Measurements of Momentum and Sensible Heat Flux Using Eddy Correlation Method in the Mina Valley During the Haj Period

Direct measurements of sensible heat flux were made in themina valley during haj period. fifteen-minute average of the correlationsbetween the fluctuations of the two signals ( w' t' ) and later thevertical turbulent heat flux were computed from a remtech fluxmeterstation. friction velocity u was deduced from the fluxmeter data aswell. it was seen particularly on dhu al-hijjah 11 starting from 2100h until next day at 0200 h on dhu al-hijjah 12, u was attained up to0.8 ms–1 at night. this may be interpreted as the direction was easterlyto south easterly wind. the wind flowed across obstacles such astents, shelters, high buildings ... etc. it was noticed always that eveningssensible heat had positive values, most probably because at nightthe long wave radiation doesn’t escape outside the valley but collideswith vertical walls and slopes of the valley and then reflects to theground. thus the contribution of large amounts of long wave and theresulting excessive heat on the floor in addition to thousands ofpilgrims standing there keep the warm lower layer of the valleyunstable throughout night.