Trends in hail and thunderstorm in China over the past 50 years under the changing monsoon climate Qinghong Zhang 1,2, Xiang Ni 1, Fuqing Zhang 2, Mingxin Li 1,2 1 Department of Atmospheric and Oceanic Sciences, Peking University, Beijing , China 2 Department of Meteorology, The Pennsylvania State University, University Park, Pennsylvania

Changnon & Changnon （ 2000) Brooks and Dotzek 2008 Tippett et al. (2015) D>20mm Xie et. al Kim and Ni 2015 D>2mm Cao 2008 Kunz et al Trends of hail occurrence Understanding the potential effects of global-scale changes on local- scale severe weather (like hail) is a persistent challenge for research. Berthet et al.2010 Eccel et al 2011 Tuovinen et al. (2009) Schuster et al. 2005

Challenge: the stark mismatch of scale It requires novel research approaches to connect the questions and processes across both weather and climate scales

Possible bridge between hail and climate change? severe convective storm Large scale circulation change ３－ ５月 ６－ ８月 Climate change ３－５月 ６－８月 May CAPE VWS PW FLH

Objective What is the trend of convective storm frequency in China? Does the contribution of hail in severe storm day changed? How does the hail intensity changed ? Is the changes of large scale circulation do associated with the changes of severe storm and hail occurrence in China?

Methodology and Data  Datasets  983 surface station observation (weather phenomenon) thunder storm (starting and ending time) hail (starting and ending time) lightning high wind heavy precipitation the maximum diameter of hailstone (start early 1980s)  Datasets  Hail data at 859 surface stations from information center of CMA hail starting and ending time NCEP/NCAR reanalysis (1961 to 2011)

Definition  Hail or thunderstorm event (hail or thunder was record within interval less than 30 min)  Hail or thunderstorm Day (hailstorm or thunderstorm was recorded at one station)  Hail intensity: Maximum hail diameter D stations (the stations with data missing rate greater than 1% are excluded)

Spatial distribution of annual thunderstorm and hail days

Seasonal variation of 5-day annual mean hail day in China Hail seasonal variation are associated with the onset of summer monsoon

Station mean annual thunderstorm Frequency Seasonal and diurnal Variation Trend (%)

Trend of station mean thunderstorm (hail) frequency and Days from 1961 to 2011 Thunderstorm Hail

Possible density of hail intensity

Objective What is the trend of convective storm in the past? Does the contribution of hail in severe storm day changed? How does the hail intensity changed ? Is the changes of large scale circulation do associated with the changes of convective storm and hail occurrence in China?

Trend of 850 hPa circulation in warm season 1961 to 2011 GPH Meridian Wind Qv K index

Trend of large scale circulation in warm season from 1961 to 2011 CAPE CIN VWS PW

Summary-hail frequency The deduction of hail frequency and days were associated with the deduction of thunderstorm days in China from 1961 to 2011.

Summary-hail frequency The deduction of hail frequency and days were associated with the deduction of thunderstorm days in China from 1961 to VWS

Summary-hail intensity Larger hail decreased less than small hail

Further Research Number thunderstorm Aerosol Large scale circulation radiation CCN reginal climate