cdo

CDO User’s Guide
Climate Data Operators
Version 1.6.4
June 2014
Uwe Schulzweida – MPI for Meteorology

Contents
1. Introduction 6
1.1. Building from sources ....................................... 6
1.1.1. Compilation ......................................... 7
1.1.2. Installation ......................................... 7
1.2. Usage ................................................ 7
1.2.1. Options ........................................... 8
1.2.2. Environment variables ................................... 9
1.2.3. Operators .......................................... 9
1.2.4. Operator chaining ..................................... 9
1.2.5. Parallelized operators ................................... 10
1.2.6. Operator parameter .................................... 10
1.3. Horizontal grids ........................................... 10
1.3.1. Grid area weights ...................................... 10
1.3.2. Grid description ...................................... 11
1.4. Z-axis description .......................................... 13
1.5. Time axis .............................................. 14
1.5.1. Absolute time ........................................ 14
1.5.2. Relative time ........................................ 15
1.5.3. Conversion of the time ................................... 15
1.6. Parameter table ........................................... 15
1.7. Missing values ............................................ 15
1.7.1. Mean and average ..................................... 16
2. Reference manual 17
2.1. Information ............................................. 18
2.1.1. INFO - Information and simple statistics ........................ 19
2.1.2. SINFO - Short information ................................ 20
2.1.3. DIFF - Compare two datasets field by field ....................... 21
2.1.4. NINFO - Print the number of parameters, levels or times ............... 22
2.1.5. SHOWINFO - Show variables, levels or times ...................... 23
2.1.6. FILEDES - Dataset description .............................. 24
2.2. File operations ........................................... 25
2.2.1. COPY - Copy datasets ................................... 26
2.2.2. REPLACE - Replace variables .............................. 27
2.2.3. DUPLICATE - Duplicates a dataset ........................... 27
2.2.4. MERGEGRID - Merge grid ................................ 27
2.2.5. MERGE - Merge datasets ................................. 28
2.2.6. SPLIT - Split a dataset .................................. 29
2.2.7. SPLITTIME - Split timesteps of a dataset ........................ 31
2.2.8. SPLITSEL - Split selected timesteps ........................... 32
2.3. Selection ............................................... 33
2.3.1. SELECT - Select fields ................................... 34
2.3.2. SELVAR - Select fields ................................... 35
2.3.3. SELTIME - Select timesteps ............................... 37
2.3.4. SELBOX - Select a box of a field ............................. 39
2.4. Conditional selection ........................................ 40
2.4.1. COND - Conditional select one field ........................... 41
2.4.2. COND2 - Conditional select two fields .......................... 41
2.4.3. CONDC - Conditional select a constant ......................... 42
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Contents Contents
2.5. Comparison ............................................. 43
2.5.1. COMP - Comparison of two fields ............................ 44
2.5.2. COMPC - Comparison of a field with a constant .................... 45
2.6. Modification ............................................. 46
2.6.1. SETPARTAB - Set parameter table ........................... 48
2.6.2. SET - Set field info ..................................... 50
2.6.3. SETTIME - Set time .................................... 51
2.6.4. CHANGE - Change field header ............................. 53
2.6.5. SETGRID - Set grid information ............................. 55
2.6.6. SETZAXIS - Set z-axis type ................................ 56
2.6.7. SETGATT - Set global attribute ............................. 57
2.6.8. INVERT - Invert latitudes ................................. 58
2.6.9. INVERTLEV - Invert levels ................................ 58
2.6.10. MASKREGION - Mask regions .............................. 59
2.6.11. MASKBOX - Mask a box ................................. 60
2.6.12. SETBOX - Set a box to constant ............................. 61
2.6.13. ENLARGE - Enlarge fields ................................ 62
2.6.14. SETMISS - Set missing value ............................... 63
2.7. Arithmetic .............................................. 65
2.7.1. EXPR - Evaluate expressions ............................... 67
2.7.2. MATH - Mathematical functions ............................. 69
2.7.3. ARITHC - Arithmetic with a constant .......................... 70
2.7.4. ARITH - Arithmetic on two datasets ........................... 71
2.7.5. MONARITH - Monthly arithmetic ............................ 72
2.7.6. YMONARITH - Multi-year monthly arithmetic ..................... 73
