Atmospheric Boundary Layer Experiments (ABLE)

The Atmospheric Boundary Layer Experiments (ABLE) (http://www.atmos.anl.gov/ABLE/) facility was established in 1997 within the Walnut River Watershed in south-central Kansas (USA), east of the city of Wichita, to support studies in boundary layer meteorology, hydrology, ecology, and atmospheric chemistry. ABLE was developed by the Atmospheric Section of the U.S. Department of Energy (DOE), Argonne National Laboratory. The ABLE facility is located within the existing boundaries of DOE's Atmospheric Radiation Measurement (ARM) Southern Great Plains (SGP) Clouds and Radiation Testbed (CART) and consists of 5 instrumented sites: Augusta (Central Site), Beaumont, Oxford, Smileyberg, and Whitewater. ABLE was initially designed primarily for investigations of and within the planetary boundary layer (PBL) (the lower part of the troposphere) where the influence of the surface is felt directly through turbulent transport. Topics of interest include the dynamics of the mixed layer during both day and night; effects of varying land use and land form; the interactive roles of precipitation, runoff, and soil moisture; storm development; and energy budgets on scales of 1•100 km. ABLE was designed to augment insufficiently comprehensive PBL data sets— in a variety of synoptic conditions — and support testing of parameterization schemes representing PBL and surface processes in weather and climate models. Existing uncertainty includes whether the wind profiles produced by PBL models are realistic (LeMone et al. 2000; Coulter et al. 1998; Wesely et al. 1997). The current emphasis (since 2000) of ABLE is evaluation of the carbon cycle at the surface. ABLE is participating in studies of the net air-surface exchange of carbon dioxide in support of AmeriFlux studies of the terrestrial carbon balance. The objectives of the measurement program are to quantify seasonal variations in carbon dioxide and water vapor fluxes, determine vegetative and climatic effects on the carbon dioxide budget, and investigate the carbon balance (through both measurements and modeling). (The AmeriFlux program is designed to provide long-term measurements of carbon dioxide, energy, and water vapor fluxes between terrestrial ecosystems and the atmosphere. See Metadata for Ameriflux registered in ORNL DAAC Mercury or visit the Ameriflux web site at http://public.ornl.gov/ameriflux/Participants/Sites/Map/index.cfm for more information.) Since 2001, ABLE (DOE Argonne) has also been participating in the DOE Water Cycle Pilot Study (WCPS), along with DOE Lawrence Berkley, Oak Ridge, Brookhaven, and Los Alamos National Laboratories (Miller et al. 2003). The pilot study has produced an extensive database and evaluations of numerical predictions of components of the water budget for three nested