Proportion and distribution of rain and snow in China from 1960 to 2018

Rainfall and snowfall have different effects on energy balance calculations and land-air interactions in terrestrial models. The identification of precipitation types is crucial to understand climate change dynamics and the utilization of water resources. However, information regarding precipitation types is not generally available. The precipitation obtained from meteorological stations across China recorded types only before 1979. This study parameterized precipitation types with air temperature, relative humidity and atmospheric pressure from 1960 to 1979, and then identified precipitation types after 1980. Results show that the main type of precipitation in China was rainfall, and the average annual rainfall days (amounts) across China accounted for 83.08% (92.55%) of the total annual precipitation days (amounts). The average annual snowfall days (amounts) in the northwestern region accounted for 32.27% (19.31%) of the total annual precipitation days (amounts), which is considerably higher than the national average. The average annual number of rainfall and snowfall days both displayed a downward trend while the average annual amounts of these two precipitation types showed an upward trend, but without significance at 0.1 levels. The annual number of rainfall and snowfall days in the southwestern region decreased significantly (-2.27 d/decade and -0.31 d/decade, p < 0.01). The annual rainfall amounts in the Jianghuai region increased significantly (40.70 mm/decade, p < 0.01), and the areas with the most significant increase in snowfall amounts were the northwestern (3.64 mm/decade, p < 0.01). These results can inform our understanding of the distribution and variation of precipitation with different types in China.

Changes in Slight and Extreme Precipitation Events From 1963 to 2017 Over Northern Xinjiang, China

Based on daily measured data from 25 stations in Xinjiang Province from 1963 to 2017, we discuss the statistical characteristics, linear trends, and temporal concentration of slight precipitation (SP) and extreme precipitation (EP) events, and consider relationships between SP and EP events and daily mean temperature. The results show that SP events contribute strongly to the total annual number of wet days, and that EP events contribute strongly to the total annual precipitation amount. In consist with the decrease in SP events and the increase in EP events over the 55-year period, the contribution of SP events to total annual number of wet days has decreased significantly while the contribution of EP events to total annual precipitation amount has increased significantly. SP event usually distributes through most months of the year, whereas EP event usually concentrates in summer (JJA). Influenced by the negative trends for SP events frequency and positive trends of EP events frequency during recent decades, the concentration degree for SP and EP events have significantly increased and decreased, respectively. Distinct differences are found between the relationships of SP events and EP events to daily mean temperature. The daily mean temperature recorded at the stations in Northern Xinjiang on days with SP events was between –35°C and +34°C, and for EP events ranged from –21°C to +30°C. Regionally averaged curves for the change in SP and EP event frequency with temperature have bimodal and unimodal distributions, respectively. Trends for daily mean temperatures and for the frequency of SP events at different temperatures agree well over nearly the entire temperature range, while trends for daily mean temperatures and for the frequency of EP events at different temperatures are not always consistent. These results will help to improve our understanding of the characteristics and variability of precipitation in arid regions within the context of climate warming.

Analysis and Optimization of the Effects of Meteorological Factors on ‘Fuji’ Fruit Quality in Two Dominant Production Regions of China

