Dryland Climatology

Cover......Page 1
Dryland Climatology......Page 3
Title......Page 5
Copyright......Page 6
Dedication......Page 7
Contents......Page 9
Preface......Page 11
Acknowledgments......Page 14
Part I The dryland environment......Page 15
1.1 EXPLORATION AND AWARENESS OF DRYLANDS......Page 17
1.2 GEOGRAPHIC EXTENT OF DRYLANDS......Page 18
1.3 PHYSICAL FEATURES OF DRYLANDS......Page 20
1.4.1 IN SITU CLIMATIC AND METEOROLOGICAL DATA......Page 22
1.4.2 REMOTE SENSING......Page 23
GEOLOGY, SURFACE FEATURES, AND SOILS......Page 25
VEGETATION......Page 26
LAND USE, LAND QUALITY, AND LAND-SURFACE CHANGE......Page 27
LAND SURFACE CHARACTERISTICS AND FLUXES......Page 28
RAINFALL MONITORING......Page 29
DUST, SMOKE AND FIRE......Page 30
1.4.4 GEOGRAPHIC INFORMATION SYSTEMS......Page 32
REFERENCES......Page 33
2.1 THE PHYSICAL SETTING......Page 38
2.2.1 DESERT UPLANDS AND SLOPES......Page 39
2.2.2 DESERT LOWLANDS......Page 40
2.2.3 DESERT LAKE BASINS......Page 41
2.3 DRAINAGE NETWORKS AND STREAMS......Page 42
2.4.2 TRANSPORT OF MATERIAL BY WIND AND WATER......Page 43
2.4.3 EROSION......Page 46
2.4.4 FORMATION OF DESERT PAVEMENTS......Page 47
2.5.1 DUNES AND OTHER AEOLIAN FEATURES......Page 48
2.5.2 DUNE FORMS......Page 49
2.5.3 CONTROLS ON DUNE MORPHOLOGY......Page 51
2.5.4 DUNE FORMATION......Page 53
2.5.5 DUNE FIELDS AND AIR FLOW AROUND DUNES......Page 54
2.6 DRYLAND SOILS......Page 55
REFERENCES......Page 57
3.1.1 VEGETATION TYPES/CLASSIFICATION......Page 60
3.1.2 GENERAL ASPECTS OF DRYLAND VEGETATION......Page 61
3.1.3 DESERT VEGETATION......Page 63
3.1.4 THE SAVANNAS......Page 64
3.1.5 MID-LATITUDE GRASSLANDS......Page 66
3.1.6 MEDITERRANEAN FOREST......Page 67
3.2.1 MOISTURE AVAILABILITY AND ITS RELATIONSHIP TO DRYLAND VEGETATION......Page 68
3.2.2 THE EFFICIENCY OF WATER USE IN DRYLAND VEGETATION......Page 69
3.3 VEGETATION–CLIMATE INTERACTION AND THE DYNAMICS OF DRYLAND ECOSYSTEMS......Page 73
3.4 HYPOTHESES FOR THE COEXISTENCE OF TREES AND GRASSES IN THE SAVANNA ECOSYSTEM......Page 74
3.5 THE EMERGING CONCEPT OF “PATCH DYNAMICS”......Page 75
REFERENCES......Page 76
Part II The meteorological background......Page 79
4.2 GLOBAL PATTERNS OF WIND AND PRESSURE......Page 81
4.3.1 SUBTROPICAL HIGH......Page 84
4.3.2 THE TRADE WINDS......Page 86
4.3.4 EQUATORIAL WESTERLIES......Page 87
4.3.5 THE MONSOONS......Page 88
4.4 SEASONAL CHANGES OF THE GENERAL ATMOSPHERIC CIRCULATION......Page 89
4.5 UPPER AIR PATTERNS......Page 90
4.6 JET STREAMS......Page 91
REFERENCES......Page 94
5.2 GLOBAL DISTRIBUTION AND ORIGIN OF THE DRYLAND CLIMATES......Page 97
5.4 RAIN-BEARING SYSTEMS......Page 99
5.4.2 MESOSCALE CONVECTIVE SYSTEMS......Page 101
5.4.3 DIAGONAL CLOUD BANDS......Page 102
5.4.4 TROPICAL WAVE DISTURBANCES......Page 105
5.4.5 TROPICAL DEPRESSIONS AND STORMS......Page 106
5.5 MESOSCALE INFLUENCES ON RAINFALL......Page 107
5.6.2 OTHER QUASI-GLOBAL PATTERNS OF VARIABILITY......Page 110
