Introduction to Hands On Training in CORDEX South Asia Data Analysis

Module-1

J. Sanjay

Centre for Climate Change Research (CCCR)Indian Institute of Tropical Meteorology (IITM), Pune

(An Autonomous Institute of the Ministry of Earth Sciences, Govt. of India)

Email: sanjay@tropmet.res.in

CORDEX-South Asia Evaluation Runs available for Hands On Analyses & Visualization

Institute

Model Experiment Resolution

Driving Model

Driving Experiment

IITM WRF3.1.1 BMJ Cu Scheme

50 km; Mercator

ERA-Interim Global 0.75o

IITM RegCM3.0 Grell Cu Scheme

50 km; Mercator

ERA-Interim Global 1.5o

IITM LMDZ AGCM

Emanuel Cu Scheme

35 km; Variable

ERA-Interim Nudged with ERA-Interim

IITM LMDZ AGCM

Tiedtke Cu Scheme

35 km; Variable

ERA-Interim Nudged with ERA-Interim

• All RCM outputs regridded on a common region and 0.5o lat./lon. Grid in NetCDF

• Monthly/Daily mean Precipitation for the period 1989-2005

Network Common Data Form•NetCDF is a set of software libraries and self-describing machine-independent data formats that support the creation, access, and sharing of array-oriented scientific data

NetCDF Utilities

•ncdump reads a netCDF dataset and prints a textual representation of the information in the dataset

•ncdump –h file.nc prints the header information in a NetCDF file

Climate Data Operators

•CDO is a collection of command line Operators to manipulate and analyse Climate and NWP model Data (from MPIM https://code.zmaw.de/projects/cdo)

•Supported data formats are GRIB 1/2, netCDF 3/4, SERVICE, EXTRA and IEG. There are more than 600 operators available

•CDO has very small memory requirements and can process files larger than the physical memory

•CDO is open source

•Full documentation available as html or pdf from homepage (https://code.zmaw.de/projects/cdo)

• CDO User’s Guide Version 1.6.1

• CDO Reference Card

Grid Analysis and Display System(from COLA http://www.iges.org/grads)

•GrADS is an interactive desktop tool that is used for easy access, manipulation, and visualization of earth science data

•GrADS has two data models for handling gridded and station data

•GrADS supports many data file formats, including binary (stream or sequential), GRIB (version 1 and 2), NetCDF, HDF (version 4 and 5), and BUFR (for station data)

• GrADS has been implemented worldwide on a variety of commonly used operating systems and is freely distributed over the Internet

•Online documentation has become the new standard for GrADS. Documentation page (http://www.iges.org/grads/gadoc) has

• User's Guide• Tutorial• useful Index for quick reference

Structure of Files

Start Virtual Box Fedora14

Login

User : CORDEXPasswd: cordex123

Home Directory: /home/CORDEX/Desktop/Modules

DATA Directories:

OBS: Observation Data -MonthlyRegCM/LMDZ/ARW: Model Data –Monthly (1989-2005)

OBS/DAILY: Daily Files (1996-2005)

What to do:

CDO & GrADS Scripts

$ cd scripts/CDA1 (Climate Data Analysis Module-1)$cd plot[1-5] (Change to each sub-module directory)

Thanks to Sandip & Sabin

Climate Data Analysis Module: CDA1 (CORDEX South Asia: Climate model outputs) – Mean & VariabilityDay 4: Friday, 30 August 2013 09:00 – 11:00 Hands on training: 1 (Trainers: J. Sanjay, Jayashree Revadekar, Rajiv Chaturvedi, Milind Mujumdar and Vimal Mishra)

Precipitation Analyses and Visualization of:

•Observed Mean spatial patterns during Summer monsoon (JJAS) and Winter (DJF) seasons

•Comparison of RCMs simulated mean spatial patterns during Summer monsoon (JJAS) season

•Area averaged mean monthly annual cycle

•Comparison of RCMs simulated spatial patterns of interannual variability (standard deviation) during Summer monsoon (JJAS) season

•Temporal evolution of area averaged interannual variability (summer monsoon season anomalies normalized with standard deviation)

Scripts provided: Analyses using CDO (Climate Data Operators) and visualization using GrADS (Graphical Analysis and Display System)

Precipitation Observed Mean Spatial patterns during Summer monsoon (JJAS) and Winter (DJF) seasons

