Surface Water Changes in Dongting Lake from 1975 to 2019 Based on Multisource Remote-Sensing Images

Dongting Lake plays an important role in water regulation and biodiversity protection, but it is vulnerable to climate change and human activities. To quantify surface water changes and factors driving them, long-term surface water variation in Dongting Lake was investigated using the multiple spectral indices method based on a decision tree classification for full time-series Landsat and MODIS datasets. Factors influencing surface water changes were explored by combining the annual maximum surface water and annual permanent occurrent water with meteorological and hydrological data. The results showed that both annual maximum surface water and annual permanent water decreased from 1975 to 2019 and the trends of rainfall and runoff at three outlets also changed. The annual maximum surface water surface of Dongting Lake increased during the 1990s due to high rainfall but decreased again after 2000. A significant change in both the hydrological stage and surface water sequence from 1986 to 2019 occurred in 2003, which coincided with the beginning of work to construct the Three Gorges Dam (TGD). The surface water decreased by about 360 km2 and runoff at the three outlets decreased by about 150 × 108 m3 after the impoundment of the TGD, which was likely the main cause of surface water changes after 2003. The area of surface water that changed from permanent water in the pre-TGD period into seasonally occurring water in the post-TGD periods is 209 km2, while the area of surface water that changed from seasonally occurring water in the pre-TGD period into permanent occurrent water in the post-TGD period is 31 km2. Meteorological elements and human activities have had a comprehensive impact on surface water changes in Dongting Lake. Rainfall and temperature account for about one-third of the influence on long-term changes of surface water, and rainfall is the main meteorological driving factor of surface water in the wet season, while temperature is the main factor in the dry season. Runoff at three outlets, four rivers and the Chenglingji explain about half of the change in surface water; the three outlets runoff is mainly affected by human activities and is the main hydrological driving factor of surface water. The monthly maximum surface water fluctuates regularly and Dongting Lake has a strong seasonal characteristic. Indeed, the seasonal changes are significantly altered when drought or flooding occurs, the causes of which are diverse and complex.

Interhemispheric comparison of mesosphere/lower thermosphere winds from GAIA, WACCM-X and ICON-UA simulations and meteor radar observations at mid- and polar latitudes

<p>There is a growing scientific interest to investigate the forcing from the middle atmosphere dynamics on the thermosphere and ionosphere. This forcing is driven by atmospheric waves at various temporal and spatial scales. In this study, we cross-compare the nudged models Ground-to-topside model of Atmosphere and Ionosphere for Aeronomy (GAIA) and Whole Atmosphere Community Climate Model Extended</p><p>Version (Specified dynamics) ( WACCM-X(SD)), a free-running version of Upper Atmosphere ICOsahedral Non-hydrostatic (ICON-UA) with six meteor radars located at conjugate polar and mid-latitudes. Mean winds, diurnal and semidiurnal tidal amplitudes and phases were obtained from the radar observations at the mesosphere and lower thermosphere (MLT) and compared to the GAIA, WACCM-X(SD), and ICON-UA data for similar locations applying a harmonized diagnostic.</p><p>Our results indicate that GAIA zonal and meridional winds show a good agreement to the meteor radars during the winter season on both hemispheres, whereas WACCM-X(SD) and ICON-UA seem to reproduce better the summer zonal wind reversal. However, the mean winds also exhibit some deviation in the seasonal characteristic concerning the meteor radar measurements, which are attributed to the gravity wave parameterizations implemented in the models. All three models tend to reflect the seasonality of diurnal tidal amplitudes, but show some dissimilarities in tidal phases. We also found systematic interhemispheric differences in the seasonal characteristic of semidiurnal amplitudes and phases. The free-running ICON-UA apparently shows most of these interhemispheric differences, whereas WACCM-X(SD) and GAIA trend to have better agreement of the semidiurnal tidal variability in the northern hemisphere.</p>

