Seasonal cycle of N_2O: Analysis of data

• Published in: Global Biogeochemical Cycles
• Main Authors: Jiang, Xun, Ku, Wai Lim, Shia, Run-Lie, Li, Qinbin, Elkins, James W., Prinn, Ronald G., Yung, Yuk L.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: American Geophysical Union 2007
• Subjects: N2O seasonal cycle; multitaper method; surface sources; South Pole; Grim; Mace; South pole
• Online Access: https://doi.org/10.1029/2006GB002691

We carried out a systematic study of the seasonal cycle and its latitudinal variation in the nitrous oxide (N_2O) data collected by National Oceanic and Atmospheric Administration–Global Monitoring Division (NOAA-GMD) and the Advanced Global Atmospheric Gases Experiment (AGAGE). In order to confirm the weak seasonal signal in the observations, we applied the multitaper method for the spectrum analysis and studied the stations with significant seasonal cycle. In addition, the measurement errors must be small compared with the seasonal cycle. The N_2O seasonal cycles from seven stations satisfied these criteria and were analyzed in detail. The stations are Alert (82°N, 62°W), Barrow (71°N, 157°W), Mace Head (53°N, 10°W), Cape Kumukahi (19°N, 155°W), Cape Matatula (14°S, 171°W), Cape Grim (41°S, 145°E) and South Pole (90°S, 102°W). The amplitude (peak to peak) of the seasonal cycle of N_2O varies from 0.29 ppb (parts-per-billion by mole fraction in dry air) at the South Pole to 1.15 ppb at Alert. The month at which the seasonal cycle is at a minimum varies monotonically from April (South Pole) to September (Alert). The seasonal cycle in the Northern Hemisphere shows the influence of the stratosphere; the seasonal cycle of N_2O in the Southern Hemisphere suggests greater influence from surface sources. Preliminary estimates are obtained for the magnitude of the seasonally varying sources needed to account for the observations. © 2007 by the American Geophysical Union. Received 13 January 2006; revised 22 August 2006; accepted 18 September 2006; published 26 January 2007. We thank T. Liao for the helpful discussions and two anonymous reviewers for helpful comments. We also want to acknowledge J. H. Butler, G. S. Dutton, and T. M. Thompson for providing their individual data sets from NOAA. We would like to acknowledge our colleagues from the AGAGE network for providing their in situ sampling data through the web and for collecting NOAA flasks at their stations (CGO, MHD). This research was ...