August Precipitation Research Articles

Emptying Water Towers? Impacts of Future Climate and Glacier Change on River Discharge in the Northern Tien Shan, Central Asia

Impacts of projected climate and glacier change on river discharge in five glacierized catchments in the northern Tien Shan, Kazakhstan are investigated using a conceptual hydrological model HBV-ETH. Regional climate model PRECIS driven by four different GCM-scenario combinations (HadGEM2.6, HadGEM8.5, A1B using HadCM3Q0 and ECHAM5) is used to develop climate projections. Future changes in glaciation are assessed using the Blatter–Pattyn type higher-order 3D coupled ice flow and mass balance model. All climate scenarios show statistically significant warming in the 21st Century. Neither projects statistically significant change in annual precipitation although HadGEM and HadCM3Q0-driven scenarios show 20–37% reduction in July–August precipitation in 2076–2095 in comparison with 1980–2005. Glaciers are projected to retreat rapidly until the 2050s and stabilize afterwards except under the HadGEM8.5 scenario where retreat continues. Glaciers are projected to lose 38–50% of their volume and 34–39% of their area. Total river discharge in July–August, is projected to decline in catchments with low (2–4%) glacierization by 20–37%. In catchments with high glacierization (16% and over), no significant changes in summer discharge are expected while spring discharge is projected to increase. In catchments with medium glacierization (10–12%), summer discharge is expected to decline under the less aggressive scenarios while flow is sustained under the most aggressive HadGEM8.5 scenario, which generates stronger melt.

Evaluation and Application of Satellite Precipitation Products in Studying the Summer Precipitation Variations over Taiwan

In March 2019, Integrated Multi-satellitE Retrievals for Global Precipitation Measurement (IMERG)-Final v6 (hereafter IMERG6) was released, with data concerning precipitation dating back to June 2000. The National Aeronautics and Space Administration (NASA) has suggested that researchers use IMERG6 to replace the frequently used Tropical Rainfall Measuring Mission (TRMM)-3B42 v7 (hereafter TRMM7), which is expected to cease operation in December 2019. This study aims to evaluate the performance of IMERG6 and TRMM7 in depicting the variations of summer (June, July, and August) precipitation over Taiwan during the period 2000–2017. Data used for the comparison also includes IMERG-Final v5 (hereafter IMERG5) and Global Satellite Mapping of Precipitation for Global Precipitation Measurement (GSMaP)-Gauge v7 (hereafter GSMaP7) during the summers of 2014–2017. Capabilities to apply the four satellite precipitation products (SPPs) in studying summer connective afternoon rainfall (CAR) events, which are the most frequently observed weather patterns in Taiwan, are also examined. Our analyses show that when using more than 400 local rain-gauge observations as a reference base for comparison, IMERG6 outperforms TRMM7 quantitatively and qualitatively, more accurately depicting the variations of the summer precipitation over Taiwan at multiple timescales (including mean status, daily, interannual, and diurnal). IMERG6 also performs better than TRMM7 in capturing the characteristics of CAR activities in Taiwan. These findings highlight that using IMERG6 to replace TRMM7 adds value in studying the spatial-temporal variations of summer precipitation over Taiwan. Furthermore, the analyses also indicated that IMERG6 outperforms IMERG5 and GSMaP7 in the examination of most of the features of summer precipitation over Taiwan during 2014–2017.

Results of studying the effects of biological products on accelerating the decomposition of the crop tailings

The article presents investigations aimed at addressing issues of utilization of the tailings of the crop as a fertilizer. It is known that the by-products of crop production left on the field interfere with the subsequent agricultural operations, and when used as a fertilizer it has a long decomposition period, which is accompanied by putrefactive processes with the release of phenolic compounds which inhibit subsequent plants. To accelerate the process of humification of plant residues, nitrogen-containing fertilizers are used, but recently biological preparations have become widespread, allowing the grain to be completely decomposed in 3–4 months. The authors propose a design of the machine that allows combining the operations of grinding the tailings of the crop with the introduction of bio preparations to speed up the decomposition process. The article presents the results of this machine field tests using various bio preparations: Agrinos 1, Sterniphag SP, humic preparation Ecorost and Biocomplex BTU. According to the linen method, the effect of the preparations on the activity of cellulose-decomposing bacteria was assessed. The dynamics of the activity of biological preparations was not linear and was largely dependent on weather conditions. The hotter temperature and the absence of abundant precipitation in August – September 2018 did not contribute to the active work of the soil biota and in the first report period the best decomposition of linen was in the variant with Biocomplex BTU and Sterniphag, respectively 3.6 and 3.3 %. On the 236th day of the experiment, the picture changed and the variants with Agrinos 1 and Ecorost showed the best performance, the decomposition was 21.2 and 21.9 %, respectively.

