Changes of Extreme Air Temperature in Jerusalem

Abstract

The annual minimum air temperature in Jerusalem increases with years. From 1993 to 2019, the minimum temperature increased by 1.47°C from-0.46°C to 1.01°C. Considering the current linear trendline, in year 2100 the minimum yearly temperature in Jerusalem will be 5.60°C, 6.06°C above year 1993 level. Also daily changes of daily average temperature increased significantly. The maximum negative change (getting colder the next day) increased from-7.98°C in year 1993 to-10.72°C in year 2019. According to the linear trendline, in year 2100 the maximum daily change will be-19.26°C. This work analyses 7 parameters of extreme temperature or extreme temperature changes, based on over 1 million air temperature records monitored at one meteorological station in Jerusalem. Content

Full text

Changes of Extreme Air Temperature in Jerusalem
by Joseph Nowarski, M.Sc., ME – Energy Conservation Expert
Abstract
The annual minimum air temperature in Jerusalem increases with years. From 1993 to
2019, the minimum temperature increased by 1.47°C from -0.46°C to 1.01°C.
Considering the current linear trendline, in year 2100 the minimum yearly temperature
in Jerusalem will be 5.60°C, 6.06°C above year 1993 level.
Also daily changes of daily average temperature increased significantly. The
maximum negative change (getting colder the next day) increased from -7.98°C in
year 1993 to -10.72°C in year 2019. According to the linear trendline, in year 2100 the
maximum daily change will be -19.26°C.
This work analyses 7 parameters of extreme temperature or extreme temperature
changes, based on over 1 million air temperature records monitored at one
meteorological station in Jerusalem.

Content
1. Source of Data
2. Minimum Yearly Temperature
3. Maximum Yearly Temperature
4. Difference between Maximum and Minimum Yearly Temperature
5. Difference between Daily Maximum and Minimum Temperature
6. Daily Changes of Minimum Temperature
7. Daily Changes of Average Temperature
8. Daily Changes of Maximum Temperature

1. Source of Data
The Israeli Meteorological Service publishes on Internet monitored records of various
meteorological parameters from many meteorological stations across the country [2].
The Israeli Meteorological Service is governmental unit.
The data can be downloaded to CSV (Text and Excel) files. The records are for every
10 minutes, which results in very big files. Number of records for one year is 52,560.
There are limits of downloaded file's size, allowing download of one parameter for
one year only.
This work applies over 1 million air temperature records monitored at one
meteorological station in Jerusalem, based on publication "Dynamic Trendline of Air
Temperature in Jerusalem" [1].
The parameter selected is "temperature", which is "dry temperature".
There are few meteorological station is Jerusalem. Among all Jerusalem stations,
Givat Ram station number 7020 has the longest database, reaching year 1993,
therefore it was selected for the purpose of this work. Givat Ram is in the center of
Jerusalem, the site of Jerusalem University, government campus, the parliament and
Israel Museum. The station is located at the Institute of Earth Science at Jerusalem
University, N31.7704° E35.1973°, elevation 770 m. This station may be regarded as
"open air" without higher buildings around, surrounded by relatively green area.
There is very large number of missing records for years 2001-2003. Therefore, this work
does not include years 2001-2003.
In addition some records are missing also in other years. Following procedure is
applied for determination of the missing records:
o Up to 11 missing records, the estimation is done as linear interpolation
between the neighboring records.
o Application of records for the relevant dates and times from other stations in
Jerusalem (Givat Shaul and Jerusalem Center) using correction coefficients.

o If no data from any alternative station is available, records from neighboring
days are applied, as an average between day before and day after the
missing period.
366 days’ years have colder average temperature than 365 days' years, because of
an additional day in winter. Therefore 29 February was removed from the
calculations.
The "year" starts on 1 January 00:00 and ends on 31 December 23:50.
All data are in degrees Celsius according to winter time – LST.
The dates are in format dd/mm.

2. Minimum Yearly Temperature
The minimum yearly temperature is calculated as a minimum of all records for the
same year.
Chart 1 - Minimum Yearly Temperature [°C]
-3.0
-2.0
-1.0
0.0
1.0
2.0
3.0
4.0
1993
1995
1997
1999
2001
2003
2005
2007
2009
2011
2013
2015
2017
2019
2021
2023
2025
2027
2029
Trendline formula:
Temp [°C] = 0.05663717 * x - 0.52123894
x
is tick number starting with 1993 as tick number 1.
Table 1 - Minimum Yearly Temperature
year °C to 1993 °C
1993 -0.46
0.00
2000 -0.07
0.40
2019 1.01
1.47
2030 1.63
2.10
2050 2.76
3.23
2075 4.18
4.64
2100 5.60
6.06
yearly 0.057
Yearly increase of the minimum temperature is 0.057°C.

