APPLICATION OF REMOTE SENSING FOR ADJUSTMENT AND CALIBRATION OF WATER QUALITY MODEL - Integrating GIS, Remote Sensing, and Mathematical Modelling for Surface Water Quality Management - page 166

8.3.2. Calibration Methods and Procedures
Both spatial and temporal calibrations were explored. The calibration methodology applying remote
sensing included two levels. The first level is a qualitative calibration of the model results using
patterns from the MODIS satellite image time series. A quantitative comparative analysis between the
model-simulated patterns and the patterns resulting from MODIS time series analysis was conducted
to check the model consistency with satellite data. This is an initial step in the remote sensing
calibration application that is seen as a suitable indicator to judge the model performance on both
spatial and temporal levels.
The second level of calibration is the quantitative calibration of the model. On this level of calibration,
both datasets MODIS time series and the SPOT5 scene are used to develop TSM and CHL-a
concentrations maps. Both data sets are used to compare the accuracy of the resulting concentration
maps and subsequently the results of the model after application of these datasets. The procedures for
calibrating the model are based on two selections: single point calibration (or specific target) and the
whole map calibration (or the overall target). In the following sections the details of the different
calibration levels, methodologies and procedures are explained along with the results of the model
calibration and discussions on each metho d. Figure (8-1) shows the flow of the model adjustments and
calibration processes.
Figure (8-1): Flowchart of calibration processes using remote sensing data
8.4. SPATIAL PATTERN CALIBRATION FOR TSM USING MODIS IMAGES
The qualitative calibration is based on a comparison of the developed concentration patterns from the
Delft3D water quality model and the patterns developed from the MODIS time series images during
the modelling period of six months. The MODIS products MOD09GQK/Terra and
MYD09GQK/Aqua are used. The specific characteristics of a MODIS image such as its medium