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AMMA-AC: African Monsoon Multidisciplinary Analysis - Atmospheric Chemistry Task Coordinators Dr. Céline Mari Prof. Joseph Propsero Introduction AMMA (the African Monsoon Multidisciplinary Analysis) is an international integrated multidisciplinary project that aims at addressing both fundamental scientific questions related to the understanding of the West African Monsoon (WAM) variability and the impacts and practical issues related to prediction and decision-making activity. The earliest phase of the project is already underway, with activities starting in 2001. The proposal herein focuses on the atmospheric chemistry component of the AMMA project, specific aspects of which will be conducted as an IGAC Task. For context, below we describe both the larger AMMA project and that aspect that comprises the IGAC AMMA Task. A full list of participants that will be participating in the atmospheric chemistry aspect of the AMMA program is given in Appendix A for reference. Information on the AMMA project in general can be accessed via the following two web pages,
and is discussed in some detail herein:  I. Motivation and background West Africa is faced with three major issues where the atmosphere is concerned: climate variability, climate change and air quality. Climate variability refers to seasonal and annual variations in temperature and rainfall patterns. The climate of the Western Africa sub-region varies greatly from north to south and is mainly governed by the seasonal movements of the Intertropical Convergence Zone. The West African monsoon (WAM) is a coupled land-ocean-atmosphere system characterized by summer rainfall over the continent and a winter dry season. The equatorial belt generally has high rainfall, whereas northern West African countries are typically desert or semidesert. However, even the parts of West Africa that usually have high rainfall experience climatic variability and extreme events such as floods or droughts. The dramatic change from wet conditions in the 50s and 60s to much drier conditions in the 70s, 80s and 90s over the whole region represents one of the strongest inter-decadal signals on the planet. Indeed, the rainfall deficits of the last thirty years in this area are unprecedented in the 20th century and possibly in the 19th as well. This anomalous period raises questions about the possibility of long-term trends in climate. Superimposed on the general aridity of the past thirty years were marked inter-annual variations with some extremely dry years that had devastating environmental and socio-economic consequences. West African populations and economies are heavily dependent on rain-fed agriculture and are therefore vulnerable to rainfall fluctuations. Unfortunately, there are still fundamental gaps in our knowledge of the coupled atmosphere-land-ocean system. These gaps arise at least partly from the lack of appropriate observational datasets but they also are due to the complex scale interactions between the atmosphere, biosphere and hydrosphere that ultimately determine the nature of the WAM. The monitoring system that does exist for observing the WAM and its variability is inadequate. Dynamical models used for prediction suffer from large systematic errors in the West African and tropical Atlantic regions. Current models have problems simulating fundamental characteristics of rainfall such as diurnal, seasonal and annual cycles. Despite significant progress in recent decades in predicting seasonal fluctuations in rainfall much further investigation is needed before fluctuations can be predicted with sufficient accuracy to enable us to anticipate the impact on food production or other human systems. It is important to recognize the impacts of climate change on the West African Monsoon variability and the role of the emissions in Western Africa on the climate change. West Africa contributes relatively little to the global emissions of carbon dioxide compared to the United States or Europe, whether measured in absolute and per capita terms. However, the region has experienced a three-fold increase of per capita emissions of carbon dioxide since 1950. The transport sector contributes the most to carbon emissions, followed by the industrial sector and the widespread use of biomass for energy. On the other hand, West Africa is a major global source of all types of gases and aerosols especially mineral dust and biomass burning products. Consequently huge plumes of desert dust and fire-generated aerosols are seen emerging from Africa during much of the year, and these extend over large areas of the ocean. We also expect that substantial quantities of aerosol are produced by reactions between organic emissions from the large amounts of vegetation that cover large areas of West Africa and emissions from localized urban and industrialized areas. However there is a clear lack of appropriate datasets to properly quantify these emissions and their impact on atmospheric aerosol concentrations and chemical properties.   