Propagation News – 21 April 2019

Last week was a little better propagation-wise. The Australian IPS T index, as used by the ASAPS computer program for predicting HF propagation frequencies, turn positive again after a week of being at zero or even negative. The T index can be best regarded as an “equivalent sunspot number” – the sunspot number which would best match the observations made by ionosondes. IPS has a network of ionosondes located in the Australasian region and can derive the most appropriate T index. This can then be used by IPS customers to get best results for their HF communications. The better T index may be due to better geomagnetic conditions, or the increased solar flux index caused by sunspot number 2738.

Next week NOAA has the SFI falling away again to 68 due to a lack of sunspots. The Kp index is predicted to be around two to three as there were no visible coronal holes on the solar equator as this report was being prepared.

Next weekend is International Marconi Day, and the money bands will no doubt be 80, 40 and 20m. I would put my money on 40m as being the liveliest band with contacts aplenty available around Europe.

VHF and up

It’s another high pressure week, with the main high over Scandinavia, linking to another over the Azores in some models, while others leave room for a trough of low pressure near to western areas. This will mean a continued chance of Tropo, although again somewhat less than ideal conditions, despite high pressure on the charts. The better periods will be when there is moist air near the surface. Some of the models are starting to hint that there may be an increased shower risk from about mid-week, which at this time of the year can mean some heavy thundery showers, and may be good for rain scatter.

As we head towards the end of April the chances of Sporadic E increase rapidly and this would be a good time to get into the habit of checking the 10m and 6m bands routinely for those chance openings. The typical times are usually late morning and particularly late afternoon and early evening. If you have never worked it before, just do this one thing and check 10m and 6m each tea time and you’ll have your first Es in the logbook well before September. Remember do keep overs short and listen to the bands to find out how the old hands are operating before jumping in.

The Lyrids meteor shower will peak on the 23rd April. This shower, associated with comet Thatcher can occasionally produce some very strong reflections. Meteor bursts and pings associated with the Lyrids should be detectable most of this week.

The moon is waning this week. It reaches its maximum declination, of this cycle, on the 25th. Maximum path loss is reached on the 29th with the largest libration on the 26th. This does not look like a great week for EME operation. However, there will probably be lots of activity and if you are looking to make your first QSO off the moon, earlier in the week is probably best.

And that’s all from the propagation team this week.

Category: GB2RS Propagation News