Abstract
This study examines the seasonal cycle of the components of the surface energy balance in the Volta basin in West Africa as part of the GLOWA-Volta project. The regional climate is characterized by a strong north–south gradient of mean annual rainfall and the occurrence of pronounced dry and wet seasons within one annual cycle, causing a strong seasonal variation in the natural vegetation cover. The observations are conducted with a combined system, consisting of a Large Aperture Scintillometer (LAS) for areally averaged sensible heat flux, radiometers and sensors for soil heat flux. For comparisons the eddy-covariance (EC) method providing the fluxes of momentum, sensible and latent heat is utilized as well. The measurements of a seasonal cycle in 2002/2003 were gathered including the rapid wet-to-dry transition after the wet season at two locations in Ghana, one in the humid tropical southern region and one in the northern region. A direct comparison and the energy balance closure of the two methods are investigated for daytime and nighttime separately. An attempt is made to understand and explain the differences between the two methods and the closure of energy budget found for these. It is found that the two systems correspond well during daytime. During nighttime the LAS seems to perform more realistically than the EC system. Considering the fact that a LAS system is much easier to use in the climate conditions of the Volta basin, it is concluded that the LAS approach is very suitable in this type of climate conditions. Surface conductances are estimated by rearranging the Penman–Monteith equation and compared to a Jarvis-type model optimised for savannah conditions. It is found that temperature dependence should be included in the conductance formulation in contrast to earlier findings. Based on the findings the gathered dataset can be used for further model studies of the climate and environment of West Africa.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Agyare, W.: 2004, ‘Soil Characterization and Modeling of Spatial Distribution of Saturated Hydraulic Conductivity at Two Sites in the Volta Basin of Ghana’, Ecology Develop. Series Vol. 17, 194 pp.
Baldocchi D., Falge E., Gu L., Olson R., Hollinger D., Running S., Anthoni P., Bernhofer Ch., Davis K., Evans R., Fuentes J., Goldstein A., Katul G., Law B., Lee X., Malhi Y., Meyers T., Munger W., Oechel W., Paw K.T., Pilegaard K., Schmid H.P., Valentini R., Verma S., Vesala T., Wilson K., Wofsy S. (2001). ‘FLUXNET: A New Tool to Study the Temporal and Spatial Variability of Ecosystem-Scale Carbon Dioxide, Water Vapor, and Energy Flux Densities’. Bull. Amer. Meteorol. Soc. 82, 2415–2434
Baldocchi D., Xu L., Kiang N. (2004). ‘How Plant Functional-Type, Weather, Seasonal Drought, and Soil Physical Properties Alter Water and Energy Fluxes of an Oak-Grass Savanna and an Annual Grassland’. Agric. For. Meteorol. 65, 21–45
Birkes D., Dodge Y. (1993). Alternative Methods of Regression. John Wiley and Sons, Inc., New York 228 pp
Bolle H.-J., Andre J.C., Arrue J.L. (1993). ‘EFEDA: European Field Experiment in a Desertification-Threatened Area’. Ann. Geophys. 11, 173–189
Burpee R.W. (1972). ‘The Origin and Structure of Easterly Waves in the Lower Troposphere of North Africa’. J. Atmos. Sci. 29, 77–90
Cobos D.R., Baker J.M. (2003). ‘Evaluation and Modification of a Domeless Net Radiometer’. Agron. J. 95, 177–183
De Bruin H.A.R., Kohsiek W., van den Hurk B.J.J.M. (1993). ‘A Verification of Some Methods to Determine the Fluxes of Momentum, Sensible Heat, and Water Vapor Using Standard Deviation and Structure Parameter of Scalar Meteorological Quantities’. Boundary-Layer Meteorol. 63, 231–257
De Bruin H.A.R., van den Hurk B.J.J.M., Kohsiek W. (1995). ‘The Scintillation Method Tested Over a Dry Vineyard Area’. Boundary-Layer Meteorol. 93, 453–468
Dolman A.J. (1993). ‘A Multiple-Source Land Surface Energy Balance Model for Use in General Circulation Models’. Agric. For. Meteorol. 65, 21–45
FAO Report, (1984). Agroclimatological Data for Africa Countries North of the Equator. Food and Agriculture Organization (FAO) of the United Nations, Rome
Foken Th., Wichura B. (1996). ‘Tools for Quality Assessment of Surface-Based Flux Measurements’. Agric. For. Meteorol. 78, 83–105
Friesen, J.: 2002, Spatio-temporal Patterns of Rainfall in Northern Ghana, Diploma thesis, University of Bonn, 81 pp.
