Temperature continues drop; Snowfall continues to increase

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Glacier
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Temperature continues drop; Snowfall continues to increase

Post by Glacier »

BC Climate.png


Notes:
  • 23 of the past 27 years have been above the 1941-2012 average.
  • Only 1996, 2008, 2009, and 2011 were below the average.
  • 1996 was the 11th coldest year since 1940, while 1998 was the warmest year.
  • I am well aware of the fact that adding 1985 (the 7th coldest year) would change the slope direction.
  • 1955 was by far the coldest year since 1940.
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Last edited by Glacier on Jun 4th, 2013, 12:29 pm, edited 3 times in total.
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hobbyguy
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Re: No warming in BC since 1986

Post by hobbyguy »

Where did the data come from?

Also, if average temperatures have been higher for some time, doesn't the 1941-2012 average keep going up?

I find this data set confusing, as I think the plot is against a moving target, which dampens the results.

Plus anecdotally, the assertion of no warming since 1986 doesn't square with my experience. My memory (as unreliable as it is) is that highs haven't moved that much, but that lows, especially the extremes, have moved up. For example: Prince George used to fairly regularly see -40 (beenthere at -43) and I just don't see those kind of numbers any more.
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Glacier
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Re: No warming in BC since 1986

Post by Glacier »

hobbyguy wrote:I find this data set confusing, as I think the plot is against a moving target, which dampens the results.

I can see why it's confusing. Basically, I matched up the average annual temperature of all weather stations in operation in both 2011 and 2012. 87.3% of these stations were warmer in 2012. Next, I compare 2010 with 2012 and find that 7.4% of stations in both years were warmer in 2012. Then I do this with every other year all the way back to 1941, and take the average of the 2012 column. Then I repeat the process for 2011 and so on. Of course, I let software do all the comparisons and calculations.

Here is what the graph all the way back to 1941 looks like....

BC Climate2.png
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hobbyguy
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Re: No warming in BC since 1986

Post by hobbyguy »

Seeing as you have all that data already in:

How about a comparison based on the 1941-1961 average (20 years give some smoothing)? If you showed that starting from 1962 it would be interesting to see.
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Re: No warming in BC since 1986

Post by ForestfortheTrees »

Glacier wrote:I can see why it's confusing. Basically, I matched up the average annual temperature of all weather stations in operation in both 2011 and 2012.... Then I do this with every other year all the way back to 1941...


I think there is a bit of a problem then with your title. It is not no warming in BC, but rather no warming in the average of all the weather stations I used. Let me give an example of what I mean.

My guess is that there are a lot more weather stations in your sample that are located in the lower mainland/coastal area than are in Northern BC. Correct? If this is the case, then there will be a greater bias towards the lower mainland (or anywhere there is a greater number of weather stations). To make this truly represent BC, you need to divide the province up into a grid and assign one temperature record to each square.

Also, I agree with Hobbyguy on the minimums. At higher latitudes it is the minimums that rise faster than the maximums. However, this is somewhat taken into consideration by using the average temp as this is calculated by subtracting the min from the max.

Thanks for posting Glacier and getting the conversation going...
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Glacier
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Re: No warming in BC since 1986

Post by Glacier »

I absolutely agree that there is a bias favouring southern BC, and especially the south coast. I had thought of that, and had considered redoing this little exercise with a grid system. I may still attempt this in the future, but first things first.

The average does take into account the rising minimum temperature, and looking at three places with very long records seems to prove that the minimum has risen faster than the maximum:

For these three places, Kaslo, Barkerville, and Agassiz, I have divided the time periods at 1950.

For Kaslo, the temperature difference has increased between the 1894-1950 period and the 1951 to 2004 period by a slight 0.2 degrees (I only have data up to 2004 at the moment). This anomaly emphasizes why we can't just take one data point and run with it.

However, for Barkerville the earlier period (1888 to 1950) varied by 1.8 degrees more than the post 1950 era. Similarly, for Agassiz the daily temperature difference between the earlier period (1889 to 1950) varied by 1.7 degrees more than the most recent time frame.

Overall, there is a definite trend toward warming at night. As a matter of fact, the daily high temperature between these three places has not changed between the two time frames, but the minimum has increased by 1.1 degrees, accounting for 100% of the average temperature increase.
Last edited by Glacier on Feb 26th, 2013, 7:41 pm, edited 1 time in total.
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Corneliousrooster
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Re: No warming in BC since 1986

Post by Corneliousrooster »

I hear Fox News weather dept. has an opening - I think they will like the way you paint a weather picture......
ForestfortheTrees
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Re: No warming in BC since 1986

Post by ForestfortheTrees »

Glacier wrote:Overall, there is a definite trend toward warming at night. As a matter of fact, the daily high temperature between these three places has not changed between the two time frames, but the minimum has increased by 1.1 degrees, accounting for 100% of the average temperature increase.


