کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
8143243 | 1523926 | 2015 | 11 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Photochemical control of the distribution of Venusian water
ترجمه فارسی عنوان
کنترل عکس شیمیایی توزیع آب ونوس
دانلود مقاله + سفارش ترجمه
دانلود مقاله ISI انگلیسی
رایگان برای ایرانیان
کلمات کلیدی
سیاره زهره، اتمسفر، ونوس اکسپرس،
موضوعات مرتبط
مهندسی و علوم پایه
علوم زمین و سیارات
فیزیک زمین (ژئو فیزیک)
چکیده انگلیسی
We use the JPL/Caltech 1-D photochemical model to solve continuity diffusion equation for atmospheric constituent abundances and total number density as a function of radial distance from the planet Venus. Photochemistry of the Venus atmosphere from 58 to 112Â km is modeled using an updated and expanded chemical scheme (Zhang et al., 2010, Zhang et al., 2012), guided by the results of recent observations and we mainly follow these references in our choice of boundary conditions for 40 species. We model water between 10 and 35Â ppm at our 58Â km lower boundary using an SO2 mixing ratio of 25Â ppm as our nominal reference value. We then vary the SO2 mixing ratio at the lower boundary between 5 and 75Â ppm holding water mixing ratio of 18Â ppm at the lower boundary and finding that it can control the water distribution at higher altitudes. SO2 and H2O can regulate each other via formation of H2SO4. In regions of high mixing ratios of SO2 there exists a “runaway effect” such that SO2 gets oxidized to SO3, which quickly soaks up H2O causing a major depletion of water between 70 and 100Â km. Eddy diffusion sensitivity studies performed characterizing variability due to mixing that show less of an effect than varying the lower boundary mixing ratio value. However, calculations using our nominal eddy diffusion profile multiplied and divided by a factor of four can give an order of magnitude maximum difference in the SO2 mixing ratio and a factor of a few difference in the H2O mixing ratio when compared with the respective nominal mixing ratio for these two species. In addition to explaining some of the observed variability in SO2 and H2O on Venus, our work also sheds light on the observations of dark and bright contrasts at the Venus cloud tops observed in an ultraviolet spectrum. Our calculations produce results in agreement with the SOIR Venus Express results of 1Â ppm at 70-90Â km (Bertaux et al., 2007) by using an SO2 mixing ratio of 25Â ppm SO2 and 18Â ppm water as our nominal reference values. Timescales for a chemical bifurcation causing a collapse of water concentrations above the cloud tops (>64Â km) are relatively short and on the order of a less than a few months, decreasing with altitude to less than a few days.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Planetary and Space Science - Volumes 113â114, August 2015, Pages 226-236
Journal: Planetary and Space Science - Volumes 113â114, August 2015, Pages 226-236
نویسندگان
Christopher D. Parkinson, Peter Gao, Larry Esposito, Yuk Yung, Stephen Bougher, Mathieu Hirtzig,