Goutorbe J.-P., Lebel T., Tinga A. (1994). ‘HAPEX-Sahel: A Large-Scale Study of Land-Atmosphere Interactions in the Semiarid Tropics’. Ann. Geophys. 12, 53–64
Gu J., Smith E.A., Merritt J.D. (1999). ‘Testing Energy Balance Closure with Goes Retrieved Net Radiation and in Situ Measured Eddy Correlation Fluxes in BOREAS’. J. Geophys. Res. 104, 27–81
Halldin S., Lindroth A. (1992). ‘Errors in Net Radiometry: Comparison and Evaluation of Six Radiometer Designs’. J. Atmos. Oceanic Technol. 9, 762–783
Harris P.P., Huntingford C., Cox P.M., Gash J.H.C., Malhi Y. (2003). ‘Effect of Soil Moisture on Canopy Conductance of Amazonian Rainforest’. Agric. For. Meteorol. 122, 215–227
Hartogensis O.K., Watts C.J., Rodriguez J.-C., De Bruin H.A.R. (2003). ‘Derivation of a Effective Height for Scintillometers: La Poza Experiment in Northwest Mexico’. J. Hydrometeorol. 4: 915–928
Heusinkveld B., Jacobs A.F.G., Holtslag A.A.M., Berkowicz S.M. (2004). ‘Surface Energy Balance Closure in an Arid Region: Role of Soil Heat Flux’. Agric. For. Meteorol. 122, 21–37
Hólm, E., Andersson, E., Beljaars, A., Lopez, P., Mahfouf, J. F., Simmons, A., and Thépaut, J. N.: 2002, Assimilation and Modeling of the Hydrological Cycle: ECMWF’s Status and Plans.
Hsieh C.I., Katul G.G., Chi T.W. (2000). ‘An Approximate Analytical Model for Footprint Estimation of Scalar Fluxes in Thermally Stratified Atmospheric Flows’. Adv. Water Res. 23, 765–772
Huntingford C., Allen S.J., Harding R.J. (1995). ‘An Inter-Comparison of Single and Dual-Source Vegetation-Atmosphere Transfer Models Applied to Transpiration from Sahelian Savannah’. Boundary-Layer Meteorol. 74, 397–418
Jarvis P. (1976). ‘The Interpretation of the Variations in Leafwater Potentials and Stomatal Conductances Found in Canopies in the Field’. Philos. Trans. Rof. Soc. London Ser. B 273, 593–610
Kasei C.N. (1988). ‘The Physical Environment of Semiarid Ghana’. In: Unger P.W., Sneed T.V., Jordan W.R., Jensen R. (eds). Challenges in Dryland Agriculture – A Global Perspective. Texas Agricultural Experiment Station, Amarillo/Bushland, pp. 350–354
Lamaud E., Ogée J., Brunet Y., Berbigier P. (2001). ‘Validation of Eddy Flux Measurements Above the Understorey of a Pine Forest’. Agric. For. Meteorol. 106, 173–186
Lee X., Hu X. (2002). ‘Forest-Air Fluxes of Carbon, Water and Energy over Non-Flat Terrain’. Boundary-Layer Meteorol. 103, 277–301
Mahrt L. (1998). ‘Flux Sampling Errors for Aircrafts and Towers’. J. Atmos. Oceanic Tech. 15, 416–429
Martano P. (2000). ‘Estimation of Surface Roughness Length and Displacement Height from Single-Level Sonic Anemometer Data’. J. Appl. Meteorol. 39, 708–715
Meijninger W.M.L., Green A.E., Hartogensis O.K., Kohsiek W., Hoedjes J.C.B., Zuurbier R.M., De Bruin H.A.R. (2002). ‘Determination of Area-Averaged Water Vapor Fluxes with Large Aperture and Radio Wave Scintillometers over a Heterogeneous Surface Flevoland-Field-Experiment’. Boundary-Layer Meteorol. 105, 63–83
Moene A.F. (2003). ‘Effects of Water Vapour on the Structure Parameter of the Refractive Index for Near-Infrared Radiation’. Boundary-Layer Meteorol. 107, 635–653
Moncrieff J.B. (1996). ‘The Propagation of Errors in Long-Term Measurements of Land Atmosphere Fluxes of Carbon and Water’. Global Change Biol. 2, 231–240
Monteith J. (1981). ‘Evaporation and Surface Temperature’. Quart. J. Roy. Meteorol. Soc. 107, 1–27
Monteith J., Unsworth M.H. (1990). Principal of Environmental Physics, (2nd ed.), Arnold, London 291 pp
Moore C. (1986). ‘Frequency Response Corrections for Eddy Correlation Systems’. Boundary-Layer Meteorol. 37, 17–35
Obukhov A.M. (1960). ‘Structure of Temperature and Velocity Fields Under Conditions of Free Convection’. Works Inst. Theor. Geophys. Acad. Sci. USSR 1, 95–115
