Green Cape trip

 Needing to get fuel for the Pajero in the near future I noticed that the price of diesel at the cheapest place in Eden was 199.9c/l: 32 cents less than Mallacoota. Is the Mallacoota servo (or their wholesaler) working on a business plan that says they have a captive market so gouge it before the tourists leave? No surely not. 😂

There were also a few groceries we needed that would be better priced in in Eden, so off we went, deciding that we would call in to Green Cape on the way home.

The drive in to Green Cape was enlivened by crossing with a few Muppets who seemed to either think it was a one way road or not have worked out that it was a dirt. (Note from the future: on the way back I estimate we crossed with at least 15 cars, all displaying this quality of conductivity.)

Our first stop was Pulpit Rock which on our previous visit had been our first sight of the Shearwater migration. This time there were only about 50 here rather than the 10,000 I estimated last visit. Here is an optimistic shrub growing above the rock platform.

This is the view to the North.

A clip showing the colour of the water off the rocks and the pattern of the backwash.  The larger waves were breaking into the pool visible above the run off.

Definitely a Hakea: I suspect H. decurrens.

The most common shrub was Banksia serrata known as Old Man Banksia or Sawleaf Banksia.  Most plants had some nice flowers.  It being a National Park they are all still there.

A view over the heath.

Spot the birdie!  A New Holland Honeyeater: the closely related Tawny-crowned Honeyeater was Bird a Day.

We finished by driving down to the Lighthouse, which we found a lot more exposed to wind than Pulpit Rock or the heath.  There were more (~300) Shearwaters here as well as a Gannet and a Kestrel.

Runs and Gusts

On our morning walk today it seemed pretty windy.  So I was quite surprised on returning home to see that the wind run for each of the past few hours was only just over 8 km.  The maximum gust was around 30 kph which seemed more like it.  It is noteworthy that as I take records at hourly intervals the run is effectively the average wind speed over the period.

This has led me to explore the relationship between wind run and maximum gust as revealed by my weather station.  This gives me ~10600 observations.  My initial interest was in the ratio of gust: run.  This couldn't be calculated for 1614 observations as the run was 0 (in 368 cases the maximum gust was also 0, so a very calm hour!)

I will start with a chart showing the number of cases in which the ratio of gust:hourly run.

 54% of the ratios are in the range 2 to 3. I have no clear idea whether that is normal.

I attempted to look at some data from my last site in Carwoola but that was very sheltered so the runs were, I think, understated.  The biggest class there was a ratio of 7 -10.  From looking at the highest ratios (>10) at  Mallacoota they all occurred where the run was was very short (1.6 km in the hour) so an understated run might well increase the ratios.

For Mallacoota there is overall a good correlation between run and gust as shown by the quite significant trend line.  The equation for the trendline (Gust = 5.46 + 1.99 Run) indicates that the gust is likely to be twice the run.

I calculated the average ratio by month.  The graph shows a reasonably significant pattern on increase around the middle of the year but none of the values are outside the 95% confidence intervals.

I also calculated the average ratio by wind direction.  With wind direction I am always tempted to display the results as a rose chart.  Doing so in this case produces

1. a pretty chart but 
2. one that doesn't show any great differences!

Possibly the second point is because the differences are quite subtle.

As always, with anything to do with wind I am suspicious about the impact of siting on observations.  In this case I think it quite likely that the location shelters the WS from the strongest gusts frm NE to SE, thus cutting down the ratios in those sectors

More on wind

I have posted in the past about a comparison of data from my weather station (WS) and the Bureau of Meteorology site  The conclusion is that my data is reasonable as a general indicator of what the weather is doing (or has done).  To some extent this is a little surprising as the anemometer is mounted about 2m above the ground rather than 10m and is not well exposed other than from about NE - N -WSW.

With that being said, as I have compiled my monthly reports it has seemed to me that the wind direction has changed in the Summer months with a much higher proportion coming from the South East than in other seasons.  So I decided to check out what my ~14 months of WS data had to say about wind direction.

Cutting to the chase, my examination that follows with (unfortunately in some views) several graphs concludes that for 2019 at least there was a seasonal pattern in the direction of the wind.  ESE in January February, then WNW or N until July with WSW-W for the rest of the year.  I took a brief foray into barometer readings to see if they explained anything but have so far failed to find the silver bullet in that regard.

There are several measures of 'amount' of wind available from the WS: average speed over preceding period; high speed over preceding period; and run over preceding period.  As I take a period as 1 hour the wind speed and run are effectively the same.  I will start off using run.

The first chart shows the average hourly run recorded x month.  Note that I have truncated the vertical scale to emphasise month to month differences.  The surprising aspect is that November appears to have the fastest winds.

 Clearly the strongest winds come from the North.  I suspect this may be related to exposure of the site to that direction, but if that is the case I am surprised that the winds from the NNW and NW are not equally strong.

What I was most interested in was whether the apparent shift between segments of the compass was real.  I tried many ways of demonstrating this and concluded that the best way of doing so was to focus on the three segments (ESE; NNW+N; and WSW+W) which together make up 85% of recordings over the year.

