A diagnostic study of the impact of El Niño on the precipitation in China

The impact of El Niño on the precipitation in China for different seasons are investigated diagnostically. It is found that El Niño can influence the precipitation in China significantly during its mature phase. In the Northern winter, spring and autumn, the positive precipitation anomalies are found in the southern part of China during the El Niño mature phase. In the Northern summer, the patterns of the precipitation anomalies in the El Niño mature phase are different from those in the other seasons. The negative precipitation anomalies appear in both southern and northern parts of China, while in between around the lower reaches of the Yangtze River and the Huaihe River valleys the precipitation anomalies tend to be positive. In the Northern winter, spring and autumn, the physical process by which El Niño affects the precipitation in the southern part of China can be explained by the features of the circulation anomalies over East Asia during the El Niño mature phase (Zhang et al., 1996). The appearance of an anticyclonic anomaly to the north of the maritime continent in the lower troposphere during the El Niño mature phase intensifies the subtropical high in the western Pacific and makes it shift westward. The associated southwesterly flow is responsible for the positive precipitation anomalies in the southern part of China. In the Northern summer, the intensified western Pacific subtropical high covers the southeastern periphery of China so that the precipitation there becomes less. In addition, the weakening of the Indian monsoon provides less moisture inflow to the northern part of China.     

The variabilities of convective precipitation and large-scale precipitation in southern China for the period 1980–2020

Theoretical and Applied Climatology - In this paper, the spatial and temporal characteristics of convective precipitation (CP) and large-scale precipitation (LSP) in southern China during...     

Variation in the number of days with heavy precipitation on the territory of Russia for the period of 1936–2000

Time variations in the number of days with heavy precipitation based on data of 93 stations on the territory of Russia are analyzed. Time series of precipitation, corrected by the elimination of main systematic errors of their measurement at the level of their diurnal sums, are used, when computing. The diurnal precipitation sum, exceeding the average long-term diurnal precipitation maximum by three times, was taken as the threshold quantitative criterion, defining “the day with heavy precipitation” concept. This value varies within 10–15 mm/day on the territory of Russia. Extremums fluctuate from 5 to 40 mm/day. Absolute values of linear trends of the annual number of days with heavy precipitation are comparatively small, they fluctuate within ±4 days on the whole territory of Russia. In relative terms, these variations are rather significant, reaching ±40% and more of the corresponding average value for 65 years. The comparison of the spatial distribution of characteristics of linear trends of the annual number of days with heavy precipitation and annual precipitation sum indicates their close conformity.     

Space-time kriging of precipitation variability in Turkey for the period 1976–2010

The purpose of this study is to revaluate the changing spatial and temporal trends of precipitation in Turkey. Turkey is located in one of the regions at greatest risk from the potential effects of climate change. Since the 1970s, a decreasing trend in annual precipitation has been observed, in addition to an increasing number of precipitation-related natural hazards such as floods, extreme precipitation, and droughts. An understanding of the temporal and spatial characteristics of precipitation is therefore crucial to hazard management as well as planning and managing water resources, which depend heavily on precipitation. The ordinary kriging method was employed to interpolate precipitation estimates using precipitation records from 228 meteorological stations across the country for the period 1976–2010. A decreasing trend was observed across the Central Anatolian region, except for 1996–2000 which saw an increase in precipitation. However, this same period is identified as the driest year in Eastern and South Eastern Anatolia. The Eastern Black Sea region has the highest precipitation in the country; after 1996, an increase in annual precipitation in this region is observed. An overall reduction is also seen in southwest Turkey, with less variation in precipitation.

     

Impacts of landscape fragmentation on simulated precipitation fields in the Amazonian sub-basin of Ji-Paraná using the Eta model

Numerical studies on impacts of landscape fragmentation due to land use and land cover change (LUCC) on precipitation fields over the Ji-Paraná basin in the Amazon region are carried out using atmospheric Eta model. Experiments consider historical data about LUCC over the basin from 1978 to 2000 and compare simulations under LUCC conditions with simulations under pristine conditions. In agreement with previous observational studies, model results do not show statistically significant impacts on precipitation in the region. Results indicate that variability in precipitation in this region is mainly controlled by large-scale atmospheric characteristics and soil moisture conditions. However, some limitations are identified in the model simulations, mainly associated to the diurnal cycle of precipitation.     

