DATA PROCESSING AND ANALYSIS

(1)

DATA PROCESSING AND ANALYSIS

13 NOV 2018 I SIMON ROSANKA, IEK-8 SABINE SCHRÖDER, IEK-8

TOOLS FOR DATA ANALYSIS – HANDS-ON SESSION

(2)

PROBLEM

CDO and NCOs

(3)

TASK

Main task:

Obtain the correlation coefficient between dry air temperature and specific humidity at a pressure level of 500 hPa for Summer and Winter over Europe.

Subtask:

1. Use CDO and NCOs

2. Include correct naming in final file 3. Stick to CF-conventions

CDO and NCOs

(4)

USEFUL WEBLINKS

• NCO:

http://nco.sourceforge.net/nco.html#Reference-Manual

• CDO:

https://code.mpimet.mpg.de/projects/cdo/embedded/cdo_refcard.pdf

CDO and NCOs

(5)

STRATEGY

1. Merge data (to obtain seasonal data)

2. Interpolate from model levels to pressure level (500 hPa) 3. Split dataset

4. Calculate correlation factor 5. Mask Europe

6. Adjust attributes

CDO and NCOs

(6)

USEFUL CDO COMMANDS

• sinfo

• mergetime

• ml2pl

• splitseas

• splitname

• timcor

• sellonlatbox

CDO and NCOs

(7)

SOLUTION (1)

1. Obtain header information cdo sinfon in.nc

2. Merge monthly data into yearly data:

cdo mergetime data_* out.nc 3. Interpolate onto pressure level:

cdo ml2pl,50000 in.nc out.nc 4. Split data into seasons:

cdo splitseas in.nc out_

CDO and NCOs

(8)

SOLUTION (2)

5. Split variables into single files:

cdo splitname in.nc out_

6. Obtain correlation factor for each season:

cdo timcor tm1_ave.nc qm1_ave.nc out.nc 7. Select only Europe:

cdo sellonlatbox,-15,-50,30,70 in.nc out.nc

CDO and NCOs

(9)

SOLUTION (3)

8. Rename correlation variable and make consistent with CF-convention:

ncrename –v tm1_ave,cor_tm1_qm1

ncatted –a long_name,cor_tm1_qm1,m,c,”correlation coefficient”

ncatted –a units,cor_tm1_qm1,m,c,”1”

CDO and NCOs

(10)

SOLUTION (4)

CDO and NCOs