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#3784 - 09/09/2009 13:53 Re: Observations of climate variation
Surly Bond Offline
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Registered: 23/08/2003
Posts: 2037
Loc: Manilla, near Tamworth NSW
Temperature anomalies, particularly those of daily maxima, clearly express the effect of received solar radiation. They show whether the climate is warm or cool.

Anomalies of daily temperature range and cloudiness relate rather to atmospheric moisture: whether the climate is humid or arid.

Rainfall anomaly is obviously another expression of moisture:



The pattern is not very different from that of cloud or the inverse of that of temperature range. The rainfall shortage of 2002 is plain to see.

All three factors are plotted together here:



The recognised drought of 2002 affects all three indicators. Less credence has been given to the peak of humid climate around spring 2005 and the extended humid climate through 2007, 2008 and early 2009.

This replaces my post of 23-08-2009 21:04 (broken links).
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#3785 - 09/09/2009 22:11 Re: Observations of climate variation
Surly Bond Offline
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Registered: 23/08/2003
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Loc: Manilla, near Tamworth NSW
Temperature trends for all the days of the year at Manilla NSW.

These graphs are based on those used in a 2001 article by Knappenberger, Michaels and Davis ,“Nature of observed temperature changes across the United States during the 20th century”
I can't tell whether the technique was original to the authors.

Columns in the graphs show the slope of trend lines fitted to each of the days of the year, ordered by temperature. I have used 9-year data sets. Shorter sets give less stable results. Each graph compares two data sets: the grey columns are earlier trends to August 2008 and the black columns current trends to August 2009.
To simplify, I have used 364-day years, omitting February 29 and August 31. There are 91 columns, each the average of four days. Text boxes noting temperatures and seasons are approximate only.



Graph No. 1 shows trends in daily maximum temperature (“Days”). Winter days show a strong cooling trend for both periods, but the trend is now weaker. Through spring and autumn trends are weak, but trends in the current data are cooler than in the earlier data by an amount (about -0.06°/Yr) that is almost the same for most days. In summer, there is even more cooling (about -0.08°/Yr): a rather weak trend to cooler mid-summer days has become a strong trend to cooler days all summer.



Graph No. 2 shows trends in daily minimum temperature (“Nights”). A trend to warmer nights in mid-winter had appeared in the earlier data. This warming now extends to most nights of the year, except summer. There is now a strong trend to much cooler mid-summer nights.

Taking days and nights together, we still have a trend for winter nights to be not much colder than winter days, as would happen at a place nearer to the ocean. Spring and autumn nights are also getting warmer relative to days. In summer, however, both days and nights are trending cooler.
Average figures show how Manilla at this time relates to the Australian warming trend since 1950 (+0.0160°/yr). In the 9 years to August 2008, days cooled at -0.0201°/yr, nights warmed at +0.0410°/yr, and the average rose at +0.0105°/yr. In the 9 years to August 2009, days cooled at -0.0463°/yr, nights warmed at +0.0641°/yr, and the average rose at +0.0089°/yr.
Manilla’s “global warming” happens mainly at night, and not in summer.

To quote Knappenberger et al:
“These findings add to the growing evidence...... that the surface air temperature change that has occurred during the period of the greatest human influence on the climate is one in which increases of [extremely] low temperatures have dominated over those of high temperatures—a climate tending toward moderation rather than the extreme. Prognostications of dire consequences built upon model projections of a climate change dominated by increasing high temperatures should be reassessed based upon a growing body of evidence to the contrary.”
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#3786 - 10/09/2009 20:25 Re: Observations of climate variation
Surly Bond Offline
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Registered: 23/08/2003
Posts: 2037
Loc: Manilla, near Tamworth NSW
As footnote to
>...a climate tending toward moderation rather than extremes...<

Manilla recently had these record-breaking daily temperature anomaly events:
Daily max 15.2 degrees below normal, 14/2/09;
Daily max 11.4 degrees above normal, 23/8/09, and daily min 14.0 degrees above normal, 25/8/09.
That is, abnormally low temperature in summer, and abnormally high temperature in winter.

