The Southern African Regional Science Initiative 2000 (SAFARI 2000) is an interdisciplinary science activity designed to increase our understanding of the southern African ecological and climate system as a whole, as well as its relationship to hemispheric and global climate. The project involves a confederation of national, regional, and global environmental research activities. NASA, through its EOS, Land Cover and Land Use Change, and Terrestrial Ecology Programs, is supporting several efforts that will contribute to SAFARI 2000. These include an extensive validation component associated with the launch of the EOS AM-1, and Landsat 7 platforms in 1999-2000.
SAFARI 2000 will address the key linkages between the physical, chemical, and biological processes, including human impacts, essential to the functioning of the regional biogeophysical system. More specifically, it will help characterize and quantify the biogenic, pyrogenic, and anthropogenic aerosol and trace gas sources and sinks; validate the understanding of these processes using atmospheric transport and chemistry models, ground-based, airborne, and satellite-based observations; and determine the climatic, hydrological, and ecosystem consequences of these biogeochemical processes.
Interest in the southern African region by the EOS validation community stems from two basic reasons: 1) unique and compelling scientific processes highly relevant to understanding climate and global change and 2) ongoing scientific investigations funded by southern African, European, and U.S. sponsors. The latter create the opportunity for leveraging off existing investigations, thereby providing maximum scientific return on limited resources.
Figure 1. Southern African Recirculation Patterns and Potential Airborne Sampling Areas.
The boundaries of the study region are defined by the atmospheric environment and the geography of Africa south of the Equator. These permit a reasonably discrete study region, which in turn permits mass-balance calculations to be performed. The semi-closed atmospheric circulation, shown in Figure 1, provides both a context and integrating mechanism between the biological and physical systems. This is especially the case during austral winter when anticyclonic circulation and associated clear sky conditions favorable for satellite and airborne remote sensing, dominate the region on as many as four out of every five days.
Marked biogeophysical gradients in vegetation type and structure, rainfall, and biogeochemistry characterize much of the study region. These gradients occur over spatial extents of thousands of kilometers both meridionally, as in the case of the Kalahari sands, and zonally, as is the case of the Miombo woodlands. The latter, which represent the largest tropical dry forest system in the world, occupies approximately 2.8 million km2 in Africa. Both rainfall, which varies annually across the region from <100 mm to >1200 mm, and fire occurrence and frequency demonstrate a strongly seasonal, generally temporally consistent, spatial progression across the study region. The wet season extends from November through May. Fire frequency peaks in August/September, coincident with the peak of the dry season (Figure 2).
Southern Africa is a highly sensitive region due to its increasing population and population migration, rain-fed subsistence agriculture, limited water and food availability, and relatively low industrial development. However, recent political and social stability has led to more rapid though sporadic economic and industrial development. Energy generation to support mining and metallurgical industries, as well as the industries themselves, has contributed to high levels of aerosol and trace gas emissions. Additionally, the region is subject to some of the most extensive biomass burning in the world, most of which is associated with human population pressures on regional ecosystems. These anthropogenic forces, along with a strong source of biogenic emissions and a large natural variability in both regional climate and ecosystem processes, combine to effect changes in the biogeochemical cycling of the region. Moreover, these forces serve as strong catalysts for large-scale changes in land cover and use.
These threats to the regional ecology and climate have led the Intergovernmental Panel on Climate Change (IPCC) and the International Geosphere-Biosphere Program (IGBP) to designate southern Africa as a focus for scientific assessment. Specifically, the IGBP and START (SysTem for Analysis, Research, and Training) have facilitated collaborative research efforts through their Kalahari, Miombo, and Subsistence Rangelands programs. Other national and international agencies such as the NOAA Climate Prediction Forum and Regional Applications Program have likewise targeted the region.
The international science community has mounted a concerted response. The Southern African Fire-Atmosphere Research Initiative 1992 (SAFARI 92) was organized under the IGAC (International Global Atmospheric Chemistry) Biomass Burning in the Global Environment (BIBEX) program. The activity involved more than 150 scientists from 14 countries and focused on biomass burning and its atmospheric effects in the Southern Hemisphere. It particularly addressed factors controlling the process and distribution of subtropical savanna fires as well as the chemistry, transport and source strength of their products. The successful program contributed substantially to our current understanding of these processes, although SAFARI 92 revealed little on their consequences.
