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#871767 - 12/07/2010 07:26 Re: Observations of climate variation [Re: Surly Bond]
Keith Offline
Meteorological Motor Mouth

Registered: 16/12/2001
Posts: 6453
Loc: Kings Langley, NSW
Hmm, don't know why that is. It's showing up here large as life.

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#871781 - 12/07/2010 10:38 Re: Observations of climate variation [Re: Keith]
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2193
Loc: Manilla, near Tamworth NSW
I have an image now. So you forecast no droughts in coastal NSW before 2013?
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#871783 - 12/07/2010 11:05 Re: Observations of climate variation [Re: Surly Bond]
Keith Offline
Meteorological Motor Mouth

Registered: 16/12/2001
Posts: 6453
Loc: Kings Langley, NSW
On the face of it, yes, no droughts there. I'm going to rerun the whole process using a Monte-Carlo simulation of the data to see how the modelling works with the equivalent of say 300+ years of observations. I've seen this done in several academic papers I've read.

I had mentioned going just from a more recent date but a neural network model will be less accurate. The more data it gets, the better..apparently.

I am generally of the view that the current drought will be further reduced but that doesn't mean of course that some areas will get dry spells in between the wet ones.

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#871798 - 12/07/2010 13:06 Re: Observations of climate variation [Re: Keith]
Keith Offline
Meteorological Motor Mouth

Registered: 16/12/2001
Posts: 6453
Loc: Kings Langley, NSW
Originally Posted By: Keith
.....that doesn't mean of course that some areas will get dry spells in between the wet ones.

Should be '..won't get..' etc.

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#872222 - 15/07/2010 08:22 Re: Observations of climate variation [Re: Keith]
Simmosturf Offline
Weatherzone Addict

Registered: 17/03/2008
Posts: 1620
Loc: Wangaratta
Every drip has a climate story to tell

WALKING into a cave of stalagmites and stalactites is like entering a Tiffany's showroom. But unlike an expensive ring, the sparkle of these formations is a precious record of climate history.

Australian scientists are using structures from the Wombeyan Caves, south-west of Sydney, to build a picture of rainfall patterns in NSW over the past 1000 years.

They reveal the area has been subject to an increasing drying trend since around the 1600s, she said.

The drought which has engulfed south-east NSW for the past decade or so now appears to be part of a larger drying period, said Dr McDonald, who presented her findings at the Australian Earth Sciences Convention conducted by the Geological Society of Australia in Canberra last week.

The historic rainfall data will be used in forecast models to better predict the area's climate cycles.

http://www.smh.com.au/environment/climat...0711-105pv.html

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#872449 - 17/07/2010 11:03 Re: Observations of climate variation [Re: Keith]
Keith Offline
Meteorological Motor Mouth

Registered: 16/12/2001
Posts: 6453
Loc: Kings Langley, NSW
Originally Posted By: Keith
I'm going to rerun the whole process using a Monte-Carlo simulation of the data to see how the modelling works with the equivalent of say 300+ years of observations.


Just a quick update..this hasn't worked as I think it needs to capture the particular statistical qualities of the data (ie not just the distribution curve, average and standard deviation). It seems to me that it's incapable of duplicating the effect of cycles and other variables.

So, still in front of the 'drawing board'...

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#874468 - 31/07/2010 23:47 Re: Observations of climate variation [Re: Keith]
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2193
Loc: Manilla, near Tamworth NSW
Cloudiness

Cloudiness at Manilla NSW has changed dramatically during the last twelve years. Data comes from observations of total cloud in Octas at about 9 am daily. More than four octas is counted as a "Cloudy morning" and is summarised as a percentage for each month. The mean pattern in the 10 years from June 1999 is:
Jan: 26.2%
Feb: 30.6%
Mar: 24.1%
Apr: 29.6%
May: 24.4%
Jun: 33.5%
Jul: 35.3%
Aug: 30.2%
Sep: 23.8%
Oct: 27.8%
Nov: 33.4%
Dec: 31.1%
I have subtracted these normal monthly values to get the anomaly values analysed here.


The first graph shows monthly cloudiness anomaly values and (in purple) values smoothed with a gaussian smoothing function of half-width 6 months.
The pattern is complex, and not easily described. It is clarified by using CUSUM analysis.
CUSUM analysis was invented in 1954 by E. S. Page, to allow early detection of changes in trends, such as those caused by damage to a die in an automatic machine. The data for a CUSUM sequential analysis is simply the sum of all values to a particular time.


