这是个棘手的问题,它将每年都不同,但我们可以缩小它与一些假设我可以给一个答案。假设将:1。都沉淀在海将成为液体接触的海面,将被认为是下雨。2。降水在南极洲在全球范围内是可以忽略的。第二个是相当合理:看看全球降水分布卫星数据的时代([引用][1])。[![在这里输入图像描述][2]][2],这些假设,我们只需要计算大量的固体沉淀在陆地上(南极洲以外)和从全球总数减去它。我们可以使用提供的数据(全球降水气候学中心)[3],提供全球平均降水在陆地上:[![在这里输入图像描述][4]][4]和液体沉淀在陆地上的分数:[![在这里输入图像描述][5]][5]我在ASCII格式,下载这两个数据集和计算液态降水的平均比例是74.1%,但我们不能使用这个值,因为它可能会强烈影响地区的降水。 So if we compute a cell by cell total SOLID precipitation per year, and multiply that for the surface of a 1°x 1° cell (considering the effects of latitude), we get a total of solid precipitation for 2016 of 1.5e13 m³. So with the additional assumption that 2016 was a representative year. **That will take your total precipitation of 5.1e14 m³ per year to 5.0e14 m³ per year of RAIN only.** Perhaps we should have expected that there is not much of a difference given that most of the rainfall happen on the sea (The total precipitation on land for 2016 was 1.1e14 m³). Now if you want to consider snowfall over the sea, I don't know of a model with such output product. Therefore, you can make a simple model or make some assumptions to use Sea Surface Temperature to figure out if precipitation will turn to rain at some high above the surface. But again, if you look at the map of global distribution of precipitation, the fraction coming from latitudes at which you could expect sea surface snow is rather small, so the correction coming from snowfall over the sea is likely to be a pretty small one too. [1]: https://link.springer.com/article/10.1007/s10712-017-9416-4 [2]: https://i.stack.imgur.com/YrxH7.png [3]: https://kunden.dwd.de/GPCC/Visualizer [4]: https://i.stack.imgur.com/cYjV6.png [5]: https://i.stack.imgur.com/XWWGs.png