An increase of early rains in Southern Israel following land-use change?

J. Otterman*, A. Manes, S. Rubin, P. Alpert, D. O.C. Starr

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

The October rains (at the onset of the rainy season that extends to April) in southern Israel have steeply increased in the last quarter century relative to the prior two decades. A less pronounced, but appreciable, increase is noted for the rest of the rainy season. This apparent reversal of desertification is attributed here to land use changes. Afforestation, increased cultivation and limitations on grazing after the establishment of the State of Israel resulted in an increased vegetation cover over the inherently high-albedo soils in this region (an area of ∼104 km2). The changes are shown in a July 1985 Landsat image of the area. The increase in precipitation is specifically attributed to intensification of the dynamical processes of convection and advection resulting from plant-induced enhancement of the daytime sensible heat flux from the generally dry surface. This enhancement results both from the reduced surface albedo and the reduced soil heat flux (reduced day-to-night heat storage in the soil) in October when insolation is strong. Stronger daytime convection can lead to penetration of the inversions capping the planetary boundary layer (which are weaker in October than in summer) while strengthened advection (sea breeze) can provide moist air from the warm Mediterranean Sea. This suggested mechanism is consistent with previous studies showing that the autumn rains in southern Israel exhibit convective mesoscale characteristics and occur predominantly in the daytime. However, other causes, such as a shift in the synoptic-scale circulation, cannot be ruled out at this stage.

Original languageEnglish
Pages (from-to)333-351
Number of pages19
JournalBoundary-Layer Meteorology
Volume53
Issue number4
DOIs
StatePublished - Dec 1990

Fingerprint

Dive into the research topics of 'An increase of early rains in Southern Israel following land-use change?'. Together they form a unique fingerprint.

Cite this