Posts Tagged ‘Queensland’

Summer Temperatures in South-Central Queensland Part 1: Diurnal Patterns of Temperature Change

October 15, 2017

In March of this year I purchased from the Bureau of Meteorology one-minute temperature data for the period 1 January to 21 March 2017, for a number of Queensland stations within 250km of Bundaberg.  “One-minute temperature data” is not the temperature of the whole minute, but means temperatures at  of the final second of each minute, so are spot samples taken at regular intervals.  Temperatures can be higher and lower in the intervening seconds, and so for example daily maxima can be several tenths of a degree or more above the final second values, as I demonstrated in earlier posts.

I have analysed data from these stations:  Maryborough, Hervey Bay Airport, Gayndah Airport, Thangool Airport, Bundaberg Airport, Rosslyn Bay, Gladstone Radar, Gladstone Airport, Rundle Island, Nambour, Kingaroy, Tewantin, Maroochydore, Gympie, Double Island Point Lighthouse, and Lady Elliott Island.  Most of these have few missing observations, but all still needed tedious checking.  Kingaroy’s record is atrocious, with days and weeks of intermittent data drop out.

I looked at: one minute temperature change, that is, from one data point to the next; temperature change after 10 minutes; the number of minutes of uninterrupted rise; the number of minutes of uninterrupted fall; and the number of minutes the temperature remained at the same value.

In this post I firstly plot averages of the above metrics across all 16 stations by time of day, to show the range of temperature variation from one minute to the next throughout the day and night, in distinctive diurnal patterns.

Figure 1:  One minute temperature change:-

Mean 1 minute dT

All stations show this distinctive shape, with some variance in range from island to inland stations.

Remember, this plot shows the average of 16 stations every minute of every day for 80 days.

Note the narrow range (averaging less than +/-0.1C) between sunset and sunrise, and the much larger swings from one minute to the next in daylight hours, especially between 09:00 and 15:00.  Outlier points are from weather events at individual stations.

The next plot shows the range of temperature change over 10 minute periods:

Figure 2:  10 minute temperature change:-

Mean 10 minute dT

Note the sharp increase from shortly after sunrise to an early morning peak, then a gradual decrease in the mean to a small dip at around 6 p.m..  Note again the small variation in the absence of the sun, and the many individual weather events shown by outliers.

The next plot counts the number of minutes when the temperature increases each minute at least +0.1C.

Figure 3:  Uninterrupted temperature increase:-

Mean Duration Rising

As you might expect, temperatures rise predominantly during daylight hours, with a sudden jump up just after sunrise, and a dip at sunset.

The next plot counts the number of minutes when the temperature decreases each minute at least -0.1C.

Figure 4:  Uninterrupted temperature decrease:-

Mean Duration Falling

Temperatures generally don’t fall very much just after sunrise.  However note that between 0900 and 1800 it is very rare for the temperature to be falling for zero minutes.  Most long temperature falls occur in daylight hours.  Surprising? What goes up must come down.

The next plot shows the length of time when the temperature does not change from one minute to the next:

Figure 5:  Unchanged temperature:-

Mean Duration Unchanged

Note that during the night on average temperatures are never the same for zero minutes (i.e. they are frequently the same), while in daylight hours temperatures are much less stationary, with a gradual rise from 1500.

The next graphs show the range of these metrics for individual stations.  This will be explored further in a future post.

Figure 6:  One minute temperature change:-

Max min dT comp

This shows the fastest minute to minute temperature change, both up and down.

Figure 7:  10 minute temperature change:-

Max min dT10 comp

Note that there was much faster cooling than warming over 10 minute periods, mostly associated with rain showers, storms, or cool changes.

Figure 8:  Uninterrupted temperature increase:-

Max Duration Rising comp

Figure 9:  Uninterrupted temperature decrease:-

Max Duration Falling comp

Note that Lady Elliott Island (far out to sea) and Rundle Island (in Gladstone Harbour) both had shorter periods of constantly rising and falling temperature.