Protein content variation in grain of soft spring wheat under the influence of meteorological conditions in the Krasnoyarsk territory

The article analyzes the closeness and links form in long-term data about the protein content in the soft spring wheat grain with the weather conditions of vegetation, which allowed to reveal its variability nature under the influence of meteorological indicators and to outline ways to improve the newly derived varieties. It was found that the protein content variation in the studied samples during the analyzed period was low and the indicator was relatively stable. The most positive effect on the protein content in the grain of soft spring wheat had temperatures in July and August, and on the contrary the precipitation in August had a negative effect on it.

Impact of Nudging Parameters on Dynamical Downscaling over CORDEX East Asia Phase II Domain: The Case of Summer 2003

AbstractIn this paper, the sensitivity of the Weather Research and Forecasting (WRF) Model to the nudging parameters in simulating July–August (JJA) precipitation was assessed with 16 experiments over the Coordinated Regional Climate Downscaling Experiment East Asia II (CORDEX-EA-II) domain. The effects of various nudging parameters in spectral nudging (referred to as SN) and grid nudging (referred to as AN) experiments are examined, including wavenumbers, relaxation time, nudging levels, and nudging variables for SN and relaxation time and nudging variables for AN. Results showed that the applications of spectral nudging and grid nudging methods in WRF simulations can improve the model’s ability to reproduce the JJA extreme precipitation event and accompanying large-scale fields in 2003. The major findings include 1) spectral nudging is superior to grid nudging in simulating heavy rainfall and low-level circulation, 2) nudging both kinematic and thermodynamic variables is efficient to better simulate the JJA precipitation for both SN and AN simulations, 3) in SN simulations, the options of wavenumbers display stronger impact on JJA precipitation if nudging solely the kinematic variables instead of both kinematic and thermodynamic variables over wet subregions, and 4) the free developed large-scale processes associated with small nudging wavenumbers can diminish the improvement from nudging both kinematic and thermodynamic variables in simulating subseasonal variations of precipitation. Overall, the experiment that adopts spectral nudging of both kinematic and thermodynamic variables, 1-h relaxation time, and four or eight nudging wavenumbers captures the characteristics of summer climate more reasonably.

The Application of the SVD Method to Reduce Coupled Model Biases in Seasonal Predictions of Rainfall

AbstractThe large systematic biases in coupled models impact seasonal prediction results. With a motivation to reduce the influence of coupled‐model biases on seasonal predictions, the singular value decomposition method was applied in our study to improve the ability to predict flood season precipitation. Based on the coupled climate model, CAS‐ESM‐C, we conducted ensemble seasonal prediction experiments from 1982 to 2018, with initial conditions provided by the assimilation system. The prediction system was integrated from March to August of each year with a focus on the June to August precipitation in China. The results showed that the prediction skills for anomalous summer precipitation were very low without bias corrections. However, the system effectively predicted the interannual variabilities in large‐scale atmospheric circulation systems that were associated with anomalous summer precipitation. We used the singular value decomposition method to reduce pattern‐dependent precipitation errors by replacing prediction patterns with observation patterns, and the predictive skill for precipitation dramatically improved. The results demonstrated that this correction method is a viable tool to reduce systematic biases in coupled model predictions.

