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The geological structure is rather complicated in Guangdong province, in China. The 10 deep fault belts are mainly oriented in North-East. The North-East fault belts are good channels for deep thermal energy upwelling, which can form a geothermal water reservoir zone. The heating of atmospheric precipitation and surface water by deep rocks is the primary formation mechanism for the hydrothermal resources in the Huangshadong geothermal field. The results show that the two-stage conversion system of flash-binary is more reasonable when the geofluid temperature is higher than 130 °C. With every 10 °C increment of geofluid temperature for flash-binary system, the power output and exergy efficiency increase by 21.6-38.7% and 6.0-13.1%, respectively. The power output and exergy efficiency will decrease by about 20-40% when cooling temperature arising from 15 °C to 25 °C. The research will provide the basic data for the demonstration of geothermal resource exploitation. [ABSTRACT FROM AUTHOR]

Variation characteristics of persistent drought events in Guangdong province are analyzed using 45-year (1961-2005) and 86-station observational precipitation data of Guangdong, and the causes of drought events are discussed from different angles (e.g., atmospheric circulation, sea surface temperature) on the basis of global coverage datasets of sea surface temperature and atmospheric elements. It is found that the occurrence frequency of persistent drought events in Guangdong province is once every 26 months on average, and autumn-winter or winter-spring persistent drought events take up the majority. The persistent drought events possess large scale spatial characteristics. While the 1960s is the most frequent and strongest decade of drought events in the latter half of the 20th century, the occurrence is more frequent and the intensity is stronger in the first five years of the 21st century (2001-2005). This reflects the response of regional extreme climatic events in Guangdong to global climatic change. The atmospheric circulation, sea surface temperature, etc, appear to have different abnormal characteristics when drought events happen in different seasons. The results of this paper provide some good reference information for the drought forecast, especially for the dynamic interpretation of climatic model products. [ABSTRACT FROM AUTHOR]

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In this paper, 1416 conventional ground-based meteorological observation stations on the mainland of China were subdivided into groups of differing spatial density. Data from each subgroup were then used to analyze variations in the tropical cyclone (TC) precipitation statistics derived from each subgroup across the mainland of China (excluding Taiwan, Hong Kong, and Macao), as well as in two regions (east China and south China) and three provinces (Guangdong, Hainan, and hiangxi) between 1981 and 2010. The results showed that for the mainland of China, total precipitation, mean annual precipitation, mean daily precipitation, and its spatial distribution were the same regardless of the spatial density of the stations. However, some minor differences were evident with respect to precipitation extremes and their spatial distribution. Overall, there were no significant variations in the TC precipitation statistics calculated from different station density schemes for the mainland of China. The regional and provincial results showed no significant differences in mean daily precipitation, but this was not the case for the maximum daily precipitation and torrential rain frequency. The maximum daily precipitation calculated from the lower-density station data was slightly less than that based on the higher-density station schemes, and this effect should be taken into consideration when interpreting regional climate statistics. The impact of station density on TC precipitation characteristics was more obvious for Hainan than for Guangdong or hiangxi provinces. In addition, the effects were greater for south China (including Guangxi Zhuang Autonomous region, Guangdong, and Hainan provinces) than east China (including Shandong, hiangsu, Zhejiang, Shanghai, Fujian, Anhui, and hiangxi provinces). Furthermore, the analysis proved that the statistical climatic characteristics began to change significantly when the station spacing was between 40 and 50 km, which are close to the mean spacing for all stations across the mainland of China. Moreover, TC areal precipitation parameters, including mean total areal precipitation and mean daily areal precipitation, also began to change significantly when the spacing was between 40 and 50 km, and were completely different when it was between 100 and 200 km. [ABSTRACT FROM AUTHOR]

