Recent Trends in Temperature/Precipitation

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5.2.1.b

Temperature

5.2.1b ONT Recent Trends in Temperature

Climate trends in Ontario must be taken in context of the whole of Canada. The reason for this is seen below. Ontario climate is subjected to systems from north, south, east and west. See also Section 5.2.1c, Lake Simcoe Ice.

ACTIVITY 1
1. Identify the climate regions in Ontario.

This section is divided into 3 parts.
1 – Ontario as part of Canada -Temperature 1900-1998
2. – Ontario as part of Canada – Temperature – Departures from average.
3. – Only Ontario – Temperature 1971 and 2000.

Part 1 – Ontario as part of Canada -Temperature 1900-1998

The temperature maps below represent the historical data from 1990 to 1998.

Note: The grey areas have no records before 1950. The areas with x have data that is significant.

Source: Zhang et al., Environment Canada, Climate, Nature, People 2003 www.ccme.ca

The overnight lows are more significant in terms of climate change because of their impact on plant activity and human health. Warmer nights do not provide relief from the high day time temperatures. See Ecosystems. See Human Health.

ACTIVITY 2
1. What is the overall trend seen in the last century?
2. What is the most significant trend in the last 50 years?
3. Find the boundaries of Ontario. How have these trends affected Ontario to date?

The graph below represents the same data for the same time period. The wavy black line represents the average mean for all the annual data plotted.

Source: Zhang et al., Environment Canada, Climate, Nature, People 2003 www.ccme.ca

ACTIVITY 3
1. Why are there no records for “All of Canada” before 1950?
2. What is the overall trend in national annual temperatures?
3. What is the difference in Southern Canada for the last decade? Why?

2. Ontario as part of Canada – Temperature – Departures from average.

For the the tenth year in a row, Canada’s annual temperature was above normal in 2002. Canada experienced its 13th warmest year (since nationwide records began in 1948) at 0.6oC above normal.

The map below shows that the Yukon, the northern part of the Northwest Territories, and the islands of Nunavut were all more than 1.5oC above normal. The Great Lakes region of Ontario was the other part of the country with temperatures more than a degree above normal.

Figure 1 Temperature Departures from Normal for 2002 (Source: Environment Canada)

The consecutive seasons graph below shows that 21 of the last 22 seasons have had temperatures above normal.

Figure 2. Consecutive Seasons graph showing national temperature departures from 1985 to 2002 (Source; Environment Canada).

ACTIVITY 4
1. Find the year you were born. Which season temperatures were above normal and which were below normal that year?
2. How many total seasons are represented by the graph? How many seasons were above normal? Represent that number as a percentage of the total.

The graph below shows the annual national temperatures departures from normal.

Figure 3. Annual national temperature departures and long-term trend from 1948 to 2002. (Source: Environment Canada).

3. When did the annual national temperature last drop below normal before 2002?
4. Describe what the dotted red line represents. Estimate the numerical value for this line.

Table 1. Annual regional temperature departures, warmest ten years in the period 194-2002 (Source: Environment Canada)

Table 2. Annual regional temperature departures, coolest ten years in the period 1948-2002

(Source Environment Canada)

ACTIVITY 4 Use Tables 1 and 2 above.
1. Find the climate regions in Table 1 showing the warmest 10 years since 1948 and in Table 2 showing the coolest ten years for the same period. Construct a bar graph showing the departures from normal for this time period, with the years in chronological order, rather than in ranked order (as in Figure 5).
2. Describe any trends you notice in the graph.
3. See Section 5.1.2c Precipitation for the same period.

Part 3 Only Ontario – Temperature 1971 and 2000.

Ontario Annual Total Temperature (mm) 1971-2000.

Source: Don MacIver et al., Environment Canada 2002

ACTIVITY 5 Note: the legend begins at 4 degrees C and changes colour each degree C to a maximum of >9 degrees C.