File: CDA1/plot1/seasonal-mean.cdo

•Select months

cdo -selmon,6,7,8,9 $DATADIR/OBS/CRU_precip_mon_1989-2005-WA.nc CRU_precip_jjas.nc

•Time average over season

cdo -timmean CRU_precip_jjas.nc CRU_precip_jjas_mean.nc

File: CDA1/plot1/seasonal-mean.gs

•GrADS script to plot & prepare output in EPS format

File: CDA1/plot1/seasonal-mean.sh

•Unix shell script for CDO analysis & GrADS output

Exercise:

•Please bring out the differences in the two seasons

Comparison of RCMs simulated mean precipitation spatial patterns during Summer monsoon (JJAS) season

File: CDA1/plot2/mul-mod-seasonal-mean.cdo

•Select JJAS monthscdo -selmon,6,7,8,9 $DATADIR/OBS/CRU_precip_mon_1989-2005-WA.nc CRU_precip_jjas.nccdo -selmon,6,7,8,9 $DATADIR/LMDZ/LMDZ1_precip_mon_1989-2005-WA.nc LMDZ1_precip_jjas.nc

•Compute JJAS mean & set relative time axis

cdo -r -settaxis,2000-07-15,00:00,1mon -timmean CRU_precip_jjas.nc CRU_precip_jjas-mean.nccdo -r -settaxis,2000-07-15,00:00,1mon -timmean LMDZ1_precip_jjas.nc LMDZ1_precip_jjas-mean.nc

•Compute Ensemble JJAS mean

cdo -ensmean LMDZ1_precip_jjas-mean.nc LMDZ2…..nc RegCM…...nc ARW……..nc ENS_precip_jjas-mean.nc

File: CDA1/plot2/mul-mod-seasonal-mean.gs

•GrADS script to plot & prepare output in EPS format

File: CDA1/plot2/mul-mod-seasonal-mean.sh

•Unix shell script for CDO analysis & GrADS output

Exercise:

•Please bring out the differences in the simulations

Area averaged mean monthly annual cycle of precipitation

File: CDA1/plot3/annual-cycle.cdo

•Compute monthly mean climatologycdo -ymonmean $DATADIR/OBS/CRU_precip_mon_1989-2005-WA.nc CRU_precip_mon_CLIM.nc cdo -ymonmean $DATADIR/LMDZ/LMDZ1_precip_mon_1989-2005-WA.nc LMDZ1_precip_mon_CLIM.nc

•Select regioncdo -sellonlatbox,70,90,10,25 CRU_precip_mon_CLIM.nc CRU_precip_mon_CLIM_IND.nccdo -sellonlatbox,70,90,10,25 LMDZ1_precip_mon_CLIM.nc LMDZ1_precip_mon_CLIM_IND.nc

•Area averagecdo -fldmean CRU_precip_mon_CLIM_IND.nc CRU_precip_mon_CLIM_IND_fldmean.nc cdo -fldmean LMDZ1_precip_mon_CLIM_IND.nc LMDZ1_precip_mon_CLIM_IND_fldmean.nc

•Set relative time axiscdo -r -settaxis,2000-01-15,12:00,1mon CRU_precip_mon_CLIM_IND_fldmean.nc CRU_precip_mon_CLIM_IND_fldmean-n.nc cdo -r -settaxis,2000-01-15,12:00,1mon LMDZ1_precip_mon_CLIM_IND_fldmean.nc LMDZ1_precip_mon_CLIM_IND_fldmean-n.nc

File: CDA1/plot3/annual-cycle.gs

•GrADS script to plot & prepare output in EPS format

File: CDA1/plot3/annual-cycle.sh

•Unix shell script for CDO analysis & GrADS output

Exercise:

•Please bring out the differences in the annual cycle

•Analyse for a region of your choice

Comparison of RCMs simulated spatial patterns of summer monsoon (JJAS) season precipitation interannual variability (standard deviation)

File: CDA1/plot4/mul-mod-seasonal-std.cdo

•Select JJAS months & seasonal mean for each year

cdo -yearmean -selmon,6/9 $DATADIR/OBS/CRU_precip_mon_1989-2005-WA.nc CRU_precip_jjas.nccdo -yearmean -selmon,6/9 $DATADIR/LMDZ/LMDZ1_precip_mon_1989-2005-WA.nc LMDZ1_precip_jjas.nc