Extreme rainfall is common from May to October in south China. This study investigates the key deviation of initial fields on ensemble forecast of a persistent heavy rainfall event from May 20 to 22, 2020 in Guangdong Province, south China by comparing ensemble members with different performances. Based on the rainfall distribution and pattern, two types are selected for analysis compared with the observed precipitation. Through the comparison of the thermal and dynamic fields in the middle and lower layers, it can be found that the thermal difference between the middle and lower layers was an important factor which led to the deviation of precipitation distribution. The dynamic factors also have some effects on the precipitation area although they were not as important as the thermal factors in this case. Correlating accumulated precipitation with atmospheric state variables further corroborates the above conclusion. This study suggests that the uncertainty of the thermal and dynamic factors in the numerical model can have a strong impact on the quantitative skills of heavy rainfall forecasts. [ABSTRACT FROM AUTHOR]

The recent intensification of extreme rainfall events has the potential to aggravate the frequency and intensity of floods in urban areas and signals the urgent need for accurate and high spatiotemporal resolution precipitation data for flood monitoring and warning to alleviate the associated damages. In this context, this paper aims to statistically assess the latest Integrated Multisatellite Retrievals from Global Precipitation Measurement (IMERG) multisatellite constellation and radar quantitative precipitation estimation (QPE) products against dense rain gauge network observations under multiple temporal scales (hourly and 3-hourly) and three spatial scales (grid cumulative, regional, and grid) over the Guangdong-Hong Kong-Macao Greater Bay Area (GBA) in China. The results indicate that (1) at the grid cumulative scale, QPE significantly outperforms IMERG products. The correlation coefficients of QPE (0.83 ≤ CORR ≤ 0.85) are much higher than those of IMERG products (0.35 ≤ CORR ≤ 0.56), the estimation of QPE is generally significantly underestimated (−0.23 ≤ BIAS ≤ -0.16), and the BIAS of IMERG products is larger than that of QPE (−0.24 ≤ BIAS ≤ 0.23). (2) At the regional scale, the accuracy of IMERG products has been significantly improved, with relatively high correlation coefficients (CORR≥0.8) and decreased root mean squared error (RMSE) values (1.18 mm ≤ RMSE ≤ 0.22 mm), and Taylor diagrams visually show that QPE is closer to the gauge observations than are IMERG products. (3) The evaluation results at the grid scale show that both IMERG products and QPE can accurately reflect the spatial distribution of precipitation. Among these results, the spatial distribution of QPE is the most consistent with the actual rainfall, although an obvious underestimation of rainfall occurs in areas with strong rainfall. (4) In terms of detection indicators, the three IMERG products are superior to QPE at capturing rainfall events and have more advantages over QPE in the estimation of instantaneous precipitation, especially for light rain events. However, QPE has better detection effects for rainfall events under rainstorm and heavy rainstorm events, indicating the hydrologic utility of this product. Among the three IMERG products, the IMERG Early Run (ER) product has the advantages of a short lag time and high accuracy, and it has the potential to be applied in flood forecasting. Future studies should improve IMERG algorithms and promote the application of QPE in urban rainstorm and flood research. • The quality of the IMERG products and radar quantitative precipitation estimation (QPE) is compared over the Guangdong-Hong Kong-Macao Greater Bay Area (GBA) in China. • The dense rain gauge network observations are used for evaluation in the GBA. • The evaluation of multisource precipitation products under different temporal and spatial scales has different results and effects. [ABSTRACT FROM AUTHOR]