Extreme events like that are not hard to take at all. laugh
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#803874 - 10/12/2009 16:31 Re: Observations of climate variation [Re: Surly Bond]
Surly Bond Offline
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Registered: 23/08/2003
Posts: 2037
Loc: Manilla, near Tamworth NSW
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#804352 - 11/12/2009 23:00 Re: Observations of climate variation [Re: Surly Bond]
Surly Bond Offline
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Registered: 23/08/2003
Posts: 2037
Loc: Manilla, near Tamworth NSW
Since no-one has felt inclined to discuss the graph above, I'll try to kick off the discussion myself.

This is a plot of just two key climate indicators, anomalies of (1) max daily temperature and (2) season total rainfall, for the last ten years at Manilla, NSW. I think the pattern will be found to be rather similar for places from central Queensland to Sydney. Unless we have been misled, the "Murray-Darling" drought-stricken area must be quite different.
I have drawn a smooth line through successive data points, making the line thicken with advancing time. The colour changes each year, from violet through to red. The data is smoothed (1:2:1)/4, except for the last data point (Spring '09) which is necessarily raw data. The standard period for rainfall is the 125-year record. The standard period for temperature (etc.) is 10 years from March 1999.

About twenty-five of the forty data points cluster about the origin, showing the general stability of the climate with time.
There are several distinct, well-organized excursions away from the origin.
1. The 2002 extreme drought. Winter and Spring 2002 were very hot and dry. The drought is evident on the graph from summer 2001-02 (already very low rainfall) to summer 2002-03 (still high temperature). The elliptical loop on the graph shows clearly that the low rainfall anomaly leads the high temperature anomaly by almost three months.
2. Extremely wet spring 2005. Three seasons were involved, with little change in temperature anomaly.
3. Extremely cold summer 2007-08, with normal rainfall.
4. Very high rainfall in spring 2008, with temperature steadily rising.
5. Winter and spring 2009 dry and extremely hot. The warming trend has persisted for nearly two years.

Over to you.
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#809092 - 23/12/2009 13:01 Re: Observations of climate variation [Re: Surly Bond]
Surly Bond Offline
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Registered: 23/08/2003
Posts: 2037
Loc: Manilla, near Tamworth NSW
A graph above traces the sequence of smoothed monthly mean maximum temperatures and rainfall totals for Manilla, NSW in the last decade. I want to put this in a wider context.

Monthly rainfall and temperature data for specified areas of Australia can be found in the "Climate/Climate Change/Australian Climate Variability and Change" section of the website of the Australian Bureau of Meteorology. They are in the "Data Portal" on this page:
http://reg.bom.gov.au/silo/products/cli_chg/
Monthly values are given for temperature from 1950 and for rainfall from 1900. Averages are cited for the standard period 1961-1990. I have subtracted these averages from the monthly data to get anomaly values.
I selected the whole of Australia.

METHOD
The graph below tracks the relation of rainfall anomaly to maximum temperature anomaly Australia-wide for the same time period as the Manilla graph: mid-1999 to the present.
This time I applied a smoothing function directly to the monthly data. It is a normal distribution function with Standard Deviation 2.5 months. This gives a sampling window (low-pass filter) with a half-width of six months. (For the final six months of data, I applied progressively narrower sampling windows.) Because the rainfall anomalies are monthly rather than seasonal values, the vertical scale is one third of that in the previous graph.

RESULTS
Australia wide, the pattern of climate variation through the decade is more regular than at Manilla. There is a strong alignment from high rainfall/low temperature to low rainfall/high temperature.
The anti-clockwise looping structure is persistent: there are six such loops. As an example, I have labelled the points for February and April 2002 (yellow) to show how the loops are caused by maximum temperature lagging behind minimum rainfall. Minimum temperature also lags behind maximum rainfall at the top of the loops.