The second graph is a CUSUM plot for this data set. There is an abrupt, very large change in the trend in mid-2007. I fitted the linear trends accurately by using the Excel Charts Trendline function on separate plots for data from 1999 to 2007 and for 2007 to 2010. The first trend line has a slope of -2.46 units per month, and the second a slope of +9.08 units per month.
Only the slopes of these trend lines, and their point of intersection in August 2007 are of interest. A CUSUM trend line of constant slope represents a constant mean line for the original data above (+) or below (-) the longer-term mean.


In the third graph I have inserted the two mean value lines that correspond to the two CUSUM trend lines. This shows the abrupt increase in mean cloudiness in August 2007 by 11.5 percentage units.
This is a very large change. Certain monthly anomaly values lie on the first mean line. The actual percentage cloudiness for those points are near 30.5%, making cloudiness near the second mean line about 42% (i.e. 30.5% + 11.5%). Expressed as numbers of cloudy mornings per month, the once typical value of nine has been replaced by twelve: an increase of one third.

Having established the two mean lines that reflect the trend lines from the CUSUM plot, I subtract them to get the de-trended cloudiness anomalies shown in the fourth graph.

The smoothed values (purple) now consistently oscillate about the zero line. The period and amplitude of oscillation is strikingly different before and after mid-2007. Counting peaks and troughs in the curve gives estimates of period of 20.5 months before mid-2007 and 8.4 months afterwards. The amplitude of oscillation changes from about 5 units to about 1.5.

So far as cloudiness at Manilla NSW is a climate indicator, there was a major change in August 2007, give or take a month or so, involving a 30% increase in the amount of cloud, and such a reduction in the amplitude and period of oscillation that Quasi-Biennial Oscillation essentially ceased.
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#875106 - 03/08/2010 19:17 Re: Observations of climate variation [Re: Surly Bond]
Keith Offline
Meteorological Motor Mouth

Registered: 16/12/2001
Posts: 6453
Loc: Kings Langley, NSW
I have been working further on the rainfall modelling I posted on earlier in this thread and have started a seperate thread here.

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#875829 - 09/08/2010 17:51 Re: Observations of climate variation [Re: Keith]
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2193
Loc: Manilla, near Tamworth NSW
Manilla Smoothed Monthly Anomalies of Climate Variables
Parametric Plots
Update for July 2010

New data for July 2010 allow updating with more smoothing applied to all months back to January 2010, which is now fully smoothed. A new commentary on the trends to replace the one in Post #866367 is not yet justified. New trends may be evident in a months time, when the summer months of 2009-10 will all be fully smoothed.

The July 2010 data, marked with orange diamonds, shows an extraordinarily moist month. Anomaly values of rainfall, cloudy days, Dew Point, temperature range and minimum temperature are so extreme that the graph margins have had to be moved.
Extreme moisture is usually associated with low maximum daily temperatures, in the "Flooding Rains" corner of the graphs, but this July the maximum temperature is not extremely low, but normal.


Sorry, the red square which should mark January 2010 is on December 2009 in the top left graph.
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#880243 - 01/09/2010 18:14 Re: Observations of climate variation [Re: Surly Bond]
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2193
Loc: Manilla, near Tamworth NSW
Manilla Smoothed Monthly Anomalies of Climate Variables
Parametric Plots
Update for August 2010

This updated set of parametric plots shows that Manilla's recent climate continues to be marked mainly by cloudier skies and a narrower daily temperature range than in the 12-year averages.
In the current plots we see final smoothed trends for summer 2009-10, plotted as filled red diamonds. Unfilled diamonds mark provisional trends for autumn of 2010 and little-smoothed to unsmoothed points for winter 2010, ending with an orange diamond for August 2010.

I last discussed these trends in June (Post #866367).

Daily Maximum Temperature
On each plot, the x-axis has the smoothed anomaly of mean daily maximum temperature. The min value in Feb 2008 (-1.61) and max value in Nov 2009 (+1.35) are also the extremes (plotted in blue) of the smoothed data set. In summer 2009-10 the smoothed temperature anomaly fell much faster than it had risen in the previous winter and spring. During autumn the max temp anomaly was near zero, and the raw value for August is so low (cold) the scale has had to be extended.

