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K. F. BOWlX’K ET AL.
which, for the significant cases, had a median value of 1.75. The median
value of rn in the power law for c,’ was 1.85. The corresponding value of n in
the power law Tor of, computed from n = 2q - m as in Eq. (9), would be
1.65, implying a K, which increased with diffusion time t but at a somewhat
slower rate than K,.
7. DEPENDENCE OF DIFFUSION ON ENVIRONMENTAL CONDITIC)NS
It was not possible, from the Irish Sea data, to establish any clear dependence of either the lateral or vertical diffusion on stability. On the other hand
1
2
5
10
Wind Speed (rnlsec)
Flc;. 4. Variation of latersll dilhsion coefficient K , with wind speed W : 0 IY70 data.
x 1971 data.
the 1970-1971 data showed a strong dependence of both K , and K , on the
current speed U and the wind speed W . Figures 4 and 5 show K , and K ,
respectively as functions of wind speed. The regression lines correspond to
K , increasing as W ’ . 6 at the 5 p; level of significance and K r as W 3 ’ ,
significant at the 0.5 level. Both K, and K , also increased with the mean
current speed 0 in a surface layer, 5 m deep, being proportional to 02.’ and