Long-term measurements and statistics study on refractive index structure parameter of surface layer

The data of C 2 n refractive index structure parameter from 1997 to 2000 at a complex terrain in Hefei are studied statistically.Results of C 2 n in different ground covers,different seasons,different heights are presented. Months goes when C 2 n in daytime from strong to weak are June, May, April,September,January. The C 2 n over the grass are larger than that over the water in daytime,while the result of the comparison in nighttime is the reverse.The C 2 n decreases with altitude increase both in day and at night. The C 2 n falls slower from 3 to 10m than 10 to 15m. C 2 ns measured and modeled agree well with each other.