Guangliang Li, Licheng Feng, Wei Zhuang, Fei Liu, Ronghua Zhang, Cuijuan Sui. Differences in Spring Precipitation over Southern China associated with Multiyear La Niña Events[J]. Acta Oceanologica Sinica. doi: 10.1007/s13131-023-2147-0
Citation:
Guangliang Li, Licheng Feng, Wei Zhuang, Fei Liu, Ronghua Zhang, Cuijuan Sui. Differences in Spring Precipitation over Southern China associated with Multiyear La Niña Events[J]. Acta Oceanologica Sinica. doi: 10.1007/s13131-023-2147-0
Guangliang Li, Licheng Feng, Wei Zhuang, Fei Liu, Ronghua Zhang, Cuijuan Sui. Differences in Spring Precipitation over Southern China associated with Multiyear La Niña Events[J]. Acta Oceanologica Sinica. doi: 10.1007/s13131-023-2147-0
Citation:
Guangliang Li, Licheng Feng, Wei Zhuang, Fei Liu, Ronghua Zhang, Cuijuan Sui. Differences in Spring Precipitation over Southern China associated with Multiyear La Niña Events[J]. Acta Oceanologica Sinica. doi: 10.1007/s13131-023-2147-0
National Marine Environmental Forecasting Center, Ministry of Natural Resources, Beijing 100081, China
2.
State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University, Xiamen 361102, China
3.
Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai 519082, China
4.
School of Atmospheric Sciences Sun Yat-Sen University, Key Laboratory of Tropical Atmosphere-Ocean System Ministry of Education, Zhuhai 519082, China
5.
School of Marine Sciences, Nanjing University of Information Science and Technology, Nanjing 210044, China
Funds:
The Natural Science Foundation of China under contract Nos 41976221, 42030410 and 41576029; the National Key Research and Development Program of China under contract No. 2019YFA0606702; the Startup Foundation for Introducing Talent of NUIST
Composite analyses were performed in this study to reveal the differences in spring precipitation over southern China during multiyear La Niña events from 1901-2015. It was found that there is significantly below normal precipitation in the first boreal spring, but above normal in the second year. The differences in spring precipitation over southern China are correlative to the changes in anomalous atmospheric circulations over the northwest Pacific, which can in turn be attributed to different anomalous sea surface temperatures (SSTs) over the tropical Pacific. During multiyear La Niña events, anomalous SSTs were stronger in the first spring than those in the second spring. As a result, the intensity of abnormal cyclones (WNPC) in the western North Pacific Ocean (WNP) in the first year is stronger, which is more likely to reduce moisture transport, leading to prolonged precipitation deficits over southern China. In contrast, the tropical SST signal is too weak to induce appreciable changes in the WNPC and precipitation over South China in the second year. The difference in SST signals in two consecutive springs leads to different spatial patterns of precipitation in southern China by causing different WNPC.
Figure 1. The time evolution of the Niño3.4 index (℃) based on the HadISST dataset from 1901 to 2020. The year indicated by blue (light blue) bars at the bottom is the year 0 of the multi-year (single-year) La Niña event.
Figure 2. Time series of the Niño3.4 index (℃) from Jun (-1) to Jun (2) for 10 multiyear La Niña events (a) and 14 single-year La Niña events (b). The solid blue line is the composite time series.
Figure 3. Observed precipitation anomalies (mm month-1) during winter (a and b) and spring (c and d) of composite multiyear La Niña events. Dots indicate the areas where precipitation anomalies are statistically significant above a 90% confidence level.
Figure 4. Observed 850 hPa horizontal wind (vector, m/s), SLP (contours, hPa) and precipitation (shading, mm/month) anomalies of the 10 multiyear La Niña events. The wind anomalies ata 90% confidence level are shown in purple.
Figure 5. Vertically integrated moisture (VIM) flux (vector; kg/ [s · m]) with convergence and divergence (shading; 10-5 kg/ [s · m2]) above the 90% confidence level are shown.
Figure 6. Vertical velocity (units, 0.01 Pa/s) at 500 hPa; red regions are anomalous ascending motion and blue regions are anomalous descending motion. Dots indicate the areas where vertical velocity anomalies are statistically significant above a 90% confidence level.
Figure 7. Observed SST anomalies (shading, ℃) and wind at 850 hPa (vector, m/s) in the first and second winters (a and b) and spring (c and d) of composite multiyear La Niña events. Dots indicate the areas where SST anomalies are statistically significant above the 90% confidence level.
Figure 8. (a) Observed SST (shading in the ocean, ℃), precipitation (shading in the land, mm/month) and 850 hPa wind anomalies (vector, m/s) in spring during single-year La Niña. (b) Precipitation and WNPC index and their correlation for the first (blue dot) and second (red dot) spring of multiyear La Niña and single-year La Niña (black dot). (c) Precipitation and Niño-3.4 index and their correlation. Dots in (a) indicate the areas where SST and precipitation anomalies are statistically significant above a 90% confidence level.