Trends in precipitation parameters in the climate zones of southern Russia (1961–2011)

The data of 19 weather stations for 1961-2011 on total and maximum daily precipitation for the plain (<500 m above the sea level), foothill (500-1000 m), and mountain (1000-2000 m) zones of the south of European Russia are used for analyzing the precipitation regime, investigating its trends, revealing the extremes, and making conclusions on zonal seasonal and annual variations in precipitation.     

Changing structure of the precipitation process during 1960–2005 in Xinjiang, China

Using daily precipitation data spanning 1960–2005 from 51 meteorological stations in Xinjiang province, China, spatial and temporal changes in consecutive maximum wet days in the year, summer, and winter were investigated. Fifteen precipitation extreme indices, which reflect the attributes of consecutive maximum wet days, were defined, and the modified Mann–Kendall test was applied to detect the tendencies, and changes in the indices were evaluated through linear regression with the F test. Results showed that: (1) two consecutive wet days occurred most frequently in the year and summer, and the fractional contributions and precipitation intensities decreased as the duration increased; in winter, one wet day had the maximum possibility, fractional contributions decreased and intensities increased as the duration increased. (2) The possibility of consecutive wet days which had short durations reduced, while those of long durations increased; annual fractional contributions of short durations decreased, while those of long durations increased; summer and winter fractional contribution of all durations decreased first and then increased; the intensities of all durations increased. (3) The wet tendency was identified in Xinjiang; the wet trend in Southern Xinjiang was more significant than Northern Xinjiang in summer, while in winter the wet tendency in Northern Xinjiang was more pronounced.     

Spatial and temporal variability of precipitation in Serbia for the period 1961–2010

Monthly, seasonal and annual sums of precipitation in Serbia were analysed in this paper for the period 1961–2010. Latitude, longitude and altitude of 421 precipitation stations and terrain features in their close environment (slope and aspect of terrain within a radius of 10 km around the station) were used to develop a regression model on which spatial distribution of precipitation was calculated. The spatial distribution of annual, June (maximum values for almost all of the stations) and February (minimum values for almost all of the stations) precipitation is presented. Annual precipitation amounts ranged from 500 to 600 mm to over 1100 mm. June precipitation ranged from 60 to 140 mm and February precipitation from 30 to 100 mm. The validation results expressed as root mean square error (RMSE) for monthly sums ranged from 3.9 mm in October (7.5% of the average precipitation for this month) to 6.2 mm in April (10.4%). For seasonal sums, RMSE ranged from 10.4 mm during autumn (6.1% of the average precipitation for this season) to 20.5 mm during winter (13.4%). On the annual scale, RMSE was 68 mm (9.5% of the average amount of precipitation). We further analysed precipitation trends using Sen’s estimation, while the Mann-Kendall test was used for testing the statistical significance of the trends. For most parts of Serbia, the mean annual precipitation trends fell between −5 and +5 and +5 and +15 mm/decade. June precipitation trends were mainly between −8 and +8 mm/decade. February precipitation trends generally ranged from −3 to +3 mm/decade.

     

Trends of precipitation extremes during 1960–2008 in Xinjiang, the Northwest China

The spatial–temporal variability of the precipitation extremes defined by eight precipitation indices based on daily precipitation dataset was analyzed using the linear regression method and the Mann–Kendall test. The results indicate that increasing trends in the precipitation amount, rainy days, and the intensity of the extreme precipitation were identified at above 70 % of the total rain stations considered in this study, with more than 30 % of them were significant, while most stations show notable decreasing trend in the annual maximum consecutive no-rain days. Significantly increasing trends of the precipitation extremes are observed mainly in the northern Xinjiang and the north of the southern Xinjiang. Most extreme precipitation indices show a potential regime shift starting from the middle of 1980s. The magnitude of the trends is compatible with their pattern of spatial stability. The generally increasing trends in precipitation extremes are found in this study.     

