טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
Ph.D Thesis
Ph.D StudentSade Rotem
SubjectSnow Dynamics in Warm Temperate Mountains: Mount Hermon
as a Case Study
DepartmentDepartment of Civil and Environmental Engineering
Supervisors Professor Alex Furman
Professor Iggi Leetor
Dr. Alon Rimer
Full Thesis textFull thesis text - English Version


Abstract

Snowmelt is an important water source in warm temperate mountains. Mt. Hermon is the source of approximately 30 % of Israel natural fresh water. The main objective of this study is to understand snow dynamics in warm temperate mountains in general and on Mt. Hermon in particular, in order to identify the key processes that affect water availability at the bottom of the snowpack. To achieve this end, we estimated the energy and mass balance of the snowpack on Mt. Hermon using a snow model. The forcing variables for the simulations were collected in two meteorological stations located at different elevation. We simulated the snowpack energy and mass balance during the winter of 2010/11 in a Deep Snowpack (DSP), and in a karstic depression known as the Bulan, where both windswept and lee-side locations were simulated. The calibration of the model for the DSP was done using snow water equivalent (W) data, collected by snow-surveys. The simulation of the Bulan was calibrated against melting cycles. Using a step function to describe wind speed over the DSP we showed that the turbulent fluxes are influenced by changes in snowpack height. The turbulent fluxes were found to be the dominant energy fluxes at the snow surface on Mt. Hermon. During winter time, vapor losses were 46 to 82 % of the total ablation. Consequently, latent heat flux consumed much of the available energy at the snow-surface, greatly limiting melting rate to 1 mm d-1. During spring time, vapor flux was positive towards the snowpack (condensation), and average melting fluxes were 86 mm d-1. The simulation of the Bulan showed that the variation in the vapor flux with time created a variation in space of the available water at the bottom of the snowpack. The decrease in vapor flux during spring time was attributed to the warm temperatures which sustain high vapor pressure in the atmosphere, even under low relative humidity. The vapor flux shows different characteristics for globally warm and cold snow location. The difference is due to the fact that the maximum possible vapor deficit in cold location is much smaller than warm locations. In conclusion, this work suggests that in warm temperate mountains, vapor exchange at the snow-atmosphere interface greatly affects the location and timing of available water at the bottom of the snowpack.