scholarly journals Distribution of precipitable water contents over Indian monsoon region

MAUSAM ◽  
2021 ◽  
Vol 58 (2) ◽  
pp. 241-250
Author(s):  
V. R. DURAI ◽  
S. K. ROY BHOWMIK ◽  
H. R. HATWAR
Keyword(s):  
Large Scale ◽  
Indian Monsoon ◽  
Weather Prediction ◽  
India Meteorological Department ◽  
Precipitable Water ◽  
Southwest Monsoon ◽  
Rainfall Events ◽  
Time Availability ◽  
Heavy Rainfall Events ◽  
Water Contents

This paper investigates the spatial distribution of precipitable water contents over Indian region for the southwest monsoon 2005. The precipitable water contents are derived from the objective analysis field of operational Numerical Weather Prediction system of India Meteorological Department. The study shows that the distribution of PWC is capable to capture large scale features of monsoon precipitation system. Real-time availability of this product is expected to be useful in monitoring and prediction of heavy rainfall events.

Heavy Rainfall Events over Central Oahu under Weak Wind Conditions during Seasonal Transitions

2020 ◽  
Vol 148 (10) ◽  
pp. 4117-4141
Author(s):  
Feng Hsiao ◽  
Yi-Leng Chen ◽  
David Eugene Hitzl
Keyword(s):  
Mixed Layer ◽  
Land Surface ◽  
Heavy Rainfall ◽  
Large Scale ◽  
Subsequent Development ◽  
Precipitable Water ◽  
Trade Wind ◽  
Heavy Rainfall Event ◽  
Rainfall Events ◽  
Heavy Rainfall Events

AbstractShort-lived afternoon heavy rainfall events may form over central Oahu during seasonal transition periods (June and October) under favorable large-scale settings. These include a deep moist layer with relatively high precipitable water (>40 mm), blocking pattern in midlatitudes with a northeast–southwest moist tongue from low latitudes ahead of an upper-level trough, absence of a trade wind inversion, and weak (<3 m s−1) low-level winds. Our high-resolution (1.5 km) model results show that immediately before the storm initiation, daytime land surface heating deepens the mixed layer over central Oahu and the top of the mixed layer reaches the lifting condensation level. Meanwhile, the development of onshore/sea-breeze flows, driven by land–sea thermal contrast, brings in moist maritime air over the island interior. Finally, convergence of onshore flows over central Oahu provides the localized lifting required for the release of instability. Based on synoptic and observational analyses, nowcasting with a lead time of 2–3 h ahead of this type of event is possible. In the absence of orographic effects after removing model topography, processes that lead to heavy rainfall are largely unchanged, and subsequent development of heavy showers over central Oahu are still simulated. However, when surface heat and moisture fluxes are turned off, convective cells are not simulated in the area. These results indicate that daytime heating is crucial for the development of this type of heavy rainfall event under favorable large-scale settings.

scholarly journals Sensitivity of Simulations of Zambian Heavy Rainfall Events to the Atmospheric Boundary Layer Schemes

Climate ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 38
Author(s):  
Mary-Jane M. Bopape ◽  
David Waitolo ◽  
Robert S. Plant ◽  
Elelwani Phaduli ◽  
Edson Nkonde ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Heavy Rainfall ◽  
Large Scale ◽  
Weather Forecasting ◽  
Weather Prediction ◽  
Wrf Model ◽  
Extreme Rainfall ◽  
Maximum Temperature ◽  
Rainfall Events ◽  
Heavy Rainfall Events

Weather forecasting relies on the use of numerical weather prediction (NWP) models, whose resolution is informed by the available computational resources. The models resolve large scale processes, while subgrid processes are parametrized. One of the processes that is parametrized is turbulence which is represented in planetary boundary layer (PBL) schemes. In this study, we evaluate the sensitivity of heavy rainfall events over Zambia to four different PBL schemes in the Weather Research and Forecasting (WRF) model using a parent domain with a 9 km grid length and a 3 km grid spacing child domain. The four PBL schemes are the Yonsei University (YSU), nonlocal first-order medium-range forecasting (MRF), University of Washington (UW) and Mellor–Yamada–Nakanishi–Niino (MYNN) schemes. Simulations were done for three case studies of extreme rainfall on 17 December 2016, 21 January 2017 and 17 April 2019. The use of YSU produced the highest rainfall peaks across all three cases; however, it produced performance statistics similar to UW that are higher than those of the two other schemes. These statistics are not maintained when adjusted for random hits, indicating that the extra events are mainly random rather than being skillfully placed. UW simulated the lowest PBL height, while MRF produced the highest PBL height, but this was not matched by the temperature simulation. The YSU and MYNN PBL heights were intermediate at the time of the peak; however, MYNN is associated with a slower decay and higher PBL heights at night. WRF underestimated the maximum temperature during all cases and for all PBL schemes, with a larger bias in the MYNN scheme. We support further use of the YSU scheme, which is the scheme selected for the tropical suite in WRF. The different simulations were in some respects more similar to one another than to the available observations. Satellite rainfall estimates and the ERA5 reanalysis showed different rainfall distributions, which indicates a need for more ground observations to assist with studies like this one.