Formation of the anomalous summer precipitation in east China in 2010 and 1998: A comparison of the impacts of two kinds of El Niño

In the summers of 1998 and 2010, severe floods occurred in the middle and lower reaches of the Yangtze River. Although an El Niño event took place preceding each of the summer floods, significant differences between the two summer floods and the two El Niño events were identified. The 1997/98 El Niño is a conventional one with strongest warming in the central-eastern Pacific, whereas the 2009/10 event is an El Niño Modoki with strongest warming in the central Pacific. In this study, summer rainfall anomalies (SRA) in the two years were first compared based on the rainfall data at 160 stations in mainland China, and a significant difference in SRA was found. To understand the underlying mechanism for the difference, the atmospheric circulation systems, particularly the western North Pacific anticyclone (WNPAC), the western Pacific subtropical high (WPSH), and the low-level air flows, were compared in the two years by using the NCEP/NCAR reanalysis data. The results display that the WNPAC was stronger in 2010 than in 1998, along with a northwestward shift, causing weakened southwesterly from the Bay of Bengal to the South China Sea but intensified southerly in eastern China. This resulted in less water vapor transport from the tropical Indian Ocean and the South China Sea but more from the subtropical western Pacific to East Asia. Subsequently, the rainband in 2010 shifted northward. The difference in the WNPAC was caused by the anomalous ascending motion associated with the warming location in the two El Niño events. Furthermore, the role of tropical sea surface temperature (SST) in modulating these differences was investigated by conducting sensitivity experiments using GFDL AM2.1 (Geophysical Fluid Dynamics Laboratory Atmospheric Model). Two experiments were performed, one with the observed monthly SST and the other with June SST persisting through the whole summer. The results suggest that the model well reproduced the primary differences in the atmospheric circulation systems in the two years. It is found that the difference in El Niño events has shaped the rainfall patterns in the two years of 1998 and 2010. At last, the case of 2010 was compared with the composite of historical El Niño Modoki events, and the results indicate that the impact of El Niño Modoki varies from case to case and is more complicated than previously revealed.     

Climatological responses of winter precipitation in Turkey to variability of the North Atlantic Oscillation during the period 1930–2001

Summary Climatological responses of winter (DJFM) precipitation at 78 stations of Turkey to variability of the North Atlantic Oscillation (NAO) were investigated for the period 1930–2001. The analysis was performed with respect to relationships between precipitation and three different NAO indices (NAOIs) and composite precipitation changes corresponding to the extreme phases of the NAOIs, and individual wet conditions and drought events linked to the extreme NAOI events. Main conclusions of the study can be evaluated as follows:(a) The Ponta Delgada–Reykjavik (PD–R) NAOI is superior among the three NAOIs compared, followed by the Lisbon–Stykkisholmur/Reykjavik NAOI, with regards to its ability to control year-to-year variability in winter precipitation series and composite precipitation conditions corresponding to the extreme NAOI phases in Turkey. (b) Variability of winter precipitation at most stations in Turkey is significantly correlated with variability of the three NAOIs. Negative relationships are stronger over the Marmara, the Mediterranean Transition and the Continental Central Anatolia regions, and the Aegean part of the Mediterranean region. (c) Composite precipitation analysis exhibited an apparent opposite anomaly pattern at the majority of stations between the weak and strong phases of the NAOIs. Composite precipitation means corresponding to the weak NAOI phase are explained mostly by wetter than long-term average conditions, whereas composite precipitation responses to the strong NAOI phase mostly produce drier than long-term average conditions. (d) Composite wet (dry) conditions during the weak (strong) phase of the NAOI are significant at about 32% (69%) of 78 stations for the PD–R NAOI, and about 38% (55%) for the L–S(R) NAOI. The dry signals from the strong NAO phases are stronger and show a larger spatial coherence over Turkey. The significant signals are evident in the west, centre and south of the country. (g) Widespread severe droughts in 1943, 1957, 1973, 1974, 1983, 1989, 1990, 1992, 1993 and 1994, and widespread strong wet conditions in 1940–1942, 1956, 1963, 1966, 1969 and 1970 were linked to the extreme high- and low-index events of at least two NAOIs, respectively.     

Time changes of atmospheric precipitation in Russia from the corrected data during 1936–2000

Homogeneous time series of atmospheric precipitation with corrected systematic errors of measurements at 100 stations in Russia for the period of 1936–2000 are obtained. Combined effects are considered of all kinds of systematic errors of standard network precipitation-measuring instruments (the raingauge with the Nifer shield and the Tret’yakov raingauge) on the measured precipitation totals. Comparative analysis is carried out of the measured and corrected long-term mean characteristics of precipitation amounts (annual totals, warm and cold season totals, and different types of precipitation). On the basis of the obtained archives of precipitation homogeneous time series, linear trends are estimated for the period under consideration with estimation of their statistical significance. Schematic charts are plotted and analyzed of time changes in the annual precipitation amounts and in the amounts of different types of precipitation.     

