Water Vapor, CO2, and Temperature Profiles in and above a Forest—Accuracy Assessment of an Unattended Measurement System

Abstract

Abstract The possibility of a global climate change has increased research interest in the least understood parts of the climate system. One of those parts is the boundary between the land surface of the earth and the lowest part of the planetary boundary layer. The structure of this layer and the exchange processes in it are still incompletely understood for a variety of situations and surfaces, especially in the boreal zone and during the dark parts of the day and the year. Progress in this area requires new data measured continuously and unattended with high accuracy and long-term reliability. A measurement system for profiles of temperature, humidity, and carbon dioxide was designed to meet the above goals. The system used thermocouples and a Li-Cor gas analyzer combined with an array of tubing to suck air from different heights. Turbulent fluctuations of water vapor and carbon dioxide concentrations were smoothed by continuous-flow mixing chambers without moving parts. Half-hourly mean differences in...