Hourly Area Prediction (HAP) charts are designed for communications between a specified base and mobile within a nominated area. HAP charts are available in several forms:
- Hourly HAP Charts
- Daily HAP Charts
- Weekly Weather Voice and Radiofax HAPs (web)
- Weekly Weather Voice and Radiofax HAPs (FTP)
SWS HAP charts have the following features.
- Each chart shows colours which represent the recommended HF frequencies for contacting the base or mobile within the area bounded by the chart for a particular hour.
- The geographic zone, which is variable, is represented by a map showing latitude and longitude.
- Charts are in Universal Time (UT).
- Daily HAP charts use the SWS world ionospheric (median) maps and can be for any place, time, or ionospheric support level. The daily HAP charts presented here are for the current UT day and were produced using the SWS daily forecast T index. You can produce your own HAP charts from our on line HF prediction tools.
- HAP charts use the regional real time foF2 (vertical MUF) map and are restricted in area, and time to that of the real time map. The real time map should track ionospheric storms, this means that the real time maps may contain storm gradients (variations in vertical MUF with location) that are not present in the median ionospheric maps. The real time HAPs can be different to the daily HAPs for the same hour, as the underlying maps may be different, particularly when the ionosphere is disturbed.