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We investigate the existence of Ion-Acoustic solitary/shock waves in a five component cometary plasma consisting of positively and negatively charged oxygen ions, kappa described hydrogen ions, hot electrons and cold electrons. The KPB equation is derived for the system; its solution is plotted for different kappa values, as well as for the temperature ratios of ions. It is found that the amplitude of solitary structure increases with increasing kappa values and negatively charged oxygen ion densities. As the temperature of the positively charged oxygen ions increases, the amplitude of solitary wave also increases. We have also studied the dependence of coefficients of the KPB equation on physical parameters relevant to comet Halley.

The mangrove ecosystem of Sundarbans region plays a significant ecological and socio-economic role in both India and Bangladesh. An increase in coastal human settlements makes the area more vulnerable to natural disasters such as tsunamis and cyclones. Mangroves, as an exclusive group of plants, provide many ecological services such as reducing the impacts of cyclonic storms and gales and minimizing the sea level rise due to global warming. Sundarbans were facing immense destruction due to super cyclones during the past years. The present study investigated the ecological disturbance caused by the cyclone Amphan in Indian Sundarbans using remote sensing multispectral imagery. The pre and post-cyclonic Landsat data were analyzed to quantify the damaged area in Sundarbans due to the effect of the cyclone, Amphan. Normalized Vegetation Index (NDVI) and Enhanced Vegetation Index (EVI) were used to estimate the vegetative changes or losses that occurred due to the cyclone. Normalized Difference Water Index (NDWI), Normalized Difference Bareness Index (NDBaI) and Normalized Difference Salinity Index (NDSI)) were the other indices used to study the effects of cyclone. The study found that from pre to post-cyclonic period, mangroves reduced from 1,851.88 km 2 to 1,643.74 km 2 and about 50.18 km 2 of vegetation becomes sparse. High salinity values were observed during the postcyclonic period which indicated that the super cyclone resulted in saltwater intrusion. From pre to post cyclone, NDBaI results showed an increase in barren land from 908.13 km 2 to 1,365.57 km 2 .

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