CIRCE project RL5 WP1 Task 1 TAU group

Prof. Pinhas Alpert

Department of Geophysics and Planetary Sciences, Faculty of Exact Sciences, Tel-Aviv University, Israel

Analysis of changes in Atmospheric water budget

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 inthe 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

• 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

Focus

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

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, P & E anomalies over American southwest

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 spread for 19 models

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.

P-E for four coupled models 1870-2100

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:

PECLWQ

Q =moisture flux divergence term

CLW =CLW flux divergence term

The contents of vertically integrated CLW can be estimated by the muti-regression equation:

highmidlow CCCw 179.0162.0127.0

wlowC midC

is the contents of vertically integrated CLW

highCand, 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