REFERENCES......Page 111
6.2 RADIATIVE PROCESSES......Page 114
6.3 THE HEAT BALANCE......Page 115
6.4 THE COMPLEXITIES OF SURFACE ALBEDO......Page 119
6.5 MICROCLIMATE: THE CLIMATE NEAR THE GROUND......Page 121
6.7 CONDUCTION OF HEAT IN THE SOIL......Page 124
REFERENCES......Page 127
7.2 GLOBAL WATER AND HEAT BALANCE......Page 129
7.3 QUANTIFICATION OF THE WATER BALANCE......Page 130
7.4.1 CLIMATOLOGICAL ESTIMATES OF EVAPOTRANSPIRATION, RUNOFF, AND SOIL MOISTURE......Page 135
7.5 WATER STORAGE AND MOVEMENT IN AN ECOSYSTEM......Page 137
REFERENCES......Page 140
8.2.1 THE CONCEPT OF POTENTIAL EVAPOTRANSPIRATION......Page 141
8.2.2 OTHER METHODS OF ASSESSING POTENTIAL EVAPOTRANSPIRATION......Page 142
8.3.1 WATER BALANCE METHODS......Page 143
8.3.2 TURBULENT TRANSFER METHODS......Page 144
8.3.3 METHODS BASED ON POTENTIAL EVAPOTRANSPIRATION......Page 145
8.4.3 EVAPOTRANSPIRATION OVER A VEGETATED SURFACE......Page 146
8.5 SPECIAL CONSIDERATIONS CONCERNING EVAPOTRANSPIRATION IN DRYLANDS......Page 148
8.5.1 SPATIAL HETEROGENEITY......Page 149
8.5.2 THE CONTRIBUTION OF TRANSPIRATION IN DRYLANDS......Page 151
8.5.3 TEMPORAL VARIABILITY: THE IMPACT OF MOISTURE PULSES ON EVAPOTRANSPIRATION......Page 153
8.5.4 CONTROLS ON EVAPOTRANSPIRATION IN DRYLANDS......Page 154
8.5.5 EVAPORATION IN THE CASE OF EXTREME ARIDITY......Page 156
8.6 ESTIMATION OF REGIONAL EVAPOTRANSPIRATION......Page 157
REFERENCES......Page 159
Part III The climatic environment of drylands......Page 163
10.2.1 GROUND TEMPERATURES......Page 176
10.2.2 NEAR-SURFACE THERMAL REGIME OF THE AIR......Page 177
10.2.4 MOISTURE CONDITIONS......Page 179
10.3.2 THERMAL ENVIRONMENT......Page 180
10.3.3 MOISTURE CONDITIONS......Page 182
10.3.4 BIOTA AND HABITATS......Page 183
10.4 MICROCLIMATIC STUDIES IN THE SAHARA......Page 184
10.5 THE MOST EXTREME NICHES: DESERT DEPRESSIONS......Page 185
10.5.1 GENERAL CLIMATIC ENVIRONMENT......Page 186
10.5.2 SURFACE THERMAL AND HYDROLOGIC REGIME: MICROCLIMATIC ASPECTS......Page 187
10.5.3 THERMAL EXTREMES......Page 188
10.6 MODERATE ENVIRONMENTS: OASES, IRRIGATED FIELDS, DESERT LAKES, AND RIPARIAN VALLEYS......Page 189
10.6.1 DESERT OASES AND IRRIGATED FIELDS......Page 190
10.6.2 DESERT LAKES......Page 191
10.6.3 RIPARIAN VALLEYS......Page 192
10.7.1 PLANT TEMPERATURES......Page 194
10.7.3 MICROCLIMATE OF A MID-LATITUDE SEMI-ARID WOODLAND......Page 198
REFERENCES......Page 200
11.1 THE NATURE OF RAINFALL IN THE DRYLANDS......Page 202
11.3.1 CHARACTERIZING THE FREQUENCY DISTRIBUTION OF RAINFALL IN DRYLANDS......Page 203
11.3.2 FREQUENCY DISTRIBUTIONS AND DAILY EVENT SIZE......Page 205
11.4.1 QUANTIFYING TEMPORAL VARIABILITY......Page 209
11.4.2 MAGNITUDE OF TEMPORAL VARIABILITY......Page 210
11.4.3 TEMPORAL STRUCTURE OF VARIABILITY......Page 213
11.4.4 SPATIAL VARIABILITY......Page 214
11.4.5 INTRASEASONAL VARIABILITY......Page 217
11.4.6 CHARACTERIZING RAINFALL EVENTS......Page 218
