Annual Average Sunshine Hours Research Articles

Temporal and Spatial Variation Analysis of Lake Area Based on the ESTARFM Model: A Case Study of Qilu Lake in Yunnan Province, China

Qilu Lake is one of the nine plateau lakes in Yunnan Province, China. In recent years, under the influence of extreme climate and human activities, the area of Qilu Lake has shrunk significantly, the water level has dropped, and the problem of water shortage has become increasingly serious. Based on the Landsat and MODIS image data from 2000 to 2020, this study applied the ESTARFM spatiotemporal fusion model to unify the data images used in the study to February, used three kinds of water body indexes, selected the water body index most suitable for the study area to extract relevant information, and analyzed the spatiotemporal change characteristics of Qilu Lake area in the last 20 years. The results showed that: (1) Based on the ESTARFM model, the Landsat and MODIS data on 18 January 2020, the Landsat and MODIS data on 9 May 2020, and the MODIS data on the date to be predicted (February 13) were fused to obtain the Landsat image data of the predicted date, which met the accuracy requirements; (2) Taking 2005 as an example, the NDWI, MNDWI, and AWEIsh indexes were used to extract the water body with the precisions of 99.0%, 99.6% and 98.6%, respectively, and then the MNDWI water body index was selected to extract the lake area; (3) In the past 20 years, the overall area of Qilu Lake has shown a downward trend, with the area reduced by 0.7132 km2. From 2000 to 2010, the lake area was relatively stable, fluctuating up and down around 36 km2. From 2010 to 2015, the lake area decreased sharply, with a change rate of −40%. After 2015, the lake area gradually increased; (4) The spatial change of Qilu Lake area mainly occurred in the southwest and west, which decreased by 0.44 km2 and 0.49 km2, respectively, and there were small fluctuations in other directions. In the past two decades, the shape index of Qilu Lake has shown a downward trend as a whole; the contour of the lake tends to be simplified, the contour is complex and stable from 2000 to 2010, and the shape index decreases from 2.17 to 1.74 from 2010 to 2020; (5) The change in the Qilu Lake area is positively correlated with the change in the water level. Polynomial models with different times were selected as the model for retrieving water level elevation from the Qilu Lake water surface area, with a highest correlation coefficient of 0.9259. The temporal and spatial changes of the Qilu Lake area in the last 20 years are the result of the joint action of natural factors and socio-economic factors. According to the analysis, the annual average temperature, annual precipitation, annual average sunshine hours, and population density are the main driving forces leading to the change. In the future, the government and relevant researchers should strengthen real-time monitoring and regular research, formulate and optimize emergency plans to deal with changes in the ecological environment of lakes, and promote the sustainable development of the ecological environment and social economy of the basin.

Correlations between content of linarin in Chrysanthemum indicum and climatic factors in habitats

Chrysanthemi Indici Flos(CIF), the capitulum of Chrysanthemum indicum, is widely used in proprietary Chinese medicine and daily chemical products. At present, CIF is mainly produced from wild resources and rarely cultivated. This study aims to reveal the correlations between linarin content in CIF and climatic factors in different habitats, and provide a theoretical basis for suitable zoning and rational production of medicinal materials. The content of linarin in CIF was determined by HPLC. Grey relational analysis and Pearson correlation analysis were carried out for linarin content with climatic factors. The results showed that the content of linarin in CIF was significantly different among different habitats. The grey relational degrees of climatic factors with linarin content was in an order of average annual precipitation>annual average sunshine hours>annual average temperature>longitude>annual frost-free period>latitude>altitude. Longitude, annual average temperature and average annual precipitation had significantly positive correlations with the content of linarin in CIF, whereas latitude and altitude showed negative correlations with it. The annual frost-free period and annual average sunshine hours had no significant correlation with the content of linarin in CIF. The content of linarin in CIF varied significantly in different habitats. High longitude, low latitude, low altitude, high annual average temperature and high annual average precipitation could be used as indicators for the habitats of high-quality Ch. indicum. This study provides a reference for selecting suitable producing areas of Ch. indicum and establishing artificial cultivation system.