This study aimed to understand the effects of meteorological factors on the ‘Fuji’ apple quality in the Circum-Bohai and Loess Plateau apple production regions of China and to guide apple production based on local climate. Fruit samples of the ‘Fuji’ apple and meteorological data were investigated from 132 commercial ‘Fuji’ apple orchards covering 44 counties in the two aforementioned production regions (22 counties per region). The partial least-squares regression (PLSR) method was first used to screen major meteorological factors that greatly affected fruit quality; these were subsequently used to establish the regression equation of fruit quality attributes and major meteorological factors. Linear programming was used to estimate optimum meteorological factors for good apple quality. The results showed that in the Circum-Bohai production region, many meteorological factors (total annual precipitation, total precipitation from April to October, lowest temperature from April to October, sunshine percentage from April to October) were significantly higher than those in the Loess Plateau production region; however, the temperature difference between day and night from April to October was significantly smaller than that in the Loess Plateau production region. The soluble solids content and skin color area of apples from the Loess Plateau production region were significantly greater than those from the Circum-Bohai production region. The same fruit quality factor of ‘Fuji’ apple was affected by different meteorological factors in the two production regions. The monthly mean temperature and monthly highest temperature from April to October of the Circum-Bohai production region had relatively larger positive effect weights on fruit quality, whereas the total annual precipitation, monthly mean relative humidity from April to October, and total precipitation from April to October of the Loess Plateau production region had relatively larger positive effect weights on fruit quality. The major influencing meteorological factors of the fruit soluble solids content were total precipitation from April to October (X7), mean annual temperature (X1), and the monthly highest temperature from April to October (X5) in the Circum-Bohai production region; however, it included the monthly mean temperature difference between day and night from April to October (X6), total annual precipitation (X2), and total precipitation from April to October (X7) in the Loess Plateau production region. In the Circum-Bohai production region, the optimum meteorological factors for ‘Fuji’ fruit quality of vigorous apple orchards were the mean annual temperature (13.4 °C), total annual precipitation (981 mm), monthly mean temperature (16.8 to 22.4 °C), lowest temperature (11.9 °C), highest temperature (19.5 to 26.8 °C), temperature difference between day and night (12.3 °C), total precipitation (336–793 mm), relative humidity (55.7% to 70.7%), and sunshine percentage (42.3% to 46.1%) during the growing period (April–October). In the Loess Plateau production region, the optimum meteorological factors for ‘Fuji’ fruit quality of vigorous apple orchards were the mean annual temperature (5.5 to 11.6 °C), total annual precipitation (714 mm), monthly mean temperature (13.3 to 19.9 °C), lowest temperature (7.9 to 9.3 °C), highest temperature (19.6 to 27.3 °C), temperature difference between day and night (7.1 to 12.4 °C), total precipitation (338–511 mm), relative humidity (56.1% to 82.4%), and sunshine percentage (37.3% to 55.9%) during the growing period (April–October). The restrictive factors for high-quality ‘Fuji’ apples of the Circum-Bohai production region were the smaller monthly mean temperature difference between day and night, higher monthly mean lowest temperature, and larger monthly mean relative humidity during the growing period; however, those of the Loess Plateau production region were drought or less precipitation from November to March, lower monthly mean temperature, and higher monthly mean highest temperature during the growing period.

Village-level climate and weather variability, mediated by village-level crop yield, is associated with linear growth in children in Uganda

IntroductionTo investigate total annual precipitation, precipitation anomaly and aridity index in relation to linear growth in children under 5 in Uganda and quantify the mediating role of crop yield.MethodsWe analysed data of 5219 children under 5 years of age who participated in the 2016 Uganda Demographic and Health Survey. Annual crop yield in kilograms per hectare for 42 crops at a 0.1° (~10 km at the equator) spatial resolution square grid was obtained from the International Food Policy Research Institute. Normalised rainfall anomaly and total precipitation were derived from the African Rainfall Estimation Algorithm Version 2 product. Linear regression models were used to associate total annual precipitation and anomalies with height-for-age z-scores and to explore the mediating role of crop yield qualitatively. The intervening effects were quantitatively estimated by causal mediation models.ResultsTwenty-nine per cent of children were stunted (95% CI 28% to 31%). After adjusting for major covariates, higher total annual precipitation was significantly associated with increasing height-for-age z-scores. At the mean, an increase of 1 standard deviation in local annual rainfall was associated with a 0.07-point higher z-score. Aridity index and precipitation anomaly were not associated with height-for-age z scores in altitude-adjusted models. Crop yields of nuts, seeds, cereals and pulses were significant mediating factors. For instance, 38% of the association between total annual precipitation with height-for-age z-scores can be attributed to the yield of sesame seeds.ConclusionsHigher total annual precipitation at the village-level was significantly associated with higher height-for-age z-scores among children in Uganda. This association can be partially explained by higher crop yield, especially from seeds and nuts. This study suggests that more attention should be paid to villages with lower annual rainfall amounts to improve water availability for agriculture.