1. a) What was the general trend of annual temperatures in Ontario over 30 years?
b) The range in oC?
2. Compare the 2 maps for similarities and differences. List three differences. Account for these. Hint: check latitude and nearness to bodies of water.
3. What and where is the affect of altitude seen in this Southern Ontario map?

Precipitation

Climate trends in Ontario must be taken in context of the whole of Canada. The reason for this is seen below. Ontario climate is subjected to systems from north, south, east and west.

Activity: Identify the climate regions in Ontario.

5.2.1 The Precipitation Section is divided as follows:
1 Ontario as part of Canada – Precipitation 1900-1998.
2 Ontario as part of Canada – Precipitation- Departures from average.
3. Only Ontario – Precipitation 1971 and 2000.

Part 1 – Ontario as part of Canada – Precipitation 1900-1998

The maps below represent almost a century of weather data. The maps show average changes in annual precipitation in percentages. The gray areas do not have data before 1950. The x’s mark areas where the data is statistically significant.

Source: Zhang et al., Environment Canada, 2000 Climate, Nature, People 2003 www.ccme.ca

ACTIVITY 6
1. What is the overall trend seen in the last century?
2. What are the two most significant trends seen in the last 50 years?
3. Find the boundaries of Ontario. How have these trends affected Ontario to date?

The graph below represents the same data for the same time period. The wavy black line represents the average mean for all the annual data plotted.

Source: Zhang et al., Environment Canada, Climate, Nature, People 2003 www.ccme.ca

ACTIVITY 7
1. Why are there no records for “All of Canada” before 1950?
2. What is the overall trend in national annual temperatures? Predict 2010.
3.What is the difference in the average mean seen for Southern Canada when compared to “All of Canada” in the last decade? Why?

Figure 1. Precipitation Departures from normal for 2002. (Source: Environment Canada)

ACTIVITY 8 Use Figure 1 to:
1. Identify the three main areas of wetter than normal conditions.
2. Identify the areas that were drier than normal. Is where you live in one of these areas?

It is important to understand that “normal” precipitation in northern Canada is generally much less than it is in southern Canada. This means that a percentage departure in the north represents much less difference in actual precipitation than the same percentage in the south.

Figure 2. Annual national precipitation departures, with weighted running mean from 1948 to 2002.

ACTIVITY 9
1. How many of the last 30 years have had below normal precipitation?
a) Which was the wettest, which was the driest year?
b) Estimate the percentage difference from normal from the graph for each of those years.

The tables below show data for Ontario for both the Great Lakes and St.Lawrence Regions and the Northern Eastern Forest.

ACTIVITY 10
1. Construct a bar graph showing the departures from normal precipitation in Ontario, for 1948-2002, using the data in Tables 1 and 2. Note: Place the years in chronological order.
2. Describe any trends you notice in the graph.

Table 1. Annual regional precipitation departures, driest ten years in the period 1948-2002

(Source: Environment Canada)

Table 1 Part A

TABLE NEEDED

 

 

Table 1 Part B

TABLE NEEDED

 

 

Table 2 Annual regional precipitation departures, wettest ten years in the period 1948-2002

(Source: Environment Canada)

Table 2 Part A

 

TABLE NEEDED

 

 

Table 2 Part B

 

 

TABLE NEEDED

 

1. Only Ontario – Precipitation – 1971 and 2000.

The graph below is Ontario Annual Total Precipitation (mm) data for both 1971 and 2000.

Source: Don MacIver et al., Environment Canada 2002

ACTIVITY 11 Questions
Note that the 16 color legend begins at <600mm and moves up 50mm per color to a maximum of > 1300mm or greater per year.
1. What is the general pattern for annual precipitation in Ontario? The range in mm/year.
2. Compare the 2 maps for similarities and differences. List three differences. Account for these.Hint: check altitude as well as latitude and distance from bodies of water.
3. Define rain-shadow and find the rain-shadow effect of the Niagara Escarpment. Check south of Georgian Bay.

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