We investigate the spatial and temporal variability of extreme precipitation events (EPEs) in the Dronning Maud Land (DML) sector of Antarctica using high-resolution ECMWF ERA5 reanalysis data. This study examines the spatial occurrence of EPEs across DML, focusing particularly on six locations spanning the coastal and interior parts of the area. The largest snowfall amounts are usually found on eastward-facing slopes in the coastal zone. EPEs occur predominantly in north-easterly to easterly flows, leading to enhanced precipitation on the windward side of the orographic features with a steep gradient. Wind during EPEs was found to be more directionally consistent in the coastal area than in the interior. An east-west couplet of a mid-tropospheric ridge and low-pressure center is essential for steering warm moist maritime airmasses into the DML region before EPEs. Approximately 40% of EPEs result from atmospheric rivers (ARs), narrow bands of moist air originating at subtropical latitudes, which provide the greatest daily precipitation amounts. From 1979 to 2018, much of the DML experienced a statistically significant (p < 0.05) increase in the number of EPEs per year, along with increased precipitation from the EPEs. These trends were associated with significant changes in moisture availability and poleward meridional winds in the Atlantic sector of the Southern Ocean. The inter-annual variability in the number of EPEs is primarily dictated by regional atmospheric variability, while the influence of the Southern Oscillation Index and Southern Annular Mode is limited.
Using the Two‐Dimensional Video Disdrometer measurements, we investigated the fall velocity of raindrops at Mahabaleshwar (17.92°N, 73.6°E, ~1.4 km above mean sea level, AMSL), a tropical site on the Western Ghats of India. The analysis is for different seasons during 2012–2015. To increase the reliability and accuracy of analysis, the raindrops with diameters in the range 0.5–2 mm and horizontal wind speed < 2 m s−1 are considered. The observed raindrop fall velocities have been corrected for the effect of air density. The ratio between the observed velocity and calculated terminal velocity is considered for estimating superterminal (positively skewed; higher than terminal velocity) and subterminal (negatively skewed; lower than terminal velocity) raindrops. The distribution of these skewed raindrops and its relationship with rain rate, drop diameter, and axis ratio for different seasons has been examined. Results indicate the presence of superterminal and subterminal raindrops in definite proportion in all the season with a majority of the drops have a diameter less than 1 mm. It is found that most of the superterminal raindrops occur at rain rates below 5 mm hr−1, while subterminal raindrops are relatively higher above this rain rate. It is observed that the superterminal raindrops are usually small in size and prolate in shape, while the subterminal raindrops are relatively large and oblate in shape. The diurnal variation of these raindrops during different seasons is also studied.
BM's Systems Network Architecture (SNA) peer-to-peer communication, called Low Entry Networking (LEN), will introduce many benefits along with a number of chal-I lenges in managing an SNA network. Prior to LEN, all host communications were hierarchical. LEN allows nodes like Personal Computers (PCs), AS400, and host applications to communicate with each other through the subarea network as peers. LEN nodes can enable cooperative processing, initiate parallel and multiple sessions simultaneously, require less predefinition, and use a common LU6.2 interface. LEN management will need to deal with the challenges of decentralized processing, changes to management definitions, and dynamic session initiation. This article will cover these challenges as they impact network management in an IBM subarea network. Research was conducted in the The Travelers' Network to determine impacts in the areas of installation, session management, problem determination, accounting, and performance.
Wireless sensor networks are considered to be a promising area to equip scientists with the capability of developing real-time monitoring systems. This paper discusses the design and development of a wireless sensor network (WSN) that can be used for monitoring purposes in the agricultural fields. This battery-powered sensor node makes the network deployment easy but limit the lifetime of the network to the limited capacity of these batteries. The main source of energy wastage in modern sensor networks is idle listening and overhearing. Duty cycling is a proven mechanism to overcome the energy wastage through idle listening. In this paper we introduce a new MAC protocol named as REMAC that minimizes the idle listening by allowing nodes to remain in sleep state until it is necessary to wakeup. It also allows the participating nodes to wake up during the sleep time, perform the data transfer and return to sleep state thereby minimizing the chances for over hearing. We show the performance of REMAC through detailed simulations in NS-2 and also compare the performance evaluation with similar synchronous protocols that employ duty cycling. In the analysis REMAC proves to be saving much energy as compared to others.
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