An experimental study of two-dimensional low level turbulence natural convection in an air filled vertical square cavity was conducted at a Ra number of 1.58 x 10(9). Turbulence quantities including T-rms＇, u(rms)＇, v(rms)＇ and Reynolds stress are presented. The fluid flow was turbulent anisotropic wall shear flow. It was in the low turbulence region with a base frequency of about 0.1-0.2 Hz. The power spectral densities moved to higher frequency along the fluid flow. The temperature and velocity fluctuations were limited in the boundary layers along the solid walls and were not in Gaussian distribution. The results indicate that the temperature and the velocity components fluctuate separately. (C) 2000 Elsevier Science Ltd. All rights reserved.