Climate-sensitive height–age models for top height trees in natural and reclaimed oil sands stands in Alberta, Canada

Climate-sensitive height–age models were developed for top height trees of trembling aspen (Populus tremuloides Michx.), jack pine (Pinus banksiana Lamb.), and white spruce (Picea glauca (Moench) Voss) in natural and reclaimed oil sands stands. We used stem analysis data collected from the Athabasca oil sands region in northern Alberta, Canada, and climate data generated by the ClimateWNA model. Height–age trajectories differed between top height trees in natural and reclaimed stands for jack pine and white spruce, but not for trembling aspen. At a given age, white spruce top height trees were taller and jack pine top height trees were shorter in reclaimed stands than those in natural stands, suggesting that it is easier to achieve similar forest productivity for oil sands sites reclaimed with white spruce stands than for sites reclaimed with jack pine stands. The principal climate variables were growing season (May to September) precipitation averaged over the previous 10 years for trembling aspen and jack pine and summer (June to August) precipitation averaged over the previous 10 years for white spruce. These variables had positive effects on the height–age trajectories.

Assessing precipitation, evapotranspiration, andNDVIas controls of U.S. Great Plains plant production

AbstractProductivity throughout the North American Great Plains grasslands is generally considered to be water limited, with the strength of this limitation increasing as precipitation decreases. We hypothesize that cumulative actual evapotranspiration water loss (AET) from April to July is the precipitation‐related variable most correlated to aboveground net primary production (ANPP) in the U.S. Great Plains (GP). We tested this by evaluating the relationship ofANPPtoAET, precipitation, and plant transpiration (Tr). We used multi‐yearANPPdata from five sites ranging from semiarid grasslands in Colorado and Wyoming to mesic grasslands in Nebraska and Kansas, mean annualNRCS ANPP, and satellite‐derived normalized difference vegetation index (NDVI) data. Results from the five sites showed that cumulative April‐to‐JulyAET, precipitation, and Tr were well correlated (R2: 0.54–0.70) to annual changes inANPPfor all but the wettest site.AETand Tr were better correlated to annual changes inANPPcompared to precipitation for the drier sites, and precipitation in August and September had little impact on productivity in drier sites. April‐to‐July cumulative precipitation was best correlated (R2 = 0.63) with interannual variability inANPPin the most mesic site, whileAETand Tr were poorly correlated withANPPat this site. Cumulative growing season (May‐to‐September)NDVI(iNDVI) was strongly correlated with annualANPPat the five sites (R2 = 0.90). UsingiNDVIas a surrogate forANPP, we found that county‐level cumulative April–JulyAETwas more strongly correlated toANPPthan precipitation for more than 80% of theGPcounties, with precipitation tending to perform better in the eastern more mesic portion of theGP. Including the ratio ofAETto potential evapotranspiration (PET) improved the correlation ofAETto bothiNDVIand mean county‐levelNRCS ANPP. Accounting for how different precipitation‐related variables controlANPP(AETin drier portion, precipitation in wetter portion) provides opportunity to develop spatially explicit forecasting ofANPPacross theGPfor enhancing decision‐making by land managers and use of grasslandANPPfor biofuels.

Plant growth and aboveground production respond differently to late-season deluges in a semi-arid grassland.

Semi-arid ecosystems are strongly water-limited and typically quite responsive to changes in precipitation amount and event size. In the C4-dominated shortgrass steppe of the Central US, previous experiments suggest that large rain events more effectively stimulate plant growth and aboveground net primary production (ANPP) than an equal amount of precipitation from smaller events. Responses to naturally occurring large events have generally been consistent with experimental results, with the exception of large events occurring later in the growing season (e.g., August). These have been reported as less effective at increasing net C uptake, despite temperatures optimal for C4 plant growth. Since atmospheric warming is increasing the frequency of statistically extreme rain events (deluges) throughout the growing season, how late-season deluges affect semi-arid ecosystems remains to be resolved. We applied deluges in August of three sizes (1.0-2.5 times average August precipitation) to assess the potential for late-season deluges to stimulate plant growth and ANPP. These late-season deluges led to significant "green-up" of this grassland, with new leaf production, and an increase in flowering of the dominant grass species. Further, these responses increased as deluge size increased, suggesting that larger or multiple deluges may lead to even greater growth responses. However, despite strong plant-level responses, no increase in ANPP was measured. Our results confirm that aboveground plant growth in the C4-dominated shortgrass steppe does respond to late-season deluges; however, if there is an increase in plant biomass, net accumulation aboveground is minimal at this time of year.

