Lake Tanganyika is one of the world's great freshwater ecosystems. In recent decades its hydrodynamic
characteristics have undergone important changes that have had consequences on the lake's primary
productivity. The establishment of a long-term Ocean Color dataset for Lake Tanganyika is a fundamental tool
for understanding and monitoring these changes. We developed an approach to create a regionally calibrated
dataset of chlorophyll-a concentrations (CHL) and attenuation coefficients at 490 nm (K490) for the period
from July 2002 to December 2006 using daily calibrated radiances retrieved from the MODIS-Aqua sensor.
Standard MODIS Aqua Ocean Color products were found to not provide a suitable calibration for high altitude
lakes such as the Lake Tanganyika. An optimization of the extraction process and the validation of the dataset
were performed with independent sets of in situ measurements. Our results show that for the geographical,
atmospheric and optical conditions of Lake Tanganyika: (i) a coastal aerosol model set with high relative
humidity (90%) provides a suitable atmospheric correction; (ii) a significant correlation between in situ data
and CHL estimates using the MODIS specific OC3 algorithm is possible; and (iii) K490 estimates provide a
good level of significance. The resulting validated time series of bio-optical properties provides a fundamental
information base for the study of phytoplankton and primary production dynamics and interannual
trends. A comparison between surface chlorophyll-a concentrations estimated from field monitoring and
from the MODIS based dataset shows that remote sensing allows improved detection of surface blooms in
Lake Tanganyika