To clarify the pattern, I have made a second graph showing only data from 2006 to date.

The last five data points show anomalously high temperatures. These temperatures may fall somewhat when later data allow the use of the same six month sampling window on these data points as on earlier ones.
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#809116 - 23/12/2009 14:08 Re: Observations of climate variation [Re: Surly Bond]
BOM99 Offline
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Registered: 23/08/2004
Posts: 4645
Loc: Australia
That is a very interesting idea Surly to do a graph like this, I was not aware of your post until now otherwise I would have commented sooner. It might be also interesting to plot a number of individual stations on the same chart where instead of anomalies you use scaled values. The interesting thing would be so see if some stations overlap each others climate in various years. For example I am thinking that the climate of Sunny Corner is now almost like Bathurst and Bathurst like Wellington etc. Perhaps Manilla is now more like what Moree use to be like?.

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#809205 - 23/12/2009 18:20 Re: Observations of climate variation [Re: BOM99]
Surly Bond Offline
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Registered: 23/08/2003
Posts: 2037
Loc: Manilla, near Tamworth NSW
Hi snowmi
I hope people will do their own comparison of stations. I suggest that comparing anomalies may trump comparing scaled values, but it is worth a try.

I have in mind to use the (cunningly hidden) BoM "Data Portal" data to get data for the area of the great "Murray-Darling" drought: roughly from 33S;140E to 39S;150E - way south of here.
For the time being, there is plenty I want to discuss in the Australia-wide data.

For Manilla data, it will be a couple of months before there is much new to say.
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#809537 - 25/12/2009 00:40 Re: Observations of climate variation [Re: Surly Bond]
Surly Bond Offline
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Registered: 23/08/2003
Posts: 2037
Loc: Manilla, near Tamworth NSW
Here are the traces of the relation of smoothed monthly rainfall anomaly to monthly mean maximum temperature anomaly Australia-wide, for each decade since 1950. Rainfall data goes back to 1900 on the linked web-page, but temperature begins at 1950.




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#810237 - 27/12/2009 15:03 Re: Observations of climate variation [Re: Surly Bond]
Surly Bond Offline
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Registered: 23/08/2003
Posts: 2037
Loc: Manilla, near Tamworth NSW
The following graphs plot the time series of monthly data for the whole of Australia, smoothed with a gaussian window of Standard Deviation 2.5 months.
The two independent series of (a) mean maximum monthly temperature anomaly in degrees celsius and (b) total monthly rainfall anomaly in mm are plotted on the same graphs, but the scale for temperature is inverted for easy comparison.
One degree on the left axis corresponds to 10 mm on the right axis, but the zero lines may differ.


There is an obvious sine-wave cycle with a wavelength of between one and three years. (This is the "quasi-biennial cycle" that A.B. Pittock identified in 1971.)
Most peaks and troughs on these independent time series almost coincide, and their relative heights and depths tend to agree. In fact. the correlation between values of temperature and rainfall is poor, but the shapes of the sinusoidal curves match extremely well.
Peaks and troughs on the rainfall curve tend to lead those on the (inverted) temperature curve by one, two, or three months. In the graphs below, rainfall values have been lagged one month, to show that many of the peaks and troughs become better aligned.



Taking the whole of Australia in the last 60 years, it is fairly clear that:
points of lowest maximum temperature have generally lagged about one month behind points of highest rainfall;
points of highest maximum temperature have generally lagged about one month behind points of lowest rainfall.

Given this lag effect, times of lowest rainfall cannot be caused by times of highest temperature, but it is possible that times of highest temperature may be caused by times of lowest rainfall.
I find it plausible that temperature swings would closely follow rainfall swings (but in the opposite sense) due to lack of cooling by evapotranspiration in times of drought and effective cooling by evapotranspiration in times of deluge.
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#810682 - 28/12/2009 19:39 Re: Observations of climate variation [Re: Surly Bond]
Surly Bond Offline
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Registered: 23/08/2003
Posts: 2037
Loc: Manilla, near Tamworth NSW
People are concerned (panicked) that climate trends seen in the sixty years since 1950 may develop into a major change.