Analysis of Eco-Tourism Climate Resources in Xingwen, China Based on the Comfort Index and the Negative Air (Oxygen) Ion

The present work investigates an analysis of Eco-Tourism Climate Resources in Xingwen, China based on the Comfort Index and Negative Air (Oxygen) Ion (“NAI” for short in this article) concentration. The daily temperature, precipitation, wind speed, sunshine hours, and relative humidity data of the Xingwen National Meteorological Station from 1999 to 2018, as well as the NAI data of Feiwu Cave station and Shoushan Lake station in Xingwen of 2018 were used in this study. Based on the analysis of the characteristics of basic meteorological elements, the index of climate comfort of human living environment and the NAI variation in Xingwen, the eco-tourism climate resources in this area were evaluated comprehensively. The results show that: The climate is mild, the precipitation is abundant and the seasonal variation trend of precipitation and heat is similar in the study area. The annual average temperature of this area is 17.8°C, the annual average precipitation is 1096 mm, the annual average precipitation days are 186 days, the annual average relative humidity is 81%, the annual average wind speed is 1.3 m/s, and the annual average sunshine hours are 999 h. The living environment comfort level reaches the “comfort” level for 6 months per year. In addition, the concentration of NAI in Xingwen remains at the highest level 7 throughout the year, and the rate of good air quality is extremely high. Overall, the study area has high-quality ecological climate resources that are conducive to the development of forest recuperation, leisure and vacation and other ecological tourism activities.

The effect of geographic variation on chemical composition, antioxidant and hypoglycemic activities of Morus alba L. polysaccharides

Morus alba L. is an edible fruit with multiple medical function. To reveal the geographic variation pattern of polysaccharide content in the mulberry fruits and its antioxidant and hypoglycemic activities, the fruit samples were collected and analyzed from seven geographic locations throughout the distribution areas in China. The polysaccharide content in the mulberry fruits ranged from 4.13 ± 0.04% to 1.07 ± 0.07%. All the polysaccharides derived from mulberry fruit showed certain antioxidant and hypoglycemic activities with a significant variation. Significant differences were observed among polysaccharide content, antioxidant activity, and sunshine hours, but no clear geographical or polysaccharide content variation patterns were observed for hypoglycemic activity. Pearson correlation analysis indicated that the annual average sunshine hours was significantly correlated to the polysaccharide content and antioxidant activity. According to the polysaccharide contents and bioactivities, certain natural populations of M. alba L. such as Xinjiang, Hunan, and Anhui were recommended for food and medical use in future. Practical applications Morus alba L. belonging to the family Moraceae, is cultivated across an extensive range of geographical, climatic, and soil conditions. Polysaccharides from mulberry fruit have been proved to have the function of enhancing immunity, antiaging, anti-inflammatory, antioxidant, hypolipidemic, and hypoglycemic effects with no toxic record in clinic. It has been reported that the phytochemicals accumulation in plants is greatly affected by genetic, climatic, and harvesting factors during the growing period. We revealed the geographic variation pattern of polysaccharide content in the mulberry fruits and its antioxidant activity. Based on the polysaccharide contents and bioactivities, certain natural populations of M. alba L. such as Xinjiang, Hunan, and Anhui were recommended for food and medical use in future. The information obtained by this study could be useful for the selection of natural populations with adequate polysaccharide content, as well as high food and medical use for M. alba L.

ASSESSING AND MAPPING THE RISK OF SOIL SALINIZATION IN THE COASTAL PLAIN OF THUA THIEN HUE PROVINCE

The coastal plain of Thua Thien Hue province covers an area of 1,080 km2, which is vulnerable to soil salinization due to significant impacts of climate change. In this study area highly vulnerable to soil salinization, saline soil occupies the area of about 6,290 hectares, is scatteredly distributed and tends to increase. To assess and map the risk levels of soil salinization, the authors chose 09 criteria, including: annual average rainfall, annual average temperature, annual average evaporation, annual average sunshine hours, number of months of dry season, soil type, vegetation cover, density of river network, submerged areas in different scenarios of sea level rise. The spatial data for determining criteria were processed by using Geographic Information System (GIS) and the Analytic Hierarchy Process (AHP) method. The study results show that the area highly vulnerable to salinization occupies about 16.4% of total area and that the coastal region of Phu Vang, Quang Dien and Phong Dien districts are the most vulnerable.