domains, two of them within the ABLE area. Data assimilated include field results from a three-month intensive observing period within the ABLE area. The WCPS has also measured changes in leaf area index (LAI) for several vegetation types and groundwater variations at three wells. The study included water isotope sampling in rainwater, streams, soil moisture, lakes, and wells as a means of tracing sources and sinks within and outside the ABLE area. During 1997 and 1999 ABLE hosted two field campaigns in connection with the Cooperative Atmosphere-Surface Exchange Study (CASES) and provided supplementary measurements and facilities for these shorter-term instrument deployments. CASES is a grassroots, multidisciplinary effort to study the interaction of the lower atmosphere with the land surface, the subsurface, and vegetation over time scales ranging from seconds to years. CASES-97, the first episodic field effort, was held during April•June 1997. CASES-97 studied the role of surface processes in the diurnal variation of the boundary layer, tested radar-based precipitation algorithms, and attempted to define relevant scaling for precipitation and soil properties (LeMone et al. 2000). A second, very successful field program (CASES-99) was conducted within the ABLE array during October 1999 to study the nocturnal boundary layer and the morning and evening boundary layer transitions (Poulos et al. 2002). (See Metadata for CASES registered in ORNL DAAC Mercury.) The equipment which is available at the ABLE includes: Three (3) Radar Wind Profilers with Radio Acoustic Sounding Systems (RASS) [measures wind profiles from (nominally) .1 km to 5 km and virtual temperature profiles from .1 km to 2.5 km.]; Three (3) Dopplar Acoustic Sounders (Minisodars) (measures wind profiles from about 10 m to 200 m above the surface, thus filling in the gap left below the minimum height of the wind profilers.); Five (5) Automated Weather Stations (AWS Systems) (instrumented 10-m towers continuously measure wind direction, wind speed, temperature, humidity, precipitation, and barometric pressure, the latter only at surface characterization sites and the Central Site); Two (2) Eddy-correlation Flux Measurement Systems (ECOR Stations) (measures surface fluxes of sensible heat, latent heat, momentum, and carbon dioxide); One (1) Energy Balance Bowen Ratio Systems (EBBR Stations) (measures surface fluxes of sensible and latent heat); and A network of twenty-eight (28) recording rain gauges. Atmospheric radiation and soil temperature, moisture, and heat flow are measured continuously at 2 locations. Canopy reflectance and leaf area index are made approximately every two weeks during the growing season at 3 sites. Continuously collected data are available at the ABLE web site in near real-time and archived form (Klazura et al., 2003). References: Coulter, R.L., G.E. Klazura, B.M. Lesht, J.D. Shannon, D.L. Sisterson, and M.L Wesely. 