1. Professor A.K.M. Saiful Islam
DSMHT 403: Climate Modelling and Adaptation
Lecture-5:
Indices of Climate Extreme
Professor A.K.M. Saiful Islam
Institute of Water and Flood Management (IWFM)
Bangladesh University of Engineering and Technology (BUET)
8 November 2016

2. Outline Prediction of climate change
Global and regional climate change predictions
Dynamic and static downscaling for impact study
Uncertainty of predictions

3. Indices of Climate Extremes
Outline of the lecture
Climate indices for extreme climate
Standard climate indices
Calculating climate indices
R-ClimIndex tool for calculating indices

4. Information on the Climate extremes
Confidence has increased that some extremes will become more frequent, more widespread and/or more intense during the 21st century (IPCC, 2007).
As a result, the demand for information services on weather and climate extremes is growing.
The sustainability of economic development and living conditions depends on our ability to manage the risks associated with extreme events. Many practical problems require knowledge of the behavior of extreme values.
In particular, the infrastructures, public services and other facilities we depend upon for food, water, energy, health, shelter and transportation are sensitive to high or low values of meteorological variables.

5. Assessment of extremes
To gain a uniform perspective on observed changes in weather and climate extremes, the joint CCl/WCRP-Clivar/JCOMM Expert Team on Climate Change Detection and Indices (ETCCDI) has defined a core set of descriptive indices of extremes.
The indices describe particular characteristics of extremes, including frequency, amplitude and persistence.
The core set includes 27 extremes indices for temperature and precipitation.

6. Climate Indices
Ott, W Environmental Indices: Theory and Practice
Indices are used to summarize and present a complex set of multivariate (several variables at the same time) changes so that the results can be easily understood and used in policy decisions made by non-specialists in the field.

7. 400 Climate Indices
ClimDex ClimDex Version 3.1: User’s Guide. cccma.seos.uvic.ca/ETCCDMI/ClimDex/climdex-v1-3-users-guide.pdf
Frich, P., L. V. Alexander, P. Della-Manta, B. Gleason, M. Haylock, A. M. G. Klein Tank and T. Peterson Observed coherent changes in climatic extremes during the second half of the twentieth century. Clim. Res., 19:
European Climate Assessment European Climate Assessment and Dataset. eca.knmi.nl/
Klein Tank, A.M.G., J.B. Wijngaard, G.P. Können, R. Böhm, G. Demarée, A. Gocheva, M. Mileta, S. Pashiardis, L. Hejkrlik, C. Kern-Hansen, R. Heino, P. Bessemoulin, G. Müller-Westermeier, M. Tzanakou, S. Szalai, T. Pálsdóttir, D. Fitzgerald, S. Rubin, M. Capaldo, M. Maugeri, A. Leitass, A. Bukantis, R. Aberfeld, A.F.V. van Engelen, E. Forland, M. Mietus, F. Coelho, C. Mares, V. Razuvaev, E. Nieplova, T. Cegnar, J. Antonio López, B. Dahlström, A. Moberg, W. Kirchhofer, A. Ceylan, O. Pachaliuk, L.V. Alexander, and P. Petrovic, Daily dataset of 20th-century surface air temperature and precipitation series for the European Climate Assessment. Int. J. Climatol., 22,
Kiktev, D., D. Sexton, L. Alexander and C. Folland Comparison of modelled and observed trends in indicators of daily climate extremes. J. Clim., 16,
Stardex Statistical and Regional dynamical Downscaling of Extremes for European regions.
Bonsal, B.R., X. Zhang, L.A. Vincent and W.D. Hogg Characteristics of daily and extreme temperatures over Canada. Journal of Climate 14 :
Klein Tank, A.M.G. and G.P. Können, Trends in indices of daily temperature and precipitation extremes in Europe, J. Climate, 16,

8. Gachon Indices of Climate Extremes
18 indices for extreme temperature and precipitation for Canadian regions
must represent regional Canadian climate conditions;
must be relevant to climate change impact studies; and
must be adapted to the main characteristics of climate conditions at the regional scale.
“providing a good mix of information – precipitation indices characterize the frequency, intensity, length of dry spells, magnitude and occurrence of wet extremes while temperature indices refer to variability, season lengths and cold and warm extremes in terms of magnitude, occurrence and duration.”

