气象参数

从中国气象数据网上下载了一些数据，发现一些数没有意义。查询了下，记录如下:

      a.32700：little precipitation
      b.32766：missing data
      c.32744：no data
      e.31XXX：snowfall(XXX: snow mass)
      f.32XXX：fog and dew(XXX: mass)
      g.30XXX：sleet (rain and snow fall)(XXX: mass)
      h. If the elevation > 50000, the elevation value is not accurate. 
      The appreximate value = evevation - 50000