scholarly journals Analysis of the Response of Long-Term Vegetation Dynamics to Climate Variability Using the Pruned Exact Linear Time (PELT) Method and Disturbance Lag Model (DLM) Based on Remote Sensing Data: A Case Study in Guangdong Province (China)

2021 ◽  
Vol 13 (10) ◽  
pp. 1873
Author(s):  
Sai Wang ◽  
Fenglei Fan
Keyword(s):  
Relative Humidity ◽  
Surface Runoff ◽  
Climatic Factors ◽  
Linear Time ◽  
Sunshine Duration ◽  
Time Lag ◽  
Vegetation Coverage ◽  
Lag Model ◽  
Vegetation Activities

The dynamic change and spatial–temporal distribution of vegetation coverage are of great significance for regional ecological evolution, especially in the subtropics and tropics. Identifying the heterogeneity in vegetation activities and its response to climate factors is crucial for projecting ecosystem dynamics. We used long-term (2001–2018) satellite-derived enhanced vegetation index (EVI) datasets and climatic factors to analyze the spatiotemporal patterns of vegetation activities in an experimental area in Guangdong Province (China), as well as their links to changes in temperature (TEM), relative humidity (HUM), precipitation (PRE), sunshine duration (SUN), and surface runoff. The pruned exact linear time change point detection method (PELT) and the disturbance lag model (DLM) were used to understand the detailed ecological coverage status and time lag relationships between the EVI and climatic factors. The results indicate the following. (1) At the whole regional scale, a significant overall upward trend in the EVI variation was observed in 2001–2018. More specifically, there were two distinct periods with different trends, which were split by a turning point in 2005. PRE was the main climate-related driver of the rising EVI pre-2005, and the increase in TEM was the main climate factor influencing the forest EVI variation post-2006. (2) A three-month time lag effect was observed in the EVI response to relative humidity. The same phenomenon was found in the sunshine duration factor. (3) The EVI of farmlands (one type of land use) exhibited the largest lags between relative humidity and the sunshine duration factor, followed by grasslands and forests. (4) The comprehensive index of surface runoff could explain the time lags of vegetation activities, and the surface runoff value showed an apparently negative relationship with the vegetation coverage change.

scholarly journals Long-term trends in solar radiation and the associated climatic factors over China for 1961-2000

2005 ◽  
Vol 23 (7) ◽  
pp. 2425-2432 ◽  
Author(s):  
F. Liang ◽  
X. A. Xia
Keyword(s):  
Solar Radiation ◽  
Climatic Factors ◽  
Sunshine Duration ◽  
Cloud Amount ◽  
Atmospheric Composition ◽  
Abrupt Decrease ◽  
Radiative Processes ◽  
Aerosol Loading ◽  
Long Term Trends

Abstract. Long-term trends in downwelling solar irradiance and associated climatic factors over China are studied in the paper. Decreasing trends in global and direct radiation are observed over much of China. The largest decrease occurs in South and East China (east of about 100° E and south of about 40° N). The spatial pattern of observed trends in diffuse irradiance is complex and inhomogeneous. An intriguing aspect of trends in global and direct irradiance is the rather abrupt decrease in annual and seasonal mean values from 1978 onward. The decreasing trends in solar radiation in China did not persist into the 1990s. The spatial and temporal patterns of trends in sunshine duration are consistent with that of global and direct irradiance. A decreasing trend in rainy days is observed over much of China, which is in agreement with the secular trend in cloud amount. The fact that trends in cloud amount and solar radiation are quite similar suggests that the cloud amount is not the primary cause for the decrease in solar radiation. Visibility in the eastern part of China has deteriorated heavily as a result of the rapid increase in aerosol loading. The statistical analysis showed that atmospheric transmission under clear conditions decreased rapidly. These facts suggest that the rapid increase in aerosol loading should be one of the principle causes for the decrease in solar radiation. The observed diurnal temperature range decreases remarkably in China, which is closely related to the increase in aerosols. The effects of anthropogenic air pollutants on climate should be further studied and included in the simulation of climate and projection of climate scenario. Keywords. Atmospheric composition and structure (Aerosol and particles; General or miscellaneous) – Meteorology and atmospheric dynamics (Radiative processes)

scholarly journals VEGETATION CHANGES AND THE RELATIONSHIP WITH CLIMATE VARIABILITY IN THE UPPER AND MIDDLE REACHES OF THE NENJIANG RIVER BASIN, CHINA

2016 ◽  
Vol XLI-B8 ◽  
pp. 889-895
Author(s):  
F. Huang ◽  
D. H. Wen ◽  
P. Wang
Keyword(s):  
Relative Humidity ◽  
River Basin ◽  
Wind Velocity ◽  
Land Surface ◽  
Sunshine Duration ◽  
Meteorological Data ◽  
Vegetation Coverage ◽  
Spring Temperature ◽  
Rescaled Range ◽  
Nenjiang River Basin