In turn, West Africa is highly susceptible to the impacts of climate change because of its dependency on agriculture and the limited financial resources that are available for development of mitigation strategies. The IPCC predicts that the greater variability and unpredictability of temperature and rainfall cycles in West Africa resulting from climate change would alter the area of suitable land for agricultural or livestock production and increase the frequency of flooding and drought. Climate change also poses a threat to human health in West Africa, through reduced nutrition and the possible expansion or creation of new habitats for disease-carrying organisms such as mosquitoes (IPCC, 1998). Latent heat release in deep cumulonimbus clouds in the ITCZ over Africa represents one of the major heat sources on the planet. The meridional migration of the WAM and associated regional circulations impact other tropical and mid-latitude regions so we must expect the atmospheric chemistry and aerosols in WA to impact these regions too. In addition, the presence of such intense sources of aerosols in close proximity to such large regions of deep convection raises questions about the possible impacts of the aerosols on cloud processes. Aerosols could affect convective processes by altering the radiative forcing distribution in the region and also by modifying cloud microphysical processes which, in turn, could change the radiative properties of the clouds, their lifetimes, and the precipitation processes. To date, there is extremely limited information about the chemical composition of aerosols over West Africa, their physical and microphysical properties, and how they impact the climate. Because we know that African aerosols are exported over great distances, these effects could be propagated over large areas. The extent to which the regional and global radiative forcing and the oxidizing capacity are being perturbed by emissions from West Africa has to be improved. Air quality in West Africa is an issue that has emerged over the last few decades, particularly in large urban centers. It has been identified as a priority issue for action because rates of urbanization in Africa are among the highest in the world, and there are enormous economic pressures for continued industrial growth. Rapid urbanization and the concentration of economic activities is leading to increasing air pollution from industry, vehicle emissions and mining (e.g. oil) activities. Combustion of traditional fuels (coals, wood, etc.) for domestic energy needs is another major source of air pollution in both urban and rural areas. Poor economic development has also contributed to air pollution by creating dependence on old vehicles and dirty fuels. Pollutants such as sulfur dioxide, nitrogen oxides, hydrocarbons and heavy metals, together with particulate matter, form dense concentrations of smog in urban centers, causing respiratory diseases, contamination of vegetation and water resources and corrosion of buildings. The objective of AMMA is to quantify the role of West African environmental changes on human
vulnerability by:
Within the larger framework of the AMMA project described above, the IGAC Task AMMA-AC will address a specific set of questions on atmospheric chemistry in the West African region. These questions have relevance both to air quality and climate. They are: Question 1: What are the interactions between lightning, biomass burning, the biosphere, the ocean, human activity and growing urbanization which determine tropospheric ozone concentrations over Western Africa? Improved understanding of the tropospheric ozone budget over Western Africa is needed for the simulations of the West African climate in models used for sub-seasonal to decadal prediction as well as those used for producing scenarios of future climate change. Due to the rather limited studies which have taken place to date in the tropics, the photochemistry of this region is still poorly understood, despite the fact that the tropics are very active in terms of photochemistry. This applies in particular to the free troposphere over West Africa. The tropical troposphere is responsible for ~70% of the total oxidation of long-lived gases such as CH4, CO, HCFCs and CH3Br. HOx (OH+HO2) is the main atmospheric constituent which oxidizes the reduced gaseous compounds, including CO, CH4, NMHCs, SO2, DMS, NOx (NO + NO2) and other hydrogenated and halogenous compounds, into forms more liable to undergo deposition. HOx and the products of these oxidation reactions are responsible for the majority of in-situ photochemical ozone production and destruction.The quantification of the HOx budget is thus a key objective in AMMA. It is also of particular interest in this region because convective injection of species present in the atmospheric boundary layer can be one of the main sources of HOx in the upper troposphere (see also Question 3). Another important objective relates to the ozone distribution and its budget. In the vicinity of the tropopause, ozone is a particularly active greenhouse effect gas and it strongly influences photochemistry, as it is a source of HOx in the presence of UV radiation and water vapor. Therefore, there is a need to determine the contribution of emissions over West Africa to the budget of ozone over this and the larger region affected by West African emissions. This is not an easy task as the West African region experiences an unique superimposition of contributions from different sources which then enter the ITCZ convection. These sources include: moist monsoon air passing over the South Atlantic ocean and the tropical rain forest (biogenic emissions), hot, dry and dusty harmattan air flowing over arid areas and polluted air from urban areas. The quantification of the sources of trace gases over Western Africa is thus also a key objective of AMMA. The emissions from soils and vegetation in both natural and disturbed ecosystems still need to be quantified. These processes yield emissions of hydrocarbons from vegetation and nitrogen compounds from soils. There is a large variability in emissions depending on the vegetation species and the vegetation and the soil response to rainfall and evaporation related to the monsoon. Anthropogenic pollution resulting from the use of fossil fuels and other human activities has increased in the high population density areas over West Africa. It is clear that there are also important but still unquantified emissions from the large urban areas in this region. Finally, West Africa has one of the most electrically active atmospheres