[EA Coast] POGO-SCOR Visiting Fellowship Report

[Shigalla Mahongo]

Dear ALL,

I would like to share with you part of a  brief report about my POGO-SCOR visiting fellowship at Rutgers University in the USA during the months of July/August 2008. I hope the report will be useful to you (see below).





Name
of Trainee: Shigalla
Mahongo                  Supervisor (Parent Institution): Javier
Zavala-Garay

 

Supervisor
(Host Institution): Benjamin
Ngatunga          Dates of Training: 16 July – 16 August, 2008

 

Subject of Training: Modelling the dynamics of the Zanzibar
Channel, Tanzania



  


1)  Please provide a brief description of
activities during the training period:

First of all, I had to compile and install the
Regional Ocean Modelling System (ROMS) in my laptop computer so that I could
run it anytime after returning to Tanzania. Compiling and installing
ROMS is a lengthy process which includes installation of various
sub-programmes. There is an upwelling test case in the ROMS tutorial which when
run successfully, is a confirmation that the model is properly installed. Since
ROMS is Unix-based, I had to install an interface (Cygwin) for running the
model in a windows platform. During the process of installation, I realized
that the latest versions of the various sub-programs do not always work; hence
returning to lower, stable sub-programmes in some instances. 

 

After completing the process of ROMS installation, I
had to learn and prepare the forcing files for ROMS with an aim of describing
the annual cycle of the Zanzibar Channel. These included boundary, surface and
initial forcing files. The boundary forcing file was obtained from the annual
cycle of HYCOM with a resolution of 1/12, kindly provided by Dr Luis Zamudio (a
friend of Dr Zavala-Garay). The surface forcing file consisted of 20 years
(1985-2004) of monthly meteorological observations from Zanzibar (rainfall flux, air temperature, air
pressure, relative humidity and winds), as well as net short-wave and long-wave
radiation fluxes from the OPENDAP server of NCEP2. After running the model for one
year it reaches a steady state describing the annual cycle. 

 

The Zanzibar Channel model is actually not the final
version, several improvements are needed. The model can however still be used
as a basic tool to guide us about what is needed to better improve the model.
There are remaining challenges to be able to get a realistic model for the
Channel. First, the bathymetry of the Channel, especially the southern portion
is incomplete (the grid was made available by Gabriela Mayorga-Adame). Secondly,
the tidal forcing has not yet been included because of current lack of data at
the boundaries. The only available software that could provide such data is the
Oregon State Tidal Prediction Software (OTPS). However the resolution in Tanzania is actually
too low to produce a nice forcing for ROMS. 

 

The model was configured to include 10 sigma layers
in the vertical. The time-step size to solve the 3D momentum equation was set
to 10 min. The meteorological variables were assumed to be uniform over the
entire domain, and the model was run for 365 days (1 year) to reach a stable
state. In my laptop, it took about 23 hours to run the model for one year.

 



2)  What applications of the training received do
you envision at your parent institution?

All the practical training modules that I received in
my training will be useful in a variety of applications at my parent
institution. The Zanzibar Channel is an area of interest for research at my
institute, but the dynamics are poorly known. Scientists working on different fields
such as fisheries, coral reefs, physical-chemical characteristics etc. are
often faced with challenges of explaining some of their findings when physical
processes are involved as causal factors. The model results will therefore assist
in understanding the driving forces of the oceanic waters both in space and
time to be able to explain many of the unknowns. The model results will also
provide an opportunity for scientists to develop a dataset that can be used for
evaluating the responses of various organisms and habitats to annual variability.
The dynamical model would as well provide the necessary information on
determining and predicting the variability of physical variables. 

 

The training has also opened up new opportunities in
modelling. First of all I may participate in the Theiss Research NSF Funded
Zanzibar Channel Project due to commence next summer. I have also submitted a
pre-proposal to START (grants in support of one year research related to global
environmental change in Africa) to carry out a
study on “Modelling the dynamics of the
Tanzanian coastal waters”. Dr Zavala-Garay has agreed to provide technical
advice if the proposal is eventually approved. I also intend to use the START
funds to purchase a customized professional workstation because ROMS requires
an exceptional computing power to perform advanced, CPU intensive calculations.
Such a computer is currently unavailable at my institute (TAFIRI). 

 

There are also plans for continued collaboration with
Dr Zavala-Garay on modelling the dynamics of the Zanzibar Channel, and we also
intend to submit one or two manuscripts for publication in the very near future
(we shall acknowledge POGO-SCOR when we do that). We intend to submit the first
manuscript in a reputable journal by December 2008. We also intend to submit
another manuscript on tides using the outputs of the model sometimes in 2009.
These publications, whose titles have not been firmly decided, will be very
useful for marine scientists in East Africa as
they will provide the basic references on the physical processes in the region.


 

3)  Please provide your comments on the
Fellowship Programme.

The fellowship programme provides an excellent
opportunity for building capacity in ocean observations for scientists from
developing countries, I would however, wish to say that the fellowship is probably
not well known to many scientists in East Africa.
One way of making the fellowship known (thereby making it much more
competitive) is to circulate the announcement through such bodies as the
regional IOC representatives and previous fellowship recipients, and ask them
to circulate widely. Having benefitted from the fellowship, I will on the other
hand, make sure that the next announcements are circulated widely in East Africa. As for the stipend, it looks adequate
depending of course on the cost of accommodation.


Best regards,

Mahongo.




      
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