Applications of satellite imageries for prediction of severe weather events along Maitri, Antarctica

The present paper is an attempt to educate the weather forecaster at Indian Scientific research Station, Maitri, Antarctica in forecasting severe weather (blizzards) using satellite images of various satellites operating in the world. The Polar stationary satellite ‘Trianna’ has been discussed .The availability of the various types of images has also been spelt. The characteristics of satellite images has been described along with overlaying of Automatic Weather station (AWS) data explaining the occurrence of Katabatic winds which also causes blizzards. Blizzard conditions often develop on the northwest side of an intense storm system the difference between the lower pressure in the storm and the higher pressure to the west creates a tight pressure gradient, which in turn results in very strong winds or blizzards. The paper also discusses about the development that took place in Antarctic satellite meteorology since beginning.

Numerical experiments for improvement in mesoscale simulation of Orissa super cyclone

& 29 vDrwcj] 1999 dks mM+hlk ds rV ij vk;k egkpØokr mM+hlk ds vc rd ds bfrgkl dk lcls izpaM rwQku Fkk ftldh 250 fd-eh- izfr ?kaVk dh rhoz xfr okyh iouksa us jkT; ds 12 rVh; ftyksa dks rgl&ugl dj MkykA rwQku ds LFky ls Vdjkus ds i'pkr~ 36 ?kaVs ls Hkh vf/kd le; rd iouksa dh izpaMrk cuh jghA bl rwQku ls tku eky dk dkQh uqdlku gqvkA yxHkx 10]000 yksxksa dh tkusa xbZA bl v/;;u esa rwQku ds eslksLdsy izfr:Ik dks csgrj cukus ds fy, dqN egRoiw.kZ igyqvksa dh tk¡p gsrq O;kid la[;kRed iz;ksx fd, x, gSaA bu igyqvksa esa xSj nzoLFkSfrd xfrd] fun’kZ {kSfrt foHksnu vkSj egRoiw.kZ izR;{k izfØ;kvksa ds izkpyhdj.k 'kkfey gSaA rwQku dk 5 fnolh; izfr:Ik ¼123 ?kaVksa ds yxkrkj lekdyu½ rS;kj djus ds fy, eslksLdsy fun’kZ ,e- ,e- 5 dk mi;ksx fd;k x;k gSA blesa le:ih foHksnu ¼30 fd-eh-½ vkSj le:ih le; J`a[kyk ds lkFk nzoLFkSfrd ¼,p-,l-½ rFkk xSj nzoLFkSfrd ¼,u- ,l-½ xfrdksa ds lg;ksx ls rwQku ds izfr:i esa xSj nzoLFkSfrdrk ds izHkko dh tk¡p dh xbZ gSA bl fof/k ls rwQku vkSj fo’ks"k :Ik ls bldh rhozrk dk xSj nzoLFkSfrd xfrdksa ds lkFk lgh izfr:i.k gksrk gSA xSj nzoLFkSfrd xfrdksa ds lkFk 90 fd-eh-] 60 fd-eh- vkSj 30 fd-eh- ds foHksnuksa ij rwQku dk izfr:i.k djrs gq, fun’kZ dh laof/kZr {kSfrt foHksnu dh egRrk dh tk¡p dh xbZ gS vkSj rwQku ds izfr:i.k esa bldk izR;{k izHkko ns[kk x;k gSA egRoiw.kZ izR;{k izfØ;k okys diklh laogu xzgh; ifjlhek Lrj ¼ih- ch- ,y-½ vkSj fofdj.k gsrq fun’kZ esa miyC/k izkpyhÑr ;kstukvksa ds csgrj lEHkkO; leUo; dk irk yxkus ds fy, la[;kRed iz;ksx Hkh fd, x,A lh- lh- ,e- 2 fofdj.k izkpyhÑr ;kstuk lesr xzsy diklh laogu vkSj gk¡x&isu ih- ch- ,y- ;kstuk ds lkFk leUo;u okyh ;kstuk ds vU; ijhf{kr ;kstukvksa dh rqyuk esa lcls csgrj ifj.kkeksa dk irk pyk gSA The super cyclone that crossed Orissa coast on 29 October 1999 was the most intense storm in the history of Orissa with 12 coastal districts of the state were battered by winds reaching 250 kmph. The fury of winds continued for more than 36 hours after landfall of the storm. The storm caused huge damage to properties and nearly 10,000 people lost their lives. In the present study, extensive numerical experiments are conducted to investigate some important aspects that may lead to the improvement in mesoscale simulation of the storm. The aspects that are addressed here include non-hydrostatic dynamics, model horizontal resolution and parameterization of important physical processes. The mesoscale model MM5 is used to produce 5-day simulation of the storm. The influence of non-hydrostaticity is investigated by simulating the storm with hydrostatic (HS) and non-hydrostatic (NS) dynamics at same resolution (30 km) and with same time step. The storm, in particular its intensity is better simulated with non-hydrostatic dynamics. The importance of increasing model horizontal resolution is investigated by simulating the storm at 90 km, 60 km and 30 km resolutions with non-hydrostatic dynamics and found to have perceptible impact in simulation of the storm. Numerical experiments also are conducted to find the best possible combination of the parameterization schemes available in the model for the important physical processes cumulus convection, planetary boundary layer (PBL) and radiation. The combination of Grell cumulus convection and Hong-Pan PBL scheme along with CCM2 radiation parameterization scheme is found to provide the best result compared to the other schemes tested.