Stability Analysis of Tuber Yield and Starch Yield in Mid-Late and Late Maturing Starch Cultivars of Potato (Solanum tuberosum)

Potato is one the of world’s most important crops. It is grown primarily for human consumption but is also used to feed cattle and to produce alcohol and starch. In modern industry, potatoes are a major source of starch. Unpredictable growing conditions strongly influence the cultivation of starch potatoes. One of the best methods for dealing with unpredictable stresses, including those caused by climate change, is cultivation of stable and high yielding cultivars. In the present work, tuber yield and starch yield from a Polish post-registration series of field trials conducted in the years 2013–2016 were analyzed using three different linear mixed models, which can be associated with three different stability measures. It is shown that cultivar Pokusa was the highest yielding and the most stable cultivar in terms of tuber yield, while cultivar Kuras was the most stable and the highest starch yielding cultivar. Moreover, using mixed model factorial regression, it is shown that temperatures in June and August and total precipitation in August had significant influence on tuber yield in the analyzed series of field trials.

Ecological modeling of Cistanche deserticola Y.C. Ma in Alxa, China

Cistanche deserticola Y.C. Ma has long been used for medical purposes in China. It mainly grows in the Chinese provinces of Inner Mongolia, Ningxia, Gansu, and Xinjiang, and the species in the Alxa region of northwest China, have the most distinct qualities. To explain the geoherbalism quality and geographical distribution of C. deserticola, we sampled 65 wild plants in Alxa, determined their echinacoside and acteoside content, and assessed the relationship between the ecological environment and quality of C. deserticola through maximum entropy modeling and geographic information system. We identified the areas suitable for the growth of high-quality C. deserticola species. The regionalization analysis of growth suitability showed that the most influential ecological factors for the growth of C. deserticola are soil type, annual sunshine duration, altitude, temperature seasonality (standard deviation ×100), vegetation type, sunshine duration in the growing season, mean precipitation in August and mean temperature in July. The most suitable areas for growing C. deserticola are southeast of Ejin Banner, central Alxa Right Banner, and north of Alxa Left Banner. The regionalization analysis of quality suitability showeds that the most influential ecological factors for glycosides in C. deserticola are sunshine duration in June, average precipitation in May, and average temperature in March, and the best-quality C. deserticola grows in Dalaihob Town, Ejin Banner. Upon inspection, the result of the experiment reached a high accuracy of 0.994, which indicates that these results are consistent with the actual distribution of C. deserticola in Alxa. The results of this study may serve as a scientific basis for site selection of artificial planting bases for C. deserticola.

Why Was the August Rainfall Pattern in the East Asia–Pacific Ocean Region in 2016 Different from That in 1998 under a Similar Preceding El Niño Background?

AbstractPrevious studies have noted that a strong El Niño event occurring in the preceding winter will result in westward stretching of the western North Pacific subtropical high (WPSH) in the following summer, causing anomalously high precipitation in the Yangtze–Huaihe River basin and anomalously low precipitation in southern China. The winters preceding the summers of 1998 and 2016 featured strong El Niño events, which, along with the El Niño event of 1982, represented the strongest El Niño events since 1950. Under these similar El Niño event backgrounds, the July precipitation anomaly in 2016 was similar to that in 1998, but the August precipitation anomalies in the two years featured opposite distributions. According to the atmospheric circulation analysis, we found that an anomalous ascending motion appeared over the Indian Ocean, while an anomalous descending motion appeared over the Pacific Ocean in August 1998. In addition, the WPSH stretched westward over southern China. However, the atmospheric circulation distribution in August 2016 was the opposite of that in 1998, and the WPSH was divided into eastern and western parts by the anomalous western Pacific cyclone. Further analysis showed that the number of tropical cyclones and typhoons over the western Pacific Ocean increased significantly in August 2016, and their activities were concentrated in the South China Sea (SCS)–southern China region and the western Pacific Ocean, resulting in the division of the WPSH. Therefore, the numbers, tracks, and strengths of tropical cyclones and typhoons were responsible for the differences in the anomalous precipitation distributions over the East Asia–Pacific Ocean region between August 2016 and August 1998.