Figure 10:  Unchanged temperature:-

Max Duration Unchanged comp

On the night of the 6th March at Maroochydore Airport the temperature was 26.1 degrees for 118 minutes.  As you can see nearly all stations had stable temperatures for nearly an hour on at least one occasion.

These results confirm that temperatures in daylight hours are very volatile, while at night temperatures change very little except in unusual weather events.  Fastest and most sustained warming is in the hour after sunrise.  Fastest and most sustained cooling is also in daylight hours.  Night time cooling is much more gradual.  Cooling is on average more rapid than warming.  Rapid warming occurs when the sun suddenly appears.  Rapid cooling is associated with weather events such as rain storms.

In Part 2 (probably not for a week or two) I will look at daily warming and cooling at individual stations.

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TC Debbie

March 29, 2017

TC Debbie hit the Whitsunday coast and areas to the south and inland yesterday.  As I spent nearly half my life in places not far from Mackay and have many friends in the region, I was very interested to see what was happening.   I began checking online from 5 a.m. Tuesday morning.

Here is some initial analysis of TC Debbie.  Firstly, here is the table of cyclone intensities as found at http://www.bom.gov.au/cyclone/faq/index.shtml#definitions .

Fig. 1:  Cyclone Intensity

TC Intensity

I began checking online from 5 a.m. Tuesday morning.

Fig. 2:  0500 forecast cyclone track map.

Debbie 5am

How accurate was the Bureau’s forecast?  Here is the forecast 22 hours later, at 0300 Wednesday morning.

Fig. 3:  Wednesday 0300 forecast cyclone track map.

Ex TC Debbie

The track forecast was pretty good.

The next images show Debbie’s progress across the Whitsunday Islands until the eyewall crossed the coast near Airlie Beach.

Fig. 4:  0720 Eyewall about to hit Hamilton Island

radar 720am debbie hayman is eye

Fig. 5:  0910  Hamilton Island near the eyewall, Hayman Island in the eye

radar 910am debbie hamilton eyewall

Fig. 6:  10.30  Hamilton Island near the eyewall, Hayman Island in the eye, and the eyewall about to pass over Airlie Beach

radar 1030am debbie hamilton eyewall

And four and a half hours later, the worst is over at Hamilton and Hayman Island and the eye is collapsing over Proserpine.

Fig. 7:  1510  Debbie weakening near Proserpine

radar 310pm eye breakup

Note the “gap” in the image in the northwest sector.  The Bowen radar failed and the Mackay radar was blocked by high mountains to the west.

What about forecasts of the cyclone’s intensity?

The next figures show plots of wind gusts, pressure, temperature, and rain at Hamilton Island, Proserpine, and Bowen, the closest stations to the cyclone’s track.

Fig. 8:  Wind gusts at Hamilton Island

wind hamilton

The black line shows the period from just before 8.00 a.m. until about 2.30 p.m. during which Hamilton Island was close to the eyewall, the area of maximum wind strength.   For nine hours from before 6.00 a.m. until nearly 3.00 p.m. wind gusts were of Category 3 strength.  From 8.00 a.m. until 12.30 p.m. gusts approached or exceeded 225 km/hr, bordering on category 4, and between 10.35 and 10.30 reached 263 km/hr three times at least- and the Bureau had forecast winds up to 270 km/hr.  While the station at Hamilton Island is too high to be completely reliable, these data are indicative that winds at 10 metres were at cat 4 level for some time.

Fig. 9:  Air Pressure at Hamilton Island

pressure hamilton

The red line shows the period from just before 8.00 a.m. until about 2.30 p.m. during which Hamilton Island was near the eyewall, the area of maximum wind strength.    From 2.00 a.m. until 5.00 p.m.  pressure was below 985 hPa (Cat, 2) and from 10.00 a.m. until 1.30 p.m. was below 970 hPa (Cat.3) but did not reach 955 hPa (Cat. 4).  Remember however that Hamilton Island was some 50 km from the centre of the eye, so 955 hPa is quite possible for central pressure.