Such major changes have recurred as a 100,000-year cycle with a 10 degree range in temperature. A cold episode is a glacial (Ice-Age), and a warm episode an interglacial.

The Australian climate record since 1950 shows "quasi-biennial" cycles of drying (to drought) with warming, followed by wetting (to deluge) with cooling.

Glacial/interglacial cycles are not like these drought/deluge cycles. Glacials are cold DRY times and interglacials warm WET times. In the Australian data plotted here, deluges are cold WET times and droughts are hot DRY times.

Glacial times, including the Younger Dryas only 12,000 years ago, had bigger lakes than now. This was not because there was more rain in ice-ages: there was less. The lakes were bigger because low temperature kept the evaporation down.

On a time-scale of a few years rather than thousands high lake levels may well reflect high rainfall rather than low evaporation. Perhaps on this short time-scale there is a positive feed-back leading to both droughts and flooding rains - as the Australian poet says.
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#836843 - 19/02/2010 23:16 Re: Observations of climate variation [Re: Surly Bond]
Surly Bond Offline
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Registered: 23/08/2003
Posts: 2037
Loc: Manilla, near Tamworth NSW
I have updated my plots of smoothed rainfall anomaly versus smoothed max temp anomaly at Manilla NSW.

This time I have treated the data the same way as in my plots for Australia as a whole. Instead of seasonal values smoothed (1:2:1)/4, I have used monthly values smoothed with a gaussian window of half-width 6 months.
For clarity, I have used shorter time-sequences than before on each graph.

Here is the plot from September 1999 to December 2005:

)

For most of this time, smoothed monthly anomalies did not exceed +/-10 mm for rainfall or +/-0.5 degrees for maximum temperature.

An extreme drought began in January 2002 with the smoothed monthly rainfall anomaly falling below -10 mm. In July, the negative rainfall anomaly peaked at -27 mm. The max temp anomaly had been rapidly rising, and it peaked at +1.44 degrees in October. By February 2003, both rainfall and max temp anomalies were again small, and the drought was over.

March 2005 again showed a peak negative rainfall anomaly, but only -13 mm. While max temp anomaly remained steady, rainfall anomaly rose rapidly to peak at +20 mm in November 2005.

The next plot shows data from January 2006 to January 2010.



July 2009 is the last month to which the chosen smoothing function can be applied. Later months have been smoothed with windows that get steadily narrower, until the last data point is a raw unsmoothed value.

From very wet conditions in the summer of 2005-06, rainfall anomaly rapidly fell until October 2006 was as dry as in March 2005. The two years 2005 and 2006 were uniformly warm while rainfall fluctuated.

The next large anomaly is the very low max temp anomalies of January and February 2008: -1.37 degrees.

Rainfall anomaly peaked again at +17 mm in October 2008, then declined to -15 mm by July 2009, while the max temp anomaly steadily rose.

The last six monthly values cannot easily be compared with the earlier ones. They swing about ever more wildly. There is no doubt that these max temp anomaly values are very high, the highest in this 11-year record, but they may have peaked already. Rainfall anomaly values may also have peaked without being extreme, as they were in 2002.
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#840068 - 01/03/2010 23:31 Re: Observations of climate variation [Re: Surly Bond]
Surly Bond Offline
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Registered: 23/08/2003
Posts: 2037
Loc: Manilla, near Tamworth NSW
Data for February 2010 can now be added to local climate change graphs.

Unsmoothed monthly anomaly values.


Many posters on these forums are recording monthly data values, so I have plotted Manilla monthly anomaly values in this graph. The extreme values here have been discussed in the forums, as they have happened over a wide area:

Extremely wet months: January 2006, November 2008;
Extremely dry months: January 2007, March 2008;
Exremely hot months: November 2009, August 2009;
Extremely cold months: June 2007, February 2008.