9. Gachon Indices related to precipitation
 INDEX
DEFINITION
UNIT
TIME SCALE
Frequency
Percentage of wet days (Threshold=1 mm)
% days
Season
Intensity
Simple daily intensity index : sum of daily precip/number of wet days
mm/wet d
Extremes
Maximum number of consecutive dry days (<1 mm)
days
Magnitude
Maximum 3-days precipitation total mm
and
90th percentile of rainday amount ( (Threshold=1 mm)
mm/days
Occurrence
Percentage of days Prec>90th percentile (61-90 based period)

10. Gachon Indices related to Temperature
Daily variability
Mean of diurnal temperature range °C
Season
Percentage of days with freeze and thaw cycle (Tmax>0°C, Tmin<0°C)
% days
Month
Season length
Frost season length :Tday<0°C more than 5 d.and Tday>0°C more than 5 d.
days
Year
Growing season length :Tday>5°C more than 5 d.and Tday<5°C more than 5 d.
Extremes
Sum of sequences > 3 days where Tmin< daily Tmin normal - 5°C
Winter
cold & hot
Sum of sequences > 3 days where Tmax> daily Tmax normal + 3°C
summer
10th percentile of daily Tmax
Magnitude 
90th percentile of daily Tmax
and
10th percentile of daily Tmin
90th percentile of daily Tmin
Occurrence
Percentage of days Tmax>90th percentile (61-90 based period)
Percentage of days Tmin<10th percentile (61-90 based period)

11. ETCCDI Rainfall related indicesID
Indicator name
Definitions
UNITS
RX1day
Max 1-day precipitation amount
Monthly maximum 1-day precipitation Mm
Rx5day
Max 5-day precipitation amount
Monthly maximum consecutive 5-day precipitation
SDII
Simple daily intensity index
Annual total precipitation divided by the number of wet days (defined as PRCP>=1.0mm) in the year
Mm/day
R10
Number of heavy precipitation days
Annual count of days when PRCP>=10mm
Days
R20
Number of very heavy precipitation days
Annual count of days when PRCP>=20mm

12. ETCCDI Rainfall related indicesID
Indicator name
Definitions
UNITS
CDD
Consecutive dry days
Maximum number of consecutive days with RR<1mm
Days
CWD
Consecutive wet days
Maximum number of consecutive days with RR>=1mm
R95p
Very wet days
Annual total PRCP when RR>95th percentile Mm
R99p
Extremely wet days
Annual total PRCP when RR>99th percentile mm
PRCPTOT
Annual total wet-day precipitation
Annual total PRCP in wet days (RR>=1mm)

13. ETCCDI Temperature related indicesID
Indicator name
Definitions
UNITS
FD0
Frost days
Annual count when TN(daily minimum)<0ºC
Days
SU25
Summer days
Annual count when TX(daily maximum)>25ºC
ID0
Ice days
Annual count when TX(daily maximum)<0ºC
TR20
Tropical nights
Annual count when TN(daily minimum)>20ºC
GSL
Growing season Length
Annual (1st Jan to 31st Dec in NH, 1st July to 30th June in SH) count between first span of at least 6 days with TG>5ºC and first span after July 1 (January 1 in SH) of 6 days with TG<5ºC
TXx
Max Tmax
Monthly maximum value of daily maximum temp ºC
TNx
Max Tmin
Monthly maximum value of daily minimum temp

14. ETCCDI Temperature related indicesID
Indicator name
Definitions
UNITS
TNx
Max Tmin
Monthly maximum value of daily minimum temp ºC
TXn
Min Tmax
Monthly minimum value of daily maximum temp
TNn
Min Tmin
Monthly minimum value of daily minimum temp
TN10p
Cool nights
Percentage of days when TN<10th percentile
Days
TX10p
Cool days
Percentage of days when TX<10th percentile
TN90p
Warm nights
Percentage of days when TN>90th percentile
TX90p
Warm days
Percentage of days when TX>90th percentile

15. Extreme climate Indices Using statistical package RClimIndex

16. Outline of the RClimDex Lecture
To download and install R
How to run R
How to use RClimDex
Input Data Format

17. To download and install R:
Go to:
Click “CRAN” in the left panel of the screen
Select your nearest site from the list of CRAN Mirrors, e.g., India, Singapore
Select the target operating system, e.g., Windows, from the main panel
Select the module “base”

18. To download and install R:
Click on “Download R for Windows” (the version number may change due to the R group development)
Choose “Run” to run the setup to install R directly without saving the .exe setup file, or “Save” to save the .exe file to your machine and run it later
If you choose “Run”, it will download the .exe file to your Windows temporary folder and then run it. The following windows will pop up subsequently:
- Choose the language, then click “Next”.