On the basis of wind gusts and pressure at Hamilton Island, I believe Debbie was a strong Category 3, weak Category 4 system.

Fig. 10:  Air temperature at Hamilton Island

T hamilton

Note the sudden jump in temperature from 8.12 a.m.- 3 degrees in 3 minutes- coinciding with a wind gust of 212 km/hr, and kept climbing to unbelievable values.  (Compare with Proserpine below.)  It is likely that the AWS probe malfunctioned, and failed altogether at 12.00 noon.

Fig. 11:  Rain at Hamilton Island

rain hamilton

Rain measurement is unlikely to be accurate in such ferocious winds.  Note how rainfall levelled off from 11.00 a.m until 2.00 p.m., then increased after 3.00 p.m.

Fig. 12:  Wind gusts at Proserpine

wind proserpine

Proserpine Airport is some 20 km inland, 41 km west of Hamilton Island and 56 km from Bowen.  As the cyclone arrived over land it began losing strength and the eye began to shrink.  From 10.00 a.m. until 2.00 p.m. gusts were at Category 2 strength and at 1.00 p.m. reached the magic 165 km/hr of Cat 3 strength.  They were very probably much stronger in the town itself 9.1 km north.

Fig. 13:  Pressure at Proserpine Airport

pressure proserpine

From 12.30 p.m. until 5.00 p.m. the pressure at the airport, some 20-30 km from the centre, was below the Category 3 value of 970 hPa.

Wind gust and pressure data indicate Debbie was very likely still Category 3 as it passed over Proserpine town.

Fig. 14:  Air temperature at Proserpine

T proserpine

Fairly stable temperature with only about 1.5C range all day.

Fig. 15:  Rain at Proserpine

rain proserpine

Steady rain all day, fairly typical of cyclonic conditions.  At Strathdickie not far from Proserpine, 193mm fell in one hour that morning, and at Dalrymple Heights about 50km south 814mm fell in 24 hours.

Fig. 16:  Wind gusts at Bowen

wind bowen

For four and a half hours wind gusts reached Category 2 strength, and were above 100 km/hr from 9.00 a.m. to 8.00 p.m.

Fig. 17:  Pressure at Bowen

pressure bowen

Pressure was at Category 2 levels from 9.00 a.m.

Fig. 18:  Air temperature at Bowen

T bowen

Winds were west south west most of the day, but as Debbie passed and winds turned northwest (over the ocean), the temperature climbed.

Fig. 19:  Rain at Bowen

rain bowen

Steady rain all day: 12 inches in 12 hours.

While no stations were directly in the cyclone’s path, nearby station data indicate that Debbie was a large Category 3 to Category 4 tropical cyclone when it hit the coast and brought very strong winds, very heavy rainfall, and widespread destruction.  It is still lingering as a tropical low 300 km inland, bringing more strong winds and very heavy rain, and will head south over the next couple of days.  The clean up begins.  We await the report from James Cook University engineers who will provide their assessment of damage and wind loadings in a few weeks’ time.

Give credit where credit is due: the Bureau of Meteorology got this one pretty right.

Another ABC Fail

February 5, 2017

Viewers of ABC-TV news, and followers of ABC News Online, were treated to a story on Friday night about “Turtle hatchlings dying in extreme heat at Mon Repos”, as it was headlined at ABC News Online:

Piles of dead turtle hatchlings are lining Queensland’s famous Mon Repos beach amid a heatwave which has pushed the sand’s temperature to a record 75 degrees Celsius.

While the majority of hatchlings break free from their nests at night when the sand is cooler, those escaping in the day face overheating.

“They can’t sweat, they can’t pant, so they’ve got no mechanism for cooling,” Department of Environment and Heritage Protection chief scientist Dr Col Limpus said.

….