The Major Interannual Modes of Late-Summer Precipitation Over the Northern China Monsoon Region

ABSTRACTSummer precipitation in the northern China monsoon region (NCMR; 35°–55°N, 108°–135°E) shows significant intraseasonal variability. The early-summer (June) and late-summer (July–August) precipitation patterns show clear differences in their formation mechanisms and the systems that affect them. We used empirical orthogonal function (EOF) analysis to investigate the two leading modes of July–August precipitation over the NCMR and their associated atmospheric circulation anomalies using linear regression. The results show that the first (EOF1) and second (EOF2) modes correspond to a pan-NCMR precipitation variation pattern and a precipitation oscillation pattern between North China (NC) and Northeast China (NEC), respectively. These two modes account for 22.1% and 10.1% of the total variance, respectively. The associated principal components (PCs) both have significant interannual variability with a period of 2–4 years. In addition, PC1 has significant interdecadal variability with a period of 20–30 years. Further analysis suggests that EOF1 and EOF2 clearly have a different relationship with the summer monsoon circulation system. In the positive phase of PC1, the East Asian subtropical westerly jet stream (EAWJS) shows a northward trend with higher intensity than normal the blocking high at mid- to high latitudes is inactive; and the western Pacific subtropical high (WPSH) is located to the north of its normal position. The NCMR is controlled by stronger southerly winds, which cause the convergence of water vapour, favouring more precipitation in this region and vice versa. In the positive phase of PC2, the EAWJS swings to the south of Lake Baikal. Significant positive height anomalies exist from western NC to NEC. Significant negative height anomalies occur to the subtropical northwestern Pacific. This indicates that the cold vortex in Northeast China is inactive, the WPSH tends to be weaker and located to the south of its normal position, and NEC (NC) is dominated by anomalous northeasterly (southeasterly) winds. The convergence (divergence) of water vapour in NC (NEC) favours more (less) precipitation in NC (NEC) and vice versa. Therefore, EOF1 is related to the large-scale circulation anomalies over East Asia and the northwest Pacific in July and August, whereas EOF2 is more closely related to the anomalies in the regional circulation over the NCMR and the subtropical northwestern Pacific.

Decisive Atmospheric Circulation Indices for July–August Precipitation in North China Based on Tree Models

Abstract Numerous circulation indices have been applied in practical climate services focused on regional precipitation. It is beneficial to identify the most influential or decisive indices, but this is difficult with conventional correlation analyses because of the underlying nonlinear mechanisms for precipitation. This paper demonstrates a set of the most influential indices for July–August precipitation in North China, based on the recursive random forest (RRF) method. These decisive circulation indices include the Polar–Eurasia teleconnection, North African subtropical high ridge position, India–Burma trough, Antarctic Oscillation, Northern Hemisphere polar vortex central latitude, North Atlantic Oscillation, and western Pacific subtropical high northern boundary position. Some of these factors have been recognized as directly influential to the regional precipitation, for example, those of the northwestern Pacific subtropical high; however, some are not easily understood. Decision tree (DT) models using these indices were developed to facilitate composite analyses to explain the RRF results. Taking one of the most interesting DT rules as an example, when the North African subtropical high ridge position is sufficiently far south, an anomalous anticyclone occurs in the upstream and an anomalous cyclone in the downstream of North China. This is unfavorable for northward moisture transport in eastern China and hence causes less precipitation in North China than climatology. The present results are not only helpful for improving diagnostic models of regional precipitation, but also enlightening for exploring how global climate change could impact a region by modulating large-scale circulation patterns.

A 400-year reconstruction of spring–summer precipitation and summer low flow from regional tree-ring chronologies in North-Eastern Austria

