Climatic and Global Validation of Daily MODIS Precipitable Water Data at AERONET Sites for Clear-sky Irradiance Modelling
Abstract
Precipitable water is a crucial atmospheric component for estimating solar irradiance at the Earth surface. Satellite imagery is an important method of estimating precipitable water. It is, therefore, important to have a thorough understanding of the accuracy of such measurement instruments. The MODIS Aqua and Terra polar orbiting satellites offer a daily gridded product that is ideal for industries such as solar forecasters. This paper validates the precipitable water product at many ground stations around the world in a variety of climates. We find that there are considerable errors that can lead to significant over or underestimates in the estimated solar irradiance and conclude that alternative gridded solutions should be explored.