Jennifer Marohasy

a forum for the discussion of issues concerning the natural environment

Archives for October 2016

No QA of bureau temperature data by CSIRO bushfire modellers

By

Despite an exceptionally cool end to this October, the CSIRO and Bureau of Meteorology have just put out a joint report claiming that there is going to be an increase in the number of hot days and thus an increased risk of devastating bushfires — based on homogenised (remodelled) temperatures, of course.

CSIRO experts forecast bushfire risk based on Bureau temperature data, but they don’t first undertake any quality assurance of the Bureau’s data.

If we consider one of the best long and continuous temperature series for southern Australia, which is the Rutherglen raw temperature data, and just maximum temperatures in summer: the hottest summer was back in 1938-1939, as shown in this chart.

Mean Maximum temperatures as measured at Rutherglen during summer (December 1912 to February 2016). Full report at http://climatelab.com.au/newclimate/10.22221/nc.2016.001/
Mean Maximum temperatures as measured at Rutherglen during summer (December 1912 to February 2016). More more information see http://dx.doi.org/10.22221/nc.2016.001.

On 13 January 1939 this region experienced one of the worst bushfire disasters in Australia’s history; it became known as Black Friday.

At 33.5°C, the summer of 1938–39 was 2.2°C hotter than the average maximum temperature during the ten most recent summers at Rutherglen, and a full 3°C hotter than the average maximum summer temperature at Rutherglen for the entire period of the record.

And yet today the Bureau and CSIRO are suggesting we should be concerned by a 1°C increase in average temperature over the last 100 years.

Rather than fear mongering, the CSIRO would do well to actually consider the actual integrity of the data being provided by its partner – the Bureau of Meteorology.

In a recent article published by On Line Opinion, I explained that the difference between the official-adjusted maximum temperature for Rutherglen on 13th January 1939 versus the actual measured value is rather large– more than 5 °C. Historical temperature data is used to model and forecast the likely impact of future bushfires, with Fire Danger Indices sensitive to small changes in temperature.

********************
1. The BOM-CSIRO State of the Climate report is here http://media.bom.gov.au/releases/308/state-of-the-climate-2016-delivers-the-latest-science-on-our-changing-climate/ , some media is here http://www.abc.net.au/news/2016-10-27/bom-csiro-forecast-more-hot-days-fire-season-climate-change/7968992

2. Homogenised temperatures, and planning for bushfires
http://www.onlineopinion.com.au/view.asp?article=18490&page=1

Wettest September on Record in Murray Darling

By

FOR over a decade the Bureau of Meteorology, and CSIRO have been predicting on-going drought in the Murray Darling Basin. Hundreds of scientists have been employed –at the expense of tax payers – to run General Simulation Models all predicting the same outcome.  This forecast decline has been blamed on global-warming and has resulted in far-reaching legislative changes, which by reducing the amount of water that can be allocated to grow crops, has affected employment in regional centers.

Yet when we look at the hard data, there has been no overall decline in rainfall. The wettest year in the Murray Darling Basin was 2010 – that is the wettest year since 1900 according to the official Bureau of Meteorology statistics.

Annual average rainfall in the Murray Darling Basin, 1900 to 2015.
Annual average rainfall in the Murray Darling Basin, 1900 to 2015.

It has also been repeatedly stated that the drought conditions are going to be most pronounced over the cooler months, specifically from April through to October.

Yet the Basin has just experienced its wettest September on record – that is the wettest September since 1900 according to the official Bureau of Meteorology statistics.

September rainfall in Murray Darling Basin, 1900 to 2016
September rainfall in Murray Darling Basin, 1900 to 2016

Some argue that the hoarding of water in the dams based on wrong forecasts by the Bureau of Meteorology has exacerbated current flooding particularly along the Murrumbidgee and Murray Rivers – perhaps also in the Lachlan River that runs through Forbes.

The problem is that the Bureau, working with the CSIRO, have become wedded to General Circulation Models, and the failed theory of anthropogenic global warming. Over the last year we have irrigators in the Murray Darling with very limited water allocations, paying ridiculously high prices for temporary water, during a season when even the Bureau was forecating above median rainfall: remember in May while Agricultural Minister Barnaby Joyce was announcing concessional loans, the price of ‘temporary water’, on the market – increasingly controlled by governments – had increased from $30 per megalitres to almost $300 per megalitres as a direct result of the water buybacks – and limited water allocations for ‘general security’ water licence holders.  This is no way to run a productive agricultural sector.

 

Understanding the Wild, Wet Weather across Southern Australia

By

The wild, wet weather across southern Australia this spring is a consequence of an unusually strong temperature gradient, especially evident in the following chart as warm water to the north of Australia (especially in the Timor and Arafura Seas), and the cold waters off the southwest of Australia.

Thanks to NOAA, http://www.esrl.noaa.gov/psd/map/clim/sst.shtml
Thanks to NOAA, http://www.esrl.noaa.gov/psd/map/clim/sst.shtml

Former head of Australia’s National Climate Centre, Bill Kininmonth, recently emailed me:

The warm water has increased the supply of moisture feeding into the airflow over Australia. The moisture increases by nearly 7 percent with each degree C temperature rise. The cold water to the south and west of Australia tightens the temperature gradient and increases the potential for storm development (technically it is called increasing baroclinic instability). It is normal to have a period of tightening temperature gradient during spring time – the nearby ocean and land of southern Australia are cold after winter but the approach of summer is warming ocean and water of north Australia. Because of this annual tightening of the gradient, spring is the wettest period with often strong storms over southeast Australia. This year has been particularly wet and stormy because of the pattern of sea surface temperature anomalies. It is not climate change.

As the oceans have a critical influence on land temperatures, this same pattern is evident in the surface temperature data for Western Australia. While Perth has had its coldest September on record, it’s actually been very warm in the north of the state.

A colleague has plotted the following fascinating chart which shows a running yearly average of mean temperatures from 180 sites as recorded by the WA Agriculture Department.

Thanks to a friend and colleague, who wishes to remain anonymous
Thanks to a friend and colleague, who wishes to remain anonymous

The top line is Kununurra, in the far north, showing temperatures are still rising. The next line is Carnarvon. The great mass of lines are the southwest corner of WA from just north of Geraldton to east of Esperance and these show temperatures are all falling. The coldest lines are at elevated places like Mt Barker. The brown line starting around 2008, and at 16.7C, is South Perth.

There is a remarkable consistency about the southwest corner where the coolest 12 months ended in mid-2006 and the average then climbed around 2.5C to a peak in late 2014 and has dropped by a little over 1C since then.

So what happens next?

The water to the far northwest is very warm as can be seen by the rise in Kununurra surface temperatures, and the orange in the NOAA sea surface temperature map.  The Leeuwin current that brings the warm water down the coast is normally weakest in the summer months and strongest over the autumn and winter.