Saturday, December 11, 2010

A 5-Year 10-Meter Es Propagation Study Using PropNET - Part 4

The Time of the Day That Es Occur:
My belief from practical experience and with other researchers was that Es seemed to be best in the late afternoon/early evening hours. I have discovered in this analysis that it was the morning hours towards midday that are the best time for Es. More operating activity from Hams generally occurs during the later hours of day, and that was the probable cause for the assumption. The afternoon hours are still very active, but not to level experienced in the morning hours. The afternoon hours still have unique characteristics.

In addition, all time charts are displayed in Daybreak (Sunrise) to Daybreak (Sunrise) order. At this location, the sun rose in the 6 AM (6) CDT hour and sets during the 8 PM (22) CDT hour. 10-Meter Es were decisively diurnal (daytime-patterned). Therefore, it was best to display all results in daytime hours first, followed by evening and twilight hours.

The following chart is the number of Spring/Summer Es captures by hour for each year of the study. After seeing different Diurnal patterns between 2005 and 2006, this encouraged me to do a third year of participation to determine a true pattern. The 2006, 2007, and 2008 data would look similar in many regards. The final year (2009) would display an equal “dual-diurnal” pattern. What I got out of these charts was that each year does have similar trends, but each has its own distinctive personality.

Once again to better display hourly trends, the next chart is displayed as a 3-hour average. For example, the plot for 6 AM is the average of 5, 6 and 7 AM. Averaging does not change the overall totals. This method works best in demonstrating what Es actually do for hour to hour.

After accumulating the 5 years together, it was very clear to see that Spring/Summer Es are diurnal and are generally better during in the late morning hours. Once the sun rises, Es rapidly increase. Once the sun sets, Es decline sharply. Most dominant in 2007, 2008 and 2009, the overall chart shows a “dual-peak” diurnal pattern.

A regression analysis on the actual data clearly indicates that Es begin at 6 AM local daylight time. During the solar noon hour (13:00) Es peak and then begin a slow decline throughout the remainder of the day, evening and twilight hours.

Hourly Activity Week to Week:
The following chart displays 3-hour average captures for the 16 week Spring/Summer Es season (8 weeks each side of the Summer Solstice). The 6th week of the season is the most active and clearly appears similar in trends to the overall seasonal data chart. The 8th week grew rapidly the last 2 years and had a distinctive dual diurnal peak. The 1st, 2nd, and 13th weeks are least active, but clearly show a diurnal pattern as well. Only the early and latter weeks of the season fail to show a dual-peaked diurnal pattern.

Next: Distance Analysis

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