scholarly journals Satellite-based study of physico-optical properties of aerosols over a westernmost location of Brahmaputra valley

2018 ◽  
Vol 3 (2) ◽  
Author(s):  
Jhuma Biswas 1
Keyword(s):  
Atmospheric Aerosols ◽  
Monsoon Season ◽  
Cloud Condensation Nuclei ◽  
Winter Season ◽  
Earth Observing System ◽  
Brahmaputra Valley ◽  
Increasing Trend ◽  
Long Term Trend ◽  
Term Analysis

This study examines the long term trend of the radiatively active atmospheric aerosols which can influence the Earth’s energy budget directly by scattering and absorbing radiation and indirectly by acting as cloud condensation nuclei. MODIS sensor on board the NASA Earth Observing System Terra and Aqua satellite based Aerosol Optical Depth (AOD) data are used for long term analysis of aerosols over Bongaigaon, Assam for the period August, 2002 to March, 2017. Highest AOD values are observed in pre-monsoon (March-May) season due to long range transportation as well as intense biomass burning activities especially as a part of Jhum cultivation. In general, AOD values are low in post-monsoon (October-November) season which may be due to wash out of aerosols by rain in the preceding months without enough replacement. The monthly AOD values vary from its highest value 0.949 in April, 2016 to its lowest value 0.107 in November, 2002 for the study period. From the comparison of MODIS Terra and Aqua AOD at 550 nm, it is clearly seen that generally Terra AOD at 10:30 hr is higher than the Aqua AOD at 13:30hr. A slowly increasing trend of both Aqua and Terra AOD at 550 nm is observed over the study location. The observed Ångström exponent value varies from its minimum value in monsoon season to its maximum value in winter season. With increasing AOD values, horizontal visibility decreases over Bongaigaon.

scholarly journals A Study of Mean RSPM And SPM Levels at Selected Sites in Assam During the Recent Decade

2016 ◽  
Vol 10 (1) ◽  
pp. 5-20
Author(s):  
Tongdi Jamir
Keyword(s):  
Air Pollution ◽  
Particulate Matter ◽  
Suspended Particulate Matter ◽  
Monsoon Season ◽  
Winter Season ◽  
Recent Decade ◽  
Brahmaputra Valley ◽  
Exponential Increase ◽  
Suspended Particulate ◽  
Increasing Trend

Abstract Air pollution is an important issue around the world. Evidence of air pollution and its impact has been well established by the scientific communities. The effects of these changes on the smaller towns in Brahmaputra valley of Assam still need to be investigated. This study concludes that Suspended Particulate Matter (SPM) and Respirable Suspended Particulate Matter (RSPM) shows increasing trend in all the seasons except during the monsoon season but significant during the winter season. The study also reveals that RSPM remained above the standards throughout the decade, unlike SPM, which rose above the standards only during the years 2006, 2008 and 2009. It is also observed that during the rainy seasons Coefficient of Variation (CV) is high in maximum numbers of stations. The study concludes that exponential increase in population; vehicular activities, rainfall and wind direction as well as geographical conditions have indirectly influenced the pollutions.

scholarly journals Biodiversity of butterflies in endosulfan-affected areas of Kerala, India

2020 ◽  
Vol 81 (1) ◽  
Author(s):  
K. N. Raghavendra ◽  
Kumar Arvind ◽  
G. K. Anushree ◽  
Tony Grace
Keyword(s):  
Monsoon Season ◽  
Winter Season ◽  
Wiener Index ◽  
Long Term Effects ◽  
Affected Area ◽  
Butterfly Assemblages ◽  
Abundance And Diversity ◽  
The One ◽  
One Way Anova

