1 Introduction
1.1 Background
1.2 Rationale, Aim and Objectives
-
to study the sensitivity of the RDI index;
-
To compare the selected methods Hargeaves (HG), Thornthwaite (ThW) and Blaney-Criddle (BC) with the FAO Penman-Monteith (PM) methodology for reference purposes;
-
To assess the impact of elevation variations for different climate conditions; and
-
To highlight the use of RDI as an aridity and climatic index.
2 Theory
2.1 Evapotranspiration Estimation
2.1.1 Hargreaves Method
2.1.2 Thornthwaite Method
2.1.3 Blaney–Criddle Method
2.1.4 Food and Agriculture Organization Penman-Monteith Method
2.2 The Reconnaissance Drought Index (RDI)
3 Materials, Data and Methods
3.1 Climate Forecasting System Reanalysis Data
Wider region | Sta ID | Latb (°) | Longc (°) | Eld (m) | RMSEe
| MBEf
| ||||
---|---|---|---|---|---|---|---|---|---|---|
1g
| 2h
| 3i
| 1g
| 2h
| 3i
| |||||
Mediterranean | ||||||||||
South Africa | LLj
| -32.63 | 19.69 | 485 | 42 | 54 | 50 | 2 | 3 | 2 |
HLk
| -31.07 | 22.19 | 1382 | 33 | 33 | 36 | 1 | 1 | 1 | |
North Iraq | LLj
| 35.75 | 44.06 | 306 | 18 | 57 | 29 | 0 | 3 | 1 |
HLk
| 35.75 | 45.25 | 1458 | 36 | 37 | 52 | 1 | 1 | 3 | |
West Australia | LLj
| -26.07 | 124.68 | 485 | 51 | 90 | 48 | 3 | 8 | 2 |
HLk
| -22.95 | 118.43 | 820 | 54 | 91 | 54 | 3 | 8 | 3 | |
South USA | LLj
| 37.31 | -120.00 | 361 | 57 | 47 | 51 | 3 | 2 | 3 |
HLk
| 39.18 | -108.75 | 1382 | 50 | 43 | 54 | 3 | 2 | 3 | |
Tropical | ||||||||||
East China | LLj
| 44.49 | 82.81 | 409 | 71 | 82 | 84 | 5 | 7 | 7 |
HLk
| 44.18 | 84.38 | 1316 | 109 | 112 | 110 | 12 | 13 | 12 | |
East Brazil | LLj
| -6.71 | -36.88 | 440 | 49 | 79 | 53 | 2 | 6 | 3 |
HLk
| -7.34 | -39.69 | 918 | 36 | 42 | 61 | 1 | 2 | 4 | |
Continental | ||||||||||
South Russia | LLj
| 38.87 | -5.31 | 403 | 102 | 57 | 62 | 10 | 3 | 4 |
HLk
| 36.99 | -3.13 | 1360 | 369 | 108 | 107 | 136 | 12 | 11 | |
South East Spain | LLj
| 52.92 | 86.25 | 438 | 35 | 40 | 43 | 1 | 2 | 2 |
HLk
| 51.36 | 97.50 | 1208 | 68 | 58 | 57 | 5 | 3 | 3 | |
Arid | ||||||||||
Sahara | LLj
| 24.82 | 17.19 | 146 | 26 | 74 | 21 | 1 | 6 | 0 |
HLk
| 24.20 | 19.38 | 604 | 25 | 59 | 21 | 1 | 4 | 0 | |
Al-Sudan | LLj
| 19.83 | 34.34 | 390 | 48 | 150 | 26 | 2 | 23 | 1 |
HLk
| 22.01 | 36.25 | 1677 | 42 | 55 | 27 | 2 | 3 | 1 | |
Humid | ||||||||||
UK | LLj
| 52.92 | -3.75 | 40 | 25 | 59 | 21 | 1 | 4 | 0 |
HLk
| 52.92 | -4.06 | 717 | 26 | 74 | 21 | 1 | 6 | 0 | |
Norway | LLj
| 6.56 | 61.35 | 490 | 50 | 86 | 82 | 2 | 7 | 7 |
HLk
| 8.13 | 61.35 | 1652 | 53 | 115 | 112 | 3 | 13 | 13 |
3.2 Data Analysis
3.3 Evaluation of the Performance
4 Results and Discussion
Wider region | Station ID | Ela (m) | RMSEb
| MBEc
| ||||
---|---|---|---|---|---|---|---|---|
1d
| 2e
| 3f
| 1d
| 2e
| 3f
| |||
Mediterranean | ||||||||
South Africa | LLg
| 485 | 2 | 3 | 3 | 21 | 34 | 26 |
HLh
| 1382 | 66 | 70 | 69 | 4 | 5 | 5 | |
North Iraq | LLg
| 306 | 34 | 92 | 40 | 1 | 8 | 2 |
HLh
| 1458 | 111 | 75 | 126 | 12 | 6 | 16 | |
