This page is a new approach of my previous work about refractive index forecasting wich is still on line at:

http://tropo.f5len.org

I thought that it would be nice if each user can choose by himself the area to monitor.
You can choose the layer to show average refractive index for a date and time (UTC). The left menu (Forecasts) are for the next due dates. The next one is the archives for one month.
Each dataset is about 4 MB. It takes few seconds to download, depends on your internet connection speed. And few seconds more for your browser to render the layer on the map.
A click on a the map, will show you the average refractive index value and QRA locator at the position of the click.
Datasets are computed 4 times a day around 2h, 8h, 14h and 20h CEST.

From Wikipedia about tropospheric radio propagation:

Sudden changes in the atmosphere’s vertical moisture content and temperature profiles can on random occasions make microwave and UHF & VHF signals propagate hundreds of kilometers up to about 2,000 kilometers (1,300 mi)—and for ducting mode even farther—beyond the normal radio-horizon. The inversion layer is mostly observed over high pressure regions, but there are several tropospheric weather conditions which create these randomly occurring propagation modes. Inversion layer’s altitude for non-ducting is typically found between 100 meters (300 ft) to about 1 kilometer (3,000 ft) and for ducting about 500 meters to 3 kilometers (1,600 to 10,000 ft), and the duration of the events are typically from several hours up to several days. Higher frequencies experience the most dramatic increase of signal strengths, while on low-VHF and HF the effect is negligible. Propagation path attenuation may be below free-space loss. Some of the lesser inversion types related to warm ground and cooler air moisture content occur regularly at certain times of the year and time of day. A typical example could be the late summer, early morning tropospheric enhancements that bring in signals from distances up to few hundred kilometers for a couple of hours, until undone by the Sun’s warming effect.

All documents, information, data, text, photographs, graphics, video, messages or any other materials whatsoever (“Content”), except as otherwise indicated elsewhere on this Website, may be viewed, downloaded and printed under the following conditions:

• The Content may be used solely for personal, informational, internal, non-commercial purposes. The sale or other commercial use of the Content is prohibited.
• The Content may not be modified or altered in any way, including the removal of any copyright or other proprietary notices.
• The Content on the Website may not be distributed.
• The Content may not be used in an offensive, derogatory, or misleading manner, or in any manner that portrays an individual or entity in a false light.
• The rights specified above to view, download and print the Content available on this Website are not applicable to the design or layout of this Website. Elements of this Website may not be copied or imitated in whole or in part without agreement from the Author.

This website is operate by a private individual Pascal Grandjean aka F5LEN for the hamradio community.