To detect changes in vegetation is desirable for modeling and predicting interactions between land surface and atmosphere. Multitemporal series of SPOT VEGETATION NDVI dataset and meteorological data were integrated to interpret vegetation dynamics and the linkage with climate variations in the upper and middle reaches of the Nenjiang River Basin (NRB) from 1999 to 2010 using the correlation analysis and the rescaled range (R/S) analysis. The results demonstrate that annual NDVI increased slightly and 26.02% vegetation coverage of the study area significantly improved. The area of significantly decreased in vegetation cover took up 13.33% of the total land in spring. In autumn, 26.2% of the study area showed a significant vegetation increase. The improved activity of vegetation might reinforce in summer and autumn, while the decreasing tendency in spring might be persistent in the future. The yearly NDVI had significant positive linkages with precipitation and relative humidity. NDVI related significantly and negatively with temperature, sunshine hours and wind velocity, because they may have effects of increasing evapotranspiration and risk of drought and cold damage of vegetation. The variations of annual NDVI were much affected by summer temperature, relative humidity and sunshine duration in autumn and spring wind velocity. Seasonal NDVI decreased in parallel with elevated temperature, but there was no correlation between NDVI and precipitation. Spring temperature, relative humidity in summer and autumn contributed markedly to NDVI variations in the same season. The vegetation improving trend may induce by the warm-wetting climate in recent twelve years.

scholarly journals Peranan Infrastruktur Jalan Terhadap Perekonomian Regional Di Indonesia

2010 ◽  
Vol 22 (2) ◽  
pp. 113-133
Author(s):  
Siti Maimunah
Keyword(s):  
Capital Stock ◽  
Regional Economy ◽  
Time Lag ◽  
Development Stage ◽  
Output Measurement ◽  
Road Infrastructure ◽  
Road Development ◽  
Lag Model

During the development stage, provision of transportation infrastructure is ven; important. It contnbutesto the regional economy and makes economic development more inclusive by giving directand indirect effects. The aim of research wants to know the role of road infrastructure to regionaleconomy in long term periods.Having panel data in the regional level (province) which is 26 provinces and a 14-year time series(1993-2006), variables that are used in this stud!; are GDP as the output measurement, labor forceand capital stock which is divided into road capital stock and non road capital stock. Road capitalstock itself is comprised of national, province and city road capital stock.Based on the model in analysis, we can say road infrastructure has significant contributions to theregional econonn; where city roads give the highest contnbution to the regional econonn;. In addition,based on the time lag model, we can see that the investment in road development will have a significanteffect on GDP in the curre11t year, as well as in the following .few years, but the effect diminishesover time. However, the significant contnbution of road development to GDP only remains for 1 yearfor all types of road.Some polictj implications that can be proposed from the above analysis are: it is still necessary toincrease the development of road infrastructure in order to provide good accessibility for all regions inIndonesia; so government should give priorihJ to develop city and province roads rather than nationalroads to increase the regional output (regional GDP). On the other hand government shouldmake it a priority to develop strategies for the development of road infrastructure based on the specificneeds of each region so it will be more effective and efficient in encouraging regional economic growthand, ultimately, in enhancing high economic growth in Indonesia as a whole.Key words: road infrastructure, regional econonn1

Trends of Estimated Potential Evapotranspiration in the Poyang Lake Basin, China

2013 ◽  
Vol 726-731 ◽  
pp. 3299-3302 ◽  
Author(s):  
Xu Chun Ye ◽  
Jian Liu ◽  
Qi Zhang
Keyword(s):  
Wind Speed ◽  
Relative Humidity ◽  
Poyang Lake ◽  
Potential Evapotranspiration ◽  
Sunshine Duration ◽  
Lake Basin ◽  
Catchment Scale ◽  
Poyang Lake Basin ◽  
Autumn And Winter

Using the Penman-Monteith method, the potential evapotranspiration (PET) was calculated over the Poyang Lake basin during 1960-2008. Our analysis indicates that except spring, PET in summer, autumn and winter shows long term decreasing trend, with the largest in summer and the least in winter. The decrease of annual PET in the Poyang Lake basin is mostly affected by the decline of summer PET. On catchment scale, although the calculated PET at all the Metero-stations shows decrease trend, the trends are not significant at some stations. Further analysis indicates that the most important predictor for the decreasing trend in potential evapotranspiration is sunshine duration and wind speed, followed by relative humidity and air temperature.

scholarly journals Quantitative Analysis of Vegetation Dynamics in Response to Climatic Factors and Human Activities in Southwest China