1998. Using the ABLE facility to observe urbanization effects on planetary boundary layer processes, Preprints, 10th Joint Conference on the Applications of Air Pollution Meteorology, Phoenix, AZ, Air and Waste Management Assn. and Amer. Meteorol. Soc., pp. J76-J79. Klazura, G.E., D.R. Cook, R.L. Coulter, R.L. Hart, D.J. Holdridge, B.M. Lesht, J.D. Lucas, T.J. Martin, M.S. Pekour, and M.L. Wesely. 2003. Atmospheric Boundary Layer Measurements in South-Central Kansas. Presented at the 30th International Symposium on Remote Sensing of Environment, 10-14 November 2003, Honolulu, Hawai'i. LeMone, M.A., R.L. Grossman, R.L. Coulter, M.L. Wesely, G.E. Klazura, G.S. Poulos, W. Blumen, J.K. Lundquist, R.H. Cuenca, S.F. Kelly, E.A. Brandes, S.P. Oncley, R.T. McMillen, and B.B. Hicks. 2000. Land-atmosphere interaction research, early results, and opportunities in the Walnut River Watershed in southeast Kansas: CASES and ABLE, Bull. Amer. Meteorol. Soc., vol 81, pp. 757-779. Miller, N.L., A.W. King, M.A. Miller, E.P. Springer, M.L. Wesely, K.E. Bashford, M.E. Conrad, K. Costigan, R.L. Coulter, P.N. Foster, H.K. Gibbs, J. Jin, G.E. Klazura, B.M. Lesht, M.V. Machavaram, F. Pan, J. Song, J. Stalker, D. Troyan, R.A. Washington-Allen. 2003. The DOE Water Cycle Pilot Study, Submitted to Bull. Amer. Meteorol. Soc. Poulos, G.S., W. Blumen, D.C. Fritts, J.K. Lundquist, J. Sun, S.P. Burns, C. Nappo, R. Banta, R. Newsom, J. Cuxart, E. Terradellas, B. Balsley, and M. Jensen, 2002: CASES-99: A comprehensive investigation of the stable nocturnal boundary layer, Bull. Amer. Meteorol. Soc., vol 83, pp. 555-581. Wesely, M.L., R.L. Coulter, G.E. Klazura, B.M. Lesht, D.L. Sisterson, and J.D. Shannon. 1997. A planetary boundary layer observational capability in Kansas, Preprints, First Symposium on Integrated Observing Systems, Long Beach, CA, Amer. Meteorol. Soc., pp. 169-171.大气边界层试验设施（Atmospheric Boundary Layer Experiments，以下简称ABLE）于1997年建于美国堪萨斯州中南部核桃河流域（Walnut River Watershed），威奇托市东侧，旨在支持边界层气象学、水文学、生态学与大气化学领域的相关研究。该设施由美国能源部（U.S. Department of Energy，简称DOE）阿贡国家实验室大气研究部门开发，坐落于DOE大气辐射测量（Atmospheric Radiation Measurement，简称ARM）南大平原（Southern Great Plains，简称SGP）云和辐射试验场（Clouds and Radiation Testbed，简称CART）的现有辖区内，共包含5个布设观测仪器的站点：奥古斯塔（中心站点）、博蒙特、牛津、斯迈利伯格与怀特沃特。 ABLE最初主要设计用于行星边界层（planetary boundary layer，简称PBL，即对流层下部受地表湍流输送直接影响的区域）的相关研究，研究主题涵盖昼夜混合层动力学、不同土地利用与地形的影响、降水、径流与土壤水分的交互作用、风暴演变，以及1×100 km尺度下的能量收支。该设施旨在补充不同天气形势下不够完备的PBL数据集，并支持天气与气候模式中表征PBL和地表过程的参数化方案的测试。目前仍存在的不确定性包括PBL模式输出的风廓线是否符合实际（LeMone等，2000；Coulter等，1998；Wesely等，1997）。 自2000年起，ABLE的研究重点转为地表碳循环评估。该设施正参与二氧化碳气-地表净交换相关研究，以支持美国通量网（AmeriFlux）的陆地碳平衡研究。观测项目的目标包括量化二氧化碳与水汽通量的季节变化、明确植被与气候对二氧化碳收支的影响，以及通过观测与模拟手段研究碳平衡。