Global Changes of the Water Cycle Intensity
Michael Bosilovich, NASA/GSFC, Greenbelt, MD; and S. Schubert and G. Walker
Hadley Centre SSTs for the the period 1902-1998 have been used to force climate simulations of the atmospheric water cycle for a period in the early 20th century and a period late in the 20th century. The simulations also use CO2 concentrations for the respective parts of the century. The global cycling rate is computed in two ways: 1) seasonal averages of TPW and precipitation and 2) a new method using time varying water tracers. While the results show only a modest increase of global precipitation, the total precipitable water increases much more. The computaiotn of cycling rate show a decrease comparing the late 20th century to the early twentieth century. To verify this result with other models, we compare 50-year simulations (available from NASA and COLA). The model simulations for the period 1949-1998 indicate close correspondacne of the models' anomalies of precipitation, total precipitable water and recycling rate. While the increase in total water is again greater than the increase in precipitation in these models (and the cycling rate subsequently decreases), the increasing trends in precipitaiton and evaporation are found to be statistically significant. While much attention is given to evaluating local cycling of water, the results point to the need to better define and understand global cycling of water.
Extended Abstract (1.2M)
Session 10, Climate Models: Evaluation and Projections, Part II (Room 608)
Thursday, 15 January 2004, 8:30 AM-9:45 AM, Room 608
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