2021 ◽  
Author(s):  
Cuiping Yang ◽  
Yongqiang Wang ◽  
Jiujiang Wu ◽  
xiaoyi ma
Keyword(s):  
Relative Humidity ◽  
Time Scale ◽  
Human Activities ◽  
Interannual Variation ◽  
Southwest China ◽  
Climatic Factors ◽  
Sunshine Duration ◽  
Spatial And Temporal Variability ◽  
Delayed Response ◽  
Mean Temperature

Abstract We determined the time scale of normalized difference vegetation index (NDVI) response to drought and used trend and correlation analyses to explore the spatial and temporal variability characteristics of the NDVI and SPEI and their sensitivity to climatic factors in southwest China from 2000 to 2020. We used a partial derivative approach to calculate the contributions of six climatic factors and human activities to the interannual variation in the NDVI. The results demonstrated that from 2000 to 2020, the annual mean NDVI in southwest China showed a slight decreasing trend at a rate of 0.0001 y−1. The NDVI had the highest sensitivity to the standardized precipitation and evapotranspiration index on a 12-month time scale. The NDVI exhibited a 1-year delayed response to drought. The SPEI has the highest sensitivity to precipitation. The percentage of pixels with a positive correlation between NDVI and precipitation, mean temperature, temperature difference, mean relative humidity, mean wind speed, and sunshine duration in the study area was 31.73%, 46.81%, 35.49%, 25.76%, 39.36%, and 39.89%, respectively. The average contributions of these six climatic factors to the interannual variation of NDVI were 0.00029, 0.00046, −0.00007, 0.00007, 0.0008, and 0.00001 y−1, respectively. The NDVI had the highest sensitivity to mean temperature and the lowest sensitivity to mean relative humidity. The average contributions of climatic factors and human activities to interannual variability in southwest China were 0.00156 and 0.00012 y−1, respectively. The positive influence of climatic factors on the NDVI was stronger than that of human activities. This study provides a theoretical basis for the sustainable management of the regional ecological environment.

scholarly journals VEGETATION CHANGES AND THE RELATIONSHIP WITH CLIMATE VARIABILITY IN THE UPPER AND MIDDLE REACHES OF THE NENJIANG RIVER BASIN, CHINA

2016 ◽  
Vol XLI-B8 ◽  
pp. 889-895
Author(s):  
F. Huang ◽  
D. H. Wen ◽  
P. Wang
Keyword(s):  
Relative Humidity ◽  
River Basin ◽  
Wind Velocity ◽  
Land Surface ◽  
Sunshine Duration ◽  
Meteorological Data ◽  
Vegetation Coverage ◽  
Spring Temperature ◽  
Rescaled Range ◽  
Nenjiang River Basin

To detect changes in vegetation is desirable for modeling and predicting interactions between land surface and atmosphere. Multitemporal series of SPOT VEGETATION NDVI dataset and meteorological data were integrated to interpret vegetation dynamics and the linkage with climate variations in the upper and middle reaches of the Nenjiang River Basin (NRB) from 1999 to 2010 using the correlation analysis and the rescaled range (R/S) analysis. The results demonstrate that annual NDVI increased slightly and 26.02% vegetation coverage of the study area significantly improved. The area of significantly decreased in vegetation cover took up 13.33% of the total land in spring. In autumn, 26.2% of the study area showed a significant vegetation increase. The improved activity of vegetation might reinforce in summer and autumn, while the decreasing tendency in spring might be persistent in the future. The yearly NDVI had significant positive linkages with precipitation and relative humidity. NDVI related significantly and negatively with temperature, sunshine hours and wind velocity, because they may have effects of increasing evapotranspiration and risk of drought and cold damage of vegetation. The variations of annual NDVI were much affected by summer temperature, relative humidity and sunshine duration in autumn and spring wind velocity. Seasonal NDVI decreased in parallel with elevated temperature, but there was no correlation between NDVI and precipitation. Spring temperature, relative humidity in summer and autumn contributed markedly to NDVI variations in the same season. The vegetation improving trend may induce by the warm-wetting climate in recent twelve years.

scholarly journals Contributions of Climatic Factors to Interannual Variability of the Vegetation Index in Northern China Grasslands

2020 ◽  
Vol 33 (1) ◽  
pp. 175-183 ◽  
Author(s):  
Wei Zhao ◽  
Zhongmin Hu ◽  
Qun Guo ◽  
Genan Wu ◽  
Ruru Chen ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Solar Radiation ◽  
Air Temperature ◽  
Vegetation Index ◽  
Climatic Factors ◽  
Explanatory Power ◽  
Regional Scale ◽  
Temperate Grasslands ◽  
Study Region ◽  
Vegetation Activities