19. To work in R:
When the installation is finished, you can run R by double-click the shortcut icon on your desktop:
or by choosing to run R in your “All Programs”.
Then, you can either use the drop-down menu or type-in command lines. Most items in the drop-down menu can be translated to command lines of function names along with parameters.

20. How to use RClimDex Loading of RClimDex
Within the R consol prompt “>”, enter source(“rclimdex.r”).
rclimdex.r

21. How to use RClimDex

22. How to use RClimDex
Once the source code is successfully loaded, the RClimDex main menu will appear-

23. Load Data and Run QC
Select “Load Data and Run QC” from the RClimDex Menu to open a window as shown below

24. Load Data and Run QC
Error messages will appear in the R console if this step has not been completed successfully. This is usually caused by the wrong input data format

25. Load Data and Run QC
The default value for n is 3 (Criteria in the “Set Parameters for Data QC”) window, but this number may be overwritten by the user. As a value of 3 may flag a very large number of values, users may wish to start by setting this value to 4. After setting the parameter, click “OK” to continue.

26. Load Data and Run QC
If there are outliers, the following window appears.

27. Load Data and Run QC
A pop-up window appears once the data QC is complete. At the same time, four Excel files, “21946tempQC.csv”, “21946prcpQC.csv”, “21946tepstdQC.csv”, and “21946indcal.csv” are created in a subdirectory called log. The first two files contain information about unreasonable values for temperature and precipitation. The third file flags all possible outliers in daily temperature with the dates on which those outliers occur. The last file contains the QC’d data and will be used for the indices calculation.

28. Load Data and Run QC
At this point, the user may check the data in the file “21946tepstdQC.csv” to determine if any value marked as an outlier is really an outlier. The file “21946indcal.csv” can be modified using Excel under Windows and any editor under Unix if any action needs to be taken.

29. Load Data and Run QC
After the completion of this step, the user may Click OK on the following window to proceed with indices calculation
the indices are computed from the QC’d data. The original input file is not altered in any manner. So if a user chose to modify the original data file to correct some of the problematic values, the Load Data and Run QC procedure needs to be performed again on the improved data set before the changes can be reflected in the indices calculation

30. Indices calculation

31. Indices calculation Base Period: 1961-2009
User defined upper threshold of daily maximum temp: MAM average temp 33°C. 30°C is taken
User defined lower threshold of daily maximum temp: 0
User defined upper threshold of daily minimum temp: DJF average temperature 14°C. 15°C is taken
User defined upper threshold of daily minimum temp: 0
User defined daily precipitation threshold: JJAS average daily rainfall 11.2 mm. 10 mm is taken

32. Indices calculation
A pop-up window will appear once the selected indices are computed.

33. Indices calculation
Resulting indices series are stored in a sub-directory called indices in Excel format. The indices files have names “21946_XXX.cvs” where XXX represents the name of the index. Data columns are separated by a comma (“,”). For the purpose of visualization, we plot annual series, along with trends computed by linear least square (solid line) and locally weighted linear regression (dashed line). Statistics of the linear trend fitting are displayed on the plots. These plots are stored in a sub-directory called plots in JPEG format. The filenames for plots follow the same rule except that “cvs” is changed to “jpg”.

34. Indices calculation
Select “Indices Calculation” from the main menu to compute additional indices for the same station. For additional stations, select “Data QC” and repeat the above process. Select “Exit” if all required calculations are completed.

35. Indices calculation
if base period is and the data also starts in 1961, one may add “ ”

36. Input Data Format ASCII text file
Columns as following sequences: Year, Month, Day, PRCP, TMAX, TMIN. (NOTE: PRCP units = millimeters and Temperature units= degrees Celsius)
The format as described above must be space delimited (e.g. each element separated by one or more spaces).
For data records, missing data must be coded as -99.9; data records must be in calendar date order. Missing dates allowed. 

37. Input Data Format
Example data Format for the initial data file (e.g. used in the ‘Quality Control’ step):

38. Define Parameter

39. Indices