“Closure” refers to how optical oceanographers measure the consistency of models and measurements. Models refer to anything that is not explicitly measured in the water, including satellite-derived variables that are estimated using empirical relationships (for example, satellite-derived chlorophyll-a concentration is estimated from the ratios between green and blue remote sensing reflectance using an empirical relationship). Closure includes measurement closure, model closure, model-data closure, and scale closure. Where model-data closure experiments show misalignment between data and models, the cause of the misalignment may be due to measurement error, issues with the model, both, or some other external factor.