scholarly journals Extreme Floods in the Eastern Part of Europe: Large-Scale Drivers and Associated Impacts

Water ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1122
Author(s):  
Monica Ionita ◽  
Viorica Nagavciuc
Keyword(s):  
Water Vapor ◽  
Heavy Rainfall ◽  
Large Scale ◽  
Vapor Transport ◽  
Water Vapor Transport ◽  
Flood Events ◽  
Rainfall Events ◽  
Catchment Areas ◽  
Large Scale Atmospheric Circulation ◽  
Heavy Rainfall Events

The role of the large-scale atmospheric circulation in producing heavy rainfall events and floods in the eastern part of Europe, with a special focus on the Siret and Prut catchment areas (Romania), is analyzed in this study. Moreover, a detailed analysis of the socio-economic impacts of the most extreme flood events (e.g., July 2008, June–July 2010, and June 2020) is given. Analysis of the largest flood events indicates that the flood peaks have been preceded up to 6 days in advance by intrusions of high Potential Vorticity (PV) anomalies toward the southeastern part of Europe, persistent cut-off lows over the analyzed region, and increased water vapor transport over the catchment areas of Siret and Prut Rivers. The vertically integrated water vapor transport prior to the flood peak exceeds 300 kg m−1 s−1, leading to heavy rainfall events. We also show that the implementation of the Flood Management Plan in Romania had positive results during the 2020 flood event compared with the other flood events, when the authorities took several precaution measurements that mitigated in a better way the socio-economic impact and risks of the flood event. The results presented in this study offer new insights regarding the importance of large-scale atmospheric circulation and water vapor transport as drivers of extreme flooding in the eastern part of Europe and could lead to a better flood forecast and flood risk management.

scholarly journals Mesoscale Analysis of Heavy Rainfall Episodes from SoWMEX/TiMREX

2012 ◽  
Vol 69 (2) ◽  
pp. 521-537 ◽  
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.

scholarly journals An attempt to deal with flash floods using a probabilistic hydrological nowcasting chain: a case study

2013 ◽  
Vol 1 (6) ◽  
pp. 7497-7515 ◽  
Author(s):  
F. Silvestro ◽  
N. Rebora ◽  
G. Cummings
Keyword(s):  
Large Scale ◽  
Weather Prediction ◽  
Precipitable Water ◽  
Flash Floods ◽  
Medium Size ◽  
Small Areas ◽  
Anticipation Time ◽  
Prediction Systems ◽  
Meteorological Models

Abstract. The forecast of flash floods is sometimes impossible. In the last two decades, Numerical Weather Prediction Systems have become increasingly reliable with very relevant improvements in terms of quantitative precipitation forecasts. However, some types of events, those that are intense and localized in small areas, are still very difficult to predict. In many cases meteorological models fail to predict the volume of precipitable water at the large scale. Despite the application of modern probabilistic chains that uses precipitation downscaling algorithms in order to forecast the streamflow, some significant flood events remain unpredicted. This was also the case with an event which occurred on 8 and 9 June 2011 in the eastern part of the Liguria Region, Italy. This event affected in particular the Entella basin, which is quite a small watershed that flows into the Mediterranean Sea. The application of a hydrological nowcasting chain as a tool for predicting flash-floods in small and medium size basins with an anticipation time of a few hours (2–5) is here presented. This work investigated the "behaviour" of the chain in the cited event and how it could be exploited for operational purposes. The results in this particular case were encouraging.

scholarly journals Study of rainfall features over Goa state during southwest monsoon season

MAUSAM ◽  
2021 ◽  
Vol 61 (2) ◽  
pp. 155-162
Author(s):  
S. M. METRI ◽  
KHUSHVIR SINGH
Keyword(s):  
Heavy Rainfall ◽  
Monsoon Season ◽  
Southwest Monsoon ◽  
Annual Rainfall ◽  
Statistical Parameters ◽  
Maximum Rainfall ◽  
Rainfall Events ◽  
Average Rainfall ◽  
Southwest Monsoon Season ◽  
Heavy Rainfall Events

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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