Abstract
We present the results of monitoring optical-turbulence profiles at the Observatorio Astronómico Nacional de San Pedro Mártir, Mexico, during 11 nights in March and April 1997 and 16 nights in May 2000. The speed of turbulent layers was also monitored, but only for the 2000 period. 6414 turbulence profiles and 3016 wind profiles were measured and statistically analyzed. The main results concerning the turbulence profiles are: (i) the seeing produced by the turbulence in the first 1.2 km at the 1.5-m and the 2.1-m telescopes, not including turbulence inside the domes, has median values of 0rlap .(arcsec) 63 and 0rlap .(arcsec) 44, respectively. (ii) The median values of the seeing produced above 1.2 km and in the whole atmosphere are 0rlap .(arcsec) 38 and 0rlap .(arcsec) 71. (iii) The isoplanatic angle for full correction adaptive optics has a median value of 1rlap .(arcsec) 87. (iv) The decorrelation time (defined as the time lag for which the temporal correlation drops to 50%) of the turbulence strength at altitudes below and above 16km above sea level is approximately equal to 2 and 0.5 hours, respectively. (v) The isoplanatic-angle decorrelation-time is estimated to be equal to 2 hours. The results concerning the wind profiles are: (vi) No significant correlation is found between the turbulence intensity (ensuremath {C_{N}^2}) and the speed of the turbulent layers V. (vii) Layers in the first 5 km and higher up than 16 km, above sea level, are similarly slow, with median speeds of 8.6 and 9.6m s(-1) . (viii) Between 9 and 16km, where the jet stream takes place in some of the nights, the median wind speed is 26.0m s(-1) . (ix) From the simultaneous measurements of C_{N}(2) (h) and V(h), we compute the temporal coherence of the turbulence layer by layer. The results obtained here places San Pedro Mártir among the best suited sites for installing next generation optical telescopes.
