204 JOURNAL OF METEOROLOGY Vol.28 No.279 May / June 2003 161 INTERNATIONAL EDITORIAL ADVISORY BOARD JOURNAL OF METEOROLOGY Dr. NICHOLAS L. BETTS "An international magazine for everyone interested in weather and climate, and Department of Geography, The Queen’s University of Belfast, Belfast, BT7 1NN, U.K. in their influence on the human and physical environment." Prof. TIMOTHY P. BURT School of Geography, Science Labs., University of Durham, Durham, DH1 3LE, U.K. Editor: Robert K. Doe Vol. 28, no. 279 May / June 2003 ROBERT A. CROWDER, formerly Lincoln College, University College of Agriculture, Canterbury, N.Z. 73 Ashgrove Terrace, Speydon, Christchurch, New Zealand Prof. JEAN DESSENS TELECONNECTION BETWEEN GLOBAL CLIMATIC EVENTS, Centre de Recherches Atmosphériques, Université Paul Sabatier, Campistrous, 65300 Lannemezan, France Prof. DEREK ELSOM ATMOSPHERIC CIRCULATION CHANGE Director of TORRO, Geography Department, Oxford Brookes University, Oxford, OX3 0BP, U.K. AND STREAM FLOW OVER THE RIVER NILE (01865) 483750, (01865) 483761 [email protected] Prof. GREGORY FORBES, formerly Professor of Meteorology, Penn State University, Pennsylvania ,USA 50 Settlers Court, Marietta, Georgia 30067-4232, USA By H. M. HASANEAN Dr. TERENCE MEADEN, formerly Professor of Physics, Dalhousie University, Halifax, N. S., Canada Faculty of Science, Dept. of Astronomy and Meteorology, Cairo University, Giza, Egypt. TORRO Tornado Division, TORRO Publications Division, Director of TORRO 1974-1994. QED House, Frome Road, Bradford-on-Avon, Wiltshire, BA15 1LD . Tel: (0870) 7701023 E-mail: [email protected] Dr. ALLEN H. PERRY Department of Geography, University College of Swansea, Singleton Park, Swansea, SA2 8PP, U.K Abstract: An overview is presented of the principal features of the El Nino Southern Oscillation Prof. RICHARD E. PETERSON, Professor of Atmospheric Science, Texas Tech University, Lubbock, Texas 74909, USA. (ENSO), Tropical Atlantic sea surface temperature and North Atlantic Oscillation (NAO), which are Prof. JOHN T. SNOW teleconnections in terms of stream flow over the River Nile. Atmospheric circulation changes associated University of Oklahoma, Sarkey Energy Center, 100 East Boyd Street, Norman, Oklahoma, 73019-0828, with wet and dry in the flood season (from July to October) are described using the NCEP/NCAR U.S.A. Reanalysis data from July to October, especially in El Nino and La Nina years. The natural stream Dr. JOHN TYRRELL flow over the River Nile depends mainly on Sahelian rainfall. Inverse relationships are found between Department of Geography, University College Cork, Cork, Ireland. Tel: 00.353.21.902326 [email protected] 3-months seasonal cycle stream flow and ENSO over the River Nile. Tropical Atlantic sea surface Dr. DENNIS A. WHEELER temperature have similar response to ENSO influence on stream flow over the Nile, which indicates Geography Department, Sunderland University, Chester Road, Sunderland, SR1 3SD, U.K. inverse relationships with stream flow. The influence of North Atlantic Oscillation (NAO) is much TORRO DIRECTORS ASSOCIATED WITH THE JOURNAL OF METEOROLOGY weaker on stream flow over the River Nile. Unlike other seasons, the spring season of stream flow indicates positive relationships with ENSO and Tropical Atlantic sea surface temperatures. The ROBERT DOE, Editor of the Journal of Meteorology, [email protected] TORRO Coastal Impacts Division, Department of Geography, University of Portsmouth, Portsmouth, duration of the rainfall amount depends upon both location of the inter-tropical convergence zone Hampshire, PO1 3HE (07816) 573267 (ITCZ) and the meridional sea surface temperature (SST) gradient in the tropical Atlantic. Tropical PETER VAN DOORN Easterly jet stream was weakened in El Nino year and enhanced in La Nina year accompanying with TORRO Ball Lightning Division, 32 Franklin Road, Shoreham-by-Sea, Sussex, BN43 6 YD. the dry and wet condition respectively. During La Nina year, easterly wind is strong not only over Tel: (01273) 888704. [email protected] North Africa but also over tropical Atlantic Ocean. The oscillation and strength of Asiatic monsoon ANTHONY GILBERT low pressure and subtropical high pressure play an important role in rainfall over the Nile River. TORRO Tornado Site Investigation Division, 51 Darwin Way, Gosport, Hampshire, PO13 8AF Tel: (023) 9250255 / (07788) 990114 [email protected] STEPHEN ROBERTS INTRODUCTION TORRO Windstorm Division, Weathernet Ltd., Kingsland House, 21 Hinton Road, Bournemouth, BH1 2DE Tel: (01202) 293868. [email protected] The Nile flood, predominantly from the Ethiopian Highlands of the Blue Nile, ALAN C. ROGERS TORRO Administration accounts for over 75% of the annual flow. The Nile flood occurs in the four months July Cherry Tree Cottage, Meshaw, S. Molton, Devon, EX36 4ND (01769) 55031 [email protected] to October. Regional precipitation has increased over most land areas, with the exception MICHAEL W. ROWE TORRO Tornado Division, 21 Bankview, Buckland Park, Lymington, Hampshire, SO41 8YG. of tropical North Africa and parts of Southern Africa, Amazonian and western South Tel: (01590) 678121 America (Mark, et al. 2001). Natural factors, which include changes in precipitation JONATHAN D.C. WEBB TORRO Thunderstorm Division (incorporating Thunderstorm Census Organisation, founded 1924) regimes particularly over the headwaters of the Blue and/or White Niles, changes in and TORRO Hailstorm Division. 10 Seacourt Road, Botley, Oxford OX2 9LD, U.K. Tel: (01865) 790611 evaporation, and changes in vegetation in the catchments, affect runoff. Such changes [email protected] RICHARD J. WILD however, may also be anthropogenic in origin with precipitation being affected by, for TORRO Heavy Snowfalls and Blizzards Division. Weathernet Ltd., Kingsland House, 21 Hinton Road, example, human-induced (Nicholson, 1988). Additional anthropogenic factors affecting Bournemouth, BH1 2DE (01202) 771407. [email protected] the total natural stream flow include the extraction of water for domestic, agricultural, JOHN WILSON TORRO Weather and Health Division. 38 Stuart Close, Arnold, Notts, NG5 8AE [email protected] industrial, or power generation purposes. On the global scale, decadal to century-scale BOOK REVIEW EDITOR variability and change in the climatic system are determined by nature e.g. solar cycle, PETER R. ROGERS, 15 Knole Road, Sevenoaks, Kent, TN13 3XH. Tel: (01732) 456911 and anthropogenic factors e.g. greenhouse gases and aerosols (IPCC 1990, and 1996). PICTURE EDITOR MARK HUMPAGE, PO BOX 5161, Bournemouth, Dorset, BH10 4WJ. Tel: (07710) 486350 162 JOURNAL OF METEOROLOGY Vol.28 No.279 May / June 2003 JOURNAL OF METEOROLOGY Vol.28 No.279 May / June 2003 203 Although ENSO has been shown to be one of the primary dominants of inter- THE JOURNAL OF METEOROLOGY annual variability of rainfall in the low-latitude, its influence on Africa remains Published in association with The Tornado and Storm Research Organisation controversial. Links between ENSO and large-scale precipitation patterns have been a privately supported research body, serving the international public interest examined since the earliest studies of this phenomenon. Indeed, the pioneering studies Edited by R.K. Doe, Editorial Office, PO Box 5161, by Walker (1923, 1924, 1928), which first documented ENSO on a global scale, were Bournemouth, Dorset, BH10 4WJ, United Kingdom. motivated by attempts to understand and predict variations in Indian monsoon rainfall Telephone: (07816) 573267; international +44 7816 573267 (Office hours only) and then were expanded to studies of precipitation around the globe. The possible relationships might exist between a climatic event, termed El-Nino Southern Oscillation [email protected] (ENSO) phenomenon, and other climatic anomalies worldwide (Ropelewski and Halpert, http://www.journalofmeteorology.com 1987). Ropelewski and Halpert (1987) indicated that oscillations in the state of the Research papers, letters, books and reports for review, news items, conference information ocean-atmosphere system in the Pacific region (ENSO) are related to inter-annual and other communications on all aspects of meteorology are to be addressed to the Editor. fluctuation of rainfall and river flow in several regions of the world. Ogallo (1985) Whenever possible authors should send their contributions by post on a floppy disk, or by illustrated the negative relationships between rainfall over many parts of Eastern Africa e-mail to [email protected]. A paper copy sent by post is also requested. and ENSO event. However, the relationship between ENSO and rainfall over that portion This speeds up processing and correspondence, and allows for efficient minor editing and agreed of the Ethiopian Plateau, which contribute to River Nile inflows has not been thoroughly major editing. investigated. Eltahir (1996) and Wang and Eltahir (1998) found significant relationship Contributions should be prepared with 1.5 or double line spacing and broad margins. Every between stream flow over the Nile and El Nino and Southern Oscillation. paper must commence with a short abstract summarising its significant and original content. The North Atlantic Oscillation (NAO) is most pronounced in winter but Authors must consult recent issues of the journal as a guide to the layout of papers. Line drawings detectable as a characteristic pattern in all months. The winter NAO pattern contributes may be prepared up to 50 to