Acta Geographica Sinica ›› 2023, Vol. 78 ›› Issue (5): 1176-1191.doi: 10.11821/dlxb202305008

• Plateau Ecosystems and Vegetation Studies • Previous Articles     Next Articles

Significant linkage of Arctic Oscillation to vegetation net primary productivity over Indo-Myanmar in winter

LAN Yunfei1,2,3(), GONG Daoyi1,2,3(), MENG Meng1,2,3   

  1. 1. Academy of Disaster Risk Science, Faculty of Geographical Science, Beijing Normal University, Beijing 100875, China
    2. Key Laboratory of Environmental Change and Natural Disaster, Ministry of Education, Beijing Normal University, Beijing 100875, China
    3. State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, Beijing 100875, China
  • Received:2022-10-10 Revised:2023-05-08 Online:2023-05-25 Published:2023-05-27
  • Contact: GONG Daoyi E-mail:17393157392@163.com;gdy@bnu.edu.cn
  • Supported by:
    National Key R&D Program of China(2020YFA0608201);National Natural Science Foundation of China(41775068)

Abstract:

The connection between Arctic Oscillation (AO) and net primary productivity (NPP) of vegetation in the Indo-Myanmar region during the period from 1981 to 2018 was quantitatively analyzed using regression analysis, composite analysis, and other methods based on AO index, vegetation NPP, and meteorological data. The results revealed that: (1) There is a significant in-phase relationship between winter AO and NPP in the Indo-Myanmar region, with a regional average NPP increasing (decreasing) significantly by 6.50 gC·m-2, and the maximum increment (decrement) reaching 20.60 gC·m-2 corresponding to a one standard deviation increase (decrease) of winter AO index. The correlation coefficient between AO and NPP time series reaches 0.57. (2) The AO primarily affects the atmospheric circulation over the Indo-Myanmar region through wave propagation, which in turn impacts precipitation and ultimately leads to abnormal NPP. During the positive (negative) phase of AO, a Rossby wave propagates eastward along the subtropical jet, resulting in anomalous cyclonic (anticyclonic) circulation in the mid-lower troposphere over the Bay of Bengal-Indo-Myanmar region. This tends to strengthen (weaken) the South-Branch Trough, which in turn enhances (weakens) the southwestward moisture transport and ascending motion ahead of the trough, both of which favor above-normal (below-normal) precipitation in the Indo-Myanmar region. With a one standard deviation increase (decrease) in the winter AO index, precipitation from five datasets significantly increases, with ERA5 and GPCC datasets showing a significant increase (decrease) of more than 12 mm at higher resolutions. The precipitation of anomalously positive AO years minus its negative ones can exceed 90 mm, and all of the correlation coefficients between the regional average precipitation and the AO index reach more than 0.50 (p < 0.01). Accompanied by a 1 mm increase (decrease) in precipitation, the NPP increase (decrease) exceeds 10.10 gC·m-2, and the correlation coefficients of the two time series exceed 0.40 (p <0.01).

Key words: vegetation NPP, Arctic Oscillation, Indo-Myanmar, precipitation anomaly, winter