2.7.7. YDAYARITH - Multi-year daily arithmetic ....................... 74
2.7.8. YHOURARITH - Multi-year hourly arithmetic ..................... 75
2.7.9. ARITHDAYS - Arithmetic with days .......................... 75
2.8. Statistical values .......................................... 76
2.8.1. CONSECSTAT - Consecute timestep periods ...................... 81
2.8.2. ENSSTAT - Statistical values over an ensemble ..................... 82
2.8.3. ENSSTAT2 - Statistical values over an ensemble .................... 84
2.8.4. ENSVAL - Ensemble validation tools ........................... 85
2.8.5. FLDSTAT - Statistical values over a field ........................ 87
2.8.6. ZONSTAT - Zonal statistical values ........................... 89
2.8.7. MERSTAT - Meridional statistical values ........................ 90
2.8.8. GRIDBOXSTAT - Statistical values over grid boxes .................. 91
2.8.9. VERTSTAT - Vertical statistical values ......................... 92
2.8.10. TIMSELSTAT - Time range statistical values ...................... 93
2.8.11. TIMSELPCTL - Time range percentile values ...................... 94
2.8.12. RUNSTAT - Running statistical values .......................... 95
2.8.13. RUNPCTL - Running percentile values ......................... 96
2.8.14. TIMSTAT - Statistical values over all timesteps ..................... 97
2.8.15. TIMPCTL - Percentile values over all timesteps .................... 98
2.8.16. HOURSTAT - Hourly statistical values ......................... 99
2.8.17. HOURPCTL - Hourly percentile values ......................... 100
2.8.18. DAYSTAT - Daily statistical values ........................... 101
2.8.19. DAYPCTL - Daily percentile values ........................... 102
2.8.20. MONSTAT - Monthly statistical values ......................... 103
2.8.21. MONPCTL - Monthly percentile values ......................... 104
2.8.22. YEARMONMEAN - Yearly mean from monthly data ................. 105
2.8.23. YEARSTAT - Yearly statistical values .......................... 106
2.8.24. YEARPCTL - Yearly percentile values .......................... 107
2.8.25. SEASSTAT - Seasonal statistical values ......................... 108
2.8.26. SEASPCTL - Seasonal percentile values ......................... 109
2.8.27. YHOURSTAT - Multi-year hourly statistical values .................. 110
2.8.28. YDAYSTAT - Multi-year daily statistical values .................... 112
2.8.29. YDAYPCTL - Multi-year daily percentile values .................... 114
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2.8.30. YMONSTAT - Multi-year monthly statistical values .................. 115
2.8.31. YMONPCTL - Multi-year monthly percentile values .................. 117
2.8.32. YSEASSTAT - Multi-year seasonal statistical values .................. 118
2.8.33. YSEASPCTL - Multi-year seasonal percentile values .................. 119
2.8.34. YDRUNSTAT - Multi-year daily running statistical values ............... 120
2.8.35. YDRUNPCTL - Multi-year daily running percentile values .............. 122
2.9. Correlation and co. ......................................... 123
2.9.1. FLDCOR - Correlation in grid space ........................... 124
2.9.2. TIMCOR - Correlation over time ............................. 124
2.9.3. FLDCOVAR - Covariance in grid space ......................... 125
2.9.4. TIMCOVAR - Covariance over time ........................... 125
2.10. Regression .............................................. 126
2.10.1. REGRES - Regression ................................... 127
2.10.2. DETREND - Detrend time series ............................. 127
2.10.3. TREND - Trend of time series .............................. 128
2.10.4. SUBTREND - Subtract a trend .............................. 128
2.11. EOFs ................................................ 129
2.11.1. EOFS - Empirical Orthogonal Functions ......................... 130
2.11.2. EOFCOEFF - Principal coefficients of EOFs ...................... 132
2.12. Interpolation ............................................ 133
2.12.1. REMAPGRID - SCRIP grid interpolation ........................ 134
2.12.2. GENWEIGHTS - Generate SCRIP grid interpolation weights ............. 136
2.12.3. REMAP - SCRIP grid remapping ............................ 138
2.12.4. REMAPETA - Remap vertical hybrid level ....................... 139
2.12.5. INTVERT - Vertical interpolation ............................ 141
2.12.6. INTLEVEL - Linear level interpolation ......................... 142
2.12.7. INTLEVEL3D - Linear level interpolation from/to 3d vertical coordinates . . . . . . 143
2.12.8. INTTIME - Time interpolation .............................. 144
2.12.9. INTYEAR - Year interpolation .............................. 145
2.13. Transformation ........................................... 146
2.13.1. SPECTRAL - Spectral transformation .......................... 147
2.13.2. WIND - Wind transformation ............................... 148
2.14. Import/Export ........................................... 149
2.14.1. IMPORTBINARY - Import binary data sets ...................... 150
2.14.2. IMPORTCMSAF - Import CM-SAF HDF5 files .................... 151
2.14.3. IMPORTAMSR - Import AMSR binary files ...................... 152
