Interannual variations in spring lightning activity and convective rainfall over South China during the TRMM era
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ORIGINAL PAPER
Interannual variations in spring lightning activity and convective rainfall over South China during the TRMM era Jiangyu Mao 1,2
&
Majun Li 1,2
Received: 6 February 2020 / Accepted: 8 July 2020 # Springer-Verlag GmbH Austria, part of Springer Nature 2020
Abstract The interannual variability of spring lightning activity over South China (SC) and its driving mechanism are examined using the Tropical Rainfall Measuring Mission (TRMM) satellite-estimated convective rain rate and merged lightning flash rate datasets together with atmospheric and oceanic reanalysis products over the TRMM period (1998–2014). SC is climatologically characterized by high lightning flash densities, strong convective rainfall, and large convective available potential energy (CAPE) during spring. The spring SC lightning activity (SCLA) has a strong year-to-year variability, and the standard deviation of flash rates shows a spatially coherent annular distribution centered over the Pearl River Delta. The interannual variations of spring SCLA are not only highly correlated with those of convective rainfall and CAPE, but also significantly correlated with El Niño– Southern Oscillation (ENSO). The anomalously frequent SCLA tends to follow El Niño events, while infrequent SCLA preferentially follows La Niña events. Composite analyses demonstrate that during spring for the more frequent SCLA cases, the upper tropospheric atmospheric response to El Niño-related sea surface temperature anomaly (SSTA) patterns leads to strong southwesterlies over SC in conjunction with tropical westerlies over the tropical Indian Ocean, forming a divergent environment over SC. The upper-level divergence is coupled with low-level moisture convergence, generating strong mid-tropospheric updrafts to lift more air parcels to reach their level of free convection, thereby producing stronger convection with frequent SCLA. In contrast, the anomalous circulation forced by La Niña-related SSTA patterns is conducive to suppressed convection over SC and infrequent SCLA.
1 Introduction Thunderstorms are a type of locally severe convective weather that is generally produced by cumulonimbus clouds and always accompanied by lightning with strong gusts of wind, heavy rainfall, and sometimes hail (Williams et al. 2000; Zipser et al. 2006). Thunderstorms can significantly disrupt socioeconomic development (Zhang et al. 2011; Dowdy and Mills 2012), and lightning strikes can directly result in loss of life, damage to infrastructure, and wildfires, especially over densely populated and economically developed regions (Holle 2008; Zhang et al. 2011; Dowdy 2016). Therefore, investigating the temporal variation and related mechanisms
* Jiangyu Mao [email protected] 1
LASG, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
2
University of Chinese Academy of Sciences, Beijing 100049, China
of regional lightning activity together with convective rainfall is of great importance for better lightning protection to efficiently prevent and re
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