The extreme heat is also conducted down to the turtle’s nest, pushing the temperature to about 34C, which is approaching the lethal level for incubation.

That is the hottest temperature recorded in a nest in more than a decade.

A record 75 degrees sand temperature? Hottest nest temperature in more than a decade?

Time for a reality check.

I have no data on temperatures inside turtle nests, but I do have data on temperature at nearby Bundaberg Aero (Hinkler Airport), which is an ACORN site.

Using monthly Acorn data, here is a plot of all January maxima at Bundy.

bundy-jan-max

January’s mean maximum of 31.6 degrees C was equalled or exceeded in 1924, 1931, 1969, 1998, 2002, 2006, 2013, and 2014.  While monthly mean doesn’t tell us about individual days, it does give us a clue about daily temperatures in hot years.  For that I also use ACORN daily data- adjusted, homogenised, and world’s best practice apparently.

How do temperatures at this time of year compare with those of previous years?  The next figures show data for the first 45 days of every year, that is from January 1 to February 14.

bundy-jan-max-daily-45

The past three weeks at Bundaberg have been at the high end of the range, but no records have been broken, and no days have been even close to 35C.  What about previous years?  The next plot shows the number of consecutive days above 35 degrees: very likely to raise sand temperature above what it has been this year.

bundy-jan-max-daily-45-over-35

No days this year above 35C, but at least 27 occasions in previous years of single days reaching 35C, at least 6 of 2 days in a row, and one of 3 days in a row above 35C.

A 7 day running mean will show whether temperatures have been consistently high.

bundy-jan-max-7d-av-45

As you can see 2017 is high but not extreme.  2002 had a 7 day average just under 35C.

This graph plots temperatures of the first 45 days of years with similarly hot January temperatures.  2017 is the thick black line.

bundy-jan-max-daily-45-hot-yrs

On one day- January 20- 2017 was hotter than the other years.  Note how in several years the temperature drops to the mid 20s when heavy rain falls.  Note also the temperature reached the high 30s in February 2002.

The final graph shows the 7 day average of the same period of similarly hot years.

bundy-jan-max-7d-av-45-hot-yrs

Several previous periods were hotter than so far this year.

Once again we see misleading claims being made and reported by the ABC as gospel, without any attempt at fact checking.  A simple check shows that, while it may be true that the reported temperatures are the hottest recorded by these researchers, it is extremely unlikely that these were as high as they were in past years.  On every count- daily, monthly mean, 7 day mean, consecutive hot days- it can be shown that this year, while hot, is not as hot as many previously, and it follows that sand temperatures would similarly have been hotter in the past.

And that’s without considering the Holocene Optimum and the Eemian.

Another ABC fail.

Putting Daily Temperature in Context

December 14, 2016

In this post I demonstrate a simple way of comparing current temperatures for a particular location with those previously recorded.  In this way it is possible to show the climatic context.

Using data from Climate Data Online, I plot maximum temperature for each day of the year, and then for a particular short period: in this case the last week of November and the first week of December, which coincides with the recent very warm spell here in Queensland.  To account for leap and ordinary years this period is 15 days.  In ordinary years 24th November is Day 328 and 7th December is Day 341, while in leap years this same calendar period is Day 329 to 342.  I also calculate the running 7 day mean TMax for this period, and the number of consecutive days above 35C.

To put the recent heatwave in context, I have chosen six locations from Central and Southern Queensland which regularly feature on ABC-TV weather: Birdsville, Charleville, Roma, Longreach, Ipswich (Amberley RAAF), and Rockhampton.

Birdsville:

Fig. 1

whole-yr-birdsville

The Police Station data are from 1954 to 2005, and the Airport from 2000.  This shows the range of temperatures throughout the year.  The red arrow indicates the current period.   The next plot shows data only for the period in question.

Fig. 2:  24 November- 7 December: Airport data

14d-comp-birdsville-air

Note there were three days where the temperature this year was the highest for those days since 2000, but didn’t exceed the highest in this time period, which was in November.  The other days were well within the historic range.

