Why is it important?
In situ data is used for validation of CoastObs data. Sometimes this is necessary, for local tuning of algorithms, sometimes it is required to match existing long-term datasets with the new data, and sometimes users want the CoastObs data to be validated on their own site to be sure it performs as required.
What does CoastObs offer?
CoastObs provides validation based on in situ field surveys, or sampling followed by analysis in the laboratory, and by in situ optical measures. Users can also provide their own in situ datasets to for validation, CoastObs will then provide a validation of the CoastObs data with these in situ data. In situ field surveys are carried out of example for observations of Seagrass coverage. This is done according to standard methods. Also, manual sampling and the following processing in the laboratory is done according to standard protocols, e.g. with HPLC analysis for Chl-a, dryweight for TSM, or Fast Repetition rate Fluorometry for phytoplankton primary production. Optical methods for validation could include manual screening with instruments such as a WISP-3 optical sensor, or semi-continuous measurements with a WISPstation. These methods provide reflectance data comparable to optical satellites, and are very suitable for validation of satellite imagery.
How was the data validated?
Dedicated field campaigns were carried out at the different regions to validate all CoastObs products. Hundreds of stations were sampled and thousands of samples were collected and analysed using standard protocols and state-of-the-art equipment to develop and assess our products.
This included core biogeochemical parameters (e.g. chl-a, TSM, turbidity), optical parameters (e.g. remote sensing reflectance, phytoplankton absorption coefficient, particulate scattering coefficient) as well as a number of parameters (e.g. phytoplankton abundance, fractionated chl-a, macrophytes, pigment profile, Primary production) to validate our innovative products. Users might not be familiar with the optical methods. The figure below therefore provides an insight in the validation results of the WISPstation with traditional in situ methods.
Figure 1. WISPstation Chl-a validated against in situ sampled Chl-a from different regions (source: Riddick et al., 2019)