South African Ocean Accounts

Standby for more cool things to come!

TABLE OF CONTENTS

Physical State

Algoa Bay in situ physical and biogeochemical condition indicators:

Interpolated mapped indicators of ocean condition including, sea temperature and salinity as a measure of physico chemical quality, dissolved oxygen as an indicator of biogeochemical cycling, turbidity and chl-a concentration as a measure of ecosystem fitness and greenhouse gas retention potential are depicted below. Data has been interpolated in a GIS application and mapped as a snap shot in time at a bay scale for ease of understanding.

Explore Data

Essential Ocean Variables (EOVs) can be viewed, tracked and monitored on the fly with the ocean data explorer tool (ODET).

Here the user can navigate through the Algoa Bay Sentinnel Site station points (PELTER 3 for example) on the interactive map  (depicted as blue stars) and the window pane below will update, allowing users to view and access the raw oceanographic CTD data through the water column at each station location.

The scatter plot depicted below is an inventive way to display large volumes of data. In this case, a 2D histogram of the data, where the colour represents the number of occurrences (logarithmic scale) of values in the range covered by each pixel in the heatmap.

It is well understood that tracking sea temperature provides a general picture of sea state and when viewed over time gives information about seasonal patterns, influences from currents and wind regimes, and over longer time scales, shifts in climate patterns.

In Algoa Bay, tracking sea temperature over the past decade can provide insight to important changes taking place. For example, over the ten year time series (2012 – 2021), a general decrease in the thermocline depth is evident. A thermocline can be thought of as a boundary layer between warmer, well mixed water above and much cooler, calm water below. This means the thermocline sits at a shallower depth than previously recorded and was detected at all 7 stations recording measurements for this time series. It is suggested that this is connected to the El Nino Southern Oscillation and an increase in the easterly wind regime leading to increased upwelling in the bay.

What is worth noting here is that long term environmental changes can be detected. For example you could see shifts in temperature at a seasonal, annual, or decadal scale or shifts in productivity in the system by tracking Chlorophyll-a for example. There are many and varied ways to use this data visualisation tool to gain insights into the health and condition of a local, heavily used environment. In the future, both real time and future scenarios will be developped and accessible with our ODET. Keep an eye on this space!