IMPACT OF CLIMATE CHANGE ON THE HYDRAULIC MODES OF OPERATION OF SURFACE RUNOFF DRAINAGE SYSTEMS

Introduction. Based on Resolution of the Government of the Russian Federation No. 782 “On water supply and wastewater disposal plans”, the volume of generated wastewater should be forecast for a period of at least 10 years. Along with this, it is also necessary to assess the hydraulic modes of operation of networks and collectors, specified earlier. However, the existing regulatory literature lacks data on the dynamics of calculated rain intensities and their prospective values. The analysis of the subject area showed that it is possible to determine the climatic parameters of an area, and thus establish the values for the characteristics of calculated rain, based on the data of long-term observations (from 20 years) with one self-recording rain gauge, or with a network of similar rain gauges, with a duration of observations of 5 years or more. A similar network of rain gauges is available in St. Petersburg. It makes it possible to assess the actual values of climatic parameters, but due to the lack of statistical data does not allow for assessing the dynamics of their changes. Therefore, the purpose of this article is to roughly estimate the dynamics of changes in climatic parameters in St. Petersburg and the degree of their impact on the hydraulic modes of operation of surface runoff drainage networks and collectors. Methods. In the course of the study, we analyzed the dynamics of changes in the total annual precipitation H and rain force in St. Petersburg and examined the influence of the dynamics of rain force changes on the operation of surface runoff drainage networks and collectors. Results. At the first stage of the study, we obtained the results of linear approximation of the H data, the calculated values of rain force changes Δ, and the results of linear approximation of the Δ data. The second stage of the study resulted in changes in the hydraulic modes of runoff input during the design period and in 50 years. Conclusion. We experimentally substantiated the possibility to determine the dynamics of rain force changes (at P = 0.33 and with acceptable accuracy) depending on the dynamics of changes in the total annual precipitation. For networks designed and laid 50 years ago, the actual rain force changes will be 9 %. As a result of climate change, water consumption in the calculation periods increased by about 26% with an increase in the total volume of discharged water by 9–10 %.

Dynamics of the status of groundwater in the Polish Lowland: the River Gwda catchment example

The aim of the present study is to monitor changes in the location of the groundwater table in the catchment area of the River Gwda within the Quaternary and Neogene water-bearing level over a 35-year period, between 1981 and 2015. In addition, on account of very diverse total annual precipitation levels in particular parts of the catchment, attempts were made to determine the influence of precipitation on the location of the groundwater table. By correlating groundwater level and meteorological parameters (precipitation), it was discovered that precipitation in the previous year made the largest impact on the groundwater table. Moreover, low precipitation totals in the southern part of the catchment are not discernible in groundwater table fluctuations, which is linked to the location of the observation well within the drainage zone as well as to water ascension from deeper aquifers.

INVESTIGATING WATER STORAGE CHANGES IN IRAN USING GRACE AND CHIRPS DATA IN THE GOOGLE EARTH ENGINE SYSTEM

Water storage in regions with the weather hot and arid or semi-arid such as Iran have many uses. Including these water storage, can be referred to groundwater. Groundwater is one of the sources of sweet waters in the world, and one of the factors is economical and social development. Hence, monitoring its changes in water resources management is of great importance. On the other hand, precipitation is one of the factors directly affecting the water storage level and groundwater level changes. In this study, water storage changes with GRACE satellite data and total annual precipitation with CHIRPS data in the Google Earth Engine system investigated for Iran during 2003–2017. The results obtained from the GRACE satellite data indicate over 10 cm reducing of the water storage levels in Iran during the period between 2008 to 2017. Also, the chart obtained from the CHIRPS data for the total annual precipitation shows that the amount of rainfall since 2008 has decreased in this region.

National Rainfall Index (1998-2003)

The National Rainfal Index (NRI) is defined as the national average of the total annual precipitation weighted by its long-term average (here, the average rainfall covering the years 1986 and 2001). The NRI can be used as an indicator of the quality of the agricultural season. Here, the median of the 1998-2003 period is provided. For more information on the NRI, please see the dedicated Climpag page: http://www.fao.org/nr/climpag/nri/nrilist_en.asp Visit the FAO Aquastat website at: http://www.fao.org/nr/water/aquastat/data/query/index.html?lang=en Agriculture Surface water