When it comes to finding climate trends the graph above is useless. There is too much noise: each month is quite unlike the next.

Smoothed monthly anomaly values.


This graph shows smoothed data. The trends to warming since January 2008 and to drying since October 2008 are beyond doubt. The 6-month smoothing window cannot yet be applied to data later than August 2009. Since I have used progressively narrower sampling windows, later data points are less reliable for showing the trends.

Both the warming trend and the drying trend seem likely to have reversed very recently.
I guess that the climate at Manilla began to moisten up about September last year and began to cool down about November last year. The "Quasi-biennial" looping patterns shown on data plots in this thread lead me to suggest that the climate here will now trend back towards being wetter and cooler than normal through this winter and perhaps next summer.
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#842256 - 08/03/2010 16:38 Re: Observations of climate variation [Re: Surly Bond]
Surly Bond Offline
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Registered: 23/08/2003
Posts: 2037
Loc: Manilla, near Tamworth NSW
Much more cloud lately

For several years Manilla's climate has been very cloudy, despite the fact that it has not been very rainy.

I reported some recent very large increases in cloudiness at Manilla in this other thread .
I received some long, thoughtful comments from ROM, but few other replies.
Extreme cloudiness has continued at Manilla since the last post on that thread and, in one sense, has become even more extreme.

These graphs plot a sequence of data points with smoothed cloudiness anomaly values on the y-axis and smoothed rainfall anomaly values on the x-axis.

The first graph, with data from September 1999 to December 2005, shows how cloudiness tended to vary with rainfall during that time. In the units used, the relation was roughly y=0.5x. Nearly all values fell between the lines y=0.5x+8 and y=0.5x-8, as shown. The climate swung between cloudy-and-wet and sunny-and-dry.



The second graph shows data from January 2006 to February 2010.

(1). While the cloudiness anomalies on the first graph did not rise above +6, nearly all of the cloudiness anomalies since October 2007 have been higher than that.

(2). Cloudiness has become much greater in relation to rainfall. Thirty of the last forty months had anomaly values higher than the relation y=0.5x+8, which had not happened before. For these months, the relation is near y=0.5x+12. Since each extra cloudy day in a month accounts for a three percent change in number of cloudy days, these months have about four more cloudy days than in the standard period. I find this increase astonishing!

Very likely, my 10-year standard period is not representative. However, the very large changes seen do not depend on this.
Manilla seems to be in more immediate danger of losing sight of the sun than of being cooked by higher temperature.

Notes.
I observe the type and amount of cloud in octas each morning at about 9 am. For each month I record the percentage of morning observations that are more than four octas. I call this "Percentage of Cloudy Days". I have adopted a monthly normal value using averages from a standard 10-year period beginning June 1999. (The most cloudy month, July, has 35.2 percent cloudy days and the least cloudy month, September, has 23.7 percent.) The anomaly value is the difference between actual and normal percentage values. Smoothing is applied as descrbed in recent posts.
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#843359 - 12/03/2010 17:53 Re: Observations of climate variation [Re: Surly Bond]
Surly Bond Offline
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Registered: 23/08/2003
Posts: 2037
Loc: Manilla, near Tamworth NSW
Cloud vs. max temperature at Manilla

These graphs are like those relating rainfall anomalies to max temperature anomalies in Posts #803874, #836843, and #840068. Cloud anomalies seem to jump in and out of step with temperature anomalies.

In the earlier graphs, high rainfall related to low temperature and vice versa, but temperature generally lagged behind rainfall. The trace typically formed a series of anti-clockwise loops, elongated from dry-then-hot to wet-then-cold. Sharp reversals were few and small.

In the graphs shown here, cloudy days and temperature relate in three distinct ways:


(1.) Cloudy days relate to low temperature and sunny days to high temperature in a rather strict linear fashion.

From May 2001 temperature
decreases with increasing cloudiness to a minimum in September 2001,
increases with decreasing cloudiness to a maximum in October 2002, then
decreases with increasing cloudiness to a minimum in May 2003.