From year 1993 to 2019, the minimum temperature increased by 1.47°C from -0.46°C
to 1.01° C. This may explain that snow, which once was almost every year in
Jerusalem, now is very rear.
Considering the current linear trendline, in year 2100 the minimum yearly temperature
in Jerusalem will be 5.60°C, 6.06°C above year 1993 level.
Chart 2 - Day of the Minimum Yearly Temperature
7-Dec
27-Dec
16-Jan
5-Feb
25-Feb
17-Mar
1993
1995
1997
1999
2001
2003
2005
2007
2009
2011
2013
2015
2017
2019
2021
2023
2025
2027
2029
2031
The day of minimum temperature was in the past in February, now moving towards
January and December, which means that February is not so cold anymore as it was
in the past.
Table 2 - Day of the Minimum Yearly Temperature
Min
13/12
Ave
28/01
Max
15/03

3. Maximum Yearly Temperature
The maximum yearly temperature is calculated as a maximum of all records for the
same year.
Chart 3 - Maximum Yearly Temperature [°C]
34
35
36
37
38
39
40
41
1993
1995
1997
1999
2001
2003
2005
2007
2009
2011
2013
2015
2017
2019
2021
2023
2025
2027
2029
Trendline formula:
Temp [°C] = 0.02610619 * x + 36.59646018
Table 3 - Maximum Yearly Temperature
year °C to 1993 °C
1993 36.62
0.00
2000 36.81
0.18
2019 37.30
0.68
2030 37.59
0.97
2050 38.11
1.49
2075 38.76
2.14
2100 39.42
2.79
yearly 0.026
The yearly increase of the maximum yearly temperature is much lower than minimum
yearly temperature, about half.

Chart 4 - Day of the Maximum Yearly Temperature
11-May
31-May
20-Jun
10-Jul
30-Jul
19-Aug
8-Sep
1993
1995
1997
1999
2001
2003
2005
2007
2009
2011
2013
2015
2017
2019
2021
2023
2025
2027
2029
2031
The highest yearly temperature is moving from July to May.
Table 4 - Day of the Maximum Yearly Temperature
Min
16/05
Ave
06/07
Max
10/09

4. Difference between Maximum and Minimum Yearly Temperature
Chart 5 - Difference between Maximum and Minimum Yearly Temperature
32
34
36
38
40
42
1993
1995
1997
1999
2001
2003
2005
2007
2009
2011
2013
2015
2017
2019
2021
2023
2025
2027
2029
Table 5 - Difference between Maximum and Minimum Yearly Temperature
year °C to 1993 °C
1993
37.09
0.00
2000
36.87
-0.21
2019
36.29
-0.79
2030
35.96
-1.13
2050
35.35
-1.74
2075
34.58
-2.50
2100
33.82
-3.27
yearly -0.031
The reason for decreasing difference is the higher increase of the minimum
temperature than of the maximum temperature.

5. Difference between Daily Maximum and Minimum Temperature
5.1. Minimum
The minimum is calculated as the year minimum of the difference between daily
maximum and minimum temperature.
Chart 6 - Difference between Daily Maximum and Minimum Temperature -
Minimum
1.0
1.2
1.4
1.6
1.8
2.0
2.2
2.4
2.6
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
Table 6 - Difference between Daily Maximum and Minimum Temperature -
Minimum
year °C to 1993 °C
1993 2.02
0.00
2000 1.93
-0.09
2019 1.69
-0.33
2030 1.55
-0.48
2050 1.29
-0.73
2075 0.97
-1.05
2100 0.65
-1.38
yearly -0.013

5.2. Average
The average is calculated as the year average of the difference between daily
maximum and minimum temperature.
Chart 7 - Difference between Daily Maximum and Minimum Temperature -
Average
8.0
8.2
8.4
8.6
8.8
9.0
9.2
1993
1995
1997
1999
2001
2003
2005
2007
2009
2011
2013
2015
2017
2019
2021
2023
2025
2027
2029
Table 7 - Difference between Daily Maximum and Minimum Temperature - Average
year °C to 1993 °C
1993 8.31
0.00
2000 8.42
0.11
2019 8.72
0.41
2030 8.90
0.59
2050 9.22
0.91
2075 9.62
1.31
2100 10.02
1.71
yearly 0.016

5.3. Maximum
The maximum is calculated as the year maximum of the difference between daily
maximum and minimum temperature.
Chart 8 - Difference between Daily Maximum and Minimum Temperature -
Maximum
14
16
18
20
22
24
26
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
Table 8 - Difference between Daily Maximum and Minimum Temperature -
Maximum
year °C to 1993 °C
1993 17.45
0.00
2000 17.62
0.16
2019 18.06
0.60
2030 18.31
0.86
2050 18.77
1.32
2075 19.35
1.90
2100 19.93
2.48
yearly 0.023

6. Daily Changes of Minimum Temperature
6.1. Maximum Negative Change
"Negative" means getting colder the next day.
Chart 9 - Daily Changes of Minimum Temperature – Maximum Negative Change
-16
-14
-12
-10
-8
-6
1993
1995
1997
1999
2001
2003
2005
2007
2009
2011
2013
2015
2017
2019
2021
2023
2025
2027
2029
2031
Table 9 - Daily Changes of Minimum Temperature - Maximum Negative Change
year °C to 1993 °C
1993 -9.17
0.00
2000 -9.39
-0.22
2019 -10.00
-0.83
2030 -10.35
-1.19
2050 -11.00
-1.83
2075 -11.80
-2.63
2100 -12.60
-3.44
yearly -0.032

