Oil slicks and spills HOLAS 3

The pressure oil slicks and spills is combination of following datasets: Illegal oil discharges (2016-2021): Value of spills (VOLUME) under OR EQUAL 1km2 was directly given to grid cell. If the spill area > 1km2, a buffer with the area was added (circular buffer based on estimated radius) and the estimated volume of the spill was divided by the spill area to get the estimated amount of oil / km2. This value was given to the entire spill area. If oil spill volume was missing, mean of values was given. If area of spill was missing (103/560), mean of values was given. If the spill was < or = 1km2, the value of spill volume was given directly to 1km2 grid cell. If the spill area was > 1km2, the estimated volume of the spill was divided by the spill area to get the estimated amount of oil / km2. This value was given to the entire spill area. Layer was log transformed and normalized. Polluting ship accidents (2016-2020): Point, spill volume (m3) converted directly to 1 x 1 km grid A mean of reported volumes was given to accidents with missing oil volume. Spill volume in m3 was given directly to 1km2 grid cell. Layer was log transformed and normalized. Layers were separately normalised. After that, layers were summed and again normalised to produce the final pressure value between 0 and 1.本溢油膜与溢油压力数据集由以下数据集组合而成： 非法船舶排油（2016-2021年）： 当溢油体积（VOLUME）对应的溢油面积小于或等于1平方千米时，直接将该体积值赋值至对应网格单元（grid cell）。若溢油面积大于1平方千米，则以估算半径构建圆形缓冲区（circular buffer）以覆盖该溢油区域，将估算溢油体积除以溢油面积，得到单位平方千米的溢油量估算值，并将该值赋值至整个溢油区域。若溢油体积缺失，则采用所有有效体积的均值进行填充；若溢油面积缺失（共103/560条记录），则采用有效数据的均值进行填充。若溢油面积小于或等于1平方千米，直接将溢油体积值赋值至1平方千米网格单元；若溢油面积大于1平方千米，则将估算溢油体积除以溢油面积得到单位平方千米溢油量估算值，并将该值赋值至整个溢油区域。该图层经对数变换（log transformed）与归一化（normalized）处理。 污染性船舶事故（2016-2020年）： 以点要素形式记录的溢油体积（单位：立方米）直接赋值至1×1平方千米网格单元；对于溢油体积缺失的事故，采用已报告体积的均值进行填充。将溢油体积（立方米）直接赋值至1平方千米网格单元，该图层经对数变换与归一化处理。 各图层分别进行归一化处理，随后将各图层叠加求和，再次进行归一化以得到取值介于0至1之间的最终压力值。