of any region in the world. The production of nitrogen monoxide by lightning in convective clouds is an important source of tropospheric NOx which in turn controls ozone concentrations. Large uncertainties surround the estimates of the magnitude and spatial/temporal distribution of this source. Question 2: What are the interactions between dust, biomass burning, the biosphere, the ocean, human activity and growing urbanization which determine aerosol production and properties over Western Africa? Western Africa is one of the most significant aerosol sources in the world. Depending on the season, aerosols in the region are a mix, in variable proportions, of mineral dust (dominant during summer months and northern part of West Africa) and carbonaceous aerosols (dominant during the dry season). Other types of aerosols are present as well including: sulfate and carbonaceous aerosols from the large urban areas, aerosol particles of marine origin which are advected by the monsoon flow, and secondary organic aerosols formed from biogenic gas emissions. The aerosol program in AMMA must take all aerosol species into consideration. The mixing state of the aerosols, their chemical composition, microphysical and radiative properties all need to be investigated over this region.Quantification of the sources of aerosols over Western Africa is a key objective of AMMA. The natural emissions of aerosols over West Africa are strongly influenced by the climatic conditions at various time scales, either directly via meteorological parameters or indirectly via the vegetation and soil properties. One of the key issue is thus the assessment of the variability of the emissions of aerosols over West Africa due, in particular, to wind erosion and biomass burning activity, and of aerosol precursors from vegetated surfaces. The final objective is to establish the degree to which their variability is related to human activities or to climatic parameters, as for example, the monsoon intensity. The most productive dust sources in the world are in the Sahara Desert and the Sahel, in areas where human pressures may be making the landscape more susceptible to wind erosion. The quantification of dust emission rates from both natural and anthropogenic (disturbed) sources with high levels of temporal and spatial resolution is a challenge for AMMA. The seasonal variability of the dust emission is strongly linked to the meteorological processes and surface properties. For example, during the wet season, the squall lines are the event main responsible for dust production and deposition in the vegetated Sahel. The characterisation of dust emissions also requires the determination of the mineral composition, size and shape of dust particles from ground-based and aircraft measurements. The main sources for carbonaceous aerosols are biomass and fossil fuel burning, and the atmospheric oxidation of biogenic and anthropogenic volatile organic compounds (VOC). West Africa supports a wide range of natural vegetation which includes tropical humid forests, dry forests and savannah. The tropical savannah in West Africa is periodically burned during the dry season with environmental consequence at global scale. During the wet season, the biomass burning maximum is located over Central and Southern Africa, with potential advection of these fire-aerosols toward the Western Africa. Important questions still remain unanswered (elevation, estimate of fuel loads, burned area or emission factors) and there is an urgent need to refine the current estimates of biomass burning emissions and their seasonal and interannual variabilities over West Africa. Large quantities of wood energy are consumed in West Africa. Fuelwood is thought to constitute 85 percent of the total energy consumption in the west african countries but the fossil fuel emissions estimates are still large. Given these uncertainties on aerosols production, mix and properties, there is an unique opportunity to address these issues within the AMMA program. Question 3: What is the role of deep convection, the monsoon circulation and other flow patterns in the transport and processing of these emissions and how do these emissions affect the dynamics of the WAM? The chemical composition of the free troposphere is intrinsically linked to dynamical as well as chemical processes. Deep convection is important for the transport of trace constituents from the boundary layer into the free troposphere and for the loss of trace constituents by heterogeneous removal processes including washout. Chemical transformations are carried out via homogeneous and/or heterogeneous processes. Heterogeneous loss processes by aqueous uptake in rain drops, aerosols or ice particles are likely to be particularly active in the tropics because of the extension of cloud cover related to convective activity. However, the details of these processes still requires further investigation. Current treatments of these processes in chemistry transport models need significant improvement and will benefit from the multi-disciplinary studies proposed as part of AMMA. The role of processes – such as stratosphere-troposphere exchange and the penetration of deep convection into the upper troposphere – in determining the chemical composition of the tropical tropopause layer and the transport of trace gases such as water vapor and CFCs to the stratosphere still need to be determined. Similarly, the transport of ozone from the stratosphere (for example across the sub-tropical jet) may be an important and, as yet, unquantified source of ozone in the troposphere. In turn, aerosols can affect the chemical and physical properties of cloud droplets, cloud radiative properties, and, potentially, precipitation regimes. These interactions could have implications for the regional hydrological budgets. For