11.5.1 FOG......Page 221
11.5.2 DEW......Page 222
REFERENCES......Page 223
12.1.2 CONTRASTS WITH HUMID REGIONS......Page 226
12.2.1 THE NATURE OF RUNOFF IN DRYLAND REGIONS......Page 227
12.2.2 OVERLAND FLOW......Page 228
12.2.3 CONTROLS ON RUNOFF......Page 229
12.2.4 INFLUENCE OF VEGETATION PATCHINESS ON RUNOFF......Page 230
12.3 DRYLAND STREAMS......Page 232
12.4.2 DRYLAND FLOODS......Page 234
12.4.3 RELATIONSHIP OF DISCHARGE TO RAINFALL......Page 236
12.5.2 GROUNDWATER RECHARGE......Page 237
12.7.1 MOISTURE PULSES......Page 238
12.7.2 FACTORS INFLUENCING THE TRANSFORMING OF PRECIPITATION PULSES TO SOIL WATER......Page 239
12.7.3 BIOLOGICAL RESPONSE TO PULSES OF MOISTURE AVAILABILITY......Page 240
REFERENCES......Page 241
13.1.2 TURBULENCE......Page 244
13.2 LOCAL WINDS......Page 245
13.3 DUST MOBILIZATION, TRANSPORT, AND DEPOSITION......Page 248
13.4.1 FORMATION......Page 250
13.4.2 MOTION, STRUCTURE AND MAINTENANCE......Page 251
13.5.2 LONG-TERM MONITORING......Page 253
13.6.1 DISTRIBUTION, SOURCES AND SOURCE STRENGTH......Page 254
13.6.2 GRAIN SIZE AND COMPOSITION......Page 257
13.6.3 THE SAHARAN AIR LAYER......Page 258
13.6.4 LONG-DISTANCE TRANSPORT AND DUST OUTBREAKS......Page 259
13.7 IMPACTS OF MINERAL DUST......Page 261
13.7.2 MODELING THE EFFECTS OF MINERAL DUST......Page 262
13.8 BIOMASS BURNING IN THE SAVANNAS......Page 264
REFERENCES......Page 266
9.2 DEFINITION AND INDICES OF ARIDITY......Page 165
9.3 CLIMATE CLASSIFICATION......Page 166
9.4 LIMITATIONS OF CLIMATE CLASSIFICATION SCHEMES IN DRYLAND REGIONS......Page 169
9.5 GENERAL CLIMATIC ENVIRONMENT OF DRYLANDS......Page 170
9.6 THERMAL EXTREMES......Page 172
REFERENCES......Page 174
Part IV The earth’s drylands......Page 269
14.1 OVERVIEW OF REGIONAL GEOGRAPHY AND CLIMATE......Page 271
14.2 PRECIPITATION REGIONS OF NORTH AMERICA......Page 272
14.3.1 GENERAL GEOGRAPHY AND CLIMATE......Page 274
14.3.3 THE NOCTURNAL PRECIPITATION MAXIMUM AND THE LOW-LEVEL JET......Page 279
14.3.4 DROUGHT......Page 280
14.4 THE GREAT BASIN......Page 281
14.4.2 THE PRECIPITATION REGIME......Page 282
14.5.1 GENERAL GEOGRAPHY......Page 283
14.5.2 THE PRECIPITATION REGIME......Page 284
14.5.3 THE NORTH AMERICAN MONSOON......Page 285
14.6 LOCALIZED DRYLAND REGIONS IN NORTH AMERICA......Page 286
REFERENCES......Page 287
15.1 OVERVIEW OF SOUTH AMERICAN CLIMATE......Page 289
15.2 THE RAINFALL REGIME......Page 290
15.3.1 THE SOUTH AMERICAN MONSOON......Page 293
15.3.2 THE RAINFALL “SEE-SAW”......Page 295
15.3.3 TRANSIENT FEATURES......Page 296
15.4.1 ARID BIOMES......Page 297
THE MONTE......Page 298
PATAGONIA......Page 300
THE PUNA......Page 301
15.5 THE SEMI-ARID XEROPHYLLOUS FORESTS AND WOODLANDS......Page 302
15.7 THE DRY ZONE OF NORTHEAST BRAZIL......Page 303
REFERENCES......Page 305
16.1.1 WIND AND PRESSURE SYSTEMS......Page 307
16.1.2 TEMPERATURE, RAINFALL AND OTHER CLIMATIC ELEMENTS......Page 311
16.2 NORTHERN AFRICA......Page 315
