Global Urban Heat Island (UHI) Data Set, 2013

The Urban Heat Island (UHI) effect represents the relatively higher temperatures found in urban areas compared to surrounding rural areas owing to higher proportions of impervious surfaces and the release of waste heat from vehicles and heating and cooling systems. Paved surfaces and built structures tend to absorb shortwave radiation from the sun and release long-wave radiation after a lag of a few hours. The Global Urban Heat Island (UHI) Data Set, 2013, estimates the land surface temperature within urban areas in degrees Celsius (average summer daytime maximum and average summer nighttime minimum) as well as the difference between those temperatures and the temperatures in surrounding rural areas, defined as a 10km buffer around the urban extent. Urban extents are from SEDAC�s Global Rural-Urban Mapping Project, Version 1 (GRUMPv1), and land surface temperatures are from SEDAC�s Global Summer Land Surface Temperature (LST) Grids, 2013, which are derived from the Aqua Level-3 Moderate Resolution Imaging Spectroradiometer (MODIS) Version 5 global daytime and nighttime Land Surface Temperature (LST) 8-day composite data (MYD11A2). For most regions, the UHI data set provides the average daytime maximum (1:30 p.m. overpass) and average nighttime minimum (1:30 a.m. overpass) temperatures in urban and rural areas, and the urban-rural temperature differences, derived from LST data representing a 40-day time-span during July-August (Julian days 185-224) in the northern hemisphere and January-February (Julian days 001-040) in the southern hemisphere. LST grid cells with missing values resulting from high cloud cover in tropical regions were filled with daytime maximum and nighttime minimum LST values from April-May 2013 in the northern hemisphere and December 2013-January 2014 in the southern hemisphere, where available. Some data gaps remain in areas where data were insufficient (e.g., Central Africa).

城市热岛效应（UHI）指的是城市区域相对于周边农村区域所表现出的相对较高温度，这一现象归因于不透水表面的高比例以及车辆排放的废热以及供暖和冷却系统的释放。铺装表面和建筑结构倾向于吸收来自太阳的短波辐射，并在数小时之后释放长波辐射。全球城市热岛（UHI）数据集（2013年版）估算城市区域内的地表温度（以摄氏度为单位，包括夏季白天最高平均温度和夏季夜间最低平均温度），以及这些温度与周边农村区域温度之间的差异，该差异被定义为环绕城市范围的10公里缓冲区。城市范围数据来源于SEDAC的全球农村-城市映射项目第1版（GRUMPv1），而地表温度数据则来源于SEDAC的全球夏季地表温度（LST）网格，2013年版，这些数据由Aqua级3中分辨率成像光谱仪（MODIS）第5版全球白天和夜间地表温度（LST）8天复合数据（MYD11A2）衍生而来。对于大多数地区，UHI数据集提供了城市和农村区域的平均白天最高温度（下午1:30过境）和平均夜间最低温度（凌晨1:30过境），以及城市与农村之间的温度差异，这些温度差异由代表7月和8月（北半球儒略日185-224）和1月和2月（南半球儒略日001-040）的LST数据得出。在热带地区由于高云层覆盖导致缺失值的LST网格单元，在北半球用2013年4月至5月的白天最高和夜间最低LST值进行填补，在南半球则用2013年12月至2014年1月的相应值进行填补，如有可用。一些数据缺口仍然存在于数据不足的区域（例如，中非地区）。