•Compute standard deviation of JJAS mean

cdo -timstd CRU_precip_jjas.nc CRU_precip_jjas-timstd.nccdo -timstd LMDZ1_precip_jjas.nc LMDZ1_precip_jjas-timstd.nc

File: CDA1/plot4/mul-mod-seasonal-std.gs

•GrADS script to plot & prepare output in EPS format

File: CDA1/plot4/mul-mod-seasonal-std.sh

•Unix shell script for CDO analysis & GrADS output

Exercise:

•Please bring out the differences in the simulations

Temporal evolution of area averaged of summer monsoon (JJAS) season precipitation interannual variability (seasonal anomalies normalized with standard deviation)

File: CDA1/plot5/IAV.cdo

•Compute JJAS mean for each year

cdo -selmon,6,7,8,9 $DATADIR/CRU_precip_mon_1989-2008-WA.nc CRU_precip_jjas.nccdo -yearmean CRU_precip_jjas.nc CRU_precip_jjas-mean.nc

•Select region and area average

cdo -sellonlatbox,70,90,10,25 CRU_precip_jjas-mean.nc CRU_precip_jjas-mean-IND.nccdo -fldmean CRU_precip_jjas-mean-IND.nc CRU_precip_jjas-mean-IND-fldmean.nc

• Compute area averaged seasonal anomalies

cdo -timmean CRU_precip_jjas-mean-IND-fldmean.nc CRU_precip_jjas-mean-IND-fldmean-timmean.nccdo -sub CRU_precip_jjas-mean-IND-fldmean.nc CRU_precip_jjas-mean-IND-fldmean-timmean.nc CRU_precip_jjas-mean-IND-anom.nc

•Prepare the observed summer monsoon precipitation index

cdo -timstd CRU_precip_jjas-mean-IND-fldmean.nc CRU_precip_jjas-mean-IND-fldmean-std.nccdo -div CRU_precip_jjas-mean-IND-anom.nc CRU_precip_jjas-mean-IND-fldmean-std.nc CRU_precip_jjas-mean-IND-std-fldmean.nccdo -r -settaxis,1989-07-15,00:00,1year CRU_precip_jjas-mean-IND-std-fldmean.nc CRU_precip_jjas-mean-IND-std-fldmean-n.nc

File: CDA1/plot5/IAV.gs

•GrADS script to plot & prepare output in EPS format

File: CDA1/plot5/IAV.sh

•Unix shell script for CDO analysis & GrADS output

Exercise:

•Please indicate the extreme monsoon years

File: CDA1/plot6/mul-mod-seas-mean-bias.cdo

•Compute JJAS long-term mean bias

File: CDA1/plot6/mul-mod-seas-mean-bias.gs

•GrADS script to plot & prepare output in EPS format

File: CDA1/plot6/mul-mod-seas-mean-bias.sh

•Unix shell script for CDO analysis & GrADS output

cdo -sub ../plot2/LMDZ1_precip_jjas-mean.nc ../plot2/CRU_precip_jjas-mean.nc LMDZ1_precip_jjas-bias.nc

Comparison of RCMs simulated Summer monsoon (JJAS) season mean precipitation bias

File: CDA1/plot7/mul-mod-seas-mean-cv.cdo

•Compute JJAS mean CV

File: CDA1/plot7/mul-mod-seas-mean-cv.gs

•GrADS script to plot & prepare output in EPS format

File: CDA1/plot7/mul-mod-seas-mean-cv.sh

•Unix shell script for CDO analysis & GrADS output

Comparison of RCMs simulated and Observed Summer monsoon (JJAS) season mean precipitation Coefficient of Variation (CV = Standard Deviation / Mean)

cdo -mulc,100.0 -div ../plot4/CRU_precip_jjas-timstd.nc ../plot2/CRU_precip_jjas-mean.nc CRU_precip_jjas-cv.nccdo -mulc,100.0 -div ../plot4/LMDZ1_precip_jjas-timstd.nc ../plot2/LMDZ1_precip_jjas-mean.nc LMDZ1_precip_jjas-cv.nc

Thanks for your attention

Email: sanjay@tropmet.res.in

Many Thanks to:

• My Team members• Sabin & Sandip