Pebbly Beach towards Shipwreck Beach

Having had reports from a few folk of making this walk recently we decided to have a crack at it today.  It seems to take about 4 hours for the full circuit and we decided to cut it short, and do an out-and-back route, after about an hour.  This is the track recorded on eBird .

Looking at the broader area on Google Earth suggests we got about half the distance.  It was a bit slow going for a while as the track was very hard to spot.

This is the heath we crossed.  The track was quite clear here.

The track was less clear in the forested area.  This was actually a medium obvious section, where it was visible on the ground.  In some place it was really only detected by the ground being compacted rather then soft and puffy.

To make it easier for you I have put in lines for the track.

Close  to our turn point we went down to the the cliff top to look out over the sea.

There was not a mass of flowers (that wouldn't be expected anyway in May)  but there were a few attractive specimens around.  This is Burchardia umbellata (Milkmaids) which according to Flora of Victoria usually flowers July - October.

A few daisies were flowering with several examples of Coronidium scorpioides which is usually September to January.

Another specimen of Coronidium, with bonus moth.  I judge the quality of my moth photos on whether the proboscis is reasonably clear: this one gets a pass mark!

The back of a Wahlenbergia.  Not a great snap but I like the colours of the calyx brought by the sun shining through.

Stylidium graminifolium a Grass Triggerplant.  I always find it hard to get a clear photo of this species.  The petals seem to reflect a lot of light.  The flowering season is given as "Mostly Aug to Nov".

Schelhammera undulata was quite common in the woodland.  September to November.

Out in the heath it was apparent that many of the incinerated shrubs were sprouting from the base of the trunk.  This is (I think) a Leptospermum sp. (Tea tree.)

This species was not very cooperative but looking closely shows the sprouts of Allocasuarina paludosa coming through the grass.  That was the dominant species in the heath prior to the fire.

I am reasonably sure this is Callistemon citrinus.  The authors of Flora of Victoria explain why they haven't followed the fad of including Callistemon within Melaleuca: if only a few other authorities did the same!

There were some nice fungi around also.  The first two species were in a shallow watercourse heading down to the cliffs.  

This is Peziza tenacella, an ascomycete cup fungus.

The next two are basidiomycetes.  A jelly fungus Tremella mesenterica.  Just about every word in that was wrong!  The experts at Fungimap have suggested it is another Ascomycete  - possibly Anthracobia muelleri, but I can't pick up the diagnostic brown hairs in the image.

Somewhere in the woodland heading back we met this Basidiomycete leather fungus Podoscypha petalodes.  I have a memory of having found a specimen of this last time we were down this way.  It grows on dead buried wood.

The next photo is largely included as a reminder to me to comment on the amount of insect damage to the epicormic shoots on the eucalypts in the forest.  Presumably these soft young leaves are easy targets for caterpillars.

Birds were not greatly evident.  I did hear the first Crescent Honeyeater of the season in the woodland near our turn point, and some Yellow-faced and White-naped Honeyeaters flew over (giving the "chip-chip" and "mew" calls respectively.  In total I recorded 10 species of which 4 were on, or over Pebbly Beach.   A Great Cormorant earnt a photo by posing nicely (it has a small crest so in Europe this would be a photo of a Shag on a rock).

One of the 5 Pied Oystercatchers was flagged.  Unfortunately it seemed to have something else on its mind so I couldn't get a read of the number.

It was a very pleasant walk.  While the difficulty of spotting the track meant we worked a little harder that is not a problem.  It is slightly (OK, very) annoying to note that the contractors - under direction from ESGC and/or Vic Parks) are still devoting effort to pruning trivially burnt vegetation on the roadside near Betka Beach rather than opening up the walking trails.

Minima at Mallacoota and Gabo Island

On a Weather Forum in which I post I wrote on 13 May:

 The BoM site is showing a minimum of 6.8C at 0640 - and may get a little lower. The surprising value is the minimum for Gabo Island at 11.2C at 0557. I know Gabo is surrounded by relatively warm sea but that seems a very large difference over such a short distance especially with wind at all sites coming from WNW.

One response to this was 

Quite similar thing happens here, I'm 2km from the coast and the min was 6.9°C morning (identical to yesterday's), yet the min at Bellambi (6km NNE and right on coast) was 12.0°C with a land breeze all night. The ocean does make a big difference to minimums.