Atmospheric and streamflow drought back to 1600 were reconstructed with provenance-verified regional Pinus-sylvestris and Pinus-nigra chronologies of earlywood, latewood and ring width, detrended by signal-free regional curve standardization, from the Weinviertel, a dry region in Eastern Austria. Linear regression models with Weinviertel latewood indices as predictor variables were used to estimate regional April–August precipitation totals (R2 = 0.47) and seven-day minimum flow from May to October (best fit: R2 = 0.65). As a novelty, the well-known dendrochronology quality measure “Expressed Population Signal” in a modified version is used to define a scaling factor for empirically estimating the reconstructions’ time-varying reliability.For the detection of drought years in the reconstructed time series, four stages of drought of increasing intensity were defined as conditions below median, and below the 33rd, 20th, and 5th percentile—representing 2-year, 3-year, 5-year and 20-year recurrence intervals.The method for the extension of time series of low flows into the past is applicable in the Weinviertel and can be a useful source of historical hydrological and meteorological information restricted by the uncertainties coming along with proxy records. Of the analyzed period back to 1600, the 19th century is the driest one closely followed by the 18th century, sharing the overall driest period from 1775 to 1813. The phase with the longest continuous atmospheric dry period is 1807–1811. The longest hydrological drought lasted from 1832 to 1839.

Black truffle winter production depends on Mediterranean summer precipitation

The unprecedented price inflation of Black truffles, recently exceeding 5000 Euro kg−1 (in Zurich), is a combined result of increasing global demands and decreasing Mediterranean harvests. Since the effects of long-term irrigation and climate variation on symbiotic fungus-host interaction and the development of belowground microbes are poorly understood, the establishment and maintenance of truffle plantations remains a risky venture. Using 49 years of continuous harvest and climate data from Spain, France and Italy, we demonstrate how truffle production rates, between November and March, significantly rely on previous June–August precipitation totals, whereas too much autumnal rainfall affects the subsequent winter harvest negatively. Despite a complex climate-host-fungus relationship, our findings show that southern European truffle yields can be predicted at highest probability (r = 0.78, t-stat = 5.645, prob = 0.000 01). Moreover, we demonstrate the reliability of national truffle inventories since 1970, and question the timing and dose of many of the currently operating irrigation systems. Finally, our results suggest that Black truffle mycorrhizal colonization of host fine roots, the sexualisation of mycelium, and the formation of peridium are strongly controlled by natural summer rainfall. Recognising the drought-vulnerability of southern Europe’s rapidly growing truffle sector, we encourage a stronger liaison between farmers, politicians and scientists to maintain ecological and economic sustainability under predicted climate change in the Mediterranean basin.

Effect of Summer Arctic Sea Ice on the Reverse August Precipitation Anomaly in Eastern China between 1998 and 2016

AbstractThe 1997/98 and 2015/16 El Niño episodes are regarded as two super–El Niño events and have exerted profound influence on eastern China summer rainfall, as expected. However, on the subseasonal time scale, summer rainfall in these two years shows dramatic diversity, although the characteristics of the two super–El Niños are similar. This study reveals that the rainfall increased (decreased) over central China (~30°–35°N) and decreased (increased) over southeastern China (south of ~25°N) in August 1998 (2016), exhibiting a dipole anomaly pattern over eastern China. Observational analyses indicate that, associated with negative interannual variability of the sea ice area (SIA) over the Barents–Kara Seas (BKS) in July and August, August rainfall shows significantly negative (positive) anomalies over central (southeastern) China. Further analyses reveal that negative SIA anomalies in the BKS induce significantly anomalous upper-level divergence over the polar region, accompanied with anomalous upper-level convergence over the Caspian Sea. The advection of vorticity by these anomalous divergent and convergent flows indicates notable Rossby wave sources near the Caspian Sea, yielding a Rossby wave train propagating eastward to East Asia that causes positive barotropic and baroclinic energy convection near the exit region of the Asian jet stream. The accumulation of perturbation energy in East Asia stimulates the formation of the Pacific–Japan teleconnection, which is favorable for the dipole rainfall anomaly pattern over eastern China. Thus, the positive and negative SIA anomaly over the BKS in 1998 and 2016 may contribute to the reverse August precipitation anomaly in eastern China.