How effective is the new generation of GPM satellite precipitation in characterizing the rainfall variability over Malaysia?

We investigated the potential of the new generation of satellite precipitation product from the Global Precipitation Mission (GPM) to characterize the rainfall in Malaysia. Most satellite precipitation products have limited ability to precisely characterize the high dynamic rainfall variation that occurred at both time and scale in this humid tropical region due to the coarse grid size to meet the physical condition of the smaller land size, sub-continent and islands. Prior to the status quo, an improved satellite precipitation was required to accurately measure the rainfall and its distribution. Subsequently, the newly released of GPM precipitation product at half-hourly and 0.1° resolution served an opportunity to anticipate the aforementioned conflict. Nevertheless, related evidence was not found and therefore, this study made an initiative to fill the gap. A total of 843 rain gauges over east (Borneo) and west Malaysia (Peninsular) were used to evaluate the rainfall the GPM rainfall data. The assessment covered all critical rainy seasons which associated with Asian Monsoon including northeast (Nov. - Feb.), southwest (May - Aug.) and their subsequent inter-monsoon period (Mar. - Apr. & Sep. - Oct.). The ability of GPM to provide quantitative rainfall estimates and qualitative spatial rainfall patterns were analysed. Our results showed that the GPM had good capacity to depict the spatial rainfall patterns in less heterogeneous rainfall patterns (Spearman’s correlation, 0.591 to 0.891) compared to the clustered one (r = 0.368 to 0.721). Rainfall intensity and spatial heterogeneity that is largely driven by seasonal monsoon has significant influence on GPM ability to resolve local rainfall patterns. In quantitative rainfall estimation, large errors can be primarily associated with the rainfall intensity increment. 77% of the error variation can be explained through rainfall intensity particularly the high intensity (> 35 mm d^-1). A strong relationship between GPM rainfall and error was found from heavy (~35 mm d^-1) to violent rain (160 mm d^-1). The output of this study provides reference regarding the performance of GPM data for respective hydrology studies in this region.     

Changes of precipitation pattern in China: 1961–2010

Theoretical and Applied Climatology - Based on the precipitation records of 2474 meteorological stations, this study investigated precipitation characteristics and trends in China from 1961 to...     

Circulation effect: response of precipitation δ18O to the ENSO cycle in monsoon regions of China

Inter-annual variation in the ratio of ¹⁸O to ¹⁶O of precipitation (δ¹⁸O_p) in the monsoon regions of China (MRC, area approximately east of 100°E) has not yet been fully analyzed. Based on an analysis of the relationships between the time series of amount-weighted mean annual δ¹⁸O in precipitation (δ¹⁸O_w) and meteorological variables such as temperature, precipitation as well as atmospheric/oceanic circulation indices, it is recognized that the El Niño-Southern Oscillation (ENSO) cycle appears to be the dominant control on the inter-annual variation in δ¹⁸O_p in the MRC. Further analysis shows that the trade wind plays a role in governing δ¹⁸O_w through affecting the intensity of the different summer monsoon circulations which are closely linked to the weakening (weaker than normal) and strengthening (stronger than normal) of the trade wind and gives the δ¹⁸O_w different values at or over inter-annual timescales. The southwest monsoon (SWM) drives long-distance transport of water vapor from Indian Ocean to the MRC, and along this pathway increasing rainout leads to more negative δ¹⁸O_w via Rayleigh distillation processes. In contrast, the southeast monsoon (SEM), which is consistent with the changes in the strength of the West Pacific subtropical high, drives short-distance water vapor transport from the West Pacific Ocean to the MRC and leads to less negative δ¹⁸O_w. Therefore, the δ¹⁸O_w value directly reflects the differences in influence between the SWM, which is strong when the SE trade wind is strong, and the SEM, which is strong when the SE trade wind is weak. In addition, the South China Sea Monsoon also transports local water vapor as well as plays a role in achieving the synchronization between the δ¹⁸O_w and ENSO. The author thus terms the δ¹⁸O_p rhythm in the MRC the “circulation effect”. In turn, the δ¹⁸O_p variation in the MRC has the potential to provide information on atmospheric circulation and the signal of δ¹⁸O_p recorded in natural archives can then be used to deduce a long-term behavior of the tropical climate system.