example recent studies suggest that mineral dust can suppress precipitation in clouds. Thus increased dust during drought cycles could have the effect of exacerbating drought and propagating drought conditions over larger areas. AMMA will provide an opportunity to observe the differential cloud response to very different aerosols (i.e. mineral dust vs. biomass burning aerosols vs. secondary organic aerosols from the vegetation). For example, in the winter months, when dust sources are extremely active in the Sahel and biomass burning is at a peak in the Sudan regions, it should be possible to make transects through lines of convection where clouds are advecting dust from the north and smoke from the south. Thus we can observe whether there are the expected gradients in cloud droplet concentrations and other physical properties. Question 4: What factors control the outflow of ozone and aerosols (and their precursors) from West Africa to the tropical Atlantic troposphere and how do they impact atmospheric processes in this region? Once emitted to the atmosphere, aerosols and gases can be rapidly lifted into the free troposphere by deep convection and transported over large distances (several 1000 kms) away from source regions. As such, emissions over West Africa can affect atmospheric properties and processes on intercontinental and global scales. It is also of interest to understand the propagation of climate-change impacts on this region to the inter-continental scale. One objective of AMMA-AC is to quantify the key transport pathways, photochemical reactivity and aerosol properties in air masses downwind from West Africa, particularly in relation to WAM dynamics with the aim of determining the net export of trace gases and aerosols from West Africa relative to other sources. The concentration of dust over the tropical Atlantic is strongly anti-correlated with rainfall in the Sahel-Soudano region of west Africa. Thus climate change in Africa (or changes in dust emissions caused by human activities) could affect aerosol concentrations over this large ocean region with the possible result of inducing significant feedback effects. For example, the high optical depths associated with dust outbreaks have the effect of reducing sea-surface temperatures in the tropical Atlantic. In turn it is known that the monsoon cycle is linked to the distribution of sea-surface temperature in the region. In addition, the region off the west coast of West Africa is the spawning ground for tropical storms and hurricanes, many of which impact the continental US. Studies carried out over the past 35 years in this region have shown that African dust outbreaks during the summer months (i.e. hurricane season) are associated with a well-defined meteorological scenario where dust is carried in a hot, dry layer called the Saharan Air Layer (SAL). These interrelated effects will be an important focus in AMMA-AC. III. The AMMA Program In order to place the IGAC AMMA-AC Task into context, below we describe the larger AMMA Program. III.1 The AMMA Program AMMA is a multi-year, multi-platform project involving 3 types of observing periods: Long-term Observing Period (LOP); Enhanced Observing Period (EOP); Special Observing Periods (SOP) (Figure 4).  The Long term Observing Period (LOP) The LOP is divided into three phases:
Co-ordination between these various projects will remain essential during this last phase of the LOP. It is also foreseen that, so far as EOP measurements demonstrate the benefit of enhanced observations for weather and climate prediction, the operational networks will be maintained at a higher level of readiness and will continue to provide data to the wider scientific community. The Enhanced Observing Period (EOP) is designed to serve as a link between the LOP and the Special Observing Periods and is planned to be of 3 years duration. It starts in January 2005. The EOP is thus designed to enhance the LOP so as to obtain a better understanding of some key factors that may play a role in the inter-annual variability and to provide a framework for the SOP. The main EOP objective is to document, over a climatic north-south transect, the annual cycle of the emissions and of the atmospheric state variables at convective to synoptic spatial scales. In addition, an aim of the EOP is to go beyond a simple documentation of the WAM variability and to investigate some mechanisms that may explain this variability. To this end, AMMA will provide key enhancements to the sustained observing system needed to support the analysis of the seasonal-to-interannual variability of the gases and aerosols in the West African Monsoon (WAM). AMMA will coordinate these enhancements with existing long-term monitoring projects in West Africa (AERONET, IDAF, MOZAIC). The long-term observing strategy over the continent will take advantage of the strong surface observational network that has been established through the CATCH hydrological project. AMMA will strengthen the atmospheric observations along this meridional transect through provision of a set of basic ground-based measurements (Appendix B). A major focus will be on improving radiosounding coverage, adding ozonesondes, and establishing surface flux stations (aerosols, chemical species, water, energy) over the continent. Such observations are not carried out operationally and are not currently part of the LOP. The Special Operation Period (SOP, 2006) will provide a multi-scale and multi-process analysis of one monsoon season. The measurement phases and their tasks are summarized as follows: SOP 0: The dry season and aerosols experiment (January-February 2006) SOP 1: The monsoon onset (May – June) and the chemistry of the low and mid-troposphere. SOP 2: The monsoon maximum (July – August) and the atmospheric chemistry during the monsoon.
