Vertical short-scale structures in the upper tropospheric and lower stratospheric temperature and ozone at la Reunion Island (20.8 degrees S, 55.3 degrees E)

The distribution and the nature of vertical short-scale structures observed in ozone and temperature are investigated in the upper troposphere and the lower stratosphere at La Reunion Island located in the vicinity of the sou thern subtropical barrier by using wavelet-based methods. A climatology of dominant wavelike patterns with short vertical wavelengths reveals the pres ence of localized structures on both the ozone and the temperature perturba tions, extracted from ozonesonde and temperature data, up to the middle str atosphere. Some case studies are presented to identify the nature of short- scale structures with 1- to 5-km vertical wavelengths in the troposphere an d the stratosphere. A climatology of short-scale structures induced by grav ity waves and the horizontal advection shows that short-scale structures ar e mainly detected in the middle and upper troposphere and in the lower stra tosphere. The weak value of the coefficient R(z) that links the ozone and t emperature perturbations induced by gravity waves is a major limit to detec ting such short-scale structures above 21-km altitude. Some structures with vertical wavelengths ranging from 1 to 5 km are attributed to gravity wave s produced by convection in summer and the subtropical jet in winter, or qu asi-horizontal large-scale motions from both sides of the subtropical barri er.