The Impact of Tropospheric Anomalies on Sea-Based JPALS Integrity

The Joint Precision Approach Landing System (JPALS) addresses tropospheric errors through double-difference and tropospheric model correction. Large residuals occur with two types of tropospheric anomalies: the vertical duct and horizontal non-nominal troposphere. Through analyzing 8 years of meteorological data from the European Center for Medium-Range Weather Forecasts (ECMWF), we find that the two types of anomalies can occur simultaneously. In addition, the existing vertical protection level (VPL) calculation method under tropospheric anomalies is based on the least squares method, which is not applicable to Sea-Based JPALS using the Kalman filter. Therefore, we start by calculating the zenith duct error by numerical integration. The maximum error observed is 45.64 mm, and the error seasonal characteristic is analyzed. For the non-nominal troposphere, the worst meteorological conditions in the Chinese surrounding sea areas are used to calculate the non-nominal errors, which are fitted to a satellite-elevation-dependent model. Then, a VPL calculation method based on the Kalman filter under tropospheric anomalies is proposed. Finally, a multiple approach simulation is conducted. The results show that the average VPL increments introduced by the duct and non-nominal troposphere anomalies are 0.082 m and 0.211 m, respectively, with growth percentages of 12.903% and 30.857%, respectively. The increment under simultaneous anomalies is 0.272 m with a growth of 40.427%. Furthermore, the average availability under normal conditions is 100%. Considering the duct and the non-nominal troposphere anomalies, the availability loss is 0.017% and 3.674%, respectively. Under simultaneous anomalies, this loss is 4.743%.

Seasonal characteristic of gonadogenesis for the sea cucumber Apostichopus japonicus Selenka

Gonads of females and males of the sea cucumber Apostichopus japonicus were collected along Primorye coast of the Japan Sea (bays Kiyevka, Sokolovskaya, Melkovodnaya, Sredniaya, and the area between Cape Genbachev and Cape DeLivron) in different seasons from May to October, 2011. The gonads were fixed in 70 % alcohol and Buena fixing agent, using Isoprep and Histomix, and subjected to histophyisiological analysis. Sex of the animals and condition of their gonads were defined visually and on histological preparations. Their whole bodies, skin and muscular bags, and sexual glands were weighted, gonad-somatic indices were calculated, dynamics of cellular composition was traced for the sex glands, timing of spawning and duration of the rest stage were determined. For the cucumbers from the Kiyevka and Melkovodnaya Bays, diameter of sex tubules varied from 0.2 mm to 1.9 mm, diameter of freely lying oocytes - from 71.4 mm to 167.0 mm, and diameter of wall oocytes - from 47.6 mm to 119.0 mm; they were ready for spawning in late July - early August, and spawned in the first 10-days of August. Plication of the tubule walls internal surface was observed later in the process of mature cells resorption in sex tubules; new generation of the cells appeared, which most likely would undergo to further destruction (small tubules with plication of their walls were observed for a specimen from the Kiyevka Bay in late September, 2011). New gametogenesis was registered both for females (small oocytes) and males (spermatocytes of I and II orders) from the Sredniaya Bay and between Cape Genbachev and Cape DeLivron in early October, simultaneously with continuing process of the tubule walls plication. The rest stage (without forming of new sex tubules) continued 1.0-1.5 months: from early August to middle September, with some variations between the areas.

STRATEGI BERTAHAN HIDUP PEREMPUAN PENJUAL BUAH-BUAHAN (Studi Perempuan di Pasar Raya Padang Kecamatan Padang Barat Kota Padang Propinsi Sumatera Barat)

This research is inspired by women’s involvement in public sectors with limited resources and access. One of the sectors is fruit selling. Various problems in selling demands the women to find strategies to continue to meet family needs. The purpose of the study is to describe factors that push women to choose selling fruits and their strategies to overcome the problem of income for the family. The theory used is the action actor from Max Weber. This research is qualitative descriptive. Data is collected through observation, interview, and documentation. Based on the results, it can be concluded: 1. Driving factors of women choosing to sell fruits are; a) economic factors; small capital is needed, b) social factors and cultural heritage; the efforts of parents and their relationships with fruit growers, c) seasonal characteristic of the fruits, and d) educational factors; most female fruit sellers are low educated. 2. Survival strategies of the women are; a) having dual income, b) reducing household spending, c) cooperating with fruit growers or agent, d) arisan (collective saving), e) changing the type of fruits sold according to the periods of the fruits, and f) changing the type of goods sold.

Analysis of the Pollution Characteristics and Influence Factors of PM2.5 in Chinese Main Capital City

In this paper, we choose the data of 24 capital cities of Chinese Mainland, with information on PM2.5 and the meteorological conditions, using the Mixed Effects Model to analysis the Pollution Characteristics and Influence Factors of PM2.5 in Chinese main capital city. The results show that the PM2.5 level has a significant seasonal characteristic; the level of PM2.5 in winter is higher than that in spring. And the weather conditions also have significant effects on the PM2.5 level.