Transcript Task 5.1.1
CIRCE project RL5 WP1 Task 1 TAU group Analysis of changes in Atmospheric water budget Prof. Pinhas Alpert Department of Geophysics and Planetary Sciences, Faculty of Exact Sciences, Tel-Aviv University, Israel Objectives Producing an integrated assessment of the expected variations of the water cycle in the Mediterranean region due to global climate changes Overall RL5 objectives : Assessment of the past variations and future projections of the water cycle in the Mediterranean environment due to global climate change. It is focused on the main components of atmospheric and inland and oceanic water cycle that are expected to be highly impacted by climate evolution Focus • Analysis of changes in the Atmospheric Moisture Budget in regional climate modelling (RCM) for the recent climate and for different future scenarios including the surface evaporation, precipitation and total moisture in the atmosphere • Assess the construction of moisture spatial distribution, features of water vapour budget components for different amount of regional precipitation, and the moisture source contributed to the regional precipitation • Comparison study with data from other sources Data and Methods The data currently (at kick-off time) available databases in TAU are: • Hadley Centre, • NASA FVGCM, • regional downscaling climate models : PRECIS1, PRECIS 2 at 50 km (A2 & B2) • ICTP-20km, ICTP-50km • Data processing and statistical analysis Example 1: Related climate change • Science Paper 5 April 2007 Seager et. Al & N. Harnik: Title: Model Projections of an Imminent Transition to a More Arid Climate in Southwestern North America P-E, P & E anomalies over American southwest Fig.1: Modeled changes in annual mean precipitation minus evaporation over the American Southwest (125º W---95º W, 25ºN---40ºN, land areas only) averaged over ensemble members for each of the 19 models. Anomalies for each model are relative to that model’s climatologies for 1950----2000. SResA1B emissions P-E spread for 19 models Fig.2: The change in annual mean P-E for 19 models relative to model climatologies for 1950-2000. Results are averaged over twenty year segments of the current century. Units are in mm/day. P-E for four coupled models 1870-2100 Fig.3: Likes Fig.2. but only from four coupled models. Results are from individual simulations of the 1860 to 2000 period forced by known and estimated climate forcings and individual projections of future climate using the SResA1B scenarios of climate forcings. Fig.4:The change in annual means of P-E for 2021-2040 minus 1995-2000 (all panels, contours) and contributions to the change in vertically integrated moisture convergence (colors) by the mean flow due to changes in the Flow (top), the specific humidity (middle) and the transient eddy moisture convergence (bottom), all for the GFDL CM2.1 model. Example 2: moisture budget neglected term Y. Shay-El#, P. Alpert , and A. daSilva, "Preliminary estimation of horizontal fluxes of cloud liquid water in relation to subtropical moisture budget studies employing ISCCP, SSMI and GEOS-1/DAS datasets", J. Geophys. Res., 105, No. D14, 18,067, 2000. #Part of Y. Shay-El Ph.D. Thesis Also: Alpert and Y. Shay-El, "The paradox of the net moisture sink over the Arabian-Iraqi desert during winter", Annales Geophysicae, 11, No. 2-3, 190-194, 1993. Another suggested solution to Peixoto & Oort paradox (1960) Consider cloud liquid water (CLW) fluxes, and neglect the water storage term, the vertically integrated moisture equation takes the form: Q CLW E P Q =moisture flux divergence term CLW =CLW flux divergence term The contents of vertically integrated CLW can be estimated by the muti-regression equation: w 0.127 Clow 0.162 C mid 0.179 C high w is the contents of vertically integrated CLW Clow , C mid and C high are the low, middle and high level cloud amount Contents of cloud liquid water for 1992, unit is mg/cm-2 First ever map of CLW for a full year Cloud liquid water flux divergence, Jan, Feb, Dec 1992