Copyright of Advances in Atmospheric Sciences is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The climatic characteristics of the precipitation in Guangdong province over the past 50 years were analyzed based on the daily rainfall datasets of 86 stations from 1961 to 2010. The rainfall was divided into five categories according to its intensity, and their spatiotemporal characteristics and variation trends were investigated. The annual rainfall amount was within 1,500 to 2,000 mm over most parts of Guangdong, but substantial differences of rainfall amount and rainy days were found among different parts of the province. There were many rainy days in the dry seasons (October to March), but the daily rainfall amounts are small. The rainy seasons (April to September) have not only many rainy days but also heavy daily rainfall amounts. The spatial distributions of light rainy days (1 mm 100 mm) are generally concentrated in three regions, Qingyuan, Yangjiang, and Haifeng/Lufeng. The average rainfall amount for rainy days increases form the north to the south of Guangdong, while decreasing as the rainfall intensity increases. The contributions from light, moderate and heavy rain to the total rainfall decreases form the north to the south. The annual rainy days show a decreasing trend in the past 50 years. The light rainy days decreased significantly while the heavy, rainstorm and downpour rainy days increased slightly. The annual total rainfall amount increased over the past 50 years, which was contributed by heavy, rainstorm and downpour rains, while the contribution from light and moderate rains decreased. [ABSTRACT FROM AUTHOR]

ABSTRACT The temporal and spatial trends of four climate extreme indices for Guangdong Province of China were calculated based on observed daily precipitation, daily maximum, and daily minimum temperatures at 24 weather stations as well as the frequency of typhoon events during the period of 1957-2013. An integrated extreme climatic index ( IECI) was derived from four individual climate extreme indices (high temperature days ( Htd), low temperature days ( Ltd), intensive precipitation days ( Ipd) and number of typhoon events ( TT)), considering their weights using an information theory model. A simple linear regression model was utilized to analyze the spatiotemporal trends of the climate extremes. The correlation analysis between the above extreme climatic indices and the socioeconomic losses [affected area of crops ( AAC), direct losses of the economy ( DLE), and affected population ( AP)] was calculated. The results indicate that Htd increased while Ltd decreased significantly at the 5% significance level. By contrast, there were no significant long-term changes in Ipd and TT. The rate of change of IECI was 0.006 per decade and no long-term trend was detected in IECI. Spatially, a positive trend was observed in the Yuexi River Basin ( YXRB) for Ipd, while a negative trend was found in the East River Basin ( ERB). Ltd followed an opposite spatial pattern to that of Htd. Extreme temperature days occurred more frequently in the Pearl River Delta ( PRD) than in other parts of Guangdong Province. Regions with positive IECI rates of change were mostly in the YXRB, the coastal area of the Yuedong River Basin ( YDRB) and the northern and southern part of the ERB. The correlation coefficients between IECI and AAC, DLE, and AP are 0.375, 0.424 and 0.603, respectively. In general, IECI correlated more strongly with the loss indices caused by extreme climatic events than did the four individual extreme climatic indices. [ABSTRACT FROM AUTHOR]

In this study, we thoroughly analyzed spatial and temporal distributions of runoff and their relation with precipitation changes based on monthly runoff dataset at 25 hydrological stations and monthly precipitation at 127 stations in Guangdong Province, south China. Trends of the runoff and precipitation are detected using Mann-Kendall trend test technique. Correlations between runoff and precipitation are tested using Spearman's and Pearson's correlation coefficients. The results indicate that: (1) annual maximum monthly runoff is mainly in decreasing tendency and significant increasing annual minimum monthly runoff is observed in the northern and eastern Guangdong Province. In addition, annual mean runoff is observed to be increasing at the stations located in the West and North Rivers and the coastal region; (2) analysis of seasonal runoff variations indicates increasing runoff in spring, autumn and winter. Wherein, significant increase of runoff is found at 8 stations and only 3 stations are dominated by decreasing runoff in winter; (3) runoff changes of the Guangdong Province are mainly the results of precipitation changes. The Guangdong Province is wetter in winter, spring and autumn. Summer is coming to be drier as reflected by decreasing runoff in the season; (4) both precipitation change and water reservoirs also play important roles in the increasing of annual minimum monthly streamflow. Seasonal shifts of runoff variations may pose new challenges for the water resources management under the influences of climate changes and intensifying human activities. [ABSTRACT FROM AUTHOR]