The Southern African Atmosphere Research Initiative 1994 (SAFARI 94), a joint South African-German flying campaign, followed SAFARI 92 and focused on the in situ chemical sampling of aerosols and trace gases across the region during the non-biomass burning season.
These initiatives, together with others addressing independent ecological and climate issues, have contributed much to our understanding of discipline-specific objectives. However, linkages between the controlling and impacted processes were given less attention. In particular, past scientific accomplishments have led to the formulation of questions that require more synthetic, integrated and interdisciplinary research. It is on this foundation that SAFARI 2000 is being developed.
The initial motivation for SAFARI 2000 evolved from several IGBP/START regional workshops that identified the global-change science priorities for the region. This led to a series of stakeholder workshops held in the summer of 1998. At a National Science Foundation (NSF)-sponsored workshop on Southern African Land-Atmosphere-Biosphere Interactions, held at Blydepoort, South Africa in July, 1998, more than 70 participants from 12 countries met to begin shaping the core elements of SAFARI 2000. Specific questions about aerosols and trace gases were developed with the following progression in mind: sources; transformations; patterns; responses; and interactive processes.
Presently, a number of precursor activities set the stage for SAFARI 2000. These include: ARREX (South AfricaÕs Aerosol Recirculation and Rainfall Experiment); INDOEX (Indian Ocean Experiment); AERONET (NASAÕs Aerosol Robotic Network); SHADOZ (NASAÕs Southern Hemisphere ADditional OZonesondes Project) and IDAF (IGAC DEBITS (Deposition of Biogeochemically Important Trace Species) Africa project). The IGBP LUCC/START Miombo Network is helping coordinate efforts that concern the miombo woodlands in the northern half of the study region. The NASA Land-Cover/Land-Use Change and Ecology programs have a number of studies currently underway in southern and central Africa.
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SAFARI 2000 will be conducted over a three-year period starting in the second half of 1999, with major field campaigns during 1999 and 2000. It will focus on the following science components: terrestrial ecosystems and biogeochemical transformations, land-cover and land-use change, fire disturbance, pyrogenic, biogenic and industrial emissions and their transport, aerosol and cloud characterization and interactions both over land and oceans, and atmospheric chemistry and deposition.
Multiple tools will be used to achieve the InitiativeÕs goals. The existing scientific database and regional infrastructure will be exploited, and be augmented by new in situ and remote measurements and comprehensive modeling efforts. In situ measurements will be largely clustered around core field sites that are representative of major regional land-cover variants, have a scientific heritage, and are subject to long-term preservation. Field sites near Mongu, Zambia, and Skukuza, South Africa, will anchor the ground network. These two sites are currently part of NASAÕs Global Land Cover Test Sites, EOS Land Validation Core Sites, and AERONET programs. A walk-up tower at each site will allow above-canopy access to investigators (Figure 3). Several other scientific towers in the region will also be employed.
Figure 3. Schematic of EOS validation tower set up that will be deployed at Mongu, Zambia, and Kruger National Park, South Africa.
Both periodic and large episodic aircraft campaigns will complement the ground measurements. The SAFARI Core sites will be overflown periodically by light aircraft hosting a small set of remote sensing instruments. More intensive aircraft measurements will occur during Intensive Field Campaigns (IFC) scheduled for August/September 1999, and February 2000, and August/September 2000. The strategy is to integrate a comprehensive wet season assessment with dry season assessments. At least two aircraft featuring extensive aerosol, trace gas, and ground observation sensors will be used during these periods. In addition, the NASA ER-2 will carry a range of simulation sensors, including MAS, AirMISR, CLS, SSFR, S-HIS, and MOPITT-A during the IFC in August/September of 2000. A full suite of satellite land and atmosphere products from the AM, Landsat 7, SeaWiFS, NOAA/AVHRR, and other satellites will be employed.
The various data sets derived from this array will help provide the initialization and validation sets required for various modeling activities. The research will incorporate models of ecosystem processes such as biophysical energy and water exchanges with the atmosphere, biogeochemical cycling, and plant demographics, as well as mesoscale atmospheric models. The observations and modeling will extend across spatial scales from plot to landscape and region scales and across time scales from hours to weeks to years.
Based on lessons learned from previous campaigns, data integration and archiving are actively being planned. A fully open data distribution policy is envisioned, with incentives for rapid data reduction and turnaround. Information from SAFARI 2000 activities will be disseminated regionally and internationally via the Internet as well as through the distribution of CD-ROMs. A mirror World Wide Web site with SAFARI-only data will likely be set up in the region. These efforts will help scientists achieve the goal of results synthesis by 2001.
