WP5.2: Variations in the precipitation component of the water cycle in the Mediterranean region

Simon Krichak (TAU)

The role of NAO

Monthly Mediterranean precipitation isaffected by the main teleconnection regimes (NAO, EA/WR , ENSO, etc.) acting over Europe.

It is also strongly influenced by the variations inthe positioning and intensity of upper troposphere jets, PV streamers, coherent tropopause disturbances as well as air moisture transport and convergence

all these factors are sensitive to the effects of topography of the region.

- Krichak, S.O., M. Tsidulko, Alpert, P. (2000) November 2, 1994 Severe Storms in the Southeastern Mediterranean, Atmospheric Research, 53, 45-62. - . Krichak, S.O., M. Tsidulko and P. Alpert (2000) Monthly Synoptic Patterns Associated with Wet/Dry Eastern Mediterranean Conditions. Theoretical and Applied Climatology, 65, 215-229. -. Krichak S.O., P. Kishcha and P. Alpert (2002) Decadal Trends of Main Eurasian Oscillations and the Mediterranean Precipitation, Teor. Appl. Climatol., 72, 29-220. - Krichak, S.O., P. Alpert (2005) Signatures of the NAO in the atmospheric circulation during wet winter months over the Mediterranean region, Teor. Appl. Climatol. 82(1-2),27-39. - Alpert, P., Price, C., Krichak, S., Ziv, B, Saaroni, H., Osetinsky, I. (2006) Mediterranean climate and some tropical teleconnections, Nuovo Cimento Della Societa Italiana Di Fisica C-Geophysics and Space Physics 29 (1): 89-97. -. Alpert, P., C. Price, SO Krichak, B. Ziv, H. Saaroni, I. Osetinski, J. Barkan, P. Kishcha, (2005) Tropical teleconnections to the Mediterranean climate and weather, Advances in Geosciences, 2, 157– 160, SRef-ID: 1680-7359/adgeo/2005-2-157.

NAO+: 1979-1993NAO-: 1958-1972

Western Mediterranean

NAO+NAO-

NAO- NAO+

NAO+NAO-

NAO- NAO+

Eastern Mediterranean

NAO- NAO+

NAO+NAO-

NAO- NAO+

NAO+NAO-

The role of PV anomalies at the tropopause

(coherent tropopause disturbances and PV streamers)

Israeli floods of 3-4 December 2001

.- Krichak, S.O., P. Alpert and M. Dayan (2004) Role of atmospheric processes associated with hurricane Olga in December 2001 flash floods in Israel. J. Hydrometeorol., vol. 5, no. 6. pp. 1259-1270. - Krichak, S.O., P. Alpert, M. Dayan, (2007) A southeastern Mediterranean PV streamer and  its role in December 2001 case with torrential rains in Israel, Nat. Hazards Earth Syst. Sci., 7, 1-12. - Krichak,S.O., P. Alpert, K. Bassat, P. Kunin (2007) The surface climatology obtained in a three-member ensemble simulation of the present-day (1961-1990) climate of the eastern Mediterranean region, Advances in Geosciences (ADGEO), (submitted).

5/12/01 06Z

15198

678296

98+151=249 mm

Another extreme event of the same period in the Atlantic

Tropical – extratropical storm – hurricane Olga

Hurricane OLGA

hurricane since 12:00 UTC Nov. 26; peak intensity at 06:00 UTC Nov. 27, 2001

PV (Ertel)

gp

f

pfgP

/

)()(

- relative vorticity in isentropic coordinatesMinus sign: makes PV positive since pressure decreases upward

PV =

f – planetary vorticity

PV - absolute vorticity times static stability

WNDT – deep layer wind shear i.e. wind at DT minus wind at 700 hPa

Strong WNDT zones indicate areas with intense convection

Coherent tropopause disturbance

Eastward propagation of the CTD is associated with advection of positive PV in lower troposphere

PV - streamer

PV - streamer

This WP is devoted to the understanding of the synoptic (physical) nature of the relations between the "secondary" factors listed and the variations in precipitation intensity over the region.

First, the jets influence the direction of synoptic scale features (also affected by topography).

Second, jets contribute to formation of upper level divergence and convergence zones.

Thirdly, they can influence moisture transport.

Finally, the jets can influence stability and be responsible for the (usually affected by topography) gravity wave formation.

It is expected that these relationships will also be changed with the global warming. We will thus provide a comprehensive image of the Mediterranean precipitation for both current climate and future climate.

Main targets:

(1) identification and analysis of the factors influencing the western Mediterranean precipitation (Task 5.2.1); (2) identification and analysis of the factors influencing the eastern Mediterranean precipitation (Task 5.2.2);

Organization of strong cooperation with RL6 (and in particular WP6.3 [Ricardo Trigo]) will be important This WP is also in strong interaction with other RLs of the CIRCE by using the data from global and regional climate modeling (links to RL1, RL2, RL4, RL5 and RL6).

Mistake in final (March 2007) version

Correct version of July 27 2006