“…R. Khosravi et al (manuscript in preparation, 2008) discuss the averaging kernels associated with HIRDLS measurements. [15] There is a certain amount of variability associated with use of ozonesondes, as each sonde is a unique instrument, especially when station-dependent factors are considered [Thompson et al, 2003a[Thompson et al, , 2003b[Thompson et al, , 2007Liu et al, 2006;Logan et al, 1999]. Among the conditions that factor into this variability are (1) the manufacturer of the instrument used (ENSCI-Corporation sondes can read 5 -10% higher than sondes from Science Pump Corporation (SPC), above 20 km [Thompson et al, 2007;Smit et al, 2007]); (2) the concentration of potassium iodide (KI) sensing cathode solution used, and whether or not it includes a buffering agent may also produce variances of 15% above the partial pressure layer peak [Johnson et al, 2002]; and (3) whether and how pump efficiency correction factors are implemented, which may also cause differences of up to 15% at upper altitudes [Johnson et al, 2002].…”