For interest, let’s now see how this year compares with the Police Station record.  (The average difference in TMax during the overlap period was 0.0 to 0.3C.)

Fig. 3:  24 November- 7 December: Police Station data

14d-comp-birdsville-police

In a similar range.

Fig. 4

7d-avg-birdsville

This heatwave was the third hottest since 2000 and fifth overall.

Fig. 5

days-over-35-birdsville-air

Five previous periods had more consecutive days above 35C.  2006 had 22.

Charleville:

Fig. 6: Charleville Aero since 1942

whole-yr-charleville-aero

Temperatures in this period reached the extremes of the range on three days.

(Although the Post Office record begins in 1889, there are too many errors in the overlap period so the two records can’t be compared.)

Fig. 7:

14d-charleville-aero

A new record for early December was set, but note this was the same temperature as 29th November 2006.

Fig. 8:

7d-avg-charleville-aero

Definitely the hottest for this period since 1942.

Fig. 9:

days-over-35-charleville-aero

Note this was not the longest warm spell by a mile: there were many previous periods with up to 26 consecutive days above 35C.

Roma

Fig. 10:

whole-yr-roma

Although there is not one day of overlap so the two records can’t be compared, you can see that Airport (from 1992) and Post Office records are similar.

Fig. 11:

14d-comp-roma-air

A new record for this time of year was set: 44.4C, and six days in a row above 40C.  Pretty hot….

Fig. 12:

days-over-35-roma-air

…but there were longer hot periods in the past (since 1992).

Longreach

Fig. 13:  Longreach Aero since 1966.

whole-yr-longreach-aero

Fig. 14:

14d-longreach-aero

Hot, but no record.

Although there is good overlap with the Post Office, temperatures for this period differ too much: from -1 to +0.7C.

Fig. 15:

7d-avg-longreach-aero

Fifth hottest period since 1966.

Fig. 16:

days-over-35-longreach-aero

And in the past there have been up to 47 consecutive days above 35C at this time of year.

Ipswich (Amberley RAAF):

Fig. 17:

whole-yr-amberley

Fig. 18:

14d-amberley

Not unusually hot for this time of year.

Fig. 19:

7d-avg-amberley

Ninth hottest since 1941.

Fig. 20:

days-over-35-amberley

Hotter for longer in the past.

Rockhampton:

Fig. 21:

whole-yr-rocky

Fig. 22:

14d-rocky-air

Very hot, but no records.  (The heat lasted another two days, with 36.6 and 37.3 on 8th and 9th.)

Fig. 23:

7d-avg-rocky

Fourth hottest 7 day average on record (since 1939).

Fig. 24:

days-over-35-rocky-air

Again, a number of hot days, but there were as many and more in the past.

To conclude: the recent heatwave was very hot certainly, and was extreme in southern inland Queensland.  While Charleville had the highest seven day mean temperature on record, NO location had as many consecutive hot days (above 35C) as in the past.

This is a handy method for showing daily data in context.  It can used for any period of the year, can be tuned to suit (I chose TMax above 35C, but temperatures below a set figure could be found), and can be used for any daily data.

If you would like a comparison done for a location that interests you, let me know in comments including time period and parameters of interest (e.g. Sydney, first 2 weeks of December, TMax above 30C say, or Wangaratta, September, daily rainfall over 10mm say.)

Not the Worst Drought in 80 Years

January 7, 2015

Last night on the 7.00 p.m. ABC TV Queensland news there was a report on the Annual Climate Statement 2014 released by the Bureau of Meteorology yesterday (January 6).  I could not believe my ears, and as soon as it was on iview ( http://iview.abc.net.au/programs/abc-news-qld/NC1530Q005S00 ) I checked- several times.

The reader, Matt Wordsworth, clearly reports that the Bureau says Queensland has experienced “the worst drought in 80 years”.  The Bureau’s Jeff Sabburg was interviewed and claimed that 37.3% of the state was covered by the lowest rainfall on record.

