Shift in the temporal trend in b

https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2019GL082666

The knowledge regarding how the boundary layer height (BLH) changes over time is still poor. Here we analyze the spatial and temporal changes of radiosonde measurements of BLH over China from 1979 to 2016. A qualitatively robust and abrupt change of BLH occurred in 2004. Over the former period (from 1979 to 2003) a spatially uniform increase was found in the BLH, while over the latter period BLH decreased in a spatially non-uniform way. Second, the meteorological influence on the rising BLH was determined to have a negative association with soil moisture (SM), lower tropospheric stability (LTS) and relative humidity (RH), and a positive association with the near-surface temperature (Tsfc). Yet, there was a different influence of meteorology on the BLH over the latter period, where a negative association was revealed with T sfc and RH. These findings shed new light on the long-term changes in air pollution across China.

关于边界层高度(BLH)如何随时间变化的知识仍然很少。本文分析了1979-2016年中国BLH探空仪测量的时空变化。2004年，BLH发生了质的巨大而突然的变化。在前一时期(1979年至2003年)，BLH出现了空间上均匀的增长，而在后一时期，BLH出现了空间上不均匀的下降。其次，气象因素对BLH上升的影响被确定为与土壤湿度、对流层下部稳定性和相对湿度负相关，与近地表温度正相关。然而，在后一时期，气象学对BLH有不同的影响，在那里发现了与天气预报中心和相对湿度的负面联系。这些发现揭示了中国空气污染的长期变化。