AbstractUnderstanding the atmosphere–land surface interaction is crucial for clarifying the responses and feedbacks of terrestrial ecosystems to climate change. However, quantifying the effects of multiple climatic factors to vegetation activities is challenging. Using the geographical detector model (GDM), this study quantifies the relative contributions of climatic factors including precipitation, relative humidity, solar radiation, and air temperature to the interannual variation (IAV) of the normalized difference vegetation index (NDVI) in the northern grasslands of China during 2000 to 2016. The results show heterogeneous spatial patterns of determinant climatic factors on the IAV of NDVI. Precipitation and relative humidity jointly controlled the IAV of NDVI, illustrating more explanatory power than solar radiation and air temperature, and accounting for higher proportion of area as the determinant factor in the study region. It is noteworthy that relative humidity, a proxy of atmospheric aridity, is as important as precipitation for the IAV of NDVI. The contribution of climatic factors to the IAV of NDVI varied by vegetation type. Owing to the stronger explanatory power of climatic factors on NDVI variability in temperate grasslands, we conclude that climate variability may exert more influence on temperate grasslands than on alpine grasslands. Our study highlights the importance of the role of atmospheric aridity to vegetation activities in grasslands. We suggest focusing more on the differences between vegetation types when addressing the climate–vegetation relationships at a regional scale.

scholarly journals Climate Variability, Dengue Vector Abundance and Dengue Fever Cases in Dhaka, Bangladesh: A Time-Series Study

Atmosphere ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 905
Author(s):  
Sabrina Islam ◽  
C. Emdad Haque ◽  
Shakhawat Hossain ◽  
John Hanesiak
Keyword(s):  
Time Series ◽  
Relative Humidity ◽  
Dengue Fever ◽  
Climatic Factors ◽  
Time Lag ◽  
Additive Model ◽  
Climate Change And Variability ◽  
Aedes Mosquitoes ◽  
Vector Abundance ◽  
The Mean

Numerous studies on climate change and variability have revealed that these phenomena have noticeable influence on the epidemiology of dengue fever, and such relationships are complex due to the role of the vector—the Aedes mosquitoes. By undertaking a step-by-step approach, the present study examined the effects of climatic factors on vector abundance and subsequent effects on dengue cases of Dhaka city, Bangladesh. Here, we first analyzed the time-series of Stegomyia indices for Aedes mosquitoes in relation to temperature, rainfall and relative humidity for 2002–2013, and then in relation to reported dengue cases in Dhaka. These data were analyzed at three sequential stages using the generalized linear model (GLM) and generalized additive model (GAM). Results revealed strong evidence that an increase in Aedes abundance is associated with the rise in temperature, relative humidity, and rainfall during the monsoon months, that turns into subsequent increases in dengue incidence. Further we found that (i) the mean rainfall and the lag mean rainfall were significantly related to Container Index, and (ii) the Breteau Index was significantly related to the mean relative humidity and mean rainfall. The relationships of dengue cases with Stegomyia indices and with the mean relative humidity, and the lag mean rainfall were highly significant. In examining longitudinal (2001–2013) data, we found significant evidence of time lag between mean rainfall and dengue cases.

EPIDEMIOLOGY, ECOLOGY AND PREVALENCE OF SOIL TRANSMITTED HELMINTHS FROM KOSHI REGION OF NORTH BIHAR.

2018 ◽  
Vol 24 (1) ◽  
Author(s):  
LAKSHMI CHOUDHARY ◽  
PRABHAWATI PRABHAWATI
Keyword(s):  
Relative Humidity ◽  
Ascaris Lumbricoides ◽  
Rainy Season ◽  
Climatic Factors ◽  
Trichuris Trichiura ◽  
Hookworm Infection ◽  
Soil Transmitted Helminths ◽  
High Incidence ◽  
Apparently Healthy

Prevalence of soil transmitted helminthes infections in apparently healthy school going children and other 528 people of different districts of Koshi regions of North Bihar were evaluated. Over all incidences of STHs infection was 39.39% during study. High incidence of STH was seen in the rainy season i.e., in the month of July and August, September, significantly higher (P<0.05) .The incidence of Ascaris lumbricoides was highest in the month of August (18.64%). The month of September was 15.25% followed by that of July (14.4%) and October with 10.16%. Also the incidence of hookworm registered the highest incidence in the month of June (19.27%) and lowest in the month of December (4.82%) during the study period. However prevalence of Trichuris trichiura was negligible and it was almost nil in the most of the months but was highest in month of September with 28.57% and lowest in October with 14.00% The climatic factors are responsible for soil transmitted helminthes which are temperature, rainfall and relative humidity. Ascariasis, Trichuriasis and Ancyclostomiasis (Hookworm infection) are found to be endemic in this region.

A distributed vaporization time-lag model for gas turbine combustor dynamics

1992 ◽  
Author(s):  
JAYESH MEHTA ◽  
P. MUNGUR ◽  
W. DODDS ◽  
L. DODGE
Keyword(s):  
Gas Turbine ◽  
Time Lag ◽  
Gas Turbine Combustor ◽  
Lag Model
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