Evapotranspiration at Starkey pasture site, 30-minute data, Pasco County, Florida, January 2010 - April 2016

The data set consists of 30-minute evapotranspiration measurements made at the USGS Starkey pasture climate station beginning January 1, 2010 and ending April 30, 2016. Annual evapotranspiration rates corrected to a near-surface energy-budget for the 12 calendar years of record at this site (2004-2015) varied from 718 millimeters (2007) to 903 millimeters (2010). The eddy-covariance method was used, with high-frequency sensors installed above the pasture to measure sensible and latent heat fluxes. Ancillary meteorological data are also included in the data set: net radiation, soil temperature and moisture, air temperature, relative humidity, wind speed and direction, rainfall, and ground-water levels. Data were collected at 30-minute resolution, with evapotranspiration corrected to the near-surface energy-budget at that timescale. Related data sets are presented at daily and monthly time intervals. The study was conducted at a nearly flat, non-irrigated site (Latitude 28 13 31” North Longitude 82 33 33 West in degrees minutes seconds, NAD 1927, Section 13, Township 26S, Range 17E) within the Anclote River Ranch property owned by the Southwest Florida Water Management District in Pasco County, Florida. The site was also within J.B. Starkey Wilderness Park. Instrumentation was installed in April 2003. The dominant (about 80 percent of surface coverage) plant cover at the study site is bahiagrass (Paspalum notatum) that varies from a lush green during the summer to a drab brown during the winter. The bahiagrass is ungrazed and grass height can reach 0.5 meter. During the study, the pasture was mowed periodically to 0.2 meters. Vegetation tables provided with the data release list when mowing occurred. Maximum grass rooting depth at the site is about 0.5 meters. Other plants at the study site, intermixed with the bahiagrass and occurring as distinct patches, include bushy broom grass (Andropogon glomeratus), rush (Juncus spp.), dog fennel (Eupatorium capillifolium), flat-topped goldenrod (Euthamia minor), and groundsel tree (Baccharis halimifolia). Forested wetlands are present on the margins of Sandy Branch, a tributary to the Anclote River southwest of the site, and a small cypress dome (40 meter diameter) is located east of the site. The effects of these forested areas are assumed to be negligible, as the pasture area extends 175 meters away from the site in all directions and satisfies upwind fetch requirements for the height of the eddy covariance sensors (more than 100 times the final height of 1.5 meters). The soils at the site are Pomona fine sands with less than 5 percent organic content. For the 13 years of record at this site, the water table was always within 2 meters of land surface.

本数据集收录了2010年1月1日至2016年4月30日期间，美国地质调查局（U.S. Geological Survey, USGS）斯塔基牧场气候站获取的30分钟分辨率蒸散量实测数据。该站点2004-2015年共12个完整日历年的近地表能量平衡校正后年蒸散速率介于718毫米（2007年）至903毫米（2010年）之间。研究采用涡度相关法（eddy-covariance method），在牧场上方布设高频传感器以测定感热通量与潜热通量。数据集同时包含配套辅助气象数据，具体包括净辐射、土壤温度与含水量、气温、相对湿度、风速与风向、降雨量以及地下水位。所有数据均以30分钟为时间分辨率采集，蒸散量已在该时间尺度下完成近地表能量平衡校正。相关数据集以日度、月度时间间隔发布。本研究场地位于佛罗里达州帕斯科县西南佛罗里达水资源管理区所属的安克洛特河牧场地块内，同时毗邻J.B.斯塔基荒野公园；场地近乎平坦且未进行灌溉，地理坐标为北纬28°13′31″、西经82°33′33″（采用北美大地坐标系1927，NAD 1927，第13分区，26S乡，17E排）。观测仪器于2003年4月完成布设。研究区域地表覆盖的优势物种为巴哈伊草（Paspalum notatum），占比约80%，其外观随季节变化：夏季为鲜绿色，冬季则呈枯黄色。该牧场未进行放牧，天然草高可达0.5米；研究期间会定期将草地修剪至0.2米，本次数据发布附带的植被表格记录了所有修剪作业的时间。该区域草地的最大根深约为0.5米。与巴哈伊草混生或呈斑块状分布的其他植物包括：簇毛须芒草（Andropogon glomeratus）、灯芯草属（Juncus spp.）、狗茴香（Eupatorium capillifolium）、平顶一枝黄花（Euthamia minor）以及千里光树（Baccharis halimifolia）。场地西南侧的安克洛特河支流Sandy Branch沿岸分布有森林湿地，场地东侧还存在一处直径约40米的小型柏木沼泽。考虑到研究区域牧场范围在各方向均延伸至距测点175米以外，且满足涡度相关传感器（最终安装高度1.5米）所需的上风侧风区要求（风区长度超过传感器高度的100倍），因此上述森林湿地对观测的影响可忽略不计。该区域土壤为波莫纳细砂，有机质含量低于5%。2003-2015年共13年的观测记录显示，该站点地下水位始终距地表不足2米。