Historical Sunshine and Cloud Data in the United States (revised 1991) (NDP-021)

This data base presents monthly sunshine data from 240 U.S. stations (including Puerto Rico and nine Pacific Islands) and monthly cloud amount data from 197 U.S. stations. The longest periods of record are 1891 through 1987 for the sunshine data and 1871 through 1987 for the cloud data. The sunshine data were derived from measurements taken by a variety of sunshine-recording instruments. The cloud data were derived from land-based estimates of fractional cloud amount, which were made with observation practices that have varied during the period of record. Station number, station name, latitude, and longitude are given for all stations in each network. The sunshine data include monthly and annual total hours of recorded sunshine, monthly and annual maximum possible hours of sunshine, monthly and annual percentages of possible sunshine (hours recorded/hours possible), and dates of use for specific types of sunshine recorders at each station. The cloud data contain monthly and annual cloud amount (in percent of sky cover).

本数据库收录了美国240个气象站（含波多黎各及9个太平洋岛屿）的月日照数据，以及197个美国气象站的月云量数据。日照数据的最长记录周期为1891年至1987年，云量数据的最长记录周期则为1871年至1987年。日照数据源自多种日照记录仪的实测记录。云量数据来源于陆基观测估算的天空云量占比，且观测方法在记录周期内曾发生调整。两类观测网络的所有台站均提供台站编号、台站名称、纬度与经度信息。日照数据涵盖月度及年度累计实测日照时长、月度及年度理论最大可能日照时长、月度及年度日照百分率（实测日照时长与理论最大可能日照时长的比值），以及各台站所使用的特定类型日照记录仪的启用日期。云量数据则包含月度及年度云量（以天空覆盖率百分比为单位）。