（AmeriFlux计划旨在长期观测陆地生态系统与大气间的二氧化碳、能量与水汽通量，详细信息可查询橡树岭国家实验室分布式活跃档案中心（Oak Ridge National Laboratory Distributed Active Archive Center，简称ORNL DAAC）的Mercury数据库中注册的AmeriFlux元数据，或访问AmeriFlux官网http://public.ornl.gov/ameriflux/Participants/Sites/Map/index.cfm获取更多内容。） 2001年起，ABLE（DOE阿贡实验室）还与DOE下属的劳伦斯伯克利、橡树岭、布鲁克黑文以及洛斯阿拉莫斯国家实验室一同参与DOE水循环先导研究计划（Water Cycle Pilot Study，简称WCPS）（Miller等，2003）。该先导计划已构建了一套大型数据库，并对3个嵌套区域的水量平衡组分数值预测进行了评估，其中2个区域位于ABLE辖区内。同化的数据包括ABLE辖区内为期3个月的强化观测期野外观测结果。WCPS还对多种植被类型的叶面积指数（Leaf Area Index，简称LAI）变化以及3口观测井的地下水变化进行了测量。该研究还对雨水、溪流、土壤水分、湖泊与井水开展了水同位素采样，以此追踪ABLE辖区内外的碳源与碳汇。 1997年与1999年，ABLE先后承办了两次与协同大气-地表交换研究（Cooperative Atmosphere-Surface Exchange Study，简称CASES）相关的野外试验，并为这些短期仪器部署提供补充观测与设施支持。CASES是一项跨学科的草根研究计划，旨在研究数秒至数年时间尺度下低层大气与地表、地下层及植被的相互作用。首次野外试验CASES-97于1997年4月至6月开展，研究了地表过程在边界层日变化中的作用，验证了基于雷达的降水算法，并尝试确定降水与土壤性质的相关尺度（LeMone等，2000）。第二次极为成功的野外计划CASES-99于1999年10月在ABLE观测阵列内开展，旨在研究夜间边界层以及早晚边界层过渡过程（Poulos等，2002）。（详细信息可查询ORNL DAAC Mercury数据库中注册的CASES元数据。） ABLE现有观测设备包括： 1. 3套配备无线电声学探测系统（Radio Acoustic Sounding Systems，简称RASS）的雷达风廓线仪：可（标称）测量0.1 km至5 km高度的风廓线，以及0.1 km至2.5 km高度的虚温廓线； 2. 3套多普勒声学探测系统（迷你声雷达，Minisodars）：可测量地表以上10 m至200 m高度的风廓线，填补了雷达风廓线仪最低观测高度以下的观测空白； 3. 5套自动气象站（Automated Weather Stations，简称AWS系统）：架设的10 m高观测塔可连续测量风向、风速、气温、湿度、降水与气压（仅在地表特征站点与中心站点测量气压）； 4. 2套涡动相关通量测量系统（Eddy-correlation Flux Measurement Systems，简称ECOR站点）：可测量感热、潜热、动量与二氧化碳的地表通量； 5. 1套能量平衡鲍恩比系统（Energy Balance Bowen Ratio Systems，简称EBBR站点）：可测量感热与潜热的地表通量； 6. 由28个自记雨量计组成的观测网络。 此外，在2个站点连续测量大气辐射、土壤温度、土壤水分与热通量。在生长季，每约两周在3个站点开展冠层反射率与叶面积指数观测。连续采集的观测数据可通过ABLE官网以近实时与存档两种形式获取（Klazura等，2003）。 参考文献： Coulter, R.L., G.E. Klazura, B.M. Lesht, J.D. Shannon, D.L. Sisterson, and M.L Wesely. 1998. 利用ABLE设施观测城市化对行星边界层过程的影响，《第10届空气污染气象应用联合会议预印本》，美国亚利桑那州凤凰城，空气与废物管理协会与美国气象学会，第J76-J79页。 Klazura, G.E., D.R. Cook, R.L. Coulter, R.L. Hart, D.J. Holdridge, B.M. Lesht, J.D. Lucas, T.J. Martin, M.S. Pekour, and M.L. Wesely. 2003. 堪萨斯州中南部大气边界层观测，提交至2003年11月10日至14日于美国夏威夷火奴鲁鲁举办的第30届国际环境遥感研讨会。 LeMone, M.A., R.L. Grossman, R.L. Coulter, M.L. Wesely, G.E. Klazura, G.S. Poulos, W. Blumen, J.K. Lundquist, R.H. Cuenca, S.F. Kelly, E.A. Brandes, S.P. Oncley, R.T. McMillen, and B.B. Hicks. 2000. 堪萨斯州东南部核桃河流域的陆-气相互作用研究：早期成果与机遇——CASES与ABLE，《美国气象学会公报》，第81卷，第757-779页。 Miller, N.L., A.W. King, M.A. Miller, E.P. Springer, M.L. Wesely, K.E. Bashford, M.E. Conrad, K. Costigan, R.L. Coulter, P.N. Foster, H.K. Gibbs, J. Jin, G.E. Klazura, B.M. Lesht, M.V. Machavaram, F. Pan, J. Song, J. Stalker, D. Troyan, R.A. Washington-Allen. 2003. DOE水循环先导研究计划，提交至《美国气象学会公报》。 Poulos, G.S., W. Blumen, D.C. Fritts, J.K. Lundquist, J. Sun, S.P. Burns, C. Nappo, R. Banta, R. Newsom, J. Cuxart, E. Terradellas, B. Balsley, and M. Jensen, 2002: CASES-99：稳定夜间边界层的综合研究，《美国气象学会公报》，第83卷，第555-581页。 Wesely, M.L., R.L. Coulter, G.E. Klazura, B.M. Lesht, D.L. Sisterson, and J.D. Shannon. 1997. 堪萨斯州的行星边界层观测能力，《第一届综合观测系统研讨会预印本》，美国加利福尼亚州长滩，美国气象学会，第169-171页。