Regional Precipitation Variability Associated with Zonal Movement of Indian Ocean High Pressure System

Several studies have linked ongoing austral winter drying conditions in southwest Western Australia (SWWA) to changes in regional and large scale sea level pressure. As the region bounded by SWWA occupies limited observation of a typical global climate model (GCM), it is not easy to infer the influence of global climate change during the drought in SWWA. In this study, we explore the relationships between early winter (May-Aug) rainfall in Kent river catchment (KRC), Southwestern Australia and Indian Ocean High Pressure system. We construct two objective indices of Indian Ocean High Pressure system (IOHPS), viz., (i) the intensity of Indian Ocean High Pressure (IOHP) and, (ii) the Indian Ocean High Longitude (IOHLN) using National Center of Environmental Prediction mean sea-level pressure (MSLP) reanalysis data. The station data of seasonal rainfall is obtained from Australian Bureau of Meteorology. A representative rainfall index for the KRC was built by averaging the seasonal rainfall three major stations for the period of 1951–2016. Significant inverse relationship is found between early wintertime precipitation in KRC, Southwestern Australia and the IOHP and IOHLN. The IOHPS accounts for more of the early winter (May–August) precipitation variation in KRC than the Southern Oscillation Index (SOI), Southern Annular mode (SAM) and Indian Ocean Dipole (IOD). Our significant findings suggest that strengthening of IOHP and zonal movement of IOHPS has a major contribution in decline of early winter precipitation in KRC.

Climatogenic reaction of Robinia pseudoacacia and Pinus sylvestris within Northern Steppe of Ukraine

Climatic changes in the environment are becoming more noticeable each year. Nonetheless, trends in the reaction of radial growth of forest trees to climate change should be studied in different climatic regions due to significant local variability in climatic conditions which are specific for any particular area. We conducted a correlation analysis of the relationship between the parameters of radial increment of black locust (Robinia pseudoacacia L.) and Scots pine (Pinus sylvestris L.) and meteorological factors of the environment in forest areas located in thenorthern steppe zone of Ukraine. We performed surveys in plantations of black locust, growing in hill slope and interfluve areas and also in sandy terrace plots of Scots pine. Over the period of intense vegetatative growth, black locust requires moisture 50% higher than the norm, and Scots pine 43% higher than the norm. It was determined that maximum increment for the studied plants occurred under the influence of a combination of factors involving reduction of the air temperature by 2.6–2.7 °С below the norm for black locust and by 2.3–2.5 °С for Scots pine. During the period of lower vegetative activity, Scots pine demonstrated lower sensitivity compared to black locust. This paper provides a statistical characteristic of the radial increment of trees in the conditions of changes in meteorological factors which limit their growth. The article provides data on multiple correlation of radial increment of the tree stands in relation to growth locations; demonstrates correlation dependency of radial increment of the studied trees on the precipitation and mean monthly temperatures over different time periods and during particular months. Radial increment of Scots pine exhibited most positive correlation with the total of precipitations throughout the period. For the stands of black locust, correlation coefficients were higher and distinguished by both positive and negative values. In the current increment of this species, a negative correlation relation was observed with the total precipitation in July, August and September, and positive correlation with the remaining months of the year. By contrast, radial increment of black locust and Scots pine positively correlated with air temperature during all time periods and particular months.

Response of Extreme Precipitation to Urbanization over the Netherlands

AbstractKnowledge of the response of extreme precipitation to urbanization is essential to ensure societal preparedness for the extreme events caused by climate change. To quantify this response, this study scales extreme precipitation according to temperature using the statistical quantile regression and binning methods for 231 rain gauges during the period of 1985–2014. The positive 3%–7% scaling rates were found at most stations. The nonstationary return levels of extreme precipitation are investigated using monthly blocks of the maximum daily precipitation, considering the dependency of precipitation on the dewpoint, atmospheric air temperatures, and the North Atlantic Oscillation (NAO) index. Consideration of Coordination of Information on the Environment (CORINE) land-cover types upwind of the stations in different directions classifies stations as urban and nonurban. The return levels for the maximum daily precipitation are greater over urban stations than those over nonurban stations especially after the spring months. This discrepancy was found by 5%–7% larger values in August for all of the classified station types. Analysis of the intensity–duration–frequency curves for urban and nonurban precipitation in August reveals that the assumption of stationarity leads to the underestimation of precipitation extremes due to the sensitivity of extreme precipitation to the nonstationary condition. The study concludes that nonstationary models should be used to estimate the return levels of extreme precipitation by considering the probable covariates such as the dewpoint and atmospheric air temperatures. In addition to the external forces, such as large-scale weather modes, circulation types, and temperature changes that drive extreme precipitation, urbanization could impact extreme precipitation in the Netherlands, particularly for short-duration events.