I have been asked a number of times whether the reduction in air traffic and general effects from rge COVID-19 pandemic have affected radio propagation at VHF through to microwave.
The question, I think, has been prompted from thoughts of lower air traffic (and the the reduced opportunities for air scatter contacts) creating fewer contrails and less “sky haze” which could prompt higher lower atmosphere temperatures and thus increased ducting opportunities.
The short answer is no. I have not seen any evidence to support that premise. It appears there has been a quite neutral effect but I am still assessing data from the last few years in case I find any significant effect .
The problem is in defining what sort of effects is one expecting to see. A school of thought is that we could return to the wide spread Autumn time tropo openings where across most of Western Europe frequencies at VHF and above were affected by elevated ducts under stable High pressure systems providing possibilities of contacts to to at least 1300-1500km. Another school of thought being the exact opposite due to lack of atmospheric seeding by human activity.
As stated the evidence I have seen in my own data on weather systems and reported contacts amateur radio contacts has suggested that there has been no significant difference. It is true that we radio amateurs have experienced some tremendously good propagation during events in September and October (my own prize being 1350km+ on 3cm), but these can not yet be classed as statistically significant when compared to previous years.
Statistical significance is quite crucial in the argument for we have to consider effects such as:-
- Activity Levels.
- Numbers of active radio amateurs
- Amateur band access
- Activity reporting/alerts
- Technology
- Signal generation
- Power levels
- Antennas
- Modulation schemes
- Weather forecasting
- Near-real time satellite imaging
- Access to multi-sensor data
- Forecasting accuracy
- Climate effects
- AGW
- Improved monitoring
- Computer modelling accuracy
Over the last 10,20 or 30 years once can safely say there has been signficant technological improvements in most of the areas above, except in the number of radio amateurs and amateur band access and this present a major threat to further coherent studies as access to 23, 13, 9 and 6cm are all threatened. All these bands have very different tropospheric characteristics and access to this part of the spectrum for terrestrial use is vital for the radio amateur experimenter/researcher.
In short, the changes in the above categories make direct comparison with the sunny, unicorn filled, uplands of past days difficult and impossible to correlate directly.
One just has to look at the effect the FT8 MGM mode has had to summertime propagation on 50MHz, or JT MGM modes on 144/432 MHz to see the difficulties.
Direct access to weather satellite data now provides near real-time data on the lower and more generally upper atmosphere. This has enabled me to nake tentative suggestion on the possibilities of skewed angle propagation , certainly for 3cm and once equipment has been developed, for the other microwave bands below 10GHz. The higher bands 24GHz – 122GHz rely much more on local changes in temperature,pressure, and humidity and these measurements are not yet available with suitable resolution over a large geographical area. In the Netherlands there is an increasing number of interconnected community weather station monitors providing sufficent resolution (and averaged accuracy) that may ber of use. I am not aware of a similar (non-monetary) based scheme in the UK.
The changes in the first three categories are enough to see how complex comparing data even from a few years ago has become. The fast pace of changes also means that a different approach is required to assess the huge amount of data now available. A huge increase in DXCluster reports across all bands has been witnessed and it is a shame that many of the reports are of little value (the length of the alphanumeric string for location from MGM modes being a particular gripe). The increased complexity also means that ultimately some new tools need to be developed to handle the data along with a kind of mathematical model to assess daily predictions. I have been looking at Anaconda ultimately a Masters in Python will probably be needed.
This prompted me to start thinking about the wider issues arising from the COVID-19 restrictions and the realisation that the effect on weather and climate of the global lockdown is complex and requires a number of different climatological issues to be considered.
It is obvious there is a crossover between how COVID-19 has affected the weather, that is the short-term climatological influence, and the longer term effect on the Climate (deliberate use of capital letter to delineate climate from weather).
It is accepted that on a global scale industrial activity was reduced by around 35%, car travel reduced by around 50% and air travel by 75% in the first few months of 2020 as a by-product in the race to control the spread of COVID-19. It is estimated that carbon dioxide emissions dropped by around 17% compared to the same time period in the previous year.
These figures seem quite satisfying until one looks over the statistics and sees that in reality not much seems to have changed in the weather apart from much cleaner air resulting in considerbly less haze, but temperatures didn’t increase due to clearer deep blue skies.
The short-term climatological changes do not stem from simply the effects of less air traffic and the associated CO2 reduction. Effects from internal combustion engines (CO2 and NOx and numerous particulate emissions of different carbon densities), and industry (CO2 and SO2 gas, white sulphate aerosols and black carbon particulates) must also be considered. To what extent is difficult to assess as greehouse gases (CO2 and methane) and aerosols remain in the atmosphere for decades (or centuries). NOx, SO2 and black carbon tend to remain in the atmosphere for a few weeks.
Obviously the subject is of great interest to academia and there is no doubt we will see publications recounting some of their findings.
There will of course be no definitive answer but simply results from various mathematical models using multiple probability simulations (Monte-Carlo Method) will help improve understanding of the influences. It also provides academia with plenty of scope to debate the issues and politicians to prevaricate, literally while Rome burns.
Looking at the data so far it looks as if there was very little overall change in temperature. Regional variations of course will be found where local temperatures were either cooler or hotter depending on local particulate or SO2 emissions.
The effect on VHF/microwave tropospheric propagation from a radio amateurs perspective has been mostly neutral on a European scale.
What is not known is the medium term effect this has on the extreme weather cycles (Monsoons, Cyclones ( Typhoons and Hurricanes), or even extreme heat and rain).
I have been cogitating for some months over this issue and have become increasingly concerned over the increase in the record numbers of tropical storms and hurricanes on the Atlantic conveyor belt into Central America and the US eastern seaboard; the number of North Atlantic hurricanes/storms arriving in Europe, their frequency being hidden by the convention that storm names are given by the local meteorological agency rather than pan-European. One cannot, of course, ignore the increasing power and devastation caused by the number of typhoons sweeping across the Pacific into the Philippines, Vietnam, China and Japan. It was reported recently that Vietnam moved over 400,000 people to relative safety ahead of the latest system to sweep across their country.
This year, 2020, is also the first year, I think since 1851, that five Category 5 hurricances have swept into North and Central America in a single season.
Remember that a Category 5 Hurricane has a 1 minute sustained wind speed of 254 km/h (158 mph; 70 m/s)
We also need to consider the CO2 and particulate contributions from the wild fires in Australia, USA-West Coast, Argentina and of course the opportune fires in Brazil. A few years ago we also had concerns over the fires in Indonesia causing widespread air pollution across Asia, although those fires were eventually controlled by the introduction of Caterpillars, habitat devastation continues.
We must not forget either the increase in ice reduction in the Polar regions, unprecedented record temperatures in Sibera and the accompanying methane gas release
The cause of these natural events is well outside the scope of this note,but it is clear a change to the Earth’s climate is happening at an worringly exponential rate. We humans are not good at handling exponential events.
The famous EU directive on harmonisation of flush water amounts in toilets across Europe in response to Greta Thunberg’s Sixth Extinction address at the European Economic and Social Committee meeting in 2019 is a good illustration of the level of importance given to climate change matters at the political. Maybe politicians (and those in the finance industry) in Washington, London, Paris, or Bruxelles will have an enlightened moment when they find themselves choking from environmental concerns.
So that is the wider climate and political issue covered. It should be ringing alarm bells that something is happening.