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Title: Factors affecting relative humidity and its relationship with the long-term variation of fog-haze events in the Yangtze River Delta

Abstract

Relative humidity (RH) is one of the most important parameters in the study of fog-haze. This paper first estimates the contributions of the key quantities (temperature, water vapor, air pollutant) and their combinations to the relative change of RH, and then investigates the relationships of RH with the long-term variation of haze and fog days based on the meteorological data in the Yangtze River Delta over the period 1970-2010.The main conclusions are as follows. (1) Temperature is the foremost factor influencing RH, with the effect of specific humidity and direct contribution of air pollutant being second and third. (2) RH shows a prominent descending trend in the Yangtze River Delta, due to global warming and the ‘analogous heat island effect’ (AHIE). (3) Decreasing RH was responsible for the reduction of fog days. The AHIE can explain the phenomenon in which fog days in metropolises are less than in small cities. (4) Granger causality analysis of inter-annual variation further shows that increasing aerosol loading Ganger-causes the increasing haze days, rather than meteorological parameters such as RH. High RH would enhance hygroscopic growth of particle and then suppress the planet boundary layer height (PBLH) and lead to more haze days, lower PBLHmore » further increases aerosols and RH, this positive feedback mechanism can be established under the condition of aerosol loading being relatively stable and beyond the threshold for haze formation. (5) If aerosol emissions maintain the status quo, climate cooling would result in serious fog-haze events occurring more frequently in Yangtze River Delta. The research provide a scientific basis for understanding the influence of meteorological factors on RH and the connection between the variation of long term fog-haze days and RH under the background of climate change.« less

Authors:
 [1];  [1];  [1];  [2];  [3]
  1. Nanjing Univ. of Information Science and Technology (China)
  2. Jiangsu Meteorological Observatory, Nanjing (China)
  3. Brookhaven National Lab. (BNL), Upton, NY (United States)
Publication Date:
Research Org.:
Brookhaven National Lab. (BNL), Upton, NY (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
OSTI Identifier:
1473634
Report Number(s):
BNL-209058-2018-JAAM
Journal ID: ISSN 1352-2310
Grant/Contract Number:  
SC0012704
Resource Type:
Accepted Manuscript
Journal Name:
Atmospheric Environment (1994)
Additional Journal Information:
Journal Name: Atmospheric Environment (1994); Journal Volume: 193; Journal Issue: C; Journal ID: ISSN 1352-2310
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES

Citation Formats

Liu, Weijia, Han, Yongxiang, Li, Jiaxin, Tian, Xinru, and Liu, Yangang. Factors affecting relative humidity and its relationship with the long-term variation of fog-haze events in the Yangtze River Delta. United States: N. p., 2018. Web. doi:10.1016/j.atmosenv.2018.09.015.
Liu, Weijia, Han, Yongxiang, Li, Jiaxin, Tian, Xinru, & Liu, Yangang. Factors affecting relative humidity and its relationship with the long-term variation of fog-haze events in the Yangtze River Delta. United States. doi:10.1016/j.atmosenv.2018.09.015.
Liu, Weijia, Han, Yongxiang, Li, Jiaxin, Tian, Xinru, and Liu, Yangang. Wed . "Factors affecting relative humidity and its relationship with the long-term variation of fog-haze events in the Yangtze River Delta". United States. doi:10.1016/j.atmosenv.2018.09.015. https://www.osti.gov/servlets/purl/1473634.
@article{osti_1473634,
title = {Factors affecting relative humidity and its relationship with the long-term variation of fog-haze events in the Yangtze River Delta},
author = {Liu, Weijia and Han, Yongxiang and Li, Jiaxin and Tian, Xinru and Liu, Yangang},
abstractNote = {Relative humidity (RH) is one of the most important parameters in the study of fog-haze. This paper first estimates the contributions of the key quantities (temperature, water vapor, air pollutant) and their combinations to the relative change of RH, and then investigates the relationships of RH with the long-term variation of haze and fog days based on the meteorological data in the Yangtze River Delta over the period 1970-2010.The main conclusions are as follows. (1) Temperature is the foremost factor influencing RH, with the effect of specific humidity and direct contribution of air pollutant being second and third. (2) RH shows a prominent descending trend in the Yangtze River Delta, due to global warming and the ‘analogous heat island effect’ (AHIE). (3) Decreasing RH was responsible for the reduction of fog days. The AHIE can explain the phenomenon in which fog days in metropolises are less than in small cities. (4) Granger causality analysis of inter-annual variation further shows that increasing aerosol loading Ganger-causes the increasing haze days, rather than meteorological parameters such as RH. High RH would enhance hygroscopic growth of particle and then suppress the planet boundary layer height (PBLH) and lead to more haze days, lower PBLH further increases aerosols and RH, this positive feedback mechanism can be established under the condition of aerosol loading being relatively stable and beyond the threshold for haze formation. (5) If aerosol emissions maintain the status quo, climate cooling would result in serious fog-haze events occurring more frequently in Yangtze River Delta. The research provide a scientific basis for understanding the influence of meteorological factors on RH and the connection between the variation of long term fog-haze days and RH under the background of climate change.},
doi = {10.1016/j.atmosenv.2018.09.015},
journal = {Atmospheric Environment (1994)},
number = C,
volume = 193,
place = {United States},
year = {2018},
month = {9}
}

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