Odd Nitrogen in the Atmosphere

Sources and sinks for atmospheric odd nitrogen are discussed and detailed calculations are presented for the altitude range 0–80 km. The mixing ratio of odd nitrogen is approximately 2×10−9 throughout the troposphere and increases in the stratosphere to a value of order 2×10−8 at 40 km. The dominant atmospheric forms of odd nitrogen are HNO3, NO2 and NO. Nitric acid is the major form below 25 km. Nitric oxide is the most abundant constituent during the day and at night is efficiently converted to NO2 below 65 km. Possible modification of stratospheric NOx by supersonic aircraft is discussed and it is concluded that the consequences may be detectable if the globally averaged source of NO from stratospheric aviation should exceed 4×107 molecules cm−2 sec−1.