Latitudinal variation in vertical distribution of meteor decay time and its relation with mesospheric Ozone in the altitude range of 80-90 km

115-124Investigations on meteor trail decay time and its evolution in the mesosphere and lower thermosphere are very important to estimate the temperature in this region. The present study focuses on the vertical distribution of meteor decay times at three different latitudes to understand the mechanism responsible for the deviation of meteor decay time from the theoretical estimations below 90 km of altitude. The present study is based on measurements from three identical meteor radars located at equatorial (Kototabang: 0.2° S, 100.3° E), low (Thumba: 8.5° N, 76.9° E) and polar latitudes (Eureka: 80.0° N, 85.8° W). The results reveal a pronounced seasonal variation of vertical distribution of meteor decay time turning altitude (inflection point) over polar latitudes as compared to that over equatorial and low latitudes. Apart from direct estimations from meteor radar observations, the meteor decay time is estimated using temperature and pressure measurements from the SABER/TIMED. Above 90 km of altitude, decay times estimated from both methods are in good agreement. However, below 90 km of altitude, these estimations start deviating and it has been noted that the deviation increases with decreasing altitude. Further, observed meteor decay times correlated with ozone concentration at three representative altitude bins. The correlation analysis reveals a significant negative correlation at 80 - 90 km of altitude over the three latitudes indicating that an increase in ozone concentration results in decrease in meteor decay time. The significance of the present results lies in analyzing the vertical distribution of meteor decay time simultaneously from three radar locations representing equatorial, low and polar latitudes and evaluating the relation between ozone concentration and meteor decay time, quantitatively

Rare occurrence of sunfish Mola mola (Linnaeus) from the coastal waters off Visakhapatnam (Bay of Bengal)

The occurrence of sunfish in any sea is a rare event. It is so rare that even fishermen engaged in fishing throughout their lives find it totally strange when they come across one. On 6 May, 1986, a local fisherman reported to the Zoology Department of the Andhra University that a very strange looking fish was part of that day's catch

Distributed collaboration for event detection in wireless sensor networks

With the advancement of technology in micro-electronics and wireless communication, small miniature devices called sensor nodes can be used to perform various tasks by form-ing themselves in to wireless sensor networks. In Wireless Sensor Networks(WSN), event detection is one of the main requirements for most of the applications. An event can be a simple event or a combination of two or more sim-ple events (Composite Event). Detecting and reporting an event desired by the application (user) inspite of stringent constraints of sensor nodes like low energy, low bandwidth, frequent failures etc., is one of the main challenges in WSN. This can be achieved with less uncertainty and masking fail-ures by considering collaboration among sensor nodes. We propose a framework for distributed event detection using collaboration in WSN. The framework consists of two pro-tocols that build a tree by using a communication model similar to the Publish-Subscribe paradigm. This framework is a part of Component Oriented Middleware for Sensor networks (COMiS). In COMiS framework, components are loaded as and when required based on the application se-mantics. If collaboration is considered, the goal of the ap-plication can be easily accomplished even in case of failures of sensors and low energy of nodes

Low latitude E-region irregularities studied using Gadanki radar, ionosonde and in situ measured electron density

In this paper, we attempt to identify the driving forces responsible for the generation of low-latitude E-region field-aligned irregularities (FAIs). It is evident that the low-latitude E-region FAIs occur both during the day and night with preferential occurrence being most during local sunrise period. Simultaneous measurements are made with Gadanki radar and nearby located Ionosonde for understanding the low-latitude Es-FAIs relationship. The observations suggest that the occurrence and SNR of FAIs have a close relationship with f<SUB>t</SUB>E<SUB>s</SUB>-f<SUB>b</SUB>E<SUB>s</SUB>. Finally, using the past electron density profiles and reasonable values of electric field, we have shown that it is generally difficult with the gradient drift instability to explain low-latitude E-region FAIs when electric field alone is considered as driving agency. We hypothesize that neutral winds play important role for the generation of irregularities at low latitudes outside the electrojet belt either by forming sharp Es layers or by enhancing the differential drift of electrons and ions or by both

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Not AvailableThe occurrence of sunfish in any sea is a rare event. It is so rare that even fishermen engaged in fishing throughout their lives find it totally strange when they come across one. On 6 May, 1986, a local fisherman reported to the Zoology Department of the Andhra University that a very strange looking fish was part of that day's catch.Not Availabl