Ocean and Beach scenes

There was a Southerly Gale blowing today so I have been down to the sea a couple of times.  The first was to Fisherman's Point to look for pelagic birds being blown inshore.  The sea suggested this was a better idea than going out in a boat looking for the birds.

 With the help of my telescope I found a few birds and could identify about 6 Gannets of various ages, a Wedge-tailed Shearwater and about 6 Fairy Prions. No albatrosses.

In the afternoon we went for a walk at Bastion Point.  The wind was causing a strange sight by eroding sand around pebbles.

 The is Gannet's head was washed up and I originally took the photo to show its plumage.

 Then I looked more closely and noticed what looks like a strap around its neck so I think this is one more victim of plastic pollution.

Another member of the Mallacoota Birds Facebook group has since opined that this looked like it was skin colour with post mortem flexing of the neck causing the feathers to fall out.  On looking closely at the original image I think she is right.  A subsequent attempt to relocate the head failed.

As we got back to the the stairs we noticed a couple of former leatherjackets getting washed up.  Apart from the interest in the individual fish I thought this might foreshadow another massive kill of these fish as we found in April 2017.  I'll try to get a species ID shortly.

 The next two images are looking from the top of the steps at Bastion Point.  The seas appeared to have died down quote a bit in the hour we were there but still nice. well separated swells coming in

May 2019 Weather Report

In summary the month was quite close to average.  Rain was only a little below median and most temperatures were close to average.  Humidity was close to average.  The month wasn't too windy.

Possibly the most 'different' thing for May was how much better (ie higher) our rainfall has been so far this year compared to last year.  The vegetation is growing again: pity about the mosquitoes!

Rain

I have looked at the variability of monthly rainfalls and for most months the pattern is a small number of high values and a much greater number of lower values.  Another way of expressing this is to say that occasional very high values inflate the mean so below mean could be expected in most years.  Here is a comparison of mean and median (the value that half observation are below) rainfalls.(since 1975) for each month.

The median rainfall  is probably a more useful measure and I will use that in the future.

We ended up with 62.8 mm of rain with falls >1 mm on 10 days.  This total was a little less than May 2018 and 92% of the median value. 

We are currently at 77% of the mean for year to date.  Doing a pro-rata expansion of the year to date value gives an estimated fall for the year of 721 mm.  If that comes to pass it would be the 5th lowest annual fall since the series began in 1975.  This next chart shows how the pro-rata estimate has changed as this year has progressed.

I heard an interesting comment about the weather recently, looking at the current number of rain-free days which was very high in most Capital cities.  I have found it easier to calculate the number of rain-days.  (I define a rain day as >0.2 mm since a decent fog or dew gives 0.2 mm.)

We had more than an average number of rainy days but most of them had small amounts.

Temperatures

The usual overall view of the temperature is to look at the maximum and minimum daily temperatures.  These data come from my weather station.

The  chart clearly shows the very warm spell at the start of the month.  The impact of this can be summarised by noting that the average temperature for the month was 0.24^oC above the long term average.  Excluding the first 3 days makes the average for the rest of the month 0.22^oC below the long term average.

For temperatures the mean and median series are very similar for both minimum and maximum temperatures.  Since "Mean" is the usually accepted non-technical meaning of "Average" I will use means in this section.

Maximum Temperatures

The average maximum temperature at the BoM station on Betka Rd was 18.3^oC.  This is a little higher than both2018 and the average.

 The time series of average maxima for May is somewhat unstable but shows a slight (but with an r² of  0.13 not significant) upwards trend.

 Minimum temperatures

The average minimum temperature at the BoM station on Betka Rd was 9.24^oC.  This is of a little higher than 2018 and almost the average of 9.30^oC.

The time series for minimum temperatures resembles a profile of the Himalayas,  Not surprisingly there is no trend in these data, but is it interesting that the ups and downs are within a very tight band from 8.03 to 10.30^oC.

Humidity

The first chart of daily data is taken from my weather station.  Not surprisingly tis tends to have slightly lower readings for rH than the BoM station which is much closer to the sea, and more exposed to wind.  Nothing surprises me in this chart.

 For the comparison with longer term values I have used data from the BoM site.  The usual "Climate Data Online" which I use for temperatures and rainfall only has a restricted amount of data available.  I have been able to extract from that humidity data as:

• a series of averages for all years 1993 to 2010; and
• individual month data from February 2018 onwards.

 These are used to generate the following graphs.  Note that the vertical axis has been truncated which exaggerates the month to month variation,

My conclusion from this is that thus far 2019 is more humid than 2018 but overall about similar to the average.

Wind

I posted recently about the interpretation of the wind observations from my weather station and how they compared with the official BoM readings from Mallacoota.  My concluiosns were:

• Wind run is an appropriate measure to use as an indicator of longer term windiness,as it includes a lot of information; and
• The information from my Weather Station is a reasonable measure of relative windiness for Mallacoota.
• Wind run has a high correlation with the 1500 speed (which occurs after the day has developed a reasonable weather pattern) and the 1500 speed is available on a daily basis so I'll choose that as my standard indicator of current windiness from now on. 
• In 44 (73%) of cases the the wind direction recorded by my weather station  was within one compass segment (22.5^o) of that reported by the BoM site.  To my mind that is an astonishing level of consistency and indicates that the wind direction data from my weather station is also fit for the purpose.

Having got all that off my chest, what about some data?    This first chart shows the 1500 Hrs speed, indicating a couple of very draughty periods with relative calm through the middle of the month.

This next chart is pretty pathetic in showing the windrun, comparing a 15 year average from BoM for Mallacoota with the three months for which my weather station has data.  As I build up data the chart will get better!