My first approach was to look at the % of run recorded from those the segments.  There is a clear Summer peak in East winds, but it is still outweighed by the NNW+N segment in all months with WSW+W becoming dominant in late Winter/early Spring.

 Adopting a slightly different approach and counting the number records from each segment emphasises that pattern with East winds dominant in January and February; the NNW+N ruling until July and then WSW+W taking over for the rest of the year.

 I wondered if I could show the strength of winds to be due in some way to barometric pressure.  My first attempt was to plot daily run against average daily pressure.  While the trend line does slope downward (low pressure is linked to stronger winds) this is not significant.

My second thought was to wonder if the change in pressure (such as might occur when a front passed through) showed a pattern.  My measure of change was the difference between the maximum and minimum pressures in a day.  The trend line is again not significant.

Figbirds and Bastion

I began the day with a visit to the fig tree.  No Topknots but an array of Figbirds.  This male took his loot across the road to pose in a palm tree.

As the sky was overcast I had to post-edit the exposure of the snap to show his colours. Thus the colourless sky.

In the afternoon we went to Bastion Point, with an aim of looking at some rocks to  identify ythe features shown in this webpage.

The weather was quite warm when we arrived - about 29^oC with a strong NW wind.  When I got to the furthest point on the blue line the wind suddenly swung round 180^o and the howled along the beach, dropping the temperature about 10^oC.

An earlier visitor had been creative.

A serrated shore platform: most this had been covered with sand.

Honeycomb weathering

I don't know the technical name for this form of weathering but is looks attractive..

The tide was not as low as we were expecting.  A pool had a colony of Southern Fan Worms (Sabellastarte australensis)

We spoke with a snorkeller, who turned out to be a chef, looking for seaweed to cook.  He pointed out this lot of Neptunes Pearls (Hormosira banksii) which he assured us was very tasty when fresh and ate some he had found underwater.

I was surprised to see a Great Egret on the rocks.

Not so surprised by the Eastern Reef Egret.  A second bird flew in on the gust of the Southerly.

Sooty Oystercatchers have been thin on the ground recently so it was pleasing to see 2 on Tpip Beach.

I was hopeful of an interesting Cormorant in this group but, alas, only Great and Little Pied.

The aim of this photo was to catch the blast of sand being blown by the gust.  I think it sort of gets the idea.

Wind and Wood

The wind has died down.  Down is the word applicable to a fair proportion of the wood in the area!  We drove out to Fisherman's Point yesterday and there were a few shrubs blown into the road,  On discussing this with the serving-person at the servo he mentioned that there were a few trees across the Casuarina Track.  So checking that out became an objective of my bike ride today.

In fact I didn't have to get as far as the Casuarina Track.  This was the situation at the top of our road: it is a short dirt cut-through goat track which makes the street more or less a cul de sac unless you need to go that way because of flooding.  My guess is there will be little pressure from residents to remove the blockage.

There were a few small trees across the Casuarina Track but I was able to go round (or jump) them until I got to this one: perhaps 60 cm high.  I had to get off and lift the bike over.

No real root ball here, but presumably some roots still in the ground as it was a substnatial bit of lumber.

Later in the day I drove to Karbeethong Rd to check out the orchid situation,  Before I got out of the 50 kph zone there was a cut up tree  beside the road,  Then I got to this one which would have thoroughly blocked the road.  Points A and B were connected but are now about 15 m apart.

This shows the daily wind runs since we moved in.  Yesterday was the second longest we have recorded at home.

I mentioned orchids as my target.  There were a lot of Caladenia catenata and a surprising number of them were pink rather than white.  I think they were all good samples of that species rather than the hybrid we found the other day (which was under part of the fallen tree).

There were also some birdy things of interest though the day.  After the Casuarina track I visited the Satin Bower Bird site on Rasmus St.  Again the owner nicked off when I arrived, but I did get a decent shot of his work.

Heading home from Karbeethong I took a few snaps of the three species of Cormorant on a jetty.  First up is  Great Cormorant.

Little Pied Cormorant

Little Black Cormorant.

Wind and waves

As you may have noticed, 7 September was pretty windy.  I recorded a strongest gust of 72 kph: about 7 minutes later a/the squall got to Gabo Island giving it its big speed of 111 kph.  The reading on my station was the highest I have recorded here (by 11 kph).  The wind run (the distance the wind traveled in a day) was 339 km - the second highest logged here.  ( A site at Mittagong reported a run of ~750 km!)

This stirred the sea up a bit.  Not a good day for fishing or a pelagic birding trip!  Here are a few photos.

WE first went to Fisherman's Point, from which lookout the Gabo Lighthouse was barely visible.

 There were a few pelagic birds visible (1 each of Great-winged Petrel, Black-browed Albatross and Shy Albatross) and several flocks of Gannets totaling at least 60 birds.

The strongest gusts of wind stirred up patches of spray ...

 .. that got quite dense at times.  Some had a rainbow effect but I didn't catch that.

 The waves were quite large.

 On the way home (dodging fallen vegetation as I didn't have my chainsaw with me) we paused to look at Betka Beach.  The waves weren't quite eroding the dune but clearly some breakers were getting over.

 At Bastion Point the breakwater was getting a workout.

 A nice breaker!

 A view along Bastion Beach.