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Geoscientific Model Development An interactive open-access journal of the European Geosciences Union
Geosci. Model Dev., 10, 673-688, 2017
https://doi.org/10.5194/gmd-10-673-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Development and technical paper
13 Feb 2017
Source apportionment of atmospheric water over East Asia – a source tracer study in CAM5.1
Chen Pan1,2,3,4, Bin Zhu1,2,3,4, Jinhui Gao1,2,3,4, and Hanqing Kang1,2,3,4 1Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration, Nanjing University of Information Science & Technology, Nanjing, China
2Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Nanjing University of Information Science & Technology, Nanjing, China
3Key Laboratory of Meteorological Disaster, Ministry of Education (KLME), Nanjing University of Information Science & Technology, Nanjing, China
4Joint International Research Laboratory of Climate and Environment Change (ILCEC), Nanjing University of Information Science & Technology, Nanjing, China
Abstract. The atmospheric water tracer (AWT) method is implemented in the Community Atmosphere Model version 5.1 (CAM5.1) to quantitatively identify the contributions of various source regions to precipitation and water vapour over East Asia. Compared to other source apportionment methods, the AWT method was developed based on detailed physical parameterisations, and can therefore trace the behaviour of atmospheric water substances directly and exactly. According to the simulation, the northern Indian Ocean (NIO) is the dominant oceanic moisture source region for precipitation over the Yangtze River valley (YRV) and southern China (SCN) in summer, while the north-western Pacific (NWP) dominates during other seasons. Evaporation over the South China Sea (SCS) is responsible for only 2.7–3.7 % of summer precipitation over the YRV and SCN. In addition, the Indo-China Peninsula is an important terrestrial moisture source region (annual contribution of  ∼  10 %). The overall relative contribution of each source region to the water vapour amount is similar to the corresponding contribution to precipitation over the YRV and SCN. A case study for the SCS shows that only a small part ( ≤  5.5 %) of water vapour originates from local evaporation, whereas much more water vapour is supplied by the NWP and NIO. In addition, because evaporation from the SCS represents only a small contribution to the water vapour over the YRV and SCN in summer, the SCS mainly acts as a water vapour transport pathway where moisture from the NIO and NWP meet.

Citation: Pan, C., Zhu, B., Gao, J., and Kang, H.: Source apportionment of atmospheric water over East Asia – a source tracer study in CAM5.1, Geosci. Model Dev., 10, 673-688, https://doi.org/10.5194/gmd-10-673-2017, 2017.
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Short summary
This paper describes the implementation of the atmospheric water tracer (AWT) method in the NCAR Community Atmosphere Model version 5.1 (CAM5.1). Compared to other source apportionment methods, the AWT method was developed based on detailed physical parameterisations, and can therefore trace the behaviour of atmospheric water substances directly and exactly. Using this method, we quantitatively identify the dominant sources of precipitation and water vapour over East Asia.
This paper describes the implementation of the atmospheric water tracer (AWT) method in the NCAR...
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