Skill of operational forecast of heavy rainfall events during southwest monsoon season over India

In this paper the rainfall features at different raingauge stations of Goa state have been studied for the period of 30 years. The statistical parameters such as mean monthly rainfall, Standard Deviation and Coefficient of Variation have been computed for each raingauge station of Goa. Some heavy rainfall events during the period have also been studied. The study shows the significant rising trend of rainfall towards the eastern parts of Goa. Goa experiences an average rainfall of about 330 cm annually and around 90% of annual rainfall occurs during southwest monsoon season i.e. (June to September). Studies revealed that most of heavy rainfall events caused due to active off-shore trough and low pressure systems formed over southeast Arabian Sea. It has also come out from the study that the orography of Goa plays an important role in rainfall distribution. Valpoi receives maximum rainfall due to its orographic effect.

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Mesoscale Analysis of Heavy Rainfall Episodes from SoWMEX/TiMREX

Journal of the Atmospheric Sciences ◽

10.1175/jas-d-11-0120.1 ◽

2012 ◽

Vol 69 (2) ◽

pp. 521-537 ◽

Cited By ~ 33

Author(s):

Christopher A. Davis ◽

Wen-Chau Lee

Keyword(s):

Heavy Rainfall ◽

Southwest Monsoon ◽

Rainfall Events ◽

Mesoscale Analysis ◽

Mesoscale Structure ◽

Profound Influence ◽

Moist Condition ◽

Virtual Temperature ◽

Convection Initiation ◽

Heavy Rainfall Events

Abstract The authors analyze the mesoscale structure accompanying two multiday periods of heavy rainfall during the Southwest Monsoon Experiment and the Terrain-Induced Mesoscale Rainfall Experiment conducted over and near Taiwan during May and June 2008. Each period is about 5–6 days long with episodic heavy rainfall events within. These events are shown to correspond primarily to periods when well-defined frontal boundaries are established near the coast. The boundaries are typically 1 km deep or less and feature contrasts of virtual temperature of only 2°–3°C. Yet, owing to the extremely moist condition of the upstream conditionally unstable air, these boundaries appear to exert a profound influence on convection initiation or intensification near the coast. Furthermore, the boundaries, once established, are long lived, possibly reinforced through cool downdrafts and prolonged by the absence of diurnal heating over land in generally cloudy conditions. These boundaries are linked phenomenologically with coastal fronts that occur at higher latitudes.

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Spatiotemporal patterns of synchronous heavy rainfall events in East Asia during the Baiu season

10.5194/egusphere-egu21-3062 ◽

2021 ◽

Author(s):

Frederik Wolf ◽

Ugur Ozturk ◽

Kevin Cheung ◽

Reik V. Donner

Keyword(s):

System Dynamics ◽

East Asia ◽

Heavy Rainfall ◽

Spatial Organization ◽

Monsoon Season ◽

Spatiotemporal Patterns ◽

Extreme Weather Events ◽

Earth System ◽

Rainfall Events ◽

Heavy Rainfall Events

Investigating the synchrony and interdependency of heavy rainfall occurrences is crucial to understand the underlying physical mechanisms and reduce physical and economic damages by improved forecasting strategies. In this context, studies utilizing functional network representations have recently contributed to significant advances in the understanding and prediction of extreme weather events.To thoroughly expand on previous works employing the latter framework to the East Asian Summer Monsoon (EASM) system, we focus here on changes in the spatial organization of synchronous heavy precipitation events across the monsoon season (April to August) by studying the temporal evolution of corresponding network characteristics in terms of a sliding window approach. Specifically, we utilize functional climate networks together with event coincidence analysis for identifying and characterizing synchronous activity from daily rainfall estimates with a spatial resolution of 0.25&#176; between 1998 and 2018. Our results demonstrate that the formation of the Baiu front as a main feature of the EASM is reflected by a double-band structure of synchronous heavy rainfall with two centers north and south of the front. Although the two separated bands are strongly related to either low- or high-level winds which are commonly assumed to be independent, we provide evidence that it is rather their mutual interconnectivity that changes during the different phases of the EASM season in a characteristic way.Our findings shed some new light on the interplay between tropical and extratropical factors controlling the EASM intraseasonal evolution, which could potentially help improving future forecasts of the Baiu onset in different regions of East Asia.&#160;Further details: F. Wolf, U. Ozturk, K. Cheung, R.V. Donner: Spatiotemporal patterns of synchronous heavy rainfall events in East Asia during the Baiu season. Earth System Dynamics (in review). Discussion Paper: Earth System Dynamics Discussions, (2020)

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