West Australia | LLg
| 485 | 78 | 140 | 78 | 6 | 20 | 6 |
HLh
| 820 | 91 | 174 | 83 | 8 | 32 | 7 | |
South USA | LLg
| 361 | 99 | 89 | 49 | 10 | 8 | 2 |
HLh
| 1382 | 142 | 108 | 159 | 20 | 12 | 25 | |
Tropical | ||||||||
East China | LLg
| 409 | 62 | 102 | 91 | 4 | 10 | 8 |
HLh
| 1316 | 240 | 162 | 164 | 58 | 26 | 27 | |
East Brazil | LLg
| 440 | 213 | 302 | 214 | 41 | 91 | 45 |
HLh
| 918 | 6 | 83 | 68 | 3 | 7 | 5 | |
Continental | ||||||||
South East Spain | LLg
| 438 | 70 | 60 | 63 | 5 | 4 | 39 |
HLh
| 1208 | 154 | 97 | 93 | 24 | 9 | 9 | |
South Russia | LLg
| 403 | 543 | 199 | 247 | 295 | 40 | 61 |
HLh
| 1360 | 417 | 122 | 124 | 174 | 15 | 15 | |
Arid | ||||||||
Sahara | LLg
| 146 | 23 | 49 | 31 | 1 | 2 | 1 |
HLh
| 604 | 12 | 30 | 10 | 0 | 1 | 0 | |
Al-Sudan | LLg
| 390 | 23 | 40 | 18 | 1 | 2 | 0 |
HLh
| 1677 | 70 | 67 | 38 | 5 | 4 | 1 | |
Humid | ||||||||
UK | LLg
| 40 | 1320 | 533 | 504 | 1742 | 284 | 254 |
HLh
| 717 | 698 | 433 | 447 | 488 | 188 | 200 | |
Norway | LLg
| 490 | 180 | 307 | 298 | 32 | 94 | 89 |
HLh
| 1652 | 232 | 596 | 607 | 54 | 355 | 368 |
Wider region | Sta ID | Elb
| RMSEc
| MBEd
| ANOVAe
| ||||||
---|---|---|---|---|---|---|---|---|---|---|---|
1f
| 2g
| 3h
| 1f
| 2g
| 3h
| 1f
| 2g
| 3h
| |||
Mediterranean | |||||||||||
South Africa | LLi
| 485 | 52 | 187 | 69 | 50 | 35 | 5 | * | * | * |
HLj
| 1382 | 31 | 115 | 41 | 29 | 13 | 2 | * | * | * | |
North Iraq | LLi
| 306 | 40 | 79 | 56 | 37 | 6 | 3 | 61 | * | * |
HLj
| 1458 | 63 | 599 | 208 | 58 | 359 | 43 | 125 | * | * | |
West Australia | LLi
| 485 | 25 | 49 | 23 | -23 | 2 | 1 | 213 | 69 | 270 |
HLj
| 820 | 89 | 31 | 77 | -78 | 1 | 6 | * | 581 | * | |
South USA | LLi
| 361 | 79 | 299 | 86 | 71 | 89 | 7 | 72 | * | * |
HLj
| 1382 | 29 | 293 | 74 | 24 | 86 | 5 | 227 | * | * | |
Tropical | |||||||||||
East China | LLi
| 409 | 111 | 186 | 52 | 102 | 35 | 3 | * | * | 144 |
HLj
| 1316 | 385 | 900 | 167 | 369 | 811 | 28 | * | * | 622 | |
East Brazil | LLi
| 440 | 166 | 247 | 229 | 159 | 61 | 53 | * | * | * |
HLj
| 918 | 87 | 341 | 130 | 84 | 116 | 17 | 91 | * | * | |
Continental | |||||||||||
South Russia | LLi
| 403 | 137 | 245 | 271 | -50 | 60 | 73 | 404 | * | * |
HLj
| 1360 | 2273 | 632 | 190 | 1583 | 399 | 36 | * | * | 944 | |
South East Spain | LLi
| 438 | 24 | 171 | 25 | 23 | 29 | 6 | 270 | * | 230 |
HLj
| 1208 | 183 | 502 | 47 | 172 | 251 | 2 | * | * | 280 | |
Arid | |||||||||||
Sahara | LLi
| 146 | 16 | 4 | 3 | 1 | 0 | 0 | 280 | * | 81 |
HLj
| 604 | 2 | 5 | 3 | 1 | 0 | 0 | 150 | * | * | |
Al-Sudan | LLi
| 390 | 5 | 3 | 9 | 2 | 0 | 0 | 180 | * | 61 |
HLj
| 1677 | 2 | 8 | 7 | 2 | 0 | 0 | 140 | * | * | |
Humid | |||||||||||
UK | LLi
| 40 | 209 | 403 | 1437 | -124 | 162 | 2064 | 268 | * | * |
HLj
| 717 | 478 | 549 | 1703 | -458 | 302 | 2901 | * | * | * | |
Norway | LLi
| 490 | 644 | 1326 | 2891 | -515 | 1758 | 8355 | 141 | * | * |
HLj
| 1652 | 279 | 395 | 893 | 231 | 156 | 797 | 106 | 388 | * |