Fig. 3

The same as Fig. 2 except for data in March and April 2004 and March and April 2005. The altitude is fixed at 40 km for all panels. a 2004 and 0930 UT, b 2004 and 1530 UT, c 2005 and 0930 UT, and d 2004 and 1530 UT. “E” indicates an area of high correlation coefficients