From June 2005 temperature
decreases with increasing cloudiness to a minimum in September 2005, then
increases with decreasing cloudiness to a maximum in January 2006.

From December 2006 temperature
decreases with increasing cloudiness to a minimum in January 2008, then
increases with decreasing cloudiness to a maximum in May 2008.

These three episodes of near-linear relations lie close to a line y=-0.7x. They account for 49 months in the 129-month record.

(2.) Much of the remaining trace is in a looping mode, with little elongation. Two loops are clockwise and two anti-clockwise. In a clockwise loop (e.g. the year 2000) the cycle was cold-cloudy-hot-sunny. In an anti-clockwise loop (e.g. January 2005) the cycle was cold-sunny-hot-cloudy.

(3.) In the 21 months since May 2008 days have continued very cloudy while the temperature has ranged from very low to the maximum in the record. At the extreme temperatures of spring 2009 the observed anomalies in cloudy days are some 18 percent above those expected from the linear trend y=-0.7x.
While the graphs relating cloud to rainfall (Post #842256) suggested that these recent months had about four more cloudy days than expected, these graphs suggest there are about six more.

These are big changes in cloudiness, suggesting a climate moving from continental to maritime. They go with reduced daily temperature ranges, as shown in Post #3784. Post #3785 shows that Manilla's daily temperature ranges have reduced during the last nine years in all seasons except (so far) for summer.


Bleat!

Although I am happy that this thread gets up to 30 "Views" per day, I am surprised that there are almost no "Replies".
I really would appreciate questions or comments on this stuff.
Is there anything that should be explained?
Do you have data that differ from mine?
Is there more advanced work in this field?
Are the results already predicted by known patterns of SOI, IOD, etc? Or not! If not, why not?

Yours
Surly


Edited by Surly Bond (12/03/2010 17:57)
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#845725 - 15/03/2010 14:11 Re: Observations of climate variation [Re: Surly Bond]
Surly Bond Offline
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Registered: 23/08/2003
Posts: 2037
Loc: Manilla, near Tamworth NSW
Dew Point vs. Max Temperature

Although Dew Point, Cloudy Days and Rainfall all indicate climatic moisture, each relates to maximum temperature differently during this eleven-year record for Manilla NSW.

Smoothed monthly Dew Point anomalies are plotted here against smoothed monthly maximum temperature anomalies.
As for Cloudy Days, there are extended periods with linear relations. These do not coincide with those noted for Cloudy Days and, unlike them, they vary widely in slope.

(1.) The trend line during the 2002 drought matches y= -0.9x-0.2. That is to say, the Dew Point falls nearly one degree for each degree of warming. The linear trend begins March 2002, more than a year later than the similar linear trend in cloudy days. It continues as temperature reaches a maximum in October 2002 and a minimum in June 2003 and then increases to October 2003: a total duration of twenty months.
(2.) An earlier linear trend line slopes the other way. From a low temperature in February 2000 the trend line is y= +0.5x+0.6. After a maximum temperature (with maximum Dew Point) in November 2000, the linear trend reverses until August 2001, for a total duration of eighteen months.
(3.) A very steep positive linear trend marks the seven-month cooling period from December 2005 to June 2006, at y= +3.1x-1.5.
(4.) A negative linear trend extends eleven months from November 2008 to (probably) September 2009: y= -0.7x.
Thus, linear relations occur for four extended periods, totalling nearly half of the record. These suggest functional relationships between humidity (as shown by Dew Point) and temperature, but relationships that take different coefficients, both positive and negative, at different times.

Dew Point versus temperature trends that have negative coefficients seem like the quasi-biennial hot-drought-to-cool-deluge cycles often mentioned in this thread. Trends with positive coefficients seem more like micro glacial (ice age) to interglacial cycles: cold-drought-to-warm-deluge.

