The Mass of the Atmosphere: A Constraint on Global Analyses

作者：Kevin E. Trenberth, Lesley Smith · 发表于：Journal of Climate · 年份：2005 · DOI：10.1175/jcli-3299.1 · 被引用次数：269 · 研究领域：Climate variability and models、Meteorological Phenomena and Simulations、Geophysics and Gravity Measurements

Abstract The total mass of the atmosphere varies mainly from changes in water vapor loading; the former is proportional to global mean surface pressure and the water vapor component is computed directly from specific humidity and precipitable water using the 40-yr European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analyses (ERA-40). Their difference, the mass of the dry atmosphere, is estimated to be constant for the equivalent surface pressure to within 0.01 hPa based on changes in atmospheric composition. Global reanalyses satisfy this constraint for monthly means for 1979–2001 with a standard deviation of 0.065 hPa. New estimates of the total mass of the atmosphere and its dry component, and their corresponding surface pressures, are larger than previous estimates owing to new topography of the earth’s surface that is 5.5 m lower for the global mean. Global mean total surface pressure is 985.50 hPa, 0.9 hPa higher than previous best estimates. The total mean mass of the atmosphere is 5.1480 × 1018 kg with an annual range due to water vapor of 1.2 or 1.5 × 1015 kg depending on whether surface pressure or water vapor data are used; this is somewhat smaller than the previous estimate. The mean mass of water vapor is estimated as 1.27 × 1016 kg and the dry air mass as 5.1352 ± 0.0003 × 1018 kg. The water vapor contribution varies with an annual cycle of 0.29-hPa, a maximum in July of 2.62 hPa, and a minimum in December of 2.33 hPa, although the total global surface ...