="3.625in" height="3.036111111111111in"}

**[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.***