Abstract Background Butterflies are considered as bio-indicators of a healthy and diversified ecosystem. Endosulfan was sprayed indiscriminately in large plantations of Kasaragod district, Kerala which had caused serious threats to the ecosystem. In this study, we surveyed the butterflies for their abundance and diversity in three differentially endosulfan-affected areas viz., Enmakaje—highly affected area, Periye—moderately affected area, Padanakkad—unaffected area, carried out between the end of the monsoon season and the start of the winter season, lasting approximately 100 days. Seven variables viz., butterfly abundance (N), species richness (S), Simpson’s reciprocal index (D), the Shannon–Wiener index (H′), the exponential of the Shannon–Wiener index (expH′), Pielou’s evenness (J) and species evenness (D/S), related to species diversity were estimated, followed by the one-way ANOVA (F = 25.01, p < 0.001) and the Kruskal-Wallis test (H = 22.59, p < 0.001). Results A population of three different butterfly assemblages comprised of 2300 butterflies which represented 61 species were encountered. Our results showed that Enmakaje displayed significantly lower butterfly diversity and abundance, compared to the other two communities. Conclusion So far, this is the first study concerning the effect of endosulfan on the biodiversity of butterfly in the affected areas of Kasaragod, Kerala, India. This study may present an indirect assessment of the persisting effects of endosulfan in the affected areas, suggesting its long-term effects on the ecosystem.

scholarly journals Analysis of 24 years of mesopause region OH rotational temperature observations at Davis, Antarctica – Part 1: long-term trends

2020 ◽  
Vol 20 (11) ◽  
pp. 6379-6394 ◽  
Author(s):  
W. John R. French ◽  
Frank J. Mulligan ◽  
Andrew R. Klekociuk
Keyword(s):  
Solar Cycle ◽  
Rotational Temperature ◽  
Winter Season ◽  
Pressure Level ◽  
Recent Analysis ◽  
Research Station ◽  
Mesopause Region ◽  
Term Trend ◽  
Long Term Trend

Abstract. The long-term trend, solar cycle response, and residual variability in 24 years of hydroxyl nightglow rotational temperatures above Davis research station, Antarctica (68∘ S, 78∘ E) are reported. Hydroxyl rotational temperatures are a layer-weighted proxy for kinetic temperatures near 87 km altitude and have been used for many decades to monitor trends in the mesopause region in response to increasing greenhouse gas emissions. Routine observations of the OH(6-2) band P-branch emission lines using a scanning spectrometer at Davis station have been made continuously over each winter season since 1995. Significant outcomes of this most recent analysis update are the following: (a) a record-low winter-average temperature of 198.3 K is obtained for 2018 (1.7 K below previous low in 2009); (b) a long-term cooling trend of -1.2±0.51 K per decade persists, coupled with a solar cycle response of 4.3±1.02 K per 100 solar flux units; and (c) we find evidence in the residual winter mean temperatures of an oscillation on a quasi-quadrennial (QQO) timescale which is investigated in detail in Part 2 of this work. Our observations and trend analyses are compared with satellite measurements from Aura/MLS version v4.2 level-2 data over the last 14 years, and we find close agreement (a best fit to temperature anomalies) with the 0.00464 hPa pressure level values. The solar cycle response (3.4±2.3 K per 100 sfu), long-term trend (-1.3±1.2 K per decade), and underlying QQO residuals in Aura/MLS are consistent with the Davis observations. Consequently, we extend the Aura/MLS trend analysis to provide a global view of solar response and long-term trend for Southern and Northern Hemisphere winter seasons at the 0.00464 hPa pressure level to compare with other observers and models.

scholarly journals Modeling and Trend Analysis of Climatic Variables of Ranchi District, Jharkhand

2021 ◽  
Vol 8 (2) ◽  
pp. 120-128
Author(s):  
PAWAN JEET ◽  
KN SINGH ◽  
RAJEEV RANJAN KUMAR ◽  
BISHAL GURANG ◽  
AK SINGH ◽  
...  
Keyword(s):  
Minimum Temperature ◽  
Monsoon Season ◽  
Arima Model ◽  
Climatic Variables ◽  
Annual Rainfall ◽  
Annual Maximum ◽  
Rainfall Trend ◽  
Average Rainfall ◽  
Increasing Trend

In this paper, an attempt has been made to study the temporal variation in monthly, seasonal and annual rainfall, and average annual maximum and minimum temperature for the period 1901-2015 over Ranchi district of Jharkhand, India. Long-term changes in rainfall, temperature was determined by Man-Kendall rank statistics and Sen’s slope, and forecasting of time series was determined by ARIMA model. The results revealed that there was significant decrease of average rainfall in the month of February and August while increase in month May and Pre-monsoon season. Average rainfall in the month of February, May, August and Pre-monsoon season showing insignificant increasing as well as decreasing rainfall trend. The average annual maximum and minimum temperature showing decreasing and increasing trend over Ranchi district during the period 1901 to 2015. This paper also describes five-year prediction of rainfall and temperature climatic variables.

