| Title | Improvement of Drag Coefficient Calculation Under Near-Neutral Conditions in Light Winds Over land |
| Authors | Liu, Changwei Li, Yubin Gao, Zhiqiu Zhang, Hongsheng Wu, Tongwen Lu, Yixiong Zhang, Xiaoye |
| Affiliation | Sun Yat Sen Univ, Sch Atmospher Sci, Zhuhai, Peoples R China Southern Marine Sci & Engn Guangdong Lab Zhuhai, Zhuhai, Peoples R China Nanjing Univ Informat Sci & Technol, Sch Atmospher Phys, Collaborat Innovat Ctr Forecast & Evaluat Meteoro, Nanjing, Peoples R China Chinese Acad Sci, Inst Atmospher Phys, State Key Lab Atmospher Boundary Layer Phys & Atm, Beijing, Peoples R China Peking Univ, Sch Phys, Dept Atmospher Sci, Beijing, Peoples R China China Meteorol Adm, Beijing Climate Ctr, Beijing, Peoples R China Chinese Acad Meteorol Sci, China Meteorol Adm, Beijing, Peoples R China |
| Keywords | TURBULENT FLUXES SURFACE FLUXES HEAT/MASS TRANSFER PARAMETERIZATION LAYER HEAT MODEL SIMILARITY VELOCITY EXCHANGE |
| Issue Date | 27-Dec-2020 |
| Publisher | JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES |
| Abstract | By analyzing the data collected over a rice paddy field in China, the occurrence of large drag coefficient in light winds (U <= 1ms(-1)) under near-neutral conditions (-0.1 <= z/L <= 0.1) is analyzed in this study. It is found that, with the use of either vector- or scalar-averaged wind speed, the drag coefficient under near-neutral conditions (C-DN) always increases with the decrease of wind speed. Such behavior of C-DN cannot be interpreted by the change of aerodynamic roughness length z(0) because it would need to be enlarged by an order of magnitude. While in light winds, the nonlocal transport, which is caused by large-scale eddies and overlooked by traditional Monin-Obukhov Similarity theory, is found to be the main cause of increased C-DN. At last, a fixing term related to nonlocal effects is proposed based on our observation, and its applicability is verified with two AmeriFlux observation sites with a landscape of forest and savanna, respectively. |
| URI | http://hdl.handle.net/20.500.11897/603118 |
| ISSN | 2169-897X |
| DOI | 10.1029/2020JD033472 |
| Indexed | SCI(E) |
| Appears in Collections: | 物理学院 |
