I was away all yesterday in the boondocks and heard on the car radio news of the Brisbane storms with hail and damage. Brisbane smashed by storm super cell: Premier calls in Army to help with clean-up –
I just post this map of rain up to 9am on the 28th (recorded up to 4am) to float the idea again that the urban heat island can attract rain. The mechanism could be due to the man made increased albedo contrasts accentuating the formation of convective storm cells. I am interested to see what readers think. I realize there is a greater concentration of rain gauges in SE Queensland.
I have had previous posts on this subject but not on Brisbane. In February I posted – Did the Adelaide urban heat island (UHI) increase rain there last night? and there is a link there to an example from Melbourne. I am sure I have read of examples from books and published papers.
interesting question.
There is considerable evidence that urban areas suppress precipitation by substantial amounts (several studies show as much as 40%).
The mechanism is probably urban aerosols seeding more persistent clouds that then precipitate downwind of the urban area.
Which is not to say, that under certain circumstances urban effects can’t cause more intense precipitation. I think it’s likely they do, by increasing the amount of precipitatable water over urban areas.
I doubt convection from lower albedo plays much of a role. Urban areas generally have a higher albedo than surrounding vegetated areas.
A very good article Warwick. The BOM would be better employed looking into the UHI effects on weather than in wasting our money on research into the effects of CO2 on weather. The latter is already made demonstrably wrong by the recent temperature record, World-wide and the notorious ‘Pause’.
Good review of UHI.
www.javeriana.edu.co/arquidis/educacion_continua/documents/Urbanclimates.pdf
No climate scientists involved.
The 1981 book “The Urban Climate” by Helmut Landsberg has 20 pages on the subject. You can buy it for under US$10 at Abebooks – I might scan if I find time- libraries should have the book.
www.abebooks.com/servlet/SearchResults?an=Landsberg&sts=t&tn=The+Urban+Climate
How about… look at the rainfall radar history?
I suggest albedo reduces, an increased thermal coupling. (how does an increased reflection increase temperature?)
Human induced lofting of water vapour.
Dust plume seeding.
Yet another failure from the BoM.
The BoM can’t predict weather like that storm, but claims that it can see future climate change that is here, now.
October 7, 2014
Bureau’s MetEye service revolutionising the way we understand the weather
The interactive service allows users to pinpoint within a six-square-kilometre area what the forecast is for their suburb or rural area for the next week.
> Crucially, the service omits weather warnings.
> The bureau warns users not to rely on it when extreme weather has been forecast.
“It is provided as a public service and data should be used entirely at your own risk.
MetEye does not replace the bureau’s official forecasts and warnings.
>It should not be used for critical decision-making,” a statement on the bureau’s website says.
MetEye is one of the products developed as part of the Next Generation Forecast and Warning System, a $30 million upgrade of weather services funded by the federal government.
www.smh.com.au/nsw/bureaus-meteye-service-revolutionising-the-way-we-understand-the-weather-20141007-10r82d.html
February 20, 2014
Bureau of Meteorology prepares to cop flak for failing to forecast Geelong storm
www.theage.com.au/environment/weather/bureau-of-meteorology-prepares-to-cop-flak-for-failing-to-forecast-geelong-storm-20140220-332dq.html
Some scanned pages from very useful 1981 book “The Urban Climate” by Helmut Landsberg
Section 8.3 URBAN PRECIPITATION pages 186-187
Pages 188 Table 8.7 Urban-Rural differences of annual precip reported in literature -189 10 year study of Urbana Illinois with map.
Page 190 St Louis METROMEX study which has been questioned – page 191 – 30 years of data from Te-Aviv – Turin from 1952-1969 – a study of four urban areas in NY State yielded negative results –
page 192 – more on St Louis METROMEX study with Table – page 193 discussion of air pollutants –
page 194 Paris study 1960-67 shows week days rain exceeds weekend rain. – page 195 arguments over La Porte, Indiana results. Start section summer rain increases over urban areas where many studies find positive results.
Page 196 map of METROMEX radar obs – page 197 Washington DC map –
Page 198 the several synoptic studies by Atkinson 1969, 1970, 9171, 1977 – page 199 London map 21 Aug 1959 –
Page 200 also London map – page 201 Chicago map and ref to puzzling obs from Berlin re summer storms. Mention of tornadoes avoiding Chicago and Tokyo –
Page 202 Table of maximum urban rural summer rain and severe weather event differences – urban effect depresses snow – page 203 Fig showing % increase in thunderstorm incidence with population.
Page 204 snow map from Lund, Sweden. page 205 more on snow including how specific air pollutant sources can trigger snow.
Page 206 map increased snow Toronto winter 1959-60 – page 207 references –
Page 208 – 209 references – page 210 references
Warwick something wrong with the links -get error 404.
Philip Bradley and Warwick the data used by Taha from Landsberg is a bit old and does not take into account the use of air conditioners. Brisbane was quite warm and humid from northerly winds before the cold front moved through. Your point about UHI does need to be researched.
If Perth is indicative of Brisbane then albedo changes over the last 30 years likely exceed by a large margin changes in the use of airconditioners.
Urban infill within 5 to 8 kilometers of the CBD has replaced vegetated backyards with new houses with reflective metal roofs, as well as new houses with metal roofs replacing older houses.