The Climate Forecast Systems (CFS) datasets provided by National Centers for Environmental Prediction (NCEP), which cover the time from 1981 to 2008, can be used to forecast atmospheric circulation nine months ahead. Compared with the NCEP datasets, CFS datasets successfully simulate many major features of the Asian monsoon circulation systems and exhibit reasonably high skill in simulating and predicting ENSO events. Based on the CFS forecasting results, a downscaling method of Optimal Subset Regression (OSR) and mean generational function model of multiple variables are used to forecast seasonal precipitation in Guangdong. After statistical analysis tests, sea level pressure, wind and geopotential height field are made predictors. Although the results are unstable in some individual seasons, both the OSR and multivariate mean generational function model can provide good forecasting as operational tests score more than sixty points. CFS datasets are available and updated in real time, as compared with the NCEP dataset. The downscaling forecast method based on the CFS datasets can predict three seasons of seasonal precipitation in Guangdong, enriching traditional statistical methods. However, its forecasting stability needs to be improved. [ABSTRACT FROM AUTHOR]

Groundwater reservoir ( GR) of both local precipitation and surplus water transferred from the Han River Basin is an effective method to prevent further lowering of the groundwater table. In this study, when the different volumes of infiltration water from the fuzzy mathematical analysis were input in the simulation, the rate at which the groundwater table rose ranged from 1.47 to 3.45 m/a. The effective storage rate ( ESR) values of GR and the local reservoir was calculated, and ranged from 80.50 to 90.95% and from 49.66 to 80.90%, respectively. In GR, the ESR decreased as artificial recharge increased. Comparison of the ESR values between local reservoir and GR showed that if the volume of artificial recharge water available was < 7.86 × 108 m3/a, then GR was a better storage method than the local reservoir. According to our results, this situation would occur 80.30% of the time. [ABSTRACT FROM AUTHOR]

Guangdong suffered from the most serious precipitation of its corresponding time during the dragon-boat race of 2008 since 1951. The relationship between the strong dragon-boat precipitation in 2008 and atmospheric low-frequency oscillation was analyzed with the methods of wavelet analysis, correlation and Lanczos filter. Results showed that the daily rainfall exhibits a significant 7 to 12-day quasi-periodic oscillation (namely quasi-10-day oscillation) during the precipitation, the daily 500 hPa height over Guangdong exhibits a significant 8 to 13-day quasi-periodic oscillation, and the daily 850 hPa zonal wind averaged over the north of the South China Sea presents a significant quasi-12-day periodic oscillation. The Guangdong rainfall during the annually first rainy season is most closely correlated with monsoon over the north of South China Sea, and less closely with an upper-level trough at 500 hPa affecting Guangdong. Strong monsoon surges induced two heavy rainfall processes in 2008. The monsoon surges joined with a westward-propagating quasi-10-day oscillation that originated from the central Pacific and was enhanced in a strong convective region east of the Philippines and a northward-propagating monsoon that originated from the southern South China Sea was enhanced. With composite analysis of typical phases, the common evolution characteristics of atmospheric circulation of the two heavy rainfall processes were analyzed for different phases. These features can be used as reference for medium prediction of heavy rainfall processes in Guangdong. [ABSTRACT FROM AUTHOR]

Changing characteristics of hazardous weather-related events have been arousing considerable public interest in recent years. Guangdong is an economically developed province in China and is prone to natural hazards. Using monthly precipitation data covering a period of 1956-2008 from 127 rain gauge stations, the probabilistic behaviors of SPI-based droughts were investigated with copulas functions. Results indicated a higher risk of droughts along the coastal regions and the western Guangdong, particularly the Pearl River Delta (PRD) region. Joint probabilities of droughts with higher intensity and longer duration were found to have relatively even geographical distribution across Guangdong. The northern parts of Guangdong are higher in altitude and have a lower risk of droughts. Identification of regions characterized by droughts of different severity and durations across Guangdong is important for scientific management of water resource and agricultural activities and also the development of social resilience under the influence of climate changes. [ABSTRACT FROM AUTHOR]