Chart 10 - Day of the highest minimum temperature drop
31-Jan
20-Feb
12-Mar
1-Apr
21-Apr
11-May
1993
1995
1997
1999
2001
2003
2005
2007
2009
2011
2013
2015
2017
2019
2021
2023
2025
2027
2029
2031
Year 2012 was removed from this analysis, as in this year the drop was unusually low
(-5.7°C).
Table 10 - Day of the highest minimum temperature drop
Min 10/02
Ave 10/04
Max 12/05

6.2. Maximum Positive Change
"Positive" means getting warmer the next day.
Chart 11 - Daily Changes of Minimum Temperature – Maximum Positive Change
6
8
10
12
14
16
18
1993
1995
1997
1999
2001
2003
2005
2007
2009
2011
2013
2015
2017
2019
2021
2023
2025
2027
2029
2031
Table 11 - Daily Changes of Minimum Temperature – Maximum Positive Change
year °C to 1993 °C
1993 8.44
0.00
2000 8.40
-0.04
2019 8.27
-0.17
2030 8.20
-0.24
2050 8.08
-0.36
2075 7.92
-0.52
2100 7.76
-0.68
yearly -0.006

7. Daily Changes of Average Temperature
7.1. Maximum Negative Change
Chart 12 - Daily Changes of Average Temperature - Maximum Negative Change
-14.0
-13.0
-12.0
-11.0
-10.0
-9.0
-8.0
-7.0
-6.0
1993
1995
1997
1999
2001
2003
2005
2007
2009
2011
2013
2015
2017
2019
2021
2023
2025
2027
2029
Trendline formula:
∆T [°C] = -0.105440327 * x - 7.873227528
Table 12 - Daily Changes of Average Temperature - Maximum Negative Change
year °C to 1993 °C
1993 -7.98
0.00
2000 -8.72
-0.74
2019 -10.72
-2.74
2030 -11.88
-3.90
2050 -13.99
-6.01
2075 -16.62
-8.65
2100 -19.26
-11.28
yearly -0.105

Chart 13 - Day of the highest average temperature drop
21-Jan
10-Feb
2-Mar
22-Mar
11-Apr
1-May
21-May
1993
1995
1997
1999
2001
2003
2005
2007
2009
2011
2013
2015
2017
2019
2021
2023
2025
2027
2029
2031
There is no change of the average day of the highest average temperature drop,
which is 6 April.
Table 13 - Day of the highest average temperature drop
Min 31/01
Ave 06/04
Max 19/05

7.2. Maximum Positive Change
Chart 14 - Daily Changes of Average Temperature - Maximum Positive Change
5.0
5.5
6.0
6.5
7.0
7.5
8.0
8.5
9.0
9.5
10.0
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
Table 14 - Daily Changes of Average Temperature - Maximum Positive Change
year °C to 1993 °C
1993 7.44
0.00
2000 7.14
-0.30
2019 6.33
-1.11
2030 5.86
-1.58
2050 5.01
-2.43
2075 3.94
-3.50
2100 2.88
-4.56
yearly -0.043

8. Daily Changes of Maximum Temperature
8.1. Maximum Negative Change
Chart 15 - Daily Changes of Maximum Temperature - Maximum Negative Change
-20
-18
-16
-14
-12
-10
-8
1993
1995
1997
1999
2001
2003
2005
2007
2009
2011
2013
2015
2017
2019
2021
2023
2025
2027
2029
Table 15 - Daily Changes of Maximum Temperature - Maximum Negative Change
year °C to 1993 °C
1993 -
12.71
0.00
2000 -
12.90
-0.19
2019 -
13.41
-0.70
2030 -
13.71
-1.00
2050 -
14.25
-1.54
2075 -
14.93
-2.22
2100 -
15.60
-2.89
yearly -
0.027

8.2. Maximum Positive Change
Chart 16 - Daily Changes of Maximum Temperature - Maximum Positive
Change
6.5
7.0
7.5
8.0
8.5
9.0
9.5
10.0
10.5
11.0
1993
1995
1997
1999
2001
2003
2005
2007
2009
2011
2013
2015
2017
2019
2021
2023
2025
2027
2029
Daily changes of maximum temperature are decreasing. The change is -0.050°C per
year, in average.
Table 16 - Daily Changes of Maximum Temperature - Maximum Positive Change
year °C to 1993 °C
1993 9.27
0.00
2000 8.92
-0.35
2019 7.97
-1.30
2030 7.42
-1.85
2050 6.42
-2.85
2075 5.17
-4.10
2100 3.92
-5.35
yearly -0.050

9. References
1. Dynamic Trendline of Air Temperature in Jerusalem, Joseph Nowarski,
www.academia.edu
2. The Government Databases / Meteorological Service
https://ims.data.gov.il/ims/7
* * *