Townsville and Brisbane. Past Rainfall correlated with sunspot number

This research was conducted by ‘RetiredWeatherMan ‘ a retired BOM meteorologist.

‘RWM’ is an active member of Australian weather forums


by retiredweatherman » Fri Aug 02, 2019 6:11 pm

The Queensland coastline from Bowen to Townsville has a more west-northwest orientation than the rest,
and even westerly in the Townsville region. The prevailing east-southeast trade winds therefore blow
more parallel to the coastline over this section producing lower rainfalls – the area being known as the
Dry Tropics. A range of hills from Cape Cleveland, northeast of Townsville runs to the south of
Townsville near Majors Creek, further protecting the Townsville region from the Trades. Therefore this
area is ideal to study for monsoonal influenced summer rains, with the monsoon flow being predominately
from the northeast to north. This region is also affected by PDO,ESNO,IOD and at the southern end of
MJO influences. And all these factors whether singly or in tandem can help to influence the rainfall
totals. As well as the coastline orientation, the lack of nearby coastal ranges largely negates rainfall
being boosted by the Trade Flow. My studies have shown these summer rainfalls may also be partly
influenced by the Solar Cycle in some instances, again whether singly or in tandem with other influences
as mentioned earlier. The attached graph shows the monsoonal summer rains, generally maximized between
November and April expressed as a percentage of the average of this 6 month period against the Solar Cycle
each year in January, back to reliable record gathering in 1872. For comparison is a similar graph for Brisbane
summer rain ( Dec to Mar ). Brisbane summer rainfall is more influenced by southern patterns then Townsville
therefore the similarities are not as well defined. One interesting parallel with the two sites is the very
long time it took to cast off the influence of the Federation Drought ( Brisbane more so than Townsville )
with the summer rainfall peaks moving generally upward roughly in line with the upwards movement of the
solar peaks from the Federation Drought period up to about 1960. The 2 graphs follow…..’