Short-term measurements of carbon dioxide, water, and energy fluxes (30 minute averages) were collected at four locations along a mean annual precipitation gradient in southern Africa during the SAFARI 2000 wet (growing) season campaign of 2000. The purpose of this research was to determine how observed vegetation-atmosphere exchange properties are functionally related to long-term climatic conditions. This research was conducted along the Kalahari Transect (KT), one in the global set of International Geosphere-Biosphere Programme (IGBP) transects, which covers a north-south aridity gradient, all on a homogenous sand formation. Eddy covariance instruments were deployed on a permanent tower in Mongu, Zambia (879 mm of rainfall per year), as well as on a portable tower in Maun (460 mm/yr), Okwa River Crossing (407 mm/yr), and Tshane (365 mm/yr), Botswana for several days at each site.
The data files are stored as ASCII text files, one file per site, in comma-separated-value (csv) format, with column headers. Each file contains measurements of the following parameters: air temperature; CO2 concentration; CO2 flux; friction velocity; heat flux; infrared surface skin temperature; longwave radiation; net radiation; photosynthetic photon flux density; photosynthesis energy; relative humidity; shortwave radiation; soil moisture; soil temperature; vapor pressure deficit; wind speed and angle; water use efficiency; and water vapor.
Additional information can be found in the companion file: http://daac.ornl.gov/daacdata/safari2k/climate_meteorology/kalahari_co2_heat_flux/comp/kt_co2_heat_flux_readme.pdf. Detailed photographs (.jpg) that complement the experimental descriptions for this data set are available on the S2K Photo Gallery pages.
Cite this data set as follows:
Scanlon, T. M., and J. D. Albertson. 2004. SAFARI 2000 Kalahari Transect CO2, Water Vapor, and Heat Flux, Wet Season 2000. Data set. Available on-line [http://daac.ornl.gov/] from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, U.S.A. doi:10.3334/ORNLDAAC/765.
Pinheiro A. and J. Privette. 2004. SAFARI 2000 Soil Properties, Moisture, and Temp, Skukuza and Mongu, 1999 to 2001. Data set. Available on-line [http://daac.ornl.gov/] from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, U.S.A.
Privette, J. L., R. B. Myneni, Y. Knyazikhin, M. Mukufute, G. Roberts, Y. Tian, Y. Wang, and S. G. Leblanc. 2002. Early spatial and temporal validation of MODIS LAI product in the Southern Africa Kalahari. Remote Sensing of Environment, 83(1-2): 232-243.
Scanlon, T. M. and J. D. Albertson. 2004. Canopy scale measurements of CO2 and water vapor exchange along a precipitation gradient in southern Africa. Global Change Biology, 10(3): 329-341.
Scholes, R. J., P. R. Dowty, K. Caylor, D. A. B. Parsons, and H. H. Shugart. 2002. Trends in savanna structure and composition along an aridity gradient in the Kalahari. Journal of Vegetation Science, 13(3): 419-428.
The data files are stored as ASCII text files, one file per site, in comma-separated-value (csv) format, with column headers. The files are named:
co2_wve_ghanzi_2000.csv
co2_wve_maun_2000.csv
co2_wve_mongu_2000.csv
co2_wve_tshane_2000.csv
Each file contains the following parameters. The first record in each file contains the column names defined below, followed by subsequent records of data values.
| Column Name | Description | Units |
|---|---|---|
| Date | Decimal Date, Year 2000 | fractional days |
| Rswin | Shortwave incoming radiation, measured by CRN-1 radiometer | W m-2 |
| Rswout | Shortwave outgoing radiation, measured by CRN-1 radiometer | W m-2 |
| Rlwin | Longwave incoming radiation, measured by CRN-1 radiometer | W m-2 |
| Rlwout | Longwave outgoing radiation, measured by CRN-1 radiometer | W m-2 |
| Net_Rad | Net Radiation, Rswin+Rlwin-Rswout-Rlwout | W m-2 |
| H | Sensible heat flux, measured in eddy covariance mode by CSAT-3 sonic anemometer, at heights of 31.2 m for Mongu, 10.4 m for Maun, 5.1 m for Ghanzi, and 10.4 m for Tshane | W m-2 |
| LE_KH2O | Latent heat flux, measured in eddy covariance mode by CSAT-3 sonic anemometer, in conjunction with a krypton hygrometer, at heights of 31.2 m for Mongu, 10.4 m for Maun, 5.1 m for Ghanzi, and 10.4 m for Tshane | W m-2 |
| LE_licor | Latent heat flux, measured in eddy covariance mode by CSAT-3 sonic anemometer, in conjunction with an open path infrared CO2/H2O gas analyzer, at heights of 31.2 m for Mongu, 10.4 m for Maun, 5.1 m for Ghanzi, and 10.4 m for Tshane | W m-2 |