Paulson C. (1970). ‘The Mathematical Representation of Wind Speed and Temperature Profiles in the Unstable Atmospheric Surface Layer’. J. Appl. Meteorol. 9, 857–861
Schaap M.G., Leij F.J., van Genuchten M. Th. (1998). ‘Neural Network Analysis for Hierarchical Prediction of Soil Water Retention and Saturated Hydraulic Conductivity’. Soil Sci. Soc. Am. 62, 847–855
Schotanus P., Nieuwstadt F., De Bruin H.A.R. (1983). ‘Temperature Measurement with a Sonic Anemometer and Its Application to Heat and Moisture Fluxes’. Boundary-Layer Meteorol. 26, 81–93
Solbrig O.T., Medina E., Silva J.F. ed. (1996). ‘Determinants of Tropical Savannas’, in Biodiversity and Savanna Ecosystem Processes – A Global Perspective, Ecological Studies Springer, Berlin
Stannard D.I., Branford J.H., Kustas W.P., Nichols W.D., Amer S.A., Schmugge T.J., Weltz M.A. (1994). ‘Interpretation of Surface Flux Measurements in Heterogeneous Terrain During the Monsoon’90 Experiment’. Water Resour. Res. 30, 1227–1239
Stull R.B. (1988). An Introduction to Boundary Layer Meteorology. Kluwer Acad., Norwell Mass 666 pp
Twine T.E., Kustas W.P., Norman J.M., Cook D.R., Houser P.R., Meyers T.P., Prueger J.H., Starks P.J. Wesely M.L. (2000). ‘Correcting Eddy-Covariance Flux Underestimates over a Grassland’. Agric. For. Meteorol. 103, 279–300
Van de Giesen N., Kunstmann H., Jung G., Liebe J., Andreini M., Vlek P.L.G. (2001). ‘The GLOWA Volta Project: Integrated Assessment of Feedback Mechanisms between Climate, Landuse, and Hydrology’. Adv. Glob. Change Res. 10, 151–170
Van Dijk A., Kohsiek W., De Bruin H.A.R. (2003). ‘Oxygen Sensitivity of Krypton and Lyman-alpha Hygrometers’. J. Atmos. Oceanic Tech. 20, 143–151
Verhoef A., Allen S.J., De Bruin H.A.R., Jacobs C.M.J., Heusinkveld B.G. (1996a). ‘Fluxes of Carbon Dioxide and Water Vapour from a Sahelian Savanna’. Agric. For. Meteorol. 80, 231–248
Verhoef A., van den Hurk B.J.J.M., Jacobs A.F.G., Heusinkveld B.G. (1996b). ‘Thermal Soil Properties for Vineyard (EFEDA-I) and Savanna (HAPEX-Sahel) Sites’. Agric. For. Meteorol. 78, 1–18
Verma S. (1989). ‘Aerodynamic Resistances to Transfers of Heat, Mass and Momentum in Estimation of Areal Evaporation’. IAHS Publ . 177 pp.
Viterbo P., Beljaars C. (1995). ‘An Improved Land Surface Parametrization Scheme in the ECMWF Model and its Validation’. J. Climate. 8, 2716–2748
Wallace, J. S., Allen, S. J., Culf, A. D., Dolman, A. J., Gash, J. H. C., Holwill, C. J., Lloyd, C. R., Stewart, J. B., Wright, I. R., Sivakumar, M. V. K., and Renard, C.: 1992, SEBEX: The Sahelian Energy Balance Experiment, ODA Report no. 92/9. IH, Wallingford, UK. 51 pp.
Webb E., Pearman G., Leuning R. (1980). ‘Correction of Flux Measurements for Density Effects Due to Heat and Water vapour Transfer’. Quart J. Roy. Meteorol. Soc. 106, 85–100
Wesely M.L. (1976). ‘The Combined Effect of Temperature and Humidity Fluctuations on Refractive Index’. J. Appl. Meteorol. 15, 43–49
Wilczak J., Oncley S., Stage S.A. (2001). ‘Sonic Anemometer Tilt Correction Algorithms’. Boundary-Layer Meteorol. 99, 127–150
Wyngaard J.C. (1973). ‘On Surface-Layer Turbulence’. In: Haugen D.A. (eds). Workshop on Micrometeorology. American Meteorological Society, Boston, Mass, pp. 101–149
Wilson K., Goldstein A., Falge E., Aubinet M., Baldocchi D., Berbigier P., Bernhofer C., Ceulemans R., Dolman H., Field C. (2002). ‘Energy Balance Closure at FLUXNET Sites’. Agric. For. Meteorol. 113, 223–243
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Schüttemeyer, D., Moene, A.F., Holtslag, A.A.M. et al. Surface Fluxes and Characteristics of Drying Semi-Arid Terrain in West Africa. Boundary-Layer Meteorol 118, 583–612 (2006). https://doi.org/10.1007/s10546-005-9028-2
Received:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10546-005-9028-2