Generic structure Leaky water tank and applications By

Generic structure: Leaky water tank and applications By Robert M. Mac. Kay, Clark College Physics and Meteorology Leaky Water Tank A model for atmospheric methyl chloroform C 2 H 3 Cl 3 Why look at methyl chloroform? • The transient behavior of methyl chloroform over the past 20 years is interesting. • Because of its stratospheric ozone destruction potential, in 1992 the Montreal protocol called for a complete phase out of methyl chloroform emissions. Modeling methyl chloroform provides an estimate of how rapidly countries from around the world complied with this emission reduction policy and how close the world has come towards zero methyl chloroform emissions. • The lifetime of methyl chloroform is very important to understanding atmospheric chemistry related to the OH radical, see Montzka et. al, 2000. The OH radical removes many pollutants from the atmosphere by oxidation. Negative feedback structure Methyl chloroform 1989 to 2004 observations taken from http: //cdiac. ornl. gov/trends/otheratg/blake/data. html and 2005 to 2009 data taken from http: //www. esrl. noaa. gov/gmd/hats/. Global mean estimates are show by black squares. Model predicted methyl chloroform concentration (1) vs. Observations (2). Using a 6. 3 yr atmospheric lifetime. Observed methyl chloroform concentration compared to five model simulation with different assumed atmospheric lifetimes. The 2000 to 2009 emissions are assumed to linearly decrease to zero by 2009 [ 0. 89 -0. 10*(time-year) ] based on Mc. Culloch (2005) Relative contributions to atmospheric chlorine loading estimated by Du Pont Corporation. Methyl chloroform in green, Model predicted methyl chloroform concentration (1) vs. Observations (2). Using a 5. 5 yr atmospheric lifetime. Emissions estimated from: Methyl chloroform sales Mc. Culloch (2005), and 5 different model simulations with assumed atmospheric lifetimes of 4. 0, 4. 5, 5. 0, 5. 5, and 6. 0 year simulations. http: //www. geiacenter. org/reviews/mcf. html (Mc. Culloch, 2005) Other application of the water tank structure hydrology Inflow=0. 0 Water volume decreasing it tanks with lifetimes of 10, 20, and 30 minutes. (half-value times of 7, 14, and 21 minutes) Approach to equilibrium from different directions. http: //cs. clark. edu/~mac/physlets/Global. Pollution/Water. Bucket. htm Four videos of a miniature water tank are included in this web based assignment At least two exponential decay time constants appear imbedded in the river flow data http: //ngm. nationalgeographic. com/big-idea/05/carbon-bath John Sternam from MIT argues the importance of the “bath tub structure to understanding global carbon emissions and atmospheric carbon dioxide. Other ideas? ? ? Prinn, R, , D. Cunnold, R. Rasmussen, P. Simmonds, F. Alyea, A. Crawford, P. Fraser, and R. Rosen, 1987. Atmospheric Trends in Methylchloroform and the Global Average for the Hydroxyl Radical. Science 13 November 1987: Vol. 238. no. 4829, pp. 945 – 950. Montzka, S. A. , C. M. Spivakovsky, J. H. Butler, J. W. Elkins, L. T. Lock, D. J. Mondeel, 2000. New Observational Constraints for Atmospheric Hydroxyl on Global and Hemispheric Scales. Science 21 April 2000: Vol. 288. no. 5465, pp. 500 - 503 Climate Change