SOP3: The late monsoon, the tropical Atlantic (August – September) and the long range transport of
chemical constituents. III.2 AMMA research tools and experimental strategy Current observing systems do not provide all the information needed to fully understand and quantify multi-scale and multi-process interactions. The spectrum of scales to cover is very broad, ranging from local (cloud complexes) to regional (the whole of West Africa) and beyond (global). The observation strategy will thus associate operational observations with long-term observations that are concentrated in a sub-regional window. These will obtained from various ongoing research projects (c.f. AERONET, IDAF). The atmospheric chemistry specific objectives will directly benefit from the meteorological support (improved radiosonde network, dropsondes, radars, etc). During the SOPs, EOP equipment will be greatly enhanced in order to study different processes in great detail within the framework of the focused field campaigns. Airborne instruments will be operated during the Special Observation Periods. Great attention will be paid to collecting and archiving historical datasets in close collaboration with researchers in the African countries in the AMMA study region. In addition, intensive multi-disciplinary observations will be performed during specific periods, focusing on the understanding of key processes. The utility of enhancing existing monitoring stations with additional observations for the future will be tested using modeling and assimilation systems. AMMA instrumented zone during the SOPs: For SOP 1 and 2, the region where intensive observations will be conducted is a sub-regional scale window currently covered by the CATCH measurements. The plan is to establish an ensemble of instruments aimed at quantifying the mass and energy budgets (i.e. heat, humidity, radiation, momentum, trace gases) over a zone that covers Benin and the region of Niamey in Niger. This region will be the CATCH -focus area- which extends between 5°N-17°N and 5°W-5°E. These special observations must be considered in relation with the larger scale and will permit linking the observed local processes with the regional and synoptic scale forcing. In addition to this ground-based equipment, instrumented aircraft will be extensively used to provide a more complete coverage of the observed events, both spatially outside the instrumented zone or the CATCH sub-regional window and temporally to follow the evolution of the selected events as they propagate over West Africa. During SOP 3, sone or two instrumented aircrafts will be based in Dakar, Senegal, or in Sal, Cape-Verde Islands.   Instrumented platforms: Aircraft: To quantify the HOx, ozone and aerosols budgets in the free and upper troposphere, a minimum set of observations is required: ozone, CO, H2O, NO, NO2, PAN, HNO3, NOy, CH4, N2O, peroxides, carbonyls, OH, HO2, SO2, H2SO4, acetone, formaldehyde and aerosol composition, size distribution and optical properties. Airborne measurements of acetaldehyde (CH3CHO) and methanol would also be very interesting for understanding the HOx budget. Measurements of radionuclides, alcohols and remote H2O would also be extremely valuable. Four aircraft are currently planning on participating on the SOP covering a large suite of measurements (Appendix C). These include: the United Kingdom BAE146 aicraft (contact Claire Reeves), the instrumented French aircraft INSU/ATR 42 (contact Gerard Ancellet), and the German (contact Hans Schlager), and French F20 aircrafts. The participation of the Russian high altitude aircraft Geophysicae is currently under investigation. Satellite observations (ENVISAT, AURA, AQUA-Train, TERRA) will strongly contribute to the objectives of the project by providing measurements in biosphere-atmosphere system). In turn, the AMMA project will provide a unique set of integrated ground observations that will be used for validation of retrievals from the current and planned satellites. Modeling and assimilation A hierarchy of models is now available to treat a very broad range of scales and the atmospheric, oceanic and chemistry processes involved in the WAM. These include Global Climate Models, Chemical Transport Models, mesoscale models and cloud resolving models. These atmospheric models have the same problems as weather forecasting models; close collaboration between these modeling communities will improve the physical parameterizations in these models. It is crucial to improve the representation of convective processes at cloud scale in terms of the dynamics and thermodynamics and also to understand the impact of convective clouds on the vertical transport and scavenging of gases and aerosols. At the regional and synoptic