Douglas J. Parker on Upper-Air Measurements Over West Africa
New Hot Paper Commentary, September 2010
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Article: THE AMMA RADIOSONDE PROGRAM AND ITS IMPLICATIONS FOR THE FUTURE OF ATMOSPHERIC MONITORING OVER AFRICA
Authors: Parker, DJ;Fink, A;Janicot,
S;Ngamini, JB;Douglas, M;Afiesimama, E;Agusti-Panareda,
A;Beljaars, A;Dide, F;Diedhiou, A;Lebel, T;Polcher,
J;Redelsperger, JL;Thorncroft, C;Wilson, GA |
Douglas J. Parker talks with ScienceWatch.com and answers a few questions about this month's New Hot Papers paper in the field of Geosciences.
Why do you think your paper is highly
cited?
This paper describes a program of upper-air measurements over West Africa which was conducted as part of the African Monsoon Multidisciplinary Analysis (AMMA; Redelsperger et al., "African Monsoon Multidisciplinary Analysis: An International Research Project and Field Campaign," Bull. Amer. Meteorol. Soc. 87: 1739-46, 2006. doi:10.1175/BAMS-87-12-1739) in the years 2005 onwards. AMMA is a very big international research program concerned with the environment and climate of the West African region, involving hundreds of researchers worldwide.
Our upper-air measurements represent the best sampling of the atmosphere which has ever been achieved over an African region, and therefore they are in demand by many studies into meteorology, hydrology, oceanography, and climate. In a sense, the AMMA upper-air program unlocked a range of connected science problems, providing the data which have been lacking for many years, to address key questions about the continental water cycle and climate dynamics.
The measurements were made by instruments called "radiosondes"—balloon-borne sensors which are released from a network of ground stations and carried from the ground, through the troposphere and up into the stratosphere, reaching around 25km altitude. Data are transmitted to a ground station and then, in principle, relayed in real time to international weather forecasting centers.
This means that our measurements then had an impact on weather forecasts for the region and around the world. Many people are also using our data indirectly—through the products of weather forecast models (and model analyses).
Radiosonde data are collected routinely from stations all around the world, including West Africa. It was a fundamental principle of the AMMA project to invest effort in the existing operational radiosonde stations of the region. Therefore, this has been a highly collaborative effort involving specialists in Africa, Europe, and the Americas.
"The significance of the paper is to describe a set of measurements which are now being used by scientists around the world to answer questions about the climate of West Africa..."
The success of the program has taught us some lessons about how the routine monitoring of weather and climate can be conducted in future years, and we hope that the international community in meteorology and climate is interested in these ideas.
Does it describe a new discovery, methodology, or synthesis of knowledge?
It might be best to describe the work as a methodology: the paper describes the planning and implementation of data collection. We intended that the article would be of value to the many people making use of the data, in describing the data sources and their limitations. We also intended that the paper should guide future efforts to sustain or increase weather and climate monitoring in Africa.
If there were discoveries made, they represented the research scientists learning about the realities of data collection in the African continent. For instance, it was shocking to learn that some stations which had been assumed to have been defunct for many years had been operating effectively, but silently though lack of communications.
Most fundamentally, we demonstrated that the climate-observing network in West Africa can operate very effectively, and produce the data required to make progress in climate research.
Would you summarize the significance of your paper in layman's terms?
The significance of the paper is to describe a set of measurements which are now being used by scientists around the world to answer questions about the climate of West Africa. This is a part of the world where rain-fed agriculture is critical to the livelihoods and survival of millions of people, and yet it is a region where our weather and climate prediction models are fundamentally unreliable.
We have made the first set of upper-air measurements of sufficient quality to measure the water budget in the atmosphere over a river catchment in Africa, and thereby to begin to test and improve prediction models. The measurements are also essential to many other studies relating to the African climate and environment; for instance studies of severe thunderstorms and their effects.
The paper also is significant in demonstrating that the African operational climate-monitoring networks can achieve a level of performance which is the equal of any in the world. Prior to AMMA there was some pessimism in the international community that the African observing networks are in terminal decline. We showed that the decline of recent decades can be reversed, with some financial investment and international cooperation.
It is a notable conclusion of the paper that the financial contributions of the African partners to this research program, through their operational budgets for radiosondes, exceeded the funding provided by the research program: this contradicts the assumption that the African agencies do not have financial resources to support a sound network.
We argue that better international cooperation is needed in order to properly make use of this African commitment. We also documented a number of problems which have been allowed to deteriorate for decades, particularly in the communications networks, and demonstrated solutions to some of these.
How did you become involved in this research, and how would you describe the particular challenges, setbacks, and successes that you've encountered along the way?
There was a necessity to do this work for the wider AMMA research program: the upper-air measurements are necessary in order to have a good set of atmospheric analyses, which are in turn essential to hydrological, oceanographic, and other studies. A large team of specialists was involved in the program, numbering about 250 people working in many countries. These included research scientists, technicians, managers, and computational specialists at the international forecasting centers.
The program was initially coordinated by Andreas Fink and myself, with Jean-Blaise Ngamini leading the implementation. Working with such a large and diverse group of specialists (and in all cases, enthusiasts) was one of the pleasures of the work.
The primary technical challenge has been in communication of data. For many years, data have increasingly been lost due to failures of communications between African stations and the international centers. Email, satellite, and dedicated electronic transmissions have been used in AMMA, and all have significant problems. Sometimes the Francophone-Anglophone barrier is also a significant obstacle to making progress.
"Our upper-air measurements represent the best sampling of the atmosphere which has ever been achieved over an African region, and therefore they are in demand by many studies into meteorology, hydrology, oceanography and climate."
It is remarkable to realize that on some stations where trained specialists are operating equipment worth hundreds of thousands of Euros, the communication of the data to forecasting centers relies on the operator riding his motorcycle several kilometers on difficult roads to the nearest cyber-café.
There have been many other challenges relating to installation of equipment, training of staff, shipping of consumables, and coordination of the whole effort, but probably everyone involved would agree that communications are the number-one problem in improving the African climate-monitoring networks.
There have been several successes to report. Primarily, we achieved a very high data volume—some 7,000 radiosondes were launched in our most intensive observational periods of 2006, with very high success rates, at times as good as any in the world.
A smaller network of six stations undertook intensive phases of eight balloon-launches per day: this seems to be a record for Africa, and we don’t believe that it has been achieved anywhere else with hydrogen-filled balloons. The data are now being widely and successfully used in scientific research.
We were involved in the reactivation of some excellent stations in the region—in some cases we simply reconnected active stations to the international communications networks, at relatively low cost. Four years after our most active research period, the long-term activity on most of the stations in the network seems still to be in reasonably good shape.