Trend and Variability Analysis of Sunshine Duration in Divisional Headquarters of Bangladesh

2021 ◽  
Vol 12 (1-2) ◽  
pp. 127-133
Author(s):  
MA Farukh ◽  
MA Islam ◽  
L Akter ◽  
R Khatun
Keyword(s):  
General Circulation ◽  
Sunshine Duration ◽  
Monsoon Season ◽  
Winter Season ◽  
Circulation Model ◽  
North East ◽  
Before And After ◽  
Post Monsoon Season ◽  
Sunshine Hour

In this study, Sunshine duration data of eight divisional headquarters of Bangladesh Meteorological Stations (Dhaka, Rangpur, Rajshahi, Mymensingh, Sylhet, Barishal, Khulna and Chattagram) were analyzed to evaluate the long-term changes and trends. The data used are the BMD data spanning from 1980 to 2010. The annual sunshine duration has decreased by the month of (June –September) from 1980 to 2010. Seasonal changes in sunshine duration were also analyzed where the maximum decline was found in rainy-monsoon season (June – September), the winter season (December – February), then the post-monsoon season (October – November) and the minimum in the pre-monsoon season (March – May). Analysis of observed data before and after 2000 represents the sunshine durations have decreasing trends in all divisional headquarters of Bangladesh except Chattagram station during the month of (January – December). General Circulation Model (GCM) defined that the maximum sunshine hour was decline north-east and south-west in all divisional headquarters of Bangladesh during the month of (June – September) and the minimum sunshine hour was decline in eastern part of the country during the month of (March – May). Environ. Sci. & Natural Resources, 12(1&2): 127-133, 2019

Interpreting the seasonal and long-term trend of nitrate in both groundwater and spring water in a typical headwater wetland with well-defined groundwater flow pathways

2016 ◽  
Vol 16 (5) ◽  
pp. 1327-1338
Author(s):  
Yingjie Cao ◽  
Changyuan Tang ◽  
Zhiwei Han ◽  
Sako Yoko ◽  
Xing Li
Keyword(s):  
Groundwater Flow ◽  
Soil Water ◽  
Residence Time ◽  
Spring Water ◽  
Hydrological Process ◽  
Term Trend ◽  
Increasing Trend ◽  
Flow Pathways ◽  
Long Term Trend

Timescale problems of nitrate behavior (i.e. seasonal variation and long-term trend) in headwater are closely related to its hydrological process. In a typical agricultural headwater catchment in the Chiba prefecture, Japan, the groundwater nitrate concentration showed an increasing trend, while for spring water, a substantial decreasing trend was observed during our monitoring period. Two key issues, (1) identification of multiple flow pathways and (2) evaluation of the residence time for different pathways, were emphasized to reveal the factors controlling the different patterns of nitrate trend. Three major flow pathways including vertical soil water flow (VF), lateral groundwater flow (LG) and deep groundwater flow (DG) along the upland-slope-valley were differentiated. Different timescales of three flow pathways were identified. The residence time of VF was calculated as 9–10 years based on the soil water budget equation and the apparent age of LG was estimated as 41 years by chlorofluorocarbon (CFC) traces. The increasing trend of NO3− in groundwater agreed well with the historical nitrate loading, and the decreasing trend of NO3− in spring was mainly influenced by nitrate behavior of LF, which substantially decreased due to reduction of nitrogen fertilizer loadings since 2000.

scholarly journals Trend Analysis of Rainfall in Prakasam District of Andhra Pradesh State in India

2020 ◽  
pp. 103-110
Author(s):  
M. Satya Swarupa Rani ◽  
R. Asha ◽  
G. M. V. Prasadarao
Keyword(s):  
Trend Analysis ◽  
Crop Production ◽  
Monsoon Season ◽  
Winter Season ◽  
Vital Role ◽  
Precipitation Trend ◽  
Large Variability ◽  
Cropping Patterns ◽  
Climate Analysis

Globally, precipitation trend analysis in different space and time has great impact on crop-planning activities. To get accurate unbiased results a long-term climate analysis of a particular area required in large variability in both spatially, temporally. For sustainable crop production long term weather analysis act as vital role in alternation of existing cropping patterns. This study aimed at analysing the trend of rainfall events in Prakasam district of Andhra state of India the data consists of annual precipitation time series from 1991-2019. Initially study concerns with analysis of data base using descriptive statistics, later trend change was detected by using non parametric tests. The results indicate an increased trend in June and monsoon season, with a decreased trend in July and winter season at 5% level of significance.

