Inter-annual temperature and precipitation variations over the Litani Basin in response to atmospheric circulation patterns

Abstract

This study examines the sensitivity of a mid-size basin's temperature and precipitation response to different global and regional climate circulation patterns. The implication of the North Atlantic Oscillation (NAO), El Niño Southern Oscillation (ENSO), Indian Monsoon and ten other teleconnection patterns of the Northern Hemisphere are investigated. A methodology to generate a basin-scale, longterm monthly surface temperature and precipitation time series has been established using different statistical tests. The Litani River Basin is the focus of this study. It is located in Lebanon, east of the Mediterranean Basin, which is known to have diverse geophysical and environmental characteristics. It was selected to explore the influence of the diverse physical and topographical features on its hydroclimatological response to global and regional climate patterns. We also examine the opportunity of conducting related studies in areas with limited long-term measured climate and/or hydrological data. Litani's monthly precipitation and temperature data have been collected and statistically extrapolated using remotely sensed data products from satellites and as well as in situ gauges. Correlations between 13 different teleconnection indices and the basin's precipitation and temperature series are investigated. The study shows that some of the annual and seasonal temperature and precipitation variance can be partially associated with many atmospheric circulation patterns. This would give the opportunity to relate the natural climate variability with the watershed's hydroclimatology performance and thus differentiate it from other anthropogenic induced climate change outcomes.

Interannual variations and trends in surface air temperature in Finland in relation to atmospheric circulation patterns, 1961–2011

“…This result expresses the nature of the EA/WR pattern during autumn when south‐eastern winds mainly transport warmer airflow from central Russia to Finland. Ramadan et al () showed negative relationships between SAT and the EA/WR pattern over western Lebanon (north‐eastern Africa in eastern Mediterranean; see also Krichak et al , ) during 1900–2008. Similarly, Lim and Kim () reported negative correlations between the EA/WR pattern and winter (December to February) SAT variations over the Arctic region during 1979–2011.…”

“…On the other hand, a negative correlation between SAT and the SCA pattern over the south and west of Europe has been reported;, e.g. El Kenawy et al () concluded that the above‐average SAT over Spain during 1920–2006 was negatively correlated with the SCA pattern; Ramadan et al () showed a similar correlation for summer season in western Lebanon and Toreti et al () a weak negative correlation between summer SAT in Italy and the SCA pattern.…”

Prolonged dry spells in the Levant region: climatologic-synoptic analysis

“…Törnros (2013) indicated that during negative (positive) MOI phases the probability of above average winter precipitation is 22% (59%), respectively. The North-Sea Caspian-Sea Pattern (NCP) and the East Atlantic -Western Russia (EA-WR) were also found significantly correlated with annual rainfall in the Levant and Israel (Kutiel and Paz, 1998;Krichak et al, 2002;Kutiel and Benaroch, 2002;Yosef et al, 2009;Krichak et al, 2014) and in the Litany Basin, located in southern Lebanon, as exemplified by Ramadan et al (2012). In addition, Ramadan et al (2012) found that the rainfall in the Litany Basin is influenced by the Tropical/Northern Hemisphere Pattern, the East Atlantic Pattern and the Polar/Eurasia Pattern.…”

“…Most drought studies deal with annual or monthly time-scales (e.g. Dunkeloh and Jacobeit, 2003;Inbar and Bruins, 2004;Xoplaki et al, 2004;Ziv et al, 2006;Ramadan et al, 2012). However, even dry periods on a shorter time-scale than the monthly or the seasonal may have severe environmental and hydrological implications.…”

On the relationship between the Mediterranean Oscillation and winter precipitation in the Southern Levant

“…Considering that the Mediterranean Oscillation is linked to the NAO especially in winter (Dünkeloh and Jacobeit, ) it is therefore also logical to examine the region's precipitation regime in terms of the Mediterranean Oscillation Index (MOI) which is expressed as differences in sea level pressure (SLP) or geopotential heights between the WM and EM. Although winter precipitation in the WM (Gonzalez‐Hidalgo et al ., ) and EM (Ramadan et al ., ) has been shown to have a negative and positive correlation with the MOI, respectively, this relationship has not been addressed in detail.…”