Now I do know that much of Queensland has been very dry for a long time, with the northwest being especially bad, having missed two wet seasons (2012-13 and 2013-14).  Before you think I am callous, uncaring, and uninformed, I should let you know I was raised on a farm, my parents, grandparents, and great-grandparents were farmers, my brother and my brother-in-law are farmers, and I take a very keen interest in the land.

However, both the ABC news item and Jeff Sabburg’s claim, if quoted correctly, are complete nonsense.  Nothing like 37% of the State has had the lowest rainfall on record, and the drought is definitely not “the worst … in 80 years”.  The facts from the Bureau’s own websites (Climate Maps and Climate Change and Variability) show otherwise.

There follows a series of graphics clearly showing the state of Queensland’s rainfall and drought record.

Fig. 1:  12 month rainfall deficiency

qld 12m drought

Obviously recent rain has improved the situation, but what about over the last two years?

Fig. 2: 24 month rainfall deficiency

qld 24m drought

A-hah, that’s showing quite a lot of serious and severe rainfall deficiency, but not a lot of “lowest on record”.  However, compare that with the 24 month period to December 2003.

Fig.3:  24 months to December 2003

qld 24m drought 2003

I have been looking at Queensland rainfall closely in the past couple of weeks.  Here are some other ways of showing rainfall for Queensland.   I have shown 2013-2014 and 1929-1935 (the supposed 80 year ago worse drought), and more recent events, for ease of comparison.

Fig. 4: 12 month running mean of rain anomalies

qld rain 12m

Fig. 5:  24 month running mean of rain anomalies

qld rain 24m

Fig. 6:  27 month running mean of rain anomalies (covering the previous two wet seasons)

qld rain 27m

There was nothing unusual about Queensland’s rain in 2014.

The next graphics are plots of the 12 month counts of 12 month running means of rainfall with below average (bottom 30%), very much below average (bottom 10%), and severe deficiency (bottom 5%) rainfall.  In other words, counts of 12 month periods (January – December, February – January, March – February etc) with rainfall in each category.

Fig. 7: Count of 12 month periods of below average rain (lowest 30% of 12 month periods)

qld drought counts 12m belavg

Fig. 8: Count of 12 month periods of very much below average rain (lowest 10% of periods)

qld drought counts 12m verybelow

Fig. 9: Count of 12 month periods of severe rain deficiency (lowest 5% of periods)

qld drought counts 12m severe

There have been no episodes of statewide severe rain deficiency since January 2004.

Fig. 10: Count of 12 month periods of 24 month below average rain (lowest 30% of 24m periods)

qld drought counts 24m belavg

Fig. 11: Count of 12 month periods of 24 month very much below average rain (lowest 10% of periods)

qld drought counts 24m verybelow

Fig. 12: Count of 12 month periods of 24 month severe rain deficiency (lowest 5% of periods)

qld drought counts 24m severe

Fig. 13: Count of 12 month periods of 27 month below average rain (lowest 30% of 27m periods)

qld drought counts 27m belavg

Fig. 14: Count of 12 month periods of 27 month very much below average rain (lowest 10% of periods)

 qld drought counts 27m verybelow

Fig. 15: Count of 12 month periods of 27 month severe rain deficiency (lowest 5% of periods)

qld drought counts 27m severe

And just for information, this map shows the 36 month rainfall deficiencies to December 1902.

Fig. 16:  36 months to December 1902- the Federation Drought

qld 1902 36m drought

Now that’s a drought!

The current drought, bad as it is, barely rates when compared with previous droughts.

Perhaps the Bureau is using different data from what is shown on their websites.  Perhaps Jeff Sabburg was quoted out of context.  Whichever way, the public has been misled- not for the first time, and unfortunately not the last.

The Bureau of Meteorology should issue an immediate clarification, and the ABC should issue an immediate apology and correction.