scholarly journals Mathematical Analysis Method for Stock Market Using MA and KDJ Indicator

2019 ◽  
Vol 4 (2) ◽  
pp. 21 ◽  
Author(s):  
Man Yuan
Keyword(s):  
Stock Market ◽  
Inflation Rate ◽  
Stock Exchange ◽  
Rapid Development ◽  
Short Term ◽  
Important Position ◽  
Long Term Trend ◽  
Term Analysis ◽  
Capital Transaction

With the rapid development of Economic Globalization as well as international trade and capital transaction, stock market take a more and more important position in the finance analysis.In this thesis, I combined the MA the KDJ, MA for long term trend analysis and KDJ for short term analysis. First I introduced MA and KDJ separately, their strength and weakness. Then I try to put them together, adjust the parameters to make them suitable for Shanghai Stock Exchange Composite Index.Then I use my model to simulate transaction in real world, estimate the rate of return and comparing with the stocks’ holding rate and inflation rate. The result is pleasant. At last, I give a conclusion and a further advice to this model.

scholarly journals Deep-reaching acceleration of global mean ocean circulation over the past two decades

2020 ◽  
Vol 6 (6) ◽  
pp. eaax7727 ◽  
Author(s):  
Shijian Hu ◽  
Janet Sprintall ◽  
Cong Guan ◽  
Michael J. McPhaden ◽  
Fan Wang ◽  
...  
Keyword(s):  
Kinetic Energy ◽  
Ocean Circulation ◽  
Global Climate ◽  
Circulation System ◽  
The Past ◽  
Tropical Oceans ◽  
Increasing Trend ◽  
Long Term Trend ◽  
Global Mean

Ocean circulation redistributes Earth’s energy and water masses and influences global climate. Under historical greenhouse warming, regional ocean currents show diverse tendencies, but whether there is an emerging trend of the global mean ocean circulation system is not yet clear. Here, we show a statistically significant increasing trend in the globally integrated oceanic kinetic energy since the early 1990s, indicating a substantial acceleration of global mean ocean circulation. The increasing trend in kinetic energy is particularly prominent in the global tropical oceans, reaching depths of thousands of meters. The deep-reaching acceleration of the ocean circulation is mainly induced by a planetary intensification of surface winds since the early 1990s. Although possibly influenced by wind changes associated with the onset of a negative Pacific decadal oscillation since the late 1990s, the recent acceleration is far larger than that associated with natural variability, suggesting that it is principally part of a long-term trend.

Long-term changes of precipitation in Latvia

2010 ◽  
Vol 41 (3-4) ◽  
pp. 241-252 ◽  
Author(s):  
Lita Lizuma ◽  
Agrita Briede ◽  
Maris Klavins
Keyword(s):  
Extreme Precipitation ◽  
Winter Season ◽  
Cold Season ◽  
Annual Precipitation ◽  
Precipitation Pattern ◽  
Term Trend ◽  
Positive Tendency ◽  
Extreme Precipitation Events ◽  
Long Term Trend

This study investigated long-term variability and trends in Latvia's annual, seasonal, monthly and daily precipitation using data from 10 meteorological stations for the period 1925–2006 and from station Riga University for the period 1850–2006. The obtained results indicate that during the 20th century a significant increase in precipitation has occurred in the cold season while the warm period showed a decreasing tendency. The annual precipitation totals showed a slight decrease, at half of the studied stations, due to opposite tendencies in cold season and warm season. The long-term trend in the annual precipitation in Riga (from 1850) was positive with large interannual and interdecadal variability. The extreme precipitation events were evaluated using a set of nine climate change indices. Of these, number of wet days, 1-day and 5-days maximum precipitation, moderate wet days and very wet days showed a well pronounced positive tendency in the cold period of the year particularly in winter. No overall long-term trend was detected in extreme precipitation in summer. As in the case of 150-year precipitation pattern, extreme precipitation exhibited cyclic fluctuations that were more pronounced than linear changes. The close correlation between North Atlantic oscillation (NAO) and extreme precipitation was found for winter season.

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