Part 3—Calculate Summer Air Temperature Averages 2021-2040
Step 1 – Calculate Summer Averages for 2021-2040
Calculate summer averages for each year, from 2021-2040. Repeat the instructions outlined in Part 2, Step 2 (numbered 1-7), replacing "1980_1999_20th_Century_Experiment" with "2021_2040_Scenario_A2".
Show me the steps
Hide- Return to ArcCatalog to make a copy of tas_June_2021_2040_Scenario_A2. Rename the copy "tas_JJA_2021_2040_20th_Century_Experiment". You will use this file for your averages.
- Drag tas_JJA_2021_2040_Scenario_A2 file from ArcCatalog to the top of the ArcMap Layer list, above the three monthly layers.
- Join each of the July (07) and August (08) attribute tables to the tas_JJA_2021_2040_Scenario_A2 attribute table using the FID field
- Open and examine the tas_JJA_2021_2040_Scenario_A2 attribute table. Verify that the joins were successful. You should have temperature data for all three months for the years 2021- 2040.
- Add new fields to this table to accommodate the calculation of the yearly JJA weighted averages for 2021- 2040. Name the new fields JJA2021avg, JJA2022avg, JJA2023avg...JJA2040avg for a total of 20 new fields.
- Calculate JJA weighted average for each year using the Field Calculator in the attribute table To prevent syntax errors copy and paste the following equation into the Field Calculator.
- Repeat for each of the 20 fields JJA2021avg-JJA2040avg
((30 *[tas_JJA_2021_2040_Scenario_A2.202106]) + (31 *[tas_July_2021_2040_Scenario_A2.202107]) + (31 *[tas_August_2021_2040_Scenario_A2.202108]))/92
Instead of recreating the Field Calculator formula each time, just change the year in the existing formula. For example: use the existing formula ((30 *[tas_JJA_2021_2040_Scenario_A2.202106]) + (31 *[tas_July_2021_2040_Scenario_A2.202107]) + (31 *[tas_August_2021_2040_Scenario_A2.202108]))/92, and just change all the 2021s to 2022s to calculate the JJA2022avg. Only change the bolded numbers.
The new weighted average formula for 2022 would look like this:
((30 *[tas_JJA_2021_2040_Scenario_A2.202206]) + (31 *[tas_July_2021_2040_Scenario_A2.202207]) + (31 *[tas_August_2021_2040_Scenario_A2.202208]))/92
if you had difficulty completing the steps above, download this completed file and place it in your NCAR climate change folder. Calculated Summer Averages for 2021-2040
tas_JJA_2021_2040_Scenario_A2_completed (Zip Archive 8.1MB Jan10 09)
tas_JJA_2021_2040_Scenario_A2_completed (Zip Archive 8.1MB Jan10 09)
Step 2 – Calculate 20-year Average for 2021-2040
Calculate the 20-year average for 2021-2040. Follow the steps outlined in Part 2, Step 3, replacing "1980_1999_20th_Century_Experiment" with "2021_2040_Scenario_A2".- Add a new field to the attribute table to accommodate the 20-year JJA Average from the years 2021_2040. Name this field JJA_A2_avg.
- If necessary, right-click on tas_JJA_2021_2040_Scenario_A2 and select Open Attribute Table
- Click on the Options button below the table and select Add Field
- In the Add Field dialog box, enter the field name JJA_A2_avg, and change type to Double
- Click OK
- Calculate 20-year mean using the Field Calculator in the Attribute table
To prevent syntax errors copy and paste the following equation into the field calculator.
([tas_JJA_2021_2040_Scenario_A2.JJA1980avg] + [tas_JJA_2021_2040_Scenario_A2.JJA1981avg] + [tas_JJA_2021_2040_Scenario_A2.JJA1982avg] + [tas_JJA_2021_2040_Scenario_A2.JJA1983avg] + [tas_JJA_2021_2040_Scenario_A2.JJA1984avg] + [tas_JJA_2021_2040_Scenario_A2.JJA1985avg] + [tas_JJA_2021_2040_Scenario_A2.JJA1986avg] + [tas_JJA_2021_2040_Scenario_A2.JJA1987avg] + [tas_JJA_2021_2040_Scenario_A2.JJA1988avg] + [tas_JJA_2021_2040_Scenario_A2.JJA1989avg] + [tas_JJA_2021_2040_Scenario_A2.JJA1990avg] + [tas_JJA_2021_2040_Scenario_A2.JJA1991avg] + [tas_JJA_2021_2040_Scenario_A2.JJA1992avg] + [tas_JJA_2021_2040_Scenario_A2.JJA1993avg] + [tas_JJA_2021_2040_Scenario_A2.JJA1994avg] + [tas_JJA_2021_2040_Scenario_A2.JJA1995avg] + [tas_JJA_2021_2040_Scenario_A2.JJA1996avg] + [tas_JJA_2021_2040_Scenario_A2.JJA1997avg] + [tas_JJA_2021_2040_Scenario_A2.JJA1998avg] + [tas_JJA_2021_2040_Scenario_A2.JJA1999avg])/20
- If necessary, right-click on tas_JJA_2021_2040_Scenario_A2 and select Open Attribute Table
- Right-click on the JJA_A2_avg field name and select Field Calculator...
- In the Field Calculator dialog box enter the following formula to calculate a 20-year average for the years 2021-2040.
- Click OK
- Exploring NCAR Climate Change Data Using GIS
- Teaching Notes
- Case Study
- Step-by-Step Instructions
- Part 1—Download and Install Software and Data
- Part 2—Calculate Summer Air Temperature Averages 1980-1999
- Part 3—Calculate Summer Air Temperature Averages 2021-2040
- Part 4—Compare Average JJA Temperatures for both Model Runs
- Part 5—Create a Temperature Anomaly Map
- Tools and Data
- Going Further
([tas_JJA_2021_2040_Scenario_A2.JJA1980avg] + [tas_JJA_2021_2040_Scenario_A2.JJA1981avg] + [tas_JJA_2021_2040_Scenario_A2.JJA1982avg] + [tas_JJA_2021_2040_Scenario_A2.JJA1983avg] + [tas_JJA_2021_2040_Scenario_A2.JJA1984avg] + [tas_JJA_2021_2040_Scenario_A2.JJA1985avg] + [tas_JJA_2021_2040_Scenario_A2.JJA1986avg] + [tas_JJA_2021_2040_Scenario_A2.JJA1987avg] + [tas_JJA_2021_2040_Scenario_A2.JJA1988avg] + [tas_JJA_2021_2040_Scenario_A2.JJA1989avg] + [tas_JJA_2021_2040_Scenario_A2.JJA1990avg] + [tas_JJA_2021_2040_Scenario_A2.JJA1991avg] + [tas_JJA_2021_2040_Scenario_A2.JJA1992avg] + [tas_JJA_2021_2040_Scenario_A2.JJA1993avg] + [tas_JJA_2021_2040_Scenario_A2.JJA1994avg] + [tas_JJA_2021_2040_Scenario_A2.JJA1995avg] + [tas_JJA_2021_2040_Scenario_A2.JJA1996avg] + [tas_JJA_2021_2040_Scenario_A2.JJA1997avg] + [tas_JJA_2021_2040_Scenario_A2.JJA1998avg] + [tas_JJA_2021_2040_Scenario_A2.JJA1999avg])/20
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tas_JJA_2021_2040_Scenario_A2_completed
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