So I thought I should investigate a bit further.  Using the excellent Climate Data Online facility at BoM I got a year's minimum records (taking 2019 as sufficient for my needs) for the two sites (Mallacoota # 084084, hereafter Airport, and Gabo Island #084016, hereafter Gabo) to see how they compared.

I omitted any days on which  either site didn't report a minimum giving me 330 records.  There were 35 null values for Gabo one of which was also blank for the Airport.  The correlation coefficient between the two series was strong at 0.935.  As would be expected from that a scatterplot of the two series shows a good significant trend.

Very few of the observations were identical.  The average difference (Mallacoota-Gabo) was -1.8^oC.  Disregarding sign the average difference is  2.0 ^oC.

The great majority of the differences are between +1^oC.  and -4^oC.   They are summarised in this chart, with the red-hot snowflake indicating the approximate position of the reading of 13 May.  So it was a relatively large negative difference!

It is still a little surprising that there are such differences between two sites within ~16.5 km.  The airport site is 200 m from the sea and 22 m elevation and I suspect the Gabo site is a similar distance and 15m elevation.

The wind direction at both sites was similar on the night between 12 and 13 May, mainly WNW with the speed a little higher (~20 kph) at Gabo than the Airport (11 -15 kph).  Perhaps the wind coming across a few kilometres of sea warmed it up?

The only other difference I can think of is that there some buildings on Gabo - but I think ~50 m from the screen.  At the airport the screen is in an open paddock (covered with mown heath in 2019) with no nearby buildings and the nearest substantial vegetation over 100 m away.

Waves

The huge swells of the past few days had died down by 5 May but there was still some interest in the sea at Bastion Point.

The first couple of images show a wave breaking over a rock ..

 ... and then the run off.

 Green algal growth was quite evident between the waves (this was about mid-tide).

 An immature Australasian Gannet passed by and was unusually cooperative in allowing photographs.

This rock, on the Tip Beach side of the Point reminded us of the illustration of fortresses in fantasy novels!

 A surfer was out in the water with a rather large - by the standards of modern fashions - board.  Not quite an old style malibu but definitely a return to traditional values.  I didn't get a chance to get his permission so I have obfuscated to block facial recognition!

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

Weather Report April 2020

The month overall was fairly bland.  Rain somewhat below normal (again) and overall temperature slightly above normal.

Rain

We totaled 61.2 mm for the month, with three days of falls greater than 10 mm.  The total was 78% of median and brought year to date to 83% of the average.  On the positive side, at least the April fall was above last year although by the end of April the total year to date was almost identical to 2019

A pro-rata estimate of the annual rainfall is now 781 mm.  The values of that projection since the start of the year suggests it is plateauing around 800 mm.

Temperatures

The temperature anomaly finished the month at +0.3^oC.  Overall more minimums were above average than below, while maxima were  almost evenly split. 

	min above	min below	total
max above	9	5	14
max below	10	6	16
total	19	11

The pattern overall was not significantly different to that expected although eyeballing the daily values hints that for the first three weeks minima were high and maxima low while the reverse was the case for the rest of the month.

The daily extremes are reasonably stable with two warm days mid-month standing out.

Maximum Temperature

The average maximum from my weather station was above average which may reflect the average coming from the BoM site, which is typically cooler than my site due to a sea breeze cooling afternoons at the airport.   

A time series of average maxima - allowing for the difference due to siting, shows the maxima are all over the place between 18^oC and 23^oC.  The "trend" is not at all significant. 

Minimum temperatures

Again the average minimum for the month was above the long-term mean.  It was however below last year's value.

 Again the time series is all over the place and no significant trend is shown.  As the series appeared more stable from 2007 onwards I looked for a trend in that but it was not significant.

Humidity

The chart of daily humidity has a couple of unusual features.  Firstly it is unusual to see so many days where the 0900 value is below than for 1500.  Secondly the very low 0900 values for 16-18 April caused me to check with the BoM data for those periods: they were almost identical.

Despite the low values referred to above the monthly average for 0900 is above the longer term mean from the BoM site and above the value for 2019 (which was very dry.

 In contrast the 1500 humidity was somewhat lower than other periods.

Wind

The month was not very windy.  The three days with long runs all preceded fronts coming through with consequent rain.  The winds on 29 April were given much hyperbole in the media (I was mildly disappointed that no one actually coined the neologism "windmageddon").

 Overall the run was less than last year and below the benchmark of BoM values adjusted for that site being much more exposed than my site.

 In terms of the direction of wind it made the usual April switch back to NW-N, with 36% of wind recordings coming from that section of the compass.