Investigating the West African Monsoons

Volume 5, Issue 1, Winter 2015

By Raphael Pope-Sussman

When Catherine Pomposi found out this April that she’d been awarded a fellowship to conduct research in Senegal through the United States Agency for International Development, she immediately logged on to her computer and started cataloguing places to go and things to see. “I was very thrilled and excited,” she says. “And probably did a little ‘woohoo!’ while at my computer.”

A doctoral student in the Department of Earth and Environmental Sciences, Pomposi studies the West African monsoon, a wind system that blows southwesterly across sub-Saharan Africa between June and September, bringing the region the majority of its annual rainfall. Through the research she conducts through her academic department at GSAS and her research affiliations at the International Research Institute for Climate Society (IRI) and the Lamont-Doherty Earth Observatory, Pomposi seeks  to better understand the dynamics and variability of the monsoon and to synthesize her research to provide useful, actionable information to farmers in the region, whose livelihoods depend on the rains of the monsoon.

Pomposi’s interest in atmospheric and climate science arose from a class on global physical climatology, which she took as an undergraduate at the University of Connecticut. “I just found the intricacies of the climate system really compelling,” she says, “as well as the applications the climate system can have on various societies through the world.”

She then began to focus on the phenomenon of monsoon systems, doing preliminary work on a study examining the variability of the Indian monsoon. “The monsoons of the world seemed really fascinating to me,” she says. “The idea that regions of the world really get the majority of their rainfall only during a single season was of course very different from the northeast United States, where I grew up.”

In 2011, Pomposi was awarded a Graduate Research Fellowship through the National Science Foundation before enrolling at GSAS, where she has had the opportunity to work closely with climate researchers such as her adviser Alessandra Giannini, who studies tropical climate dynamics. And, through a new initiative open exclusively to NSF Graduate Research Fellows, she’s had the opportunity to see the monsoon and how it affects life in West Africa up close and on the ground.

The GROW with USAID Fellowship, a new partnership from the NSF’s Graduate Research Opportunities Worldwide program and the United States Agency for International Development, pairs researchers on development issues with host organizations in seven countries: Brazil, Colombia, India, Indonesia, the Philippines, South Africa, and Senegal, where Pomposi did her research. These host organizations identify and communicate a local development need to USAID, which matches fellows in relevant disciplines with hosts.

As luck would have it, Pomposi’s research focus meshed perfectly with work being done by a climate scientist in Senegal, Ousmane Ndiaye, M.Phil.’07, Ph.D. ’10, Earth and Environmental Sciences. Both an alumnus of the department and a research affiliate of the IRI, Ndiaye, who works out of Dakar for Senegal’s national meteorological agency, had put together a project for the USAID Research and Innovation Fellowship Catalog, “Producing and Delivering Climate Information for Better Food Security,” with the aim of examining the seasonal forecast of the monsoon and using the findings to help farmers with their crop management.

“I saw Ousmane’s project, and since I had been researching West African monsoon dynamics for a number of months by that point, it seemed like a really great opportunity to actually travel to the region and see how seasonal forecasting is done in real time, and in the actual region where the information is being used,” Pomposi explains.

She immediately brought the project to her advisers, Giannini and Yochanan Kushnir, who said it aligned perfectly with her current research and encouraged her to apply. Because the GROW-USAID fellowship requires applicants to arrange a potential match as part of their application, Pomposi had to connect with Ndiaye to discuss the project and whether it would be a good fit. “It was originally described by one of the USAID staff members as being sort of like online dating,” Pomposi says of the process. “In our case, Ousmane and I spoke a few times over Skype about my background and interests in the project, as well as his work in Senegal and on seasonal forecasting and food security.” They ultimately agreed that Pomposi’s research was a good fit, and Ndiaye provided her a formal letter of invitation for the project.

With the invitation in hand, Pomposi submitted her formal application to the NSF. Her proposal was approved by the NSF, and then by USAID; that was when Pomposi found out she was headed to Senegal.

Leading up to her planned departure for Senegal in June, the beginning of the monsoon season, Pomposi looked at seasonal monsoon variability—the extent to which precipitation levels and patterns vary within a given season—as well as variability across decades.

Senegal resides within a region of Africa known as the Sahel, a band of semiarid grassland just below the Sahara desert that runs across the continent. The summer monsoon brings about three quarters of the Sahel’s annual precipitation. In wet years, total precipitation can be as much as 700 millimeters (28 inches); in dry years, it can be as little as 300 millimeters (12 inches). The goal of examining variability, Pomposi explains, is to try to understand why some monsoon years are particularly dry while others are particularly wet, and to identify indicators that can help predict the intensity of a given monsoon.

When Pomposi arrived in Senegal, she joined Ndiaye and his research colleagues as they met with farmers in the Fatick and Kaffrine regions of the country to discuss the monsoon. Through these meetings, or workshops, Pomposi explains, the scientists collect information from the farmers about traditional methods for developing a monsoon forecast. The farmers use indicators like the phases of the moon and changes in local flora and fauna to predict the starting date and intensity of the coming monsoon.

Meanwhile, the scientists bring their seasonal forecast, which relies on a range of global models, to the farmers. This past season, Pomposi says, traditional indicators suggested that the monsoon would be in the average or wetter-than-average range. The seasonal forecast, on the other hand, predicted a drier-than-average monsoon. The season ultimately turned out to be closer to the scientific forecast—it was a relatively dry year—though the month of August was slightly wetter than average in some parts of the country. But the purpose of the workshops, Pomposi emphasizes, is not to measure the predictions against each other. Rather, it is to add to the toolbox from which the farmers can draw, while helping the scientists better understand the nature of the monsoon.

The workshops, then, also serve to build a lasting partnership between researchers and farmers. Collecting rainfall data in situ, for example, can be very difficult for the scientists, so they distribute rain gauges to the farmers. Pomposi explains that this collaboration allows the farmers “to feel more involved in the process and have some kind of ownership over the data,” which they report back to the scientists for analysis.

Ndiaye stressed the importance of Pomposi’s work with the farmers, explaining, “For a useful climate product, it is always important to maintain a close eye on demand from users.” He also said that Pomposi’s work helped build a relationship between the meteorological agency and Columbia, which also helped further the cause of research on the monsoon.

Pomposi is hoping she can continue that relationship by returning to Senegal this coming summer. Currently, Ndiaye is collecting information about crop growth in the region where the seasonal forecast was used, which they will be able to compare to growth  in the areas where it wasn’t. Pomposi says she’s looking forward to spending more time with Ndiaye and studying some of the more complex scientific and technical elements of seasonal forecasting, a major area of his expertise. If all goes according to plan, she will again be able to visit at the beginning of the monsoon season, to write up the findings of this year’s research, and to meet with the same farmers to discuss the next year’s forecast.

It will be a fitting conclusion to the work she has conducted under the GROW with USAID Fellowship, both the capstone of her research into the monsoon system and the beginning of a stronger working relationship between scientists and farmers—an imbrication of science, international collaboration, and sustainable development practices that reflects the highest ideals of the fellowship’s creators.