 A rather interesting wind rose in which the slices of the pie reflect the proportion of observations of wind.  There were no observations for the directions ENE, E or SSE.I have marked the position of South outside the pie to reinforce the view that 3/4 of our wind comes from the Western half of the rose, but spread fairly evenly between those 8 segments.  (An eyeball of the BoM climate summary for May comes to a very similar conclusion: looking at the directions of max gust; 0900 and 1500 reading there are very few readings between NNW and S!)

I have just checked the maximum gusts for the month:

• Angophora WS: 54.7 kph at 2000 on 27 May
• BoM Mallacoota: 76 kph at 1933 on 27 May
• BoM Gabo Island: 98 kph at 2000 om 27 May

The relativities are as expected (possibly my WS has done better than expected) and the timings all line up very nicely!

Surf ....

... was available today.  Photos taken by phone at Bastion Point at noon.

We also went to Quarry Beach about 1515 and I think the waves were even bigger - well over 2m,  Some of them broke right up to the vegetation which caused us to return, not wishing to get wet feet!

It's Lennie time!

One of our references is The Cloudspotters Guide by Gavin Pretor-Pinney,  He also formed the Cloud Appreciation Society so I thought it apt to link to their site!

He describes lenticular clouds as a species of alto-cumulus clouds.  They are orographic: ie formed when air is forced upwards as it goes over an obstacle such as a hill or Mountain. Apparently glider pilots refer to them as "lennies".

With the wind coming from the NW today a bunch of good lennies formed to our NW later in the day.

 The classic shape is likened to a flying saucer.  This one looks more like a cigar - or perhaps a roll-your-own!

 Mt Imlay is certainly a mountain!

As the sunsets the colours got stronger.

Sunset 25 May

Spectacular sunsets are the rule at Mallacoota, especially from our house.    Here are a set of photos I took on the 25^th.   I particularly like the textures in the clouds in the later photos.

The foggy, foggy dew.

This post does get to weather eventually.  Trust me!  (Whether what happens in that discussion is comprehensible is a separate question.)

I hate to disappoint any followers of archetypal Pom folk songs but I'm not a weaver and no young maidens will be saved in this blog post.  I will disappoint them further by not including a you-tube link to that song as everything on line seemed to either be:

• by Burl Ives or Marty Robbins - who have no connection with England - or 
• a version by Benjamin Britten which is about as folky as "Nessun dorma"  (Incidentally the answer to the question posed in that video is clearly Jussi Bjorling.).  or
• a much more modern Irish song (The Foggy Dew) about the Easter Uprising. 

To meteorological business.  In recent mornings I have noticed a heavy dew on the pavers out the front of our house.  The area concerned is approximated by the red/yellow rectangle in this image.

My weather station (WS), located at the aqua circle, produces data on the dew point as well as the actual temperature.  I was interested to see what the WS said about dew point, temperatures and humidity.  In principle I thought that to get a heavy dew the actual temperature and the dew point should be the same.  This first chart shows the hourly temperature and dew point for the first 20 days of May ( I haven't been able to work out how to get the dates in the axis ).

 Note the area boxed with dashed lines.  In that area of the chart, overnight the temperature and dew point are very close together.

The two measures never actually achieve equal values but the difference is less than 1^oC for some periods, which I suspect is equality within the accuracy of the equipment.

I also wanted to compare this with measures of relative Humidity (since dew point is a function of humidity and temperature).  When Humidity is high (ie close to 100) the difference between temperature and dew point is low which makes a messy chart, so I plotted (100 - rH ) which I am calling "inverted rH". As the two series are of different scale I have used the LH scale for difference in temperature and the RH one for inverted humidity.

With all that adjustment I am unsure how much reality is left in the information!  However it does show that the basic story of high humidity gives dew point close to the recorded temperature is supported by my data.  The two series plotted show a correlation coefficient f 0.996!

As a third way of looking at dew, Frances noted that on the morning of the 21st there was much less dew on the pavers and no condensation on the glass screens on the northern side of the house (red lines in the first image).  As with the paver area the screens are sheltered from the wind so are possibly more likely to get condensation than the more exposed WS position.

Tern and Dolphins

I know I said this blog was to be about things other than birds, but occasionally an excellent bird comes along and gets a guernsey.  Especially when there are other things to include!

I commented a few days ago about a White-fronted Tern which terned (sic) into a Little Tern.  The link there includes a couple of maps illustrating the migration of the White-fronted Tern from NZ to Australia.

Today there was an early alert about a Common Tern at Betka Beach.  However that terned out to be ....... an immature White-fronted Tern.  Amusingly one of the key field marks is that a Common Tern has more white on the front of its head  (or to put it another way, the White-fronted has more black in that area).  Here are a few photos.

This first one mainly gives an idea of the bird's size relative to Silver Gulls and a Crested Tern.

 In this one, the black scalloping on the bird's back (another strong field mark) is just hinted at,

 The scalloping is perhaps a bit more visible here.

 A nice close up.

 I ten went down to Quarry Beach.  Just as I was about to leave a pod of about 6 Bottle-nosed Dolhins appeared.  They were doing the whole athletic bit: surfing down waves and jumping completely clear of the waves.  It is pretty much impossible to tell where they were going to appear along a 200m stretch of surf so I just pointed the camera and pressed the button where I last saw them.  This snap is not too bad!

 This was my second best shot: one fin and the suggestion of a shape surfing!

 Imagine how bad the other photos were!

As a result of comments on Facebook by Dan Ashdown and Janine Duffy I now know these to be Indo-Pacific Bottlenosed Dolphins Tursiops aduncus. See this site for a field guide.

We were standing on a rock to get snaps and I thought these shells and green kelp were interesting.  They were about 1 metre above the current water level which needs a bit of thought as most of the tides are not that high.