2.14.4. INPUT - Formatted input ................................. 153
2.14.5. OUTPUT - Formatted output .............................. 154
2.15. Miscellaneous ............................................ 156
2.15.1. GRADSDES - GrADS data descriptor file ........................ 157
2.15.2. FILTER - Time series filtering .............................. 158
2.15.3. GRIDCELL - Grid cell quantities ............................. 159
2.15.4. SMOOTH9 - 9 point smoothing .............................. 160
2.15.5. REPLACEVALUES - Replace variable values ...................... 160
2.15.6. TIMSORT - Timsort .................................... 161
2.15.7. VARGEN - Generate a field ................................ 161
2.15.8. ROTUV - Rotation .................................... 163
2.15.9. MASTRFU - Mass stream function ............................ 163
2.15.10.DERIVEPAR - Sea level pressure ............................. 164
2.15.11.ADISIT - Potential temperature to in-situ temperature and vice versa ........ 165
2.15.12.RHOPOT - Calculates potential density ......................... 165
2.15.13.HISTOGRAM - Histogram ................................ 167
2.15.14.SETHALO - Set the left and right bounds of a field .................. 167
2.15.15.WCT - Windchill temperature .............................. 168
2.15.16.FDNS - Frost days where no snow index per time period ................ 168
2.15.17.STRWIN - Strong wind days index per time period ................... 168
2.15.18.STRBRE - Strong breeze days index per time period .................. 169
2.15.19.STRGAL - Strong gale days index per time period ................... 169
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Contents Contents
2.15.20.HURR - Hurricane days index per time period ..................... 169
2.15.21.FILLMISS - Fill missing values .............................. 170
2.16. Climate indices ........................................... 171
2.16.1. ECACDD - Consecutive dry days index per time period ................ 173
2.16.2. ECACFD - Consecutive frost days index per time period ............... 173
2.16.3. ECACSU - Consecutive summer days index per time period .............. 174
2.16.4. ECACWD - Consecutive wet days index per time period ................ 174
2.16.5. ECACWDI - Cold wave duration index w.r.t. mean of reference period ....... 176
2.16.6. ECACWFI - Cold-spell days index w.r.t. 10th percentile of reference period . . . . . 176
2.16.7. ECAETR - Intra-period extreme temperature range .................. 178
2.16.8. ECAFD - Frost days index per time period ....................... 178
2.16.9. ECAGSL - Thermal Growing season length index .................... 179
2.16.10.ECAHD - Heating degree days per time period ..................... 180
2.16.11.ECAHWDI - Heat wave duration index w.r.t. mean of reference period ....... 180
2.16.12.ECAHWFI - Warm spell days index w.r.t. 90th percentile of reference period . . . . 182
2.16.13.ECAID - Ice days index per time period ......................... 182
2.16.14.ECAR75P - Moderate wet days w.r.t. 75th percentile of reference period ...... 183
2.16.15.ECAR75PTOT - Precipitation percent due to R75p days ............... 183
2.16.16.ECAR90P - Wet days w.r.t. 90th percentile of reference period ............ 184
2.16.17.ECAR90PTOT - Precipitation percent due to R90p days ............... 184
2.16.18.ECAR95P - Very wet days w.r.t. 95th percentile of reference period ......... 185
2.16.19.ECAR95PTOT - Precipitation percent due to R95p days ............... 185
2.16.20.ECAR99P - Extremely wet days w.r.t. 99th percentile of reference period ...... 186
2.16.21.ECAR99PTOT - Precipitation percent due to R99p days ............... 186
2.16.22.ECAPD - Precipitation days index per time period ................... 187
2.16.23.ECARR1 - Wet days index per time period ....................... 188
2.16.24.ECARX1DAY - Highest one day precipitation amount per time period ........ 188
2.16.25.ECARX5DAY - Highest five-day precipitation amount per time period ........ 190
2.16.26.ECASDII - Simple daily intensity index per time period ................ 190
2.16.27.ECASU - Summer days index per time period ...................... 191
2.16.28.ECATG10P - Cold days percent w.r.t. 10th percentile of reference period ...... 192
2.16.29.ECATG90P - Warm days percent w.r.t. 90th percentile of reference period . . . . . 192
2.16.30.ECATN10P - Cold nights percent w.r.t. 10th percentile of reference period . . . . . 193
2.16.31.ECATN90P - Warm nights percent w.r.t. 90th percentile of reference period . . . . 193
2.16.32.ECATR - Tropical nights index per time period ..................... 194
2.16.33.ECATX10P - Very cold days percent w.r.t. 10th percentile of reference period . . . 194
2.16.34.ECATX90P - Very warm days percent w.r.t. 90th percentile of reference period . . . 195
A. Environment Variables 197
B. Parallelized operators 198
C. Standard name table 199
D. Grid description examples 200
D.1. Example of a curvilinear grid description ............................. 200
D.2. Example description for an unstructured grid .......................... 201
Operator index 202
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