Atmospheric O 2 , CO 2 and δ 13 C measurements from aircraft sampling over Griffin Forest, Perthshire, UK

Regular vertical aircraft sampling has been performed in the lower troposphere above Griffin Forest, near Aberfeldy, Perthshire, UK (56°37′N, 3°47′W), between February 2003 and May 2004, for analysis of O 2 /N 2 , CO 2 and δ 13 C of CO 2 . We sampled flasks between 800 and 3100 m above sea level. The peak‐to‐peak amplitude of the seasonal cycle of O 2 /N 2 decreases from 171 per meg at 800 m to 113 per meg at 3100 m. Furthermore, the seasonal cycle is shifted from low to high altitudes with a lag of about 1 month. The same features are observed for CO 2 with a decrease in the peak‐to‐peak amplitude of the seasonal cycle from 17.6 ppm at 800 m to 11.4 ppm at 3100 m. The vertical profiles show decreasing O 2 /N 2 ratios in summer and increasing O 2 /N 2 ratios in wintertime with increasing sampling height, due to surface exchange of oxygen with the land biosphere and the ocean. The O 2 :CO 2 exchange ratios of the vertical profiles vary between −1.5 and −2.4 mol O 2 /mol CO 2 . Copyright © 2005 John Wiley & Sons, Ltd.