Cool :discodance: thanks for that extra bit of info Glacier, and interesting about all the rise coming from the minimums. It is information that is often not well communicated.

I feel you pain in trying to find continuous temperature datasets across the province. I have done this kind of work in the past and it seems that environment canada just keeps closing stations, while opening up others for random periods of time. What you have done is a lot of work. Thanks!
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Re: No warming in BC since 1986

Post by zzontar »

Corneliousrooster wrote:I hear Fox News weather dept. has an opening - I think they will like the way you paint a weather picture......


Fox schmox, I'm waiting for him to take over when Mike Roberts steps down.
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Glacier
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Re: No warming in BC since 1986

Post by Glacier »

Corneliousrooster wrote:I hear Fox News weather dept. has an opening - I think they will like the way you paint a weather picture......


I can assure you that any bias is not intentional. Rather, it's a consquence of not taking the extra time to separate the province into a grid - which, by the way, creates it's own set of problems. eg. there are barely 10 weather stations in the entire province common to both 1941 and 2012. Between 1919 and 2004, there is only 1.

The title of this thread, on the other hand, is meant to get your attention. :sillygrin:
Last edited by Glacier on Feb 27th, 2013, 9:00 pm, edited 1 time in total.
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Re: No warming in BC since 1986

Post by logicalview »

Corneliousrooster wrote:I hear Fox News weather dept. has an opening - I think they will like the way you paint a weather picture......


:127: :skippingsheep: :skippingsheep:
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Re: No warming in BC since 1986

Post by hobbyguy »

I found the information that it was the lows dominating the rise in average temperature to be of interest.

In the back of my head is the single data point (which is therefore extremely unreliable for rendering conclusions) of the 911 weather effect. http://www.greenmedinfo.com/blog/artificial-weather-revealed-post-9-11-flight-groundings

Makes me wonder...
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Glacier
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Re: No warming in BC since 1986

Post by Glacier »

I've heard of that. It's unfortunate that Environment Canada cutbacks meant the elimination of almost all weather stations recording sunshine hours in 2001.

Here is how the maximum temperature and sunshine hours compare in the UK where they still record such things...

http://tallbloke.files.wordpress.com/20 ... mp-uk1.png

And here is how sunshine hours and temperature compare in Asia...

Image


Just for fun, here is the entire dataset for BC going all the way back to 1874. The black line is the 20 year running average.

weatherstations-entire BC Record.png


For the first couple of decades there were only a few weather stations in operation, and even some years with no stations. From the few that were in place, it's clear that 1998 was the hottest year on record for most of the province, especially in our area. In the north, it looks like 1926 was the hottest year, in the central interior it was 1987, and still other areas of the province, namely along the coast, 1958 was the hottest year. I would say that the hottest years on record were 1998, 1987, 1958, and 1992.

There's not enough data to tell if some of those 1800s years were indeed colder than 1955 or 1916, but if I were to hazard a guess, I would say that 1875, 1893, 1955, and 1916 were the coldest years on record, and in that order. Of course, there are provincial variations. eg. 18 of the 36 weather stations common to both 1955 and 1916 were colder in 1916 including Vernon and Kelowna, but it's pretty clear that area covered by each station that 1955 was colder in at least 80% of the province.

And for even more fun, here is the same graph for precipitation. Note: There were very few stations pre-1890, which is why you get some exaggerations.

precipitationrecord.png
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Glacier
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Re: No warming in BC since 1986

Post by Glacier »

So what do you think, is there any correlation between precipitation and temperature? Remember to ignore the trend lines pre-1900 (especially for temperature).

It's interesting that the 15 year running average for temperature bottomed out in 1922 and the 15 year running average for precipitation bottomed out a mere 8 years later in 1930. Does this mean that there is a lag between the two? Keep in mind that both trend lines peaked within the last decade and only a couple years apart.

temperatureprecipitation.png



BTW, there has been no precipitation increase in BC since 1988.

precipTrend.png
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Glacier
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Re: Temperature tanks to values not seen in 30 years

Post by Glacier »

http://sunshinehours.wordpress.com/2013 ... f-25-years

Sectioning off the past in 5 year increments reveals that the most recent period (2008-2012) is the coldest in 30 years. 87% of BC weather stations conclude that the past 5 years has been either the coldest or second coldest 5 year section over the past 25 years. It is also the only 5 year period below the 1971-2000 average since the 80s.

The warmest periods on record:
    1) 2003-2007
    2) 1938-1942
    3) 1988-1992
    4) 1998-2002
    5) 1993-1997

The coldest periods on record:
    1) 1948-1952
    2) 1893-1897
    3) 1908-1912
    4) 1918-1922
    5) 1913-1917
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