Analysis of total precipitable water from radiometric observations

Abstract

Total precipitable water (TPW) is defined as the total amount of water vapor in the atmospheric column. Measurements of the solar radiation transmitted through the atmosphere in the water vapor absorption band allow the TPW to be estimated. This work analyzes 8 meteorological stations with more than 15 years of data from the AERONET network, located around the world and with different climates according to the K¨oppen climate classification. At the stations of Banizoumbou and Sede Boker, both with the same climate, there is a clear difference between their TPW values. This is mainly due to their latitudes, since these stations are respectively located on strong convergence and subsidence zones, together with their average temperature differences. The key factor affecting the TPW at the stations of Iza˜na and Mauna Loa is their high altitude, which determines the columnar amount of water above the ground and also has an inverse proportionality with temperature. The annual temperature variation, along with other particular factors that affect each station, also end up having a more relevant impact on the TPW values than the climate definition. This leads to the conclusion that, while the K¨oppen-Geiger climate classification system is useful to describe the climate conditions, it is not enough to justify and discuss other meteorological variables, such as the total precipitable water.