Evaporation, energy balance, and paleohydrology of the lakes along the Dead Sea rift

Résumé fourni par la source

Lake evaporation is a dominant yet poorly constrained component of water and energy budgets. This uncertainty critically undermines necessary paleoclimate reconstructions, particularly for terminal lakes, whose levels are considered the best direct indicators of the precise balance between catchment precipitation and evaporative losses. We address this by applying a physically grounded framework for lake evaporation based on a hybrid approach of direct measurements and theoretical analysis of lake energy-balance and its thermal-equilibrium solution, combined with calibrated bulk formulae. High-resolution data from long-term eddy-covariance measurements at three adjacent Dead Sea Rift lakes—spanning wide gradients in salinity (freshwater to hypersaline), climate (Mediterranean to hyper-arid), and thermal structure—were used to calibrate bulk formulae relating environmental forcing to heat fluxes. We show that the thermal equilibrium approach depends on the lake’s thermal response time; shallow lakes reach equilibrium at intra-annual timescales, whereas deeper stratified lakes require annual forcing. These observations, combined with accurate bulk formulae that relates to the environmental conditions, provides tools for modeling global lake evaporation using only standard environmental data and for reconstructing paleo-evaporation. Applying this framework to the Last Glacial Maximum (LGM) highstand of Lake Lisan (the Levant), we bound evaporation rates and determine that a minimum annual water inflow approximately four times greater than modern levels was required to stabilize the lake. These results indicate significantly higher precipitation in the Dead Sea watershed during the LGM.

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