Browsing by Subject "PRECIPITATION"

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  • Manninen, Antti J.; O'Connor, Ewan J.; Vakkari, Ville; Petäjä, Tuukka (2016)
    Current commercially available Doppler lidars provide an economical and robust solution for measuring vertical and horizontal wind velocities, together with the ability to provide co- and cross-polarised backscatter profiles. The high temporal resolution of these instruments allows turbulent properties to be obtained from studying the variation in radial velocities. However, the instrument specifications mean that certain characteristics, especially the background noise behaviour, become a limiting factor for the instrument sensitivity in regions where the aerosol load is low. Turbulent calculations require an accurate estimate of the contribution from velocity uncertainty estimates, which are directly related to the signal-to-noise ratio. Any bias in the signal-to-noise ratio will propagate through as a bias in turbulent properties. In this paper we present a method to correct for artefacts in the background noise behaviour of commercially available Doppