Exercise 1: Trend maps

1 Exercise 1: Trend maps Calculate trend maps for all variables in GFDL-ESM2M-am over the period (past to present) by using CDO. Look at the trend map...

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Exercise 1: Trend maps 1950-2000 Calculate trend maps for all variables in GFDL-ESM2M-am-1950-2050 over the period 19502000 (past to present) by using CDO. Look at the trend maps of clear-sky surface solar radiation (rsdscs), aerosol optical depth (od550aer), downwelling thermal radiation (rlds), and surface temperature (ts) with Panoply. Hint: Use a symmetric Blue-White-Red color table. a) Make a first guess: Is there global increase or decrease in the aforementioned parameters? b) Where in the world (and why) do you see distinct trend signals (positive and negative) inclear-sky solar radiation and the aerosol optical depth? c) Quantify the global decadal trends (1950-2000) of all variables in the data file (see example A in appendix).

Exercise 1: Trend maps 1950-2000 Calculate trend maps for all variables in GFDL-ESM2M-am-1950-2050 over the period 19502000 (past to present) by using CDO. Look at the trend maps of clear-sky surface solar radiation (rsdscs), aerosol optical depth (od550aer), downwelling thermal radiation (rlds), and surface temperature (ts) with Panoply. Hint: Use a symmetric Blue-White-Red color table. a) Make a first guess: Is there global increase or decrease in the aforementioned parameters? clear-sky surface solar radiation aerosol optical depth downwelling thermal radiation surface temperature

→ aerosols → Industrial activities → GHGs → enhanced downwelling thermal radiation

b) Where in the world (and why) do you see distinct trend signals (positive and negative) inclear-sky solar radiation and the aerosol optical depth? c) Quantify the global decadal trends (1950-2000) of all variables in the data file (see example A in appendix).

Exercise 1: Trend maps 1950-2000 b) Where in the world (and why) do you see distinct trend signals (positive and negative) in clear-sky solar radiation and the aerosol optical depth?

Exercise 1: Trend maps 1950-2000 b) Where in the world (and why) do you see distinct trend signals (positive and negative) in clear-sky solar radiation and the aerosol optical depth?

Exercise 1: Trend maps 1950-2000 c) Quantify the global decadal trends (1950-2000) of all variables in the data file (see example A in appendix).

#

Short Var -1 od550aer -2 clt -3 prw -4 rlds -5 rsds -6 rsdscs -7 rsdt -8 rsut -9 ts -10 pr

Long Var [unit] Ambient Aerosol Opitical Thickness at 550 nm [1] Total Cloud Fraction [%] Water Vapor Path [kg m-2] Surface Downwelling Longwave Radiation [W m-2] Surface Downwelling Shortwave Radiation [W m-2] Surface Downwelling Clear-Sky Shortwave Radiation [W m-2] TOA Incident Shortwave Radiation [W m-2] TOA Outgoing Shortwave Radiation [W m-2] Surface Temperature [K] Precipitation [kg m-2 s-1]

Dec.Trend 0.005 -0.064 0.232 0.994 -0.115 -0.178 0.028 -0.118 0.111 0.000

Exercise 1: Trend maps 1950-2000 Look at the time series (1950-2000) of global annual clear-sky radiation (rsdscs), aerosol optical depth (od550aer), surface temperature (ts), and downwelling thermal radiation (rlds) by calculating the global field means (see example B in appendix). Visualize the time series in Panoply. a) Describe the temporal evolution of the parameters. b) Are the global linear trends over the period 1950-2000 as calculated in 1) adequate to describe the temporal changes? Why yes? Why not? c) Correlate the time series (cdo -timcor, see E in appendix) of clear-sky solar radiation with the aerosol optical thickness, and the surface temperature with longwave radiation (tradsd) and water vapor (qvi). How do the variables relate to each other?

Exercise 2: Global mean time series a) Describe the temporal evolution of the parameters. b) Are the global linear trends over the period 1950-2000 as calculated in 1) adequate to describe the temporal changes? Why yes? Why not?

Linear?

Exercise 2: Global mean time series c) Correlate the time series (cdo -timcor, see E in appendix) of clear-sky solar radiation with the aerosol optical thickness, and the surface temperature with longwave radiation (tradsd) and water vapor (qvi). How do the variables relate to each other?

Var 1

Var2

R

Clear-sky shortwave rsdscs

AOD 550 od550aer

-0.598

Surface temperature ts

Longwave radiation rlds

0.972

Surface emperature ts

Water vapor Path prw

0.951

However : Correlat io n

≠ Causati

on

Exercise 3: Global mean time series Calculate the global mean “present-day” (year 2000) surface temperature (cdo output -fldmean -selyear,2000) and compare it to the surface temperature of 2050. a) By how much does the temperature increase in the future? b) What is the decadal trend (2000-250) and how does it compare to the trend over the period 19502000?

Year

Global Mean Temp [k]

Diff [K]

1950

288.195

-

2000

288.887

0.692

0.14

2050

289.871

0.984

0.20

IPCC AR5 (2013)

Dec.Trend [K/10y]

Exercise 3: Global mean time series

c) Compute the trend maps (see task 1) for the period 2000-2050 (swdclsky, TAU_2D, tsurf). What is different to the period 1950-2000?

AOD 550

Surface Temperature

1950-2000

2000-2050

Exercise 3: Global mean time series

c) Compute the trend maps (see task 1) for the period 2000-2050 (swdclsky, TAU_2D, tsurf). What is different to the period 1950-2000?

Surface Shortwave Downward Radiation Clear-Sky

1950-2000

2000-2050

Exercise 4: Case Study Europe Extract Central Europe by applying a suitable “lon-lat-box” (see D in appendix) and calculate the European time series (1950-2050) for the variables tsurf, swdclsky, TAU_2D, qvi, tradsd. a) Describe the temporal evolution of the parameters and identify periods of different trend signals. b) Quantify the Central European decadal trends for some of the variables (swdclsky, tsurf, TAU_2D, tradsd) over periods that distinctly differ, e.g., 1950-1980 (“dimming” period) as compared to 19802000 (“brightening period”) and 2000-2050 (future, RCP8.5 scenario). c) In which period do you find the strongest warming? Think about the concept of “dimming” and “brightening”.

Exercise 4: Case Study Europe Extract Central Europe by applying a suitable “lon-lat-box” (see D in appendix) and calculate the European time series (1950-2050) for the variables tsurf, swdclsky, TAU_2D, qvi, tradsd. a) Describe the temporal evolution of the parameters and identify periods of different trend signals.

Brightening

Dimming

Exercise 4: Case Study Europe b) Quantify the Central European decadal trends for some of the variables (swdclsky, tsurf, TAU_2D, tradsd) over periods that distinctly differ, e.g., 1950-1980 (“dimming” period) as compared to 19802000 (“brightening period”) and 2000-2050 (future, RCP8.5 scenario). c) In which period do you find the strongest warming? Think about the concept of “dimming” and “brightening”.

#

Short Var -1 od550aer -2 clt -3 prw -4 rlds -5 rsds -6 rsdscs -7 rsdt -8 rsut -9 ts -10 pr

Long Var [unit] Ambient Aerosol Opitical Thickness at 550 nm [-] Total Cloud Fraction [%] Water Vapor Path [kg m-2] Surface Downwelling Longwave Radiation [W m-2] Surface Downwelling Shortwave Radiation [W m-2] Surface Downwelling Clear-Sky Shortwave Radiation [W m-2] TOA Incident Shortwave Radiation [W m-2] TOA Outgoing Shortwave Radiation [W m-2] Surface Temperature [K] Precipitation [kg m-2 s-1]

Dec.Trend 1950-1980 1980-2000 2000-2050 0.039 -0.076 -0.028 0.235 -0.834 -0.503 -0.119 0.483 0.308 -0.680 2.815 1.506 -0.439 1.996 0.564 -1.034 2.713 1.043 0.011 -0.018 -0.009 1.009 -2.588 -0.551 -0.287 0.933 0.337 0.000 0.000 0.000

Exercise 5: Case Study China

Extract China (ID: 40, see example C) and calculate the corresponding time series (1950-2050) for the variables rsdscs and od550aer.

a) Identify the “dimming” and “brightening” periods in China. What is different as compared to Central Europe?

b) Quantify the decadal trends in surface temperature over the periods 1950-2000 and 2000-2050 and compare them to the Central European and global trends: By how much are the trends enhanced in the future? c) Can you explain why the regional trends (Europe, China, global) differ?

Exercise 5: Case Study China

Extract China (ID: 40, see example C) and calculate the corresponding time series (1950-2050) for the variables rsdscs and od550aer.

a) Identify the “dimming” and “brightening” periods in China. What is different as compared to Central Europe?

Dimming

Brightening

Exercise 5: Case Study China b) Quantify the decadal trends in surface temperature over the periods 1950-2000 and 20002050 and compare them to the Central European and global trends: By how much are the trends enhanced in the future? c) Can you explain why the regional trends (Europe, China, global) differ?

1950-2000 2000-2050

Temp. Trend [K/10y] Europe China Global 0.04 0.06 0.08 0.34 0.29 0.22

China and Europe show decreased decadal temperature trends from 1950-2000 and increased trends from 2000-2050 compared to the global trends in those periods 1950-2000: Masking effects due to clouds & aerosols slow down warming (dimming) 2000-2050: no more (less) masking effects in the later period (brightening)

Exercise 5: Case Study China

For more information about aerosol radiation effects see e.g. IPCC (2013) Chaper 7 and references therin

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