Monthly Total Rainfall (y-axis (inverted), first graph)
The rainfall anomaly showed a very mild drought throughout the last winter, spring, and summer. Autumn seems to have been less droughty, much like the previous autumn, but with the opposite trend. July 2010 was very wet, but August rainfall was normal.


Cloudy Mornings %
During winter 2009, the positive cloudiness anomaly fell as the max temp anomaly rose. During summer 2009-10 it rose again as the max temp anomaly fell. However, for a given max temp anomaly the cloudiness anomaly was now more positive (it was cloudier). Since the end of summer, skies have been extremely cloudy (See Post #874468).



Early Morning Dew Point
The final year's data on this graph plots like that of the previous graph. However, Dew Point anomalies were not so positive: in winter and spring 2009 they were quite strongly negative. By autumn 2010, Dew Points seem normal, and recent values are high (humid climate).


Daily Temperature Range
Again, the last year's pattern on this graph is like that on the previous two. This time values low on the graph are negative anomalies, representing narrow daily temperature ranges. For a given max temp anomaly, the anomaly of daily temperature range was lower during the summer than it had been the previous winter. Fully smoothed temperature range anomalies for autumn 2010 seem likely to be low enough to match the minimum of the smoothed record (blue), and the raw values this winter have been even lower (equable climate).
(Note that, despite the label in the corner of the graph, this August's max temp (16.8 degrees) is actually much higher than that of Macquarie Island (5.0 degrees), and the daily temperature range (11.9 degrees) is still much wider than that of Macquarie Island (3.5 degrees).)


Daily Minimum Temperature
Summer 2010 began with a record maximal value of smoothed daily minimum temperature anomaly, and the value stayed high through the season. Values may have been lower in autumn, then they seem to have risen even higher (very warm nights).


Subsoil Temperature
Subsoil temperature anomalies have remained close to zero for 17 months, despite big changes in the anomalies of other temperatures.
_________________________
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#884837 - 22/09/2010 21:16 Re: Observations of climate variation [Re: Surly Bond]
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2193
Loc: Manilla, near Tamworth NSW
Nearly all nights now much warmer at Manilla NSW
New Manilla data show that nearly all nights of the year have become much warmer during the last nine years.

Graphs like these (but one year older) are introduced in Post #3785 on Page 3 of this thread. All the days (or nights) of the year are ranked from the coldest on the left to the hottest on the right. Columns show whether that day or night has tended warmer or cooler during the nine years. Season labels, and the temperature boundaries between them are not stricly correct. It is well known that the hottest days of 2009 were in spring, not summer.
In today’s graphs, blue columns show the temperature trends for the earlier nine-year period to August 2009, and red columns for the nine-year period to August 2010.

Graph No. 1 shows trends in daily maximum temperature (“Days”). In the earlier period the strongest trend had been to cooler summer days, but this trend has now ceased. A trend to cooler winter days in the earlier period has now expanded to the whole of the cooler half of the year. Trends to warmer days are grouped at the boudary between summer and spring or autumn. This pattern returns to one seen in the period to August 2008. Over all, in the latest 9-year period, days have been getting cooler at the rate of -0.0287°/yr.
Graph No. 2 shows trends in daily minimum temperature (“Nights”). The new curve is almost the same shape as the earlier one, but each trend has moved in the positive direction. Just a few of the hottest nights are still getting cooler, but all other nights have been warming rapidly. The over-all average rate for night-time warming is +0.1506°/yr.
Taking days and nights together, the mean temperature rose by +0.0609°/yr, about six times the Australian 100-year mean rate of warming. However, the difference between days and nights – the daily temperature range – is a more striking result: it narrowed by -0.1792°/yr. Over the nine years the linear trend of the mean daily temperature range fell by an astonishing 1.6°, from 16.2° to 14.6°.
This narrowing of the daily temperature range at Manilla in the last decade agrees with the sharp increase in cloudy days noted in Post #874468.

The published graphs and trends for Australian climate change show that narrowing of the daily temperature range has been nearly as great as the rise in mean temperature during the last 100 years. Daily minimum temperature has risen much faster than daily maximum temperature in all states except Victoria and Western Australia.
_________________________
Data are cheap; information is expensive!

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#887038 - 01/10/2010 18:10 Re: Observations of climate variation [Re: Surly Bond]
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2193
Loc: Manilla, near Tamworth NSW
Manilla Smoothed Monthly Anomalies of Climate Variables
Parametric Plots
Update for September 2010: "Flooding Rains".

