THE EXTERNAL SEEING AND THE WIND

J. Navarrete, ESO La Silla & Paranal Observatory

May 2005

 

DIMM Seeing statistics for 4 years of operation in Paranal (2001-2004), over 778127, samples.

 

 

CASE 1: For each wind direction, the frequency when a given direction was coincident with

DIMM seeing better or equal than 0.5 arcsec , the frequency of the wind speed in steps of 1 m/s. is shown too.

 

 

 

 

CASE 2: For each wind direction, the frequency when a given direction was coincident with 0.5<DIMM seeing<=0.8 , the frequency of the wind speed in steps of 1 m/s. is shown too.

 

 

 

 

 

 

 

 

CASE 3: For each wind direction, the frequency when a given direction was coincident with 0.8<seeing<=1.2, and the frequency of the wind speed in steps of 1 m/s. is shown too.

 

 

 

 

 

 

 

CASE 4: For each wind direction, the frequency when a given direction was coincident with

seeing worse than 1.2 arcsec , the frequency of the wind speed in steps of 1 m/s is shown too..

 

 

 

 

 

 

 

 

 

The good seeing (<=0.5) as function of the wind The bad seeing (>1.2) as function of the wind.

 

 

 

FWHM<=0.5

0.5<FWHM<=0.8

0.8<FWHM<=1.2

FWHM>1.2

 

7%

39%

36%

18%

All data , 778127 samples

 

 

 

 

 

The DIMM seeing by years:

 

FWHM<=0.5

0.5<FWHM<=0.8

0.8<FWHM<=1.2

FWHM>1.2

 

9%

40%

35%

16%

2001

2%

33%

42%

23%

2002

9%

43%

32%

16%

2003

7%

39%

36%

18%

2004