scale, atmospheric and chemistry models focus on the dynamics of the African Easterly Jet, the meridional gradients and surface fluxes, and the dry and wet convection. These major dynamical features have a great impact on the location of origin and chemical composition of air masses in the convective outflow, which is transported over large distances. In turn, the spatial distribution, chemical properties and size of the aerosols in West Africa represent a complicated superposition of contributions from different African source regions (oceanic, combustion, urban pollution and desert). Chemistry models have to take into account this variety in order to evaluate the radiative impact of the aerosols and their effect on the dynamics. The numerical strategy will be based on a multi-scale approach from the local scale of a convective cell to the climatic impact. This approach has been followed successfully in the GCSS (GEWEX Cloud System Studies) framework and it should be extended to include atmospheric chemistry. Ground-based platforms:
Secondary sites with basic instrumentations will operate during the EOP:
Measurements of ozone and ozone precursors Measurements of ozone and its precursors will be enhanced by the instrumented site of Lamto in Ivory \ Coast and Djougou in Benin. Emission measurements (biogenic and anthropogenic) IV. Applications, training and education In the planning of AMMA, significant attention has been paid to generating benefits that move beyond answering the scientific questions and whose duration extends beyond the period of the project. Below we describe some of these benefits. Building capacity in partnership with African Institutions A key aspect of the AMMA project is the development of blended training and education activities for African research and technical institutions. As of September, 2004 three scientists from West Africa are present on the international organizing committee for AMMA: Cherif Diop (Sénégal), Abou Amani (Niger), Leykan Oyebande (Nigéria). In addition, researchers from the major West African environmental laboratories are involved in AMMA through the IGAC/IDAF network, a component of the IGAC DEBITS Task. Further, a major objective of the project is to build links between scientific research and the application of what is learned to policy decisions. Models and data sets will be developed in collaboration with African institutions and international bodies so that they can test and use them as tools for decision making and to develop adaptation strategies in response to the evolving West Africa environment. The collaboration between scientists working on processes and those involved in applications will be fostered through training sessions. The project will also provide updated global climate change scenarios for stakeholders. Summer schools, supervised PhDs, visiting scientists opportunities for African scientists and participation of researchers outside Africa and teaching in African Universities are among the various tools that will be used to build a strong link with African scientific communities. Such links already exist at national levels through specific programs but the project will provide the opportunity to develop and promote these efforts. Communications between all AMMA participants have been and will continue to be facilitated by a web-based tool, the AMMA community network, AMMANET. Since 2002, West African scientists – from both universities and national meteorological and hydrological services – have collaborated via AMMANET (http://www.ird.ne/ammanet/). AMMANET is coordinated by a steering committee of 7 scientists, including: Abou Amani, (Hydrology, AGRHYMET Centre - Niamey, Niger); Amadou Gaye (Lecturer at LPA - Dakar, Senegal); Adamou Garba (Lecturer at EAMAC - Niamey, Niger); Abdallah Nassor (ACMAD - Niamey, Niger); Delphin Ochou (Lecturer at LAPA - Abidjan, Ivory Coast). In addition, each African country involved in AMMA has identified a national co-ordinator. This contact person is in charge of producing reports about the AMMA activities and collaborations in her country. AMMANET will contribute to the reinforcement of the capacities of the various national or regional institutions and the universities. The national committees must regularly organize meetings to discuss the scientific aspects and co-ordination between the various teams. Finally, we note that travel and educational support for the West African partners will be funded into the EU and French Integrated Project. Monitoring strategies Socio-economic implications Long-term archiving system Peer-reviewed manuscripts International cooperation: Links to other IGBP Programs Task coordinators | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