New data for September 2010 allow updating with more smoothing applied to all months back to March 2010, which is now fully smoothed. A new commentary on the trends to replace the one in Post #880243 will be held over for two months, when the autumn months of 2010 will all be fully smoothed.

The September 2010 data, marked with orange diamonds, are in the "Flooding Rains" area in the bottom left corner of five of the six graphs. Anomaly values of rainfall, cloudy days, Dew Point, temperature range and subsoil temperature are extreme. The Minimum temperature anomaly has remained very high for a year.
_________________________
Data are cheap; information is expensive!

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#891875 - 17/10/2010 12:30 Re: Observations of climate variation [Re: Surly Bond]
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2193
Loc: Manilla, near Tamworth NSW
Warmer nights at Manilla

This post adds to Post #884837
which presented the daily temperature trends for every day of the year during the 9-year period to August 2010

The smaller graphs here show Manilla's average figures year by year, with linear trend lines. (Years begin in September before the labelled year, and end in August.)

The year “ ’08” was very cold, by day and by night. It was remarkably cold in December 2007 and January, February, March, April and August 2008. It was as if Manilla had moved 400 km south or 150 metres higher.
Apart from the year “ ’08”, the trends are rather steady. Days hardly warmed or cooled at all at Manilla in these nine years, but nights warmed a lot. (Affecting electric blanket sales, I wonder?)
These trends will soon change. However, they reflect long-term climate trends that should be better known.
See these Bureau of Meteorology charts. (Set the running average slider to “T”. The trend-line slope is in tiny print below the graph.) For Australia during the last 100 years the warming trend of daily maximum temperatures has been only 0.08°/decade, but the warming trend of daily minimum temperatures has been 0.12°/decade. Nights have warmed 50% faster than days. For NSW the figures are 0.05°/decade and 0.11°/decade: nights have warmed more than twice as fast as days.

It is as if we are all moving down to the coast.
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Data are cheap; information is expensive!

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#893980 - 28/10/2010 00:14 Re: Observations of climate variation [Re: Surly Bond]
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2193
Loc: Manilla, near Tamworth NSW
Cycles of 30 months, 20 months, and 8.6 months

The Quasi-Biennial Oscillation has appeared frequently in this thread. See discussion in Post #863801

The period of the QBO, as estimated using fast fourier transforms is roughly 30 months. I originally estimated the period of oscillations in my data, and in BoM long-term monthly temperature and rainfall data, as about 20 months. I did this by inspection of plots of smoothed monthly time series.
I thought that the shorter period I observed was probably an artifact, as the eye tends to see the shortest periods in an oscillating time series (e.g. in river meanders).
Later, in a Post on cloudiness I estimated that a periodicity of 20.5 months was replaced suddenly in August 2007 by one of 8.4 months.

It seems that these three periodicities may be real after all.
In a 1994 paper, M.P.Baldwin and Ka Kit Tung find that the equatorial stratospheric 30-month QBO interacts with annual oscillations to form stable harmonics of period 20 months and 8.6 months in extra-tropical areas.


This topic clearly fits within the Forum "Climate and Climate Change" but there is no suitable thread there.
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Data are cheap; information is expensive!

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#894250 - 29/10/2010 08:47 Re: Observations of climate variation [Re: Surly Bond]
BOM99 Offline
Weatherzone Addict

Registered: 23/08/2004
Posts: 4645
Loc: Australia
Some good work there Surly. To have warm nights increasing faster than cooler days is what you would expect if the climate was on a warming trend.
You do not do any grass readings by any chance?.
One thing that fascinates me are grass readings compared to the screen readings. I have long believed that if CO2 was to have the expected result on the climate then there should be a measurable change in the differences between grass and screen. The differences should get smaller given the same humidity. Unfortunately this is nearly impossible to prove because there are no decent historical records of grass readings.

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#894262 - 29/10/2010 09:27 Re: Observations of climate variation [Re: BOM99]
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2193
Loc: Manilla, near Tamworth NSW
No, Snowmi, I have no grass readings.
Actually, I don't have a lawn or a lawnmower!

