Past Projects

The Role of Biosphere in the Climate of Tropical Regions

The objective of this project is to advance understanding of the role of the biosphere in the climate of tropical regions. During the last few years, we developed a general theory that defines the role of vegetation in sustaining large scale atmospheric circulations, and in shaping the climate of the tropics. We applied this theory in investigating the role of vegetation in the dynamics of West African monsoons and obtained new insights regarding the possible link between observed deforestation and occurrence of droughts. Although, in the past we concentrated on the problem of defining the role of the static vegetation in climate processes at the interannual time scale, we are currently investigating the two-way interactions between vegetation dynamics and atmospheric variability at decadal and longer time scales.

Sustainability Considerations in the Design of Big Dams

In this case study of the Merowe Dam on the Nile Basin in Sudan, our environmental assessment team will analyze the current hydropower dam design, and then propose design and operational changes to improve sustainability. The design process will be shaped by engineering as well as environmental constraints. The project will emphasize the long-term issues that are important for sustainability of large dams. The following will be our areas of focus:

* Sedimentation build-up in the reservoir
* Climate change and its impact in the hydrological regime
* Smaller scale Impacts — Archaeological sites, population resettlement, affects on public health due to water-borne diseases introduced by the new reservoir.

Pilot Study on Biosphere-Atmosphere Interactions in Dhofar, Oman

The aim of this pilot study is on the one hand to understand the different natural factors and study the human activities that influence on the ecosystem in Dhofar, as well as to develop strategies to prevent and combat desertification in the region.

As a first step we aim to understand the natural factors that shape the climate system Dhofar. For this part of the study we do not take into account the human influence on the system.
We analyzed data on the large scale climate, like sea surface temperature (SST), wind, pressure. We also studied local data from climate stations in Dhofar and along the Coast to the Arabian Sea.
An atmospheric model was set up for the region. The control runs are conducted at this point. Once the model is successful in representing the climate in Dhofar, it will be used to study the influence of large-scale climate on the Dhofar ecosystem. For example we will model the influence of the observed increase in Sea Surface Temperature of the Arabian Sea on the precipitation of Dhofar.
We also conducted an extensive literature research. Two excerpts of this research are included to this web-page: (1) a review about the climate in Dhofar and in Oman in general and (2) a review about ecosystems that are influenced by clouds (cloud forests).

As a second step we will take into account the influence of human activity on the system and finally we will investigate how the system can be managed in a way that prevents desertification and helps to conserve and probably reestablish the unique ecosystem of Dhofar.

Mosquitoes, Monsoons, and Malaria in Africa

Hydrological and climatological determinants of African anopheline habitat Within the semi-arid Sahel zone of Africa, serious malaria epidemics arise as a result of the annual wet season. We are studying the environmental determinants of malaria outbreak occurrence in this region with the aid of numerical modeling techniques. We are involved in an inter-disciplinary study to investigate the dependence of mosquito breeding and infection rates on factors such as surface water pooling which is the result of various hydroclimatological variables. In a unique approach, individual mosquitoes in a small study area in Niger will be modeled numerically in a simulation coupled with a small-scale hydrology model. Model input will include satellite-acquired remotely sensed data for vegetation, soil moisture and topography. With results validated by field investigations, variation in mosquito abundance and infection rates will be simulated. This numerical modeling tool will shed light on dynamics of outbreak occurrence and will help the targeting of intervention efforts.

Evaluating Regional Climate Models Over the American Midwest

Weather and climate affect almost every facet of human activity, which makes the pursuit to understand the hydrologic and atmospheric systems of the Earth, as well as the effects of anthropogenic activities on these systems, one of the most important areas of scientific research today. One approach used to gain a better understanding of local land- atmosphere processes is regional modeling. Though limited in predictive ability by the use of boundary conditions and prescribed sea surface temperatures (SSTs), regional models are able to resolve important processes at sub-general circulation model (GCM) resolutions.

El Niño and the Hydrology of Tropical Rivers

El Niño is the most significant phenomenon that shapes the variability of climate in tropical regions at the interannual time scale. We are studying the relationship between Sea Surface Temperature in the Pacific Ocean, a measure of El Niño, and the flow in several large tropical rivers. The objective is to develop new methodologies for long-range forecasting of river flow, using El Niño forecasts, which can improve significantly the options for water resources management in the tropics. [Sponsored by the Sloan Foundation, and the Winslow Chair]