Traditional and novel time-series approaches reveal submarine groundwater discharge dynamics under baseline and extreme event conditions

Groundwater is a vital resource for humans and groundwater dependent ecosystems. Coastal aquifers and submarine groundwater discharge (SGD), both influenced by terrestrial and marine forces, are increasingly affected by climate variations and sea-level rise. Despite this, coastal groundwater resources and discharge are frequently poorly constrained, limiting our understanding of aquifer responses to external forces. We apply traditional and novel time-series approaches using an SGD dataset of previously unpublished resolution and duration, to analyze the dependencies between precipitation, groundwater level, and SGD at a model site (Kīholo Bay, Hawaiʻi). Our objectives include (1) determining the relative contribution of SGD drivers over tidal and seasonal periods, (2) establishing temporal relationships and thresholds of processes influencing SGD, and (3) evaluating the impacts of anomalous events, such as tropical storms, on SGD. This analysis reveals, for example, that precipitation is only a dominant influence during wet periods, and otherwise tides and waves dictate the dynamics of SGD. It also provides time lags between intense storm events and higher SGD rates, as well as thresholds for precipitation, wave height and tides affecting SGD. Overall, we demonstrate an approach for modeling a hydrological system while elucidating coastal aquifer and SGD response in unprecedented detail.

An Efficient GPU Implementation of a Coupled Overland-Sewer Hydraulic Model with Pollutant Transport

Numerical simulation of flows that consider interaction between overland and drainage networks has become a practical tool to prevent and mitigate flood situations in urban environments, especially when dealing with intense storm events, where the limited capacity of the sewer systems can be a trigger for flooding. Additionally, in order to prevent any kind of pollutant dispersion through the drainage network, it is very interesting to have a certain monitorization or control over the quality of the water that flows in both domains. In this sense, the addition of a pollutant transport component to both surface and sewer hydraulic models would benefit the global analysis of the combined water flow. On the other hand, when considering a realistic large domain with complex topography or streets structure, a fine spatial discretization is mandatory. Hence the number of grid cells is usually very large and, therefore, it is necessary to use parallelization techniques for the calculation, the use of Graphic Processing Units (GPU) being one of the most efficient due to the leveraging of thousands of processors within a single device. In this work, an efficient GPU-based 2D shallow water flow solver (RiverFlow2D-GPU) is fully coupled with EPA’s Storm Water Management Model (SWMM). Both models are able to develop a transient water quality analysis taking into account several pollutants. The coupled model, referred to as RiverFlow2D-GPU UD (Urban Drainge) is applied to three real-world cases, covering the most common hydraulic situations in urban hydrology/hydraulics. A UK Environmental Agency test case is used as model validation, showing a good agreement between RiverFlow2D-GPU UD and the rest of the numerical models considered. The efficiency of the model is proven in two more complex domains, leading to a >100x faster simulations compared with the traditional CPU computation.

Coastal Boulder Dynamics Inferred from Multi-Temporal Satellite Imagery, Geological and Meteorological Investigations in Southern Apulia, Italy

Boulder dynamics may provide essential data for coastal evolution and hazards assessment and can be focused as a proxy for the onshore effect of intense storm waves. In this work, detailed observations of currently available satellite imagery of the Earth surface allowed us to identify several coastal boulders displacements in the Southern Apulia coast (Italy) for a period between July 2018 and June 2020. Field surveys confirmed the displacements of several dozens of boulders up to several meters in size, and allowed us to identify the initial position for many of them. Two possible causative storms were identified analysing archive weather maps, and calculations based on analytical equations were found in agreement with the displacement by storm waves for most of the observed boulders. The results help to provide insights about the onshore effect of storm waves on the coastal hydrodynamics and the possible future flooding hazard in the studied coast.