Why would you expect CO2 to relate to grass/screen difference?
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#894296 - 29/10/2010 14:09 Re: Observations of climate variation [Re: Surly Bond]
BOM99 Offline
Weatherzone Addict

Registered: 23/08/2004
Posts: 4645
Loc: Australia
You do not need a lawn to take a grass reading, just the surface of the Earth in whatever form you have will do, gravel, dirt, the term "grass" just refers to the level above the surface that is within 1-2cm. By measuring the temperature at the exact interface of the Earth surface and the atmosphere you are measuring what effect the Earth surface is having on the heating or cooling of the atmosphere. The solid Earth surface is what is heating and cooling the atmosphere over the continents. Without the continents to absorb the Suns rays the Earth would turn into an Europa ice ball and without the oceans the Earth would swing from +100 to -100deg C between winter and summer.

As the sun sets the Earth immediately and rapidly starts to emit the excess IR back into space and you suddenly get a very rapid drop in temps right at the surface (grass level). The rate and amount of this drop in temperature is controlled by the amount of greenhouse gasses, if it is more humid the drop will be less and also in theory if there is more CO2 then the drop in temperature at the very surface should also be a little less.

If I could look at detailed records of humidity and temperature of two sensors one at screen level and one at grass level over the last 50 years then if CO2 does what its suppose to do then there would have to be a measurable change in the differences between screen and grass. Eg I would expect an average difference to change by say 0.5deg during lower humidity's from say 5.5deg difference to 5.0deg difference at 30% RH. The difference being caused by a change in CO2 from 300ppm to 390ppm. But as far as I know no one has made any accurate measurements like this 50 years ago.

Grass temps are a constant puzzle for me which is why I have contributed a fair bit to this thread.
http://forum.weatherzone.com.au/ubbthreads.php/topics/57739/3


Edited by snowmi (29/10/2010 14:10)

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#894317 - 29/10/2010 15:31 Re: Observations of climate variation [Re: BOM99]
Keith Offline
Meteorological Motor Mouth

Registered: 16/12/2001
Posts: 6453
Loc: Kings Langley, NSW
If CO2 was involved it could hardly make any real difference given its fraction ..very small.. of the total atmospheric pressure. In any case the grass would continue to absorb CO2 at the rate it always does, wouldn't it? If it absorbed more due to more CO2 then that's a good thing (for AGW supporters) and probably not a bad thing anyway.

The standard (I think worldwide) criterion for measurement of minimum temperatures on the ground (labelled 'terrestrial') is that the thermometer should be at the top of the tips of grass blades..obviously not long ones. I guess if one wanted to do a more elaborate study one could indeed measure temperatures over gravel or other surfaces.

It's true that the rate of drop of the temperature is controlled by moisture in the air, but also by wind and cloud cover, amount and depth, and I guess whether there is a lot of visible pollution like dust or smoke. I can't see how CO2 could possibly affect it, short of suffocating the whole human race.

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#894376 - 29/10/2010 20:05 Re: Observations of climate variation [Re: Keith]
BOM99 Offline
Weatherzone Addict

Registered: 23/08/2004
Posts: 4645
Loc: Australia
I am not so sure that the effect would be negligible. It is very difficult to estimate though, but lets say that at 100% humidity there is 1% of the total weight of the air as water. However at this RH the grass temp will be the same as the air temp. So lets lower the RH to 70% to start to get some ground cooling. Also however CO2 takes up 3% of the effect of water at 300ppm and 4% of the effect of water at 400ppm (since that .04% is 4% of the 1% of water). So then you are comparing an RH of 70% or 74% on the grass temperature and that could easily be a measurable difference of close to 0.5deg. Even these calculations are not quite right as the air thins and holds less relative moisture as you rise through the column of air above until you reach space where the IR is dissipated. The amount of CO2 increase in the last 50 years is almost the same as like adding 1% RH to all the humidity's worldwide that could have a measurable effect on radiation loss from the surface.

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#895601 - 03/11/2010 22:25 Re: Observations of climate variation [Re: BOM99]
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2193
Loc: Manilla, near Tamworth NSW
Manilla Smoothed Monthly Anomalies of Climate Variables
Parametric Plots
Update for October 2010: "More Flooding Rains".

New data for October 2010 allow updating with more smoothing applied to all months back to April 2010, which is now fully smoothed. A new commentary on the trends to replace the one in Post #880243 will be held over for another month, when the autumn months of 2010 will all be fully smoothed.

The October 2010 data, marked with orange diamonds, are again in the "Flooding Rains" area in the bottom left corner of five of the six graphs. Anomaly values of rainfall, cloudy days, Dew Point, temperature range and subsoil temperature are extreme. The Minimum temperature anomaly is now near zero but falling rapidly.
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