THE EXTERNAL SEEING AND THE VERTICAL TEMPERATURE PROFILE IN THE SURFACE LAYER

J. Navarrete, ESO La Silla & Paranal Observatory

February 2006

Statistics of the last 4 years of operation in Paranal (2001-2004), over 778127, samples.

Figure 1: Histogram of the vertical temperature gradient between 30m and 2m above ground at Paranal (nighttime & clear sky only).

Figure 2: Histogram of the seeing measured at 6m above ground at Paranal for various levels of vertical temperature gradient between 30m and 2m above ground (nighttime & clear sky only).

Figure 3: Seeing records at 6m above ground at Paranal as a function of 30m wind direction (N=0, E=90) and of the vertical temperature gradient between 30m and 2m above ground (nighttime & clear sky only).

Figure 4: Vertical temperature gradient between 30m and 2m above ground (nighttime & clear sky only) as a function of wind direction (N=0, E=90) measured at 30m.

Figure 5: Wind rose measured at 30m for bad seeing conditions and strong vertical temperature gradient between 30m and 2m above ground (nighttime & clear sky only).

Figure 6: Wind rose measured at 30m for good to average seeing conditions and strong vertical temperature gradient between 30m and 2m above ground (nighttime & clear sky only).