I think most weather stations are located outside cities. For instance, Orléans-Bricy is on a military airfield, next to a small village. I don't know how it looked like 100 years ago, but it already existed in the 50s.
Of course, not the whole story. But these climate warming temperature graphs (and polar ice melting graphs) are also not the whole story. One should consider effects of technology shift and methodology shift on measurements. If going digital causes more than +1°C shift in temperature readings, then it would be absurd to worry about the climate warming at rate 0.5°C per half the century.
Ehhh... the skepticism of measurements taken at a local site with changes in methodology and environmental factors are reasonable -- but it is the broader global trends that have solid science behind them, e.g., More Than 50 Years of Successful Continuous Temperature Section Measurements by the Global Expendable Bathythermograph Network, Its Integrability, Societal Benefits, and Future .
Tallinn Harku weather station is outside the city. I suppose, that Estonia has several times lower population density than France. But there has been significant construction activity nearby the weather station. It was initially very lonely building there. Now it is surrounded with new logistics centres and some new industrial enterprices. The traffic on nearby roads has increased multiple times. That all changes local microclimate. It should be taken acount as a separate thing from the global climate warming. If you take local microclimate changes as a reference for calculating how large the global warming is, then you are fooling yourself (and maybe many others). Global warming should be calculated from data, where tecnology shift, methodological shift and local microclimate shift are elliminated.
I didn’t get the sense that @vitog was attempting to prove anything about climate change (aka global warming) when he shared his charts on weather statistics in the Vancouver area over the past 85 years. I believe it was intended to illustrate an interesting local trend; not the whole story of course. There’s no need to create a paper tiger here.
@Margot , I'm just explaining why I'd like to know, when Vancouver Airport made its shift towards digital measurements. For comparision I present graph about Tartu, Estonia:
These websites may help you find the information you are looking for: Data sources - Climate-Data.org Daily Data Report for January 2022 - Climate - Environment and Climate Change Canada Contact Us - Climate - Environment and Climate Change Canada
Our weather stations show publicly the year, since when their measurements are completely automatic. In case of Tartu Tõravere this year is 2003. Tallinn Harku is completely automatic since 2001.
I don't have any detailed information about YVR technology or methodology, and I agree that the points that you have raised can affect the value of the long term temperature changes. However, my primary interest is in recent trends, which should not be seriously affected by those points. The slope and changes to the slope of the 30 year average during the last 10 years point to the future, which is more of a concern than what happened many years ago. I'm waiting for the kink in the hockey stick curve.
I can't see there hockey stick curve. Yes, there was step in the end of last century, but last 30 years have been pretty steady at the same level with slight jumps up and down. Pay attention to the yellow line:
This conversation makes me think of a common expression usually used for other subjects than the weather : "Ce n'est pas en cassant le thermomètre qu’on fait tomber la fièvre", "breaking the thermometer does not bring down the fever"... ;0) "The most important thing to understand is that correlation is not the same as causation – sometimes two things can share a relationship without one causing the other. For example, the more fire engines are called to a fire, the more damage the fire is likely to do."
Well, another year has ended, providing more YVR weather data; so, the updated weather charts are attached. Note that the 2022 average temperature was below the 30 year average, and we have experienced well below average minimum winter temperatures for two years in a row. This recent downward swing is not indicative of any long term trend but seems to reflect the influence of the current La Nina, which is one of the longest lasting since the start of record-keeping (1979 on this website: MEI.v2: NOAA Physical Sciences Laboratory). To investigate the influence of El Nino/La Nina (ENSO) on average yearly temperature, I compared the yearly average of the index values in that website with the yearly YVR average temperature minus the 30 year average for that year, using the Microsoft Excel formula CORREL. This formula provides a measure of correlation that varies from -1 (for 100% negative correlation) to +1 (for 100 % positive correlation), with 0 indicating no correlation. This calculation yielded a value of 0.545, which is pretty good considering the differences in the units and calculations being compared. Suspecting that there might be a delay in YVR weather's response to ENSO, I also compared the correlation of the two sets of numbers when the ENSO index values are shifted back by one month at a time and found a peak value of 0.649 at 3 months. This is a significantly better number that seems to show a 3 month average delay in YVR weather's response to ENSO conditions.
Not nearly so professional as your charts and analysis, @vitog, here is what a local fellow came up with for Nanoose Bay, BC - drought conditions from July to December 2022.
What year Canadian meteorologists switched to digital instruments? Analogue meters and digital meters do respond slightly differently to temperature.
Sulev, I asked that question on the government weather website after you brought it up last year but received no response. I'll try again and let you know if I get a response this time.
Sulev, I finally received a reply to my question about when YVR weather instrumentation transitioned to digital. Two requests using the online contact form receved no reply, but a telephone request (had to leave a message) resulted in an almost immediate response. The answer from Canadian Weather Services was January, 1953. This seems rather early, but it goes along with a change in the data available in the YVR weather database. Wind and snow-on-ground data were added to the database in January, 1955.
Thank you, @vitog ! 1953 is surprisingly early. Then, again, there could be second or even third generation of digital devices in use for now. I don't believe, that they still use the same type of digital sensors as back then. I have visited weather stations in Tallinn and Tõravere, both use still analogue meters as a backup for digital. So it is possible to see, what is the difference between their readings. Of course, those meters are slightly in different conditions - analogue meter in a old school Stevenson screen, but digital meter is integrated into modern compact automatic weather station. So certain difference is normal. It still seems to me, that modern digital instruments have less inertia and react faster to any temperature jump. And the difference can be significant.
Wow, two days after I received the response discussed in Reply #93, a belated reply to one of my earlier requests arrived. However, the answer to the question about YVR's transition to digital temperature monitoring provided a much later date: January 13, 2013. So, I don't know which of the two dates is correct; but I think it is the later one, because the wording of the response was more directly related to the question asked.
Happy New Year, I hope! Here are updated charts for YVR weather, in case anyone is interested. The yearly minimum temperature chart is not included because December was so mild that the lowest temperature for this winter is bound to be in January or February. The yearly data for the past year was not very notable, but it will be interesting to see if El Nino affects 2024 temperatures significantly. The rainfall total was well below normal.
Speaking of unusual weather.....here in the North Shuswap, we don't have a single snowflake on the ground! Yes, we had one snowfall of about 6 inches, followed by a second snowfall of about 8 inches, but much to everyone's surprise the weather has been surprisingly very warm and it has all melted away. Usually by this time we would have a foot or more of snow on the ground. And it would have been so for several weeks by now. We do have minimal snow forecast over the next couple of days, but it doesn't look like it will stick. Closing in on midnight here, the temperature is still 2.1º above zero. This is about 10ºC above what we generally have by now. The only concern about all this lovely warm weather, is that we may end up woefully short of water if we don't get a decent snowpack soon.
