The cold-humid effect of perennially flooded marshes on clear days in the Sanjiang Plain of Northeast China----中国科学院东北地理与农业生态研究所

Understanding the micro-climate of a marsh ecosystem helps elucidate the functional and biogeochemical processes of the ecosystem. This study combines field measurements and 2-D atmospheric models to investigate the characteristics of air temperature and relative humidity at the surface of a perennially flooded marsh. We found that the marsh air temperature was lower and the relative humidity was higher than the surrounding farmlands, which reflects the significant cold-humid effect of marshes. With increasing distance from the marsh, the cold-humid effect became weaker. The daily variation of air temperature and relative humidity between the marsh and farmlands was similar, with the biggest difference occurring between 12:00 and 14:00 (local standard time) at a height of 0.5 m above ground. The seasonal variation of the cold-humid effect was clear and most significant in July. The numerical model was effective at simulating the profiles of potential temperature and specific humidity under 1000 m over marsh area. The simulated potential temperature was more accurate than the specific humidity.