Abstract. Extreme precipitation (EP) is a major external agent driving various natural hazards in the Loess Plateau (LP), China. Yet, the characteristics of spatiotemporal EP responsible for such hazardous situations remain poorly understood. We integrate universal multifractals with a segmentation algorithm to characterize a physically meaningful threshold for EP (EPT). Using daily data from 1961 to 2015, we investigate the spatiotemporal variation of EP over the LP. Our results indicate that EPTs range from 17.3 to 50.3 mm/d while the mean annual EP increases from 35 to 138 mm from northwest to southeast LP. Further, EP frequency (EPF) has historically spatially varied from 54–116 days, with the highest EPF occurring in the mid-southern and southeastern LP where precipitation is much more abundant. However, EP intensities tend to be strongest in the central LP where precipitation also tends to be scare, and get progressively weaker as we move towards the margins (similarly with EP severity). An examination of atmosphere circulation patterns indicates that the central LP is the boundary where tropical cyclones reach furthest into inland China, resulting in the highest EP intensities and EP severities being in this area. Under the control of the East Asian monsoon, precipitation from June to September accounts for 72 % of the total amount, while 91 % of the total EP events are concentrated in June to August. Further, EP events occur, on average, 11 days earlier than the wettest part of the season. These phenomena are responsible for the most serious natural hazards in the LP, especially in the Central region. Spatiotemporally, 91.4 % of the LP has experienced a downward trend of precipitation, while 62.1 % of the area has experienced upward trends of the EP indices, indicating the potential risk of more serious hazardous situations.
A tornado occurred in northern parts of Delhi at 1805 IST on 17 March 1978 lasting for about three minutes. It caused death of 28 persons and injuries to 700 others. Damage to property was estimated to be more than Rupees 10 million. The study gives an account of the details of the areas affected and the synoptic situation resulting in its occurrence. The tornado is classified as F2 P2 P2 of Fujita Pearson (FPP) Tornado scale (Fujita 1973).
The unusually heavy rain which occurred in New Delhi and parts of Haryana and of the plains of west Uttar Pradesh on 30 June 1981 has been studied in this paper. Rohtak, Agra and New Delhi (Palam) recorded 30, 26and22cmofrain respectively during the 24hours ending at 0830 I.S.T. on 30 June 1981. New Delhi (Safdarjung) recorded 19 cm. The heavy rainfall has been associated with availability of moisture in abundance over and near these areas as deduced from the analysis of radiosonde ascents taken at New Delhi, Patiala, Gwalior, Jodhpur and Lucknow. The trigger for the vertical motion was provided by the low level convergence associated with the seasonal trough which was well-marked and whose axis on sea level chart passed through Amritsar, Delhi, Lucknow and Gaya on 29 June.
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