Abstract:Based on the data of turbulence flux observed from January 2009 to December 2010 at the Xilinhot National Climate Observatory, the bulk transfer coefficients for momentum and heat are estimated by using the eddy correlation method. The results show that bulk transfer coefficients for momentum (〖WTBX〗C〖WTBZ〗d) and heat(〖WTBX〗C〖WTBZ〗h) exhibit obvious same seasonal variation and different diurnal variation. The seasonal variation was the strongest in summer and the weakest in winter. The diurnal cycle of 〖WTBX〗C〖WTBZ〗d showed a single peak, while 〖WTBX〗C〖WTBZ〗h showed double peaks. With the increase of height the 〖WTBX〗C〖WTBZ〗d decreased, but the 〖WTBX〗C〖WTBZ〗h decreased with the increase of height only in summer. In the unstable atmosphere, both 〖WTBX〗C〖WTBZ〗d and 〖WTBX〗C〖WTBZ〗h decreased with the increasing wind speed. While in the stable atmospheric condition, 〖WTBX〗C〖WTBZ〗d decreased with the wind speed if under 6 m/s, then increased with the wind speed if over 6 m/s. But 〖WTBX〗C〖WTBZ〗h had no obvious trend with the wind speed. As the surface was colder than the air, 〖WTBX〗C〖WTBZ〗d and 〖WTBX〗C〖WTBZ〗h increased with the decrease of temperature difference between surface and air. On the contrary, the larger the temperature difference the stronger the 〖WTBX〗C〖WTBZ〗d, and the 〖WTBX〗C〖WTBZ〗h was inversely proportional to the variation of temperature difference.