| G1 | Soil heat flux, measured by model HFT3 soil heat flux plates, of bare soil patch at depth of 5 cm | W m-2 |
| G2 | Soil heat flux, measured by model HFT3 soil heat flux plates, of vegetated patch at depth of 5 cm | W m-2 |
| IRT1 | Infrared surface skin temperature, measured by model IRTS-S infrared thermometers (Mongu - aimed from top of tower at surface; Maun - aimed at vegetated patch; Ghanzi - aimed at combination vegetated/bare soil; Tshane - aimed at vegetated patch) | degrees C |
| IRT2 | Infrared surface skin temperature, measured by model IRTS-S infrared thermometers (Mongu - not measured; Maun- aimed at combination vegetated/bare soil; Ghanzi - aimed at bare soil; Tshane - aimed at bare soil) | degrees C |
| IRT3 | Infrared surface skin temperature, measured by model IRTS-S infrared thermometers (Mongu - not measured; Maun - aimed at bare soil; Ghanzi - aimed at vegetated patch; Tshane - aimed at combination vegetated/bare soil) | degrees C |
| Tsoil1 | Soil temperature at depth of 7.5 cm for vegetated patch, as measured by soil thermocouples. At the Mongu site, these data were provided by Pinhiero and Privette (2004) and were measured at a depth of 5 cm (107L Campbell Scientific). | degrees C |
| Tsoil2 | Soil temperature at depth of 2.5 cm for vegetated patch, as measured by soil thermocouples | degrees C |
| Tsoil3 | Soil temperature at depth of 7.5 cm for bare soil patch, as measured by soil thermocouples) | degrees C |
| Tsoil4 | Soil temperature at depth of 2.5 cm for bare soil patch, as measured by soil thermocouples | degrees C |
| theta1 | Volumetric soil moisture, averaged over a depth of 0-30 cm, measured by time domain reflectometry (TDR) for a vegetated patch | unitless |
| theta2 | Volumetric soil moisture, averaged over a depth of 0-30 cm, measured by time domain reflectometry (TDR) for a bare soil patch | unitless |
| zeta | Atmospheric stability parameter | unitless |
| air_temp | Air temperature measured by model HMP45C temperature and relative humidity sensor, at heights of 31.2 m for Mongu, 10.4 m for Maun, 5.1 m for Ghanzi, and 10.4 m for Tshane | degrees C |
| RH | Relative humidity measured by model HMP45C temperature and relative humidity sensor, at heights of 31.2 m for Mongu, 10.4 m for Maun, 5.1 m for Ghanzi, and 10.4 m for Tshane | percent |
| wind_speed | Wind speed measured by CSAT-3 sonic anemometer, at heights of 31.2 m for Mongu, 10.4 m for Maun, 5.1 m for Ghanzi, and 10.4 m for Tshane | m s-1 |
| Ustar | Friction velocity measured by CSAT-3 sonic anemometer, at heights of 31.2 m for Mongu, 10.4 m for Maun, 5.1 m for Ghanzi, and 10.4 m for Tshane | m s-1 |
| wind_dir | Wind angle, measured by CSAT-3 sonic anemometer, at heights of 31.2 m for Mongu, 10.4 m for Maun, 5.1 m for Ghanzi, and 10.4 m for Tshane | radians |
| CO2_conc | CO2 concentration measured by open path infrared CO2/H2O gas analyzer at heights of 31.2 m for Mongu, 10.4 m for Maun, 5.1 m for Ghanzi, and 10.4 m for Tshane | mg m-3 |
| WV_conc | Water vapor concentration, measured by open path infrared CO2/H2O gas analyzer at heights of 31.2 m for Mongu, 10.4 m for Maun, 5.1 m for Ghanzi, and 10.4 m for Tshane | g m-3 |
| r2_WV/CO2 | Correlation coefficient between CO2 and water vapor concentrations, measured by open path infrared CO2/H2O gas analyzer at heights of 31.2 m for Mongu, 10.4 m for Maun, 5.1 m for Ghanzi, and 10.4 m for Tshane | unitless |
| CO2_flux | Carbon dioxide flux, measured in eddy covariance mode by CSAT-3 sonic anemometer, in conjunction with an open path infrared CO2/H2O gas analyzer at heights of 31.2 m for Mongu, 10.4 m for Maun, 5.1 m for Ghanzi, and 10.4 m for Tshane | µmol m-2 s-1 |
| VPD | Vapor pressure deficit derived from air temperature and relative humidity measurements made by model HMP45C, at heights of 31.2 m for Mongu, 10.4 m for Maun, 5.1 m for Ghanzi, and 10.4 m for Tshane | mb |
| WUE | Water use efficiency, divide Carbon dioxide flux by Latent heat flux and convert units | mg CO2 (g H2O)-1 |
| Photosyn | Photosynthesis energy, convert Carbon dioxide flux to units of energy flux | W m-2 |
| PPFD | Photosynthetic photon flux density, taken as 0.475* 2 Rswin, with units conversion | µmol m-2 s-1 |
Additional information about the data format, methodology, instrumentation, and parameters measured is found in the companion file: http://daac.ornl.gov/daacdata/safari2k/climate_meteorology/kalahari_co2_heat_flux/comp/kt_co2_heat_flux_readme.pdf.
2004/9/13
2004/9/13
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