The Relevance of Grated Inlets within Surface Drainage Systems in the Field of Urban Flood Resilience. A Review of Several Experimental and Numerical Simulation Approaches

Urban drainage networks should be designed and operated preferably under open channel flow conditions without flux return, backwater, or overflows. In the case of extreme storm events, urban pluvial flooding is generated by the excess of surface runoff that could not be conveyed by pressurized sewer pipes, due to its limited capacity or, many times, due to the poor efficiency of surface drainage systems to collect uncontrolled overland flow. Generally, the hydraulic design of sewer systems is addressed more for underground networks, neglecting the surface drainage system, although inadequate inlet spacings and locations can cause dangerous flooding with relevant socio-economic impacts and the interruption of critical services and urban activities. Several experimental and numerical studies carried out at the Technical University of Catalonia (UPC) and other research institutions demonstrated that the hydraulic efficiency of inlets can be very low under critical conditions (e.g., high circulating overland flow on steep areas). In these cases, the hydraulic efficiency of conventional grated inlets and continuous transverse elements can be around 10–20%. Their hydraulic capacity, expressed in terms of discharge coefficients, shows the same criticism with values quite far from those that are usually used in several project practice phases. The grate clogging phenomenon and more intense storm events produced by climate change could further reduce the inlets’ performance. In this context, in order to improve the flood urban resilience of our cities, the relevance of the hydraulic behavior of surface drainage systems is clear.

Coastal Boulder Dynamics Inferred from Multi-Temporal Satellite Imagery, Geological and Meteorological Investigations in Southern Apulia, Italy

Boulder dynamics may provide essential data for the coastal evolution and hazards assessment and can be focused as a proxy for the onshore effect of intense storm waves. In this work, detailed observations of currently available satellite imagery of the Earth surface allowed to identify several coastal boulders displacements in the Southern Apulia coast (Italy), in a period between July 2018 and June 2020. Field surveys confirmed the displacements of several dozens of boulders up to several meters in size, also allowing the determination of the initial position for many of them. Archive weather analyses identified two possible causative storms during the same period, and calculations based on analytical equations are found in agreement with the displacement by storm waves for most of the observed boulders. The results help to give insights about the onshore effect of high storm waves on the coastal hydrodynamics and the possible future flooding hazard in the studied coast.

Performance Evaluation of a Nowcasting Modelling Chain Operatively Employed in Very Small Catchments in the Mediterranean Environment for Civil Protection Purposes

The Hydro-Meteorological Centre (CMI) of the Environmental Protection Agency of Liguria Region, Italy, is in charge of the hydrometeorological forecast and the in-event monitoring for the region. This region counts numerous small and very small basins, known for their high sensitivity to intense storm events, characterised by low predictability. Therefore, at the CMI, a radar-based nowcasting modelling chain called the Small Basins Model Chain, tailored to such basins, is employed as a monitoring tool for civil protection purposes. The aim of this study is to evaluate the performance of this model chain, in terms of: (1) correct forecast, false alarm and missed alarm rates, based on both observed and simulated discharge threshold exceedances and observed impacts of rainfall events encountered in the region; (2) warning times respect to discharge threshold exceedances. The Small Basins Model Chain is proven to be an effective tool for flood nowcasting and helpful for civil protection operators during the monitoring phase of hydrometeorological events, detecting with good accuracy the location of intense storms, thanks to the radar technology, and the occurrence of flash floods.

Cyclone Tauktae Documents a Climate Trend in the Tropics

The western Indian Ocean has been warming at a rate faster than any other region in the tropical oceans, a pattern that is contributing to more frequent and intense storm activity.

Lightning environment in the vicinity of the CN tower during major storms

Based on the North American Lightning Detection Network data and the return-stroke currents recorded at the CN Tower, the lightning environment within 100 km from the CN Tower is thoroughly investigated, especially while the tower was struck with major storms in 2011 and 2005. On Aug 24, 2011, video records showed that the tower was struck with 52 flashes within about 84 minutes, pointing out to the most intense storm that has ever been observed at the tower. During this most intense storm, the tower’s current measurement system recorded 32 flashes, containing 161 return strokes, resulting in an average flash multiplicity of 5, which is 80% higher than the average multiplicity of flashes occurring in the vicinity of the tower. Since the tower is repeatedly hit by lightning and its flashes produce markedly higher number of strokes, then it definitely poses an electromagnetic interference risk to nearby sensitive installations, including those in downtown Toronto.