Not that we actually know for sure that the last ice-age was droughty, or whether that drought had low precipitation, or low humidity, or sunny skies, or strong winds, or all of those. We can be quite sure of two things about the last ice-age (say 60,000 to 20,000 years ago): there was an awful lot of ice about on land (but not here), and the sea level was way, way down.
We are profoundly ignorant of the glacial and interglacial climates during the very brief life of the human species.
(Pontification ends.)

Notes. I use Dew Point as an index of absolute humidity of the atmosphere (at sea level). For stability, I prefer early morning observations. I estimate early morning Dew Point by applying the daily maximum Relative Humidity reading to the daily minimum Dry Bulb temperature, using a cook-book formula. For values before July 2005 I adapt 6 am readings from Bureau of Meteorology records at Tamworth Airport. My standard period is the 10 years from March 1999. Manilla normal early morning Dew Points vary from 14.9 degrees in February to 2.4 degrees in July and August.
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#845752 - 15/03/2010 15:04 Re: Observations of climate variation [Re: Surly Bond]
aerology Offline
Weather Freak

Registered: 05/11/2009
Posts: 92
I have been posting on this site for most of a year usually in the climate comment sections, but since you asked for other opinions, I have been looking at the 18.6 year pattern of lunar declination (LD) and it's production of tidal effects in the atmosphere.

I posted a few comments on Morning Glory wave production several years ago, tying them to LD tides and was able to forecast them on drop bears site. Lately I have been looking at tornado generation patterns in the USA in relation to LD tides.
Latest hypothesis on how the global circulation is driven by complex patterns interacting through the interactions of the lunar tidal periods and solar wind strength due to Earth's interactions with the outer planets.

http://research.aerology.com/aerology-analog-weather-forecasting-method/

With global patterns of circulation there are periods that repeat that you might find helpful toward the end of the above link there is a link to some Pacific Ocean animated satellite photos that if viewed 18 or 19 years apart, IE the month 18 years ago should look a lot like this month, if you adjust for the 11 day slewing of the period in the pattern you could get a preview of up coming patterns of global circulation better than guessing months in advance.

I find it most refreshing that you are using dew points as it has a lot to do with the specific heat capacity of the air masses, and the trans-evaporation trends...The AGW crowd seem to be missing that as a valid point of interest, although they are overly concerned with temps, they seem to not care about heat content???

Just some thoughts of my own to brighten your day keep up the good work.
Richard Holle

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#846194 - 15/03/2010 22:03 Re: Observations of climate variation [Re: aerology]
Surly Bond Offline
Weatherzone Addict

Registered: 23/08/2003
Posts: 2037
Loc: Manilla, near Tamworth NSW
Thanks, Richard.
Even the sixty year data sequence of monthly data from BoM is not long enough to resolve an 18-year cycle. I tried doing Fast Fourier Transforms. I think I got valid results, but the strongest periodicity was 29.8 months (2.48 years). I then tried fitting a cycle of that wavelength to the data trace. I utterly failed to match the cycle to the data. Every attempt to tweak the cycle gave an increase in the residual variance, not the hoped-for decrease.


Edited by Surly Bond (15/03/2010 22:04)
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#846312 - 15/03/2010 23:55 Re: Observations of climate variation [Re: Surly Bond]
BOM99 Offline
Weatherzone Addict

Registered: 23/08/2004
Posts: 4645
Loc: Australia
What you have discovered Surly is that the climate is far more random and chaotic than we would want to believe. As much as we wish to find regularity like sunrise/sunset and the seasons it just does not seem to be there appart from just that.

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#846512 - 16/03/2010 10:53 Re: Observations of climate variation [Re: BOM99]
aerology Offline
Weather Freak

Registered: 05/11/2009
Posts: 92
years of monthly data will show almost nothing, try using daily data, then look for 109.3 day cycles in anomalies from norm because of the seasonal shifts. Is there somewhere I can down load the complete BOM daily records? I would like to generate a forecast for Australia, many here have said that would be interesting. Complete details on how to do that is included in the link above.

Richard Holle

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