SAFARI 2000 provides northern and southern hemisphere researchers opportunities for capacity recognition as well as the transfer of technology and expertise from North to South and perhaps, more importantly, from South to North. An important component of the SAFARI 2000 objectives is model and satellite product evaluation by local experts, as well as the promotion of informed use of these models and data by regional scientists.
The ambitious goals of SAFARI 2000 will be achieved with the help of the comprehensive data sets expected from the new generation of EOS sensors. High-spatial-resolution sensors such as ASTER on AM-1 and ETM+ on Landsat 7 will detect fine-scale land-cover change and use, and facilitate the scaling of point and short-transect measurements over much larger areas. Likewise, MODIS, SeaWiFS, and AVHRR will be used for full regional views and retrospective analysis. Particularly encouraging is the anticipated ability of MODIS to more accurately detect thin cirrus clouds, fire temperature, areal extent, and thermal energy, and detect surface features through the occasionally pervasive smoke layers. The highly variable aerosol forcing problem will largely be attacked with the accurate aerosol and 3-D cloud products expected from MISR. This sensor may also help resolve savanna and woodland variability through its bidirectional sampling capabilities. Finally, MOPITT will help resolve large-scale source, sink, and transport questions associated with carbon monoxide and methane emissions.
In return, a significant contribution to EOS validation will be made by SAFARI 2000. In addition to planned regional activities by members of the MODIS, MISR, ASTER, and MOPITT instrument teams, three AM-1 validation investigations are funded in the region. These three activities include: Southern African Validation of EOS (SAVE): Coordinated Augmentation of Existing Networks, J. L. Privette (PI); Vertical Profiles of Carbon Monoxide and Other Gases in the Troposphere, P. C. Novelli (PI); Biomass Burning and Emission of Trace Gases and Aerosols: Validation of EOS Biomass Burning Products, W. M. Hao/D. E. Ward (PIs). The AERONET program will capture aerosol information with a relatively dense deployment of sunphotometers. Together, these groups will coordinate ground and air measurements around the Core Sites to validate both atmospheric and surface satellite products. When possible, investigators will leverage their analyses on independently gathered data sets. Standing acquisition requests have been negotiated with the respective instrument teams for products at each of the Core Sites. An extensive set of airborne in situ measurements will be made over the various surface sites and coordinated with the EOS satellite overpasses. In addition to the NASA ER-2, the U.S. will support the University of Washington CV-580 for in situ measurements of clouds, aerosols, trace gases, and radiation. This large range of measurements combines to make SAFARI 2000 the largest coordinated validation activity planned for AM-1.
SAFARI was chosen as a rallying acronym for the Initiative, centered on the millennium, and with a heritage of international collaboration within the region. It is envisaged that through open participation in SAFARI 2000, new in situ data collection combined with advances in the modeling of the biogeophysical systems and improvements in satellite monitoring, will lead to an improved understanding of regional and global environmental change in southern Africa.
Government and scientific agencies from the U.S., Europe and Southern Africa have been briefed on the plans for SAFARI 2000. The SAFARI 2000 Science Plan is under development and should be ready for open distribution in early 1999. The outline of the Science Plan, developed at the Blydepoort planning meeting, received preliminary endorsement at the BIBEX Meeting held in Seattle, Washington, USA, in August, 1998, and will be presented to the IGAC steering committee in late spring of 1999.
The anticipated schedule of SAFARI 2000 milestone events is as follows:
February 1999: Science Plan distribution
July 1999: Second SAFARI 2000 workshop in Gaborone,
BotswanaÑcompletion of the Implementation Plan of SAFARI 2000
August/September 1999: First Intensive Flying /Ground Campaign (dry season)
February/March 2000: Second Intensive Flying /Ground
Campaign (wet season)
April 2000: Third SAFARI 2000 workshop, location TBD
August/September 2000: Third Intensive Flying/Ground Campaign (dry season)
The SAFARI 2000 initiative is open to international participation. Although no explicit core funding is available to U.S. investigators, various funding programs have expressed interest in entertaining SAFARI 2000 proposals submitted through normal funding channels. For further information on SAFARI 2000, please contact the authors and/or visit the SAFARI 2000 World Wide Web page - http://safari.gecp.virginia.edu