16.2.1 THE CENTRAL SAHARA......Page 317
GEOGRAPHICAL OVERVIEW......Page 318
THE RAINFALL REGIME......Page 319
EASTERLY WAVES, CONVECTION, AND THE AFRICAN EASTERLY JET......Page 320
16.2.3 INTERANNUAL VARIABILITY......Page 321
16.3 EASTERN AFRICA......Page 322
16.3.2 THE RAINFALL REGIME......Page 323
16.3.3 CAUSES OF ARIDITY IN EASTERN AFRICA......Page 324
16.3.4 FACTORS CONTROLLING RAINFALL AND ITS SEASONALITY......Page 325
16.3.5 INTERANNUAL VARIABILITY......Page 326
16.3.6 THE THERMAL REGIME......Page 327
16.3.7 OTHER CLIMATIC ELEMENTS......Page 328
16.4.1 GENERAL ATMOSPHERIC CIRCULATION......Page 329
16.4.2 CONTROLS ON DAY-TO-DAY WEATHER......Page 330
16.4.4 INTERANNUAL VARIABILITY OF PRECIPITATION......Page 331
16.4.5 THE THERMAL REGIME......Page 333
REFERENCES......Page 334
17.2.1 LARGE-SCALE CIRCULATION......Page 337
17.2.2 PRECIPITATION REGIME......Page 338
17.2.4 REGIONAL WIND SYSTEMS......Page 341
17.4 NORTH AFRICA AND THE NORTHERN SAHARA......Page 342
17.5 THE ARABIAN PENINSULA......Page 344
17.6.1 TURKEY......Page 346
THERMAL REGIME......Page 347
17.6.3 SYRIA......Page 348
17.6.6 IRAQ......Page 349
REFERENCES......Page 350
18.1 THE AUSTRALIAN DESERT......Page 351
18.2 CLIMATIC CONTROLS......Page 353
18.4 THE RAINFALL REGIME......Page 356
18.4.1 SEASONALITY......Page 358
18.4.2 RAIN-PRODUCING SYSTEMS......Page 359
18.5 THERMAL REGIME......Page 361
18.6 OTHER CLIMATIC ELEMENTS......Page 362
REFERENCES......Page 363
19.1 INTRODUCTION......Page 365
19.2.1 AN OVERVIEW OF PRECIPITATION, TEMPERATURE, AND OTHER CLIMATIC ELEMENTS......Page 367
19.2.2 CLIMATIC CONTROLS......Page 369
19.3 THE COLD DESERTS OF CENTRAL ASIA......Page 371
19.3.1 GENERAL CLIMATOLOGY......Page 372
19.3.2 THE GOBI......Page 373
19.3.3 THE TARIM BASIN AND TAKLAMAKAN DESERT......Page 374
LOCAL WINDS......Page 375
MOISTURE REGIME......Page 376
19.4.3 THE TURKESTAN DESERT......Page 377
19.5 EASTERN SIBERIA......Page 378
19.7 THE WARM DESERTS OF ASIA......Page 380
THERMAL REGIME......Page 381
WINDS......Page 382
19.7.3 THE THAR DESERT......Page 383
REFERENCES......Page 385
20.1 ORIGIN AND LOCATION......Page 388
20.2 THE ROLE OF COASTAL JETS......Page 389
20.3 GENERAL CLIMATIC CHARACTERISTICS......Page 390
20.4.1 CLIMATIC OVERVIEW......Page 391
20.4.2 THE MOISTURE REGIME......Page 393
20.4.3 EL NIÑO......Page 394
NORTHERN SECTOR......Page 395
SOUTHERN SECTOR......Page 396
WESTERN CORDILLERAN SLOPES AND INTERMONTANE VALLEYS......Page 397
20.5 THE NAMIB DESERT......Page 398
20.5.1 GEOGRAPHIC ASPECTS......Page 399
20.5.2 PRECIPITATION......Page 402
20.5.3 CLIMATIC GRADIENTS......Page 404
20.5.4 EAST–WEST GRADIENTS: COAST VERSUS INTERIOR......Page 405
20.5.5 WIND REGIME......Page 406
20.6.1 OVERVIEW......Page 408
20.6.2 THERMAL REGIME......Page 409
20.6.3 MOISTURE REGIME......Page 410
20.6.5 VEGETATION......Page 412
20.7 THE WESTERN LITTORAL OF THE SAHARA......Page 413
REFERENCES......Page 415
Part V Life and change in the dryland regions......Page 419
21.2.1 DEFINING DROUGHT......Page 421
21.2.3 DROUGHT INDICES......Page 422
21.2.4 CAUSES OF METEOROLOGICAL DROUGHT......Page 424
21.2.5 BIOGEOPHYSICAL FEEDBACK IN DROUGHT......Page 425
21.2.6 CHARACTERISTICS OF METEOROLOGICAL DROUGHT......Page 427
21.2.7 DROUGHT PREDICTION......Page 428
21.3.1 THE IMPACT OF DROUGHT......Page 429
21.3.2 SOCIETAL RESPONSE TO DROUGHT......Page 430
21.3.3 TECHNOLOGICAL MANAGEMENT OF DROUGHT......Page 431
21.3.4 DROUGHT MONITORING AND EARLY WARNING......Page 432
21.4.1 THE DOWNDRAFT HABOOB......Page 433
21.4.3 DUST STORMS ASSOCIATED WITH DEPRESSIONS, COLD FRONTS, AND EASTERLY WAVES......Page 434
21.4.4 RELATIONSHIP TO RAINFALL AND DROUGHT......Page 435
21.4.6 IMPACT OF DUST STORMS......Page 436
21.5 DRYLAND FLOODS......Page 438
BIG THOMPSON CANYON, 1976......Page 439
21.6 SNOW IN THE LOW-LATITUDE DESERTS......Page 440
REFERENCES......Page 441
22.2 DEVELOPMENT OF THE CONCEPT......Page 445
22.3 THE CONTROVERSY SURROUNDING DESERTIFICATION......Page 448
22.5 SUSCEPTIBILITY OF DRYLANDS TO DESERTIFICATION......Page 449
22.6 CAUSES OF DESERTIFICATION......Page 450
22.7 THE MANIFESTATIONS OF DESERTIFICATION......Page 451
22.9 REVERSIBILITY: ISSUES OF RESILIENCE AND RESISTANCE......Page 453
22.9.2 FACTORS INFLUENCING RESILIENCE......Page 454
22.10 MONITORING DESERTIFICATION......Page 455
22.11 IMPACTS ON WEATHER AND CLIMATE......Page 456
REFERENCES......Page 458
23.2 HEAT BALANCE AND COMFORT OF THE HUMAN BODY......Page 462
23.3 ARCHITECTURE......Page 464
23.4 AGRICULTURE......Page 467
23.5.1 WATER SUPPLY IN DRYLANDS......Page 469
23.5.2 IRRIGATION......Page 470
23.5.3 RAIN HARVESTING......Page 472
23.5.4 WEATHER MODIFICATION......Page 473
23.6 ENERGY RESOURCES......Page 474
23.7 MODERN EXPLOITATION OF THE DRYLAND ENVIRONMENT: OASES, PLAYAS, RIVERS, AND LAKES......Page 475
23.7.2 PLAYAS, MINING, AND OTHER NATURAL RESOURCES......Page 476
THE ARAL SEA......Page 477
THE SALTON SEA......Page 478
REFERENCES......Page 479
24.2 PLANT ADAPTATIONS TO THE DESERT ENVIRONMENT......Page 482
24.3 PERENNIALS OF THE NAMIB DESERT......Page 488
24.5 SOME TYPICAL DESERT INHABITANTS......Page 490
24.6 TENEBRIONID BEETLES OF THE NAMIB AND OTHER INSECTS......Page 493
REFERENCES......Page 494
25.2 NATURE OF CLIMATIC VARIABILITY AND CLIMATE CHANGE......Page 496
25.3.1 INDICATORS OF PAST CLIMATE......Page 499
25.3.2 INTERPRETATION OF PROXY RECORDS......Page 500
GLACIAL TIME SCALES......Page 506
25.4.2 THE EL NIÑO/SOUTHERN OSCILLATION (ENSO) PHENOMENON......Page 507
25.4.4 THE INFLUENCE OF MANKIND......Page 509
25.5.2 THE LAST TWO MILLENNIA......Page 510
AFRICA......Page 511
SOUTH AMERICA......Page 513
25.6.2 HISTORICAL FLUCTUATIONS OF CLIMATE......Page 514
AFRICA......Page 515
NORTH AMERICA......Page 516
AUSTRALIA AND SOUTH AMERICA......Page 517
25.8 PREDICTING CLIMATE CHANGE AND ITS IMPACT......Page 518
REFERENCES......Page 519
Index......Page 524