Ozone Perturbations Research Articles

A temperature dependence kinetics study of the reactions of Cl (2P3/2) with O3, CH4, and H2O2

The technique of flash photolysis–resonance fluorescence has been utilized to study the temperature dependences of two chlorine atom reactions of considerable fundamental importance to stratospheric chemistry. These reactions have been studied using a wide range of experimental conditions to ensure the absence of complicating secondary processes. The reactions of interest with their corresponding rate constants are expressed in units of cm3 molecule−1 s−1: Cl+O3→ClO O2 (k1), ΔU°298=−164 kJ mol−1, k1 = (3.08±0.30) ×10−11 exp[−(576±60/RT)], (220–350) K; Cl+CH4→CH3+HCl (k2), ΔU°298=−164 kJ mol−1, k2 = (7.44±0.75) ×10−12 exp[−(2437±110/RT)], (218–401) K. In addition, the followong reaction was studied at 300 K: Cl+H2O2→HCl+HO2 (K3), ΔU°298=−56.8 kJ mol−1, k3?5.8×10−13 (±factor 2.0), 300 K. A direct implication of the new rate data is the need to revise downward by a factor of 2.4 to 3 the magnitude of the ozone perturbation predicted by earlier model calculations due to the presence of ClOx species in the stratosphere.

Nitrogen cycle factors contributing to N2O production from fertilizers

Nitrogen cycle factors contributing to N2O production and associated ozone perturbations are examined. It is pointed out that fertilizer nitrogen losses are non‐linear and increase with application rate. Losses are apportioned between rapid denitrification (∼ 1 year) and slower transfer processes of 10² to 10³ years between nitrogen reservoirs. It is concluded that different estimates of N2O production result from selecting nitrogen models with different denitrification and transfer efficiencies. A significant ozone perturbation cannot be ruled out because of uncertainties in the relative efficiency of agricultural denitrification.

Solar eclipse: Temperature, wind, and ozone in the stratosphere

The occurrence of a total eclipse at Tartagal, Argentina, on November 12, 1966, prompted a rocket sounding experiment to determine temperature, wind, and ozone perturbations in the stratosphere caused by the eclipse. Soundings were made in the 65- to 30-km region of the atmosphere before, during, and after the total eclipse. Twelve rockets were successfully fired; nine of the rocket instruments were designed to measure temperature and three were designed to determine ozone concentration in the atmosphere. Wind speed was determined for each sounding from the trajectory of the radar-reflective parachute.