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Thompson, RL, Dlugokencky E, Chevallier F, Ciais P, Dutton G, Elkins JW, Langenfelds RL, Prinn RG, Weiss RF, Tohjima Y, O'Doherty S, Krummel PB, Fraser P, Steele LP.  2013.  Interannual variability in tropospheric nitrous oxide. Geophysical Research Letters. 40:4426-4431.   10.1002/grl.50721   AbstractWebsite

Observations of tropospheric N2O mixing ratio show significant variability on interannual timescales (0.2ppb, 1 standard deviation). We found that interannual variability in N2O is weakly correlated with that in CFC-12 and SF6 for the northern extratropics and more strongly correlated for the southern extratropics, suggesting that interannual variability in all these species is influenced by large-scale atmospheric circulation changes and, for SF6 in particular, interhemispheric transport. N2O interannual variability was not, however, correlated with polar lower stratospheric temperature, which is used as a proxy for stratosphere-to-troposphere transport in the extratropics. This suggests that stratosphere-to-troposphere transport is not a dominant factor in year-to-year variations in N2O growth rate. Instead, we found strong correlations of N2O interannual variability with the Multivariate ENSO Index. The climate variables, precipitation, soil moisture, and temperature were also found to be significantly correlated with N2O interannual variability, suggesting that climate-driven changes in soil N2O flux may be important for variations in N2O growth rate.

Patra, PK, Takigawa M, Ishijima K, Choi B-C, Cunnold D, Dlugokencky EJ, Fraser P, Gomez-Pelaez AJ, Goo T-Y, Kim J-S, Krummel P, Langenfelds R, Meinhardt F, Mukai H, O'Doherty S, Prinn RG, Simmonds P, Steele P, Tohjima Y, Tsuboi K, Uhse K, Weiss R, Worthy D, Nakazawa T.  2009.  Growth rate, seasonal, synoptic, diurnal variations and budget of methane in the lower atmosphere. Journal of the Meteorological Society of Japan. 87:635-663.: Meteorological Society of Japan, 1-3-4, Ote-machi Chiyoda-ku Tokyo 100-0004 Japan, [], [URL:]   10.2151/jmsj.87.635   AbstractWebsite

We have used an AGCM (atmospheric general circulation model)-based Chemistry Transport Model (ACTM) for the simulation of methane (CH sub(4)) in the height range of earth's surface to about 90 km. The model simulations are compared with measurements at hourly, daily, monthly and interannual time scales by filtering or averaging all the timeseries appropriately. From this model-observation comparison, we conclude that the recent (1990-2006) trends in growth rate and seasonal cycle at most measurement sites can be fairly successfully modeled by using existing knowledge of CH sub(4) flux trends and seasonality. A large part of the interannual variability (IAV) in CH sub(4) growth rate is apparently controlled by IAV in atmospheric dynamics at the tropical sites and forest fires in the high latitude sites. The flux amplitudes are optimized with respect to the available hydroxyl radical (OH) distribution and model transport for successful reproduction of latitudinal and longitudinal distribution of observed CH sub(4) mixing ratio at the earth's surface. Estimated atmospheric CH sub(4) lifetime in this setup is 8.6 years. We found a small impact (less than 0.5 integrated over 1 year) of OH diurnal variation, due to temperature dependence of reaction rate coefficient, on CH sub(4) simulation compared to the transport related variability (order of +/-15 at interannual timescales). Model-observation comparisons of seasonal cycles, synoptic variations and diurnal cycles are shown to be useful for validating regional flux distribution patterns and strengths. Our results, based on two emission scenarios, suggest reduced emissions from temperate and tropical Asia region (by 13, 5, 3 Tg-CH sub(4) for India, China and Indonesia, respectively), and compensating increase (by 9, 9, 3 Tg-CH sub(4) for Russia, United States and Canada, respectively) in the boreal Northern Hemisphere (NH) are required for improved model-observation agreement.

Broecker, WS, Peacock SL, Walker S, Weiss R, Fahrbach E, Schroeder M, Mikolajewicz U, Heinze C, Key R, Peng TH, Rubin S.  1998.  How much deep water is formed in the Southern Ocean? Journal of Geophysical Research-Oceans. 103:15833-15843.   10.1029/98jc00248   AbstractWebsite

Three tracers are used to place constraints on the production rate of ventilated deep water in the Southern Ocean. The distribution of the water mass tracer PO4* ("phosphate star") in the deep sea suggests that the amount of ventilated deep water produced in the Southern Ocean is equal to or greater than the outflow of North Atlantic Deep Water from the Atlantic. Radiocarbon distributions yield an export flux of water from the North Atlantic which has averaged about 15 Sv over the last several hundred years. CFC inventories are used as a direct indicator of the current production rate of ventilated deep water in the Southern Ocean. Although coverage is as yet sparse, it appears that the CFC inventory is not inconsistent with the deep water production rate required by the distributions of PO4* and radiocarbon. It has been widely accepted that the major part of the deep water production in the Southern Ocean takes place in the Weddell Sea. However, our estimate of the Southern Ocean ventilated deep water flux is in conflict with previous estimates of the flux of ventilated deep water from the Weddell Sea, which lie in the range 1-5 Sv. Possible reasons for this difference are discussed.