Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Time series of averaged PM2.5, VC and WS in Tianjin (a), radiation and the length of 48-h air mass backward trajectory (b), surface temperature and relative humidity (c) for the five HEs observed at NKU supersite. The hourly air mass trajectories were colored with their corresponding clusters (Fig. S6, cluster 1: SW, cluster 2: N, cluster 3: NE, and cluster 4: NW).
