Department of Geography

The water cycle

Understanding variability and change in the water cycle from days to decades

TWP-ICETropical convection observed from research aircraft during the AMIE experiment

The flux of water around the planet through the atmosphere, oceans and land surfaces is a core component of the global climate system, driving atmospheric circulations and dominant climate feedbacks. Water as a resource is also central to human existence and well-being and is arguably our greatest sensitivity to climate changes.

The aim of our work at Sussex is to unravel the processes of variability and change in global and regional precipitation in both the real world and in the climate models we use to make predictions. This will help us determine the extent to which we can trust the future climate projections to inform decisions on adaptation. Our process-based analysis covers scales from extreme weather events through intraseasonal variability, to the interannual to decadal patterns that link climate variability and change. We also extend our analysis back to the mid Holocene period to understand the processes driving abrupt changes in the past.

Key staff: Martin Todd, Yi Wang, Dom Kniveton, Kate Ward

Selected initiatives

1. African Climate Variability

Sussex researchers have a long history of research into the climate of Africa. Africa is the most vulnerable continent to climate and many aspects of climate remain poorly understood. Some recent highlights include

  • Fennec: Saharan Climate System project (see Atmospheric Aerosols) focussed on the hottest part of the Sahara, the heat low region, during the summer. This is also the season of the West African Monsoon and the Saharan Heat Low feature plays an important role in driving the onset of the monsoon. This interaction has been scarcely studied before now but the unique data of Fennec provides the potential to unravel these connections.
  • The Peter Carpenter African Climate Initiative

2. Understanding the Madden-Julian Oscillation (MJO)

The MJO is the dominant pattern of variability in global tropical convection at the intraseasonal timescale (30-60 day cycle). Sussex researchers are involved in two large international projects aim to understand better how the MJO initiates and propagates from the Indian to the Pacific ocean regions, and how we can improve its representation in climate models

3. Tropical cloud processes

  • Tropical Warm Pool International Cloud Experiment (TWP-ICE):  The TWP-ICE project of 2006 in the area around Darwin, Australia provided one of the most complete data sets on tropical convection and cirrus clouds ever collected. The data allows us to understand better the convective life cycle and production of thin high level cirrus cloud and their impact on the environment.


Tropical Warm Pool - International Cloud ExperimentTropical Warm Pool - International Cloud Experiment

Selected publications

Lazenby, M., Todd M.C. and Wang, Y., Evaluation of Model Performance using CMIP5 Climate Model Simulations to Identify and Evaluate Interannual Variability of the South Indian Convergence Zone, Climate Dynamics. In review

Williams, C J R and Kniveton, Dominic R (2012) Atmosphere-land surface interactions and their influence on extreme rainfall and potential abrupt climate change over southern Africa. Climatic Change, 112 (3-4). pp. 981-996. ISSN 0165-0009

Kniveton, D R, Layberry, R, Williams, C J R and Peck, Mika (2009) Trends in start of the wet season over Africa. International Journal of Climatology, 29 (9). pp. 1216-1225. ISSN 0899-8418

Ambrosino, C, Chandler, R.E and Todd, M.C (2011) Southern African monthly rainfall variability: an analysis based on generalised linear models. Journal of Climate, 24 (17). pp. 4600-4617. ISSN 0894-8755

Liu, X, and Y. Wang (2011) Contrasting impacts of spring thermal conditions over Tibetan Plateau on late-spring to early-summer precipitation in southeast China, Atmospheric Science Letters, 12, 309-315, doi:10.1002/asl.343.

Wang, Y, C. N. Long, J. H. Mather, and X. Liu (2011) Convective signals from surface measurements at DOE ACRF Tropical Western Pacific site: Manus, Climate Dynamics, 36, 431-449, doi:10.1007/s00382-009-0736-z.

Wang, Y, C. N. Long, L. R. Leung, J. Dudhia, S. A. McFarlane, J. H. Mather, S. J. Ghan, and X. Liu (2009) Evaluating regional cloud-permitting simulations of the WRF model for the TWP-ICE (Darwin, 2006), JGR-Atmosphere, 114, D21203, doi:10.1029/2009JD012729.

Wang, Y, M Notaro, Z Liu, R Gallimore, S Levis, and JE Kutzbach (2008) Detecting vegetation-precipitation feedbacks in mid-Holocene North Africa from two climate models, Climate of the Past, 4, 59-67, doi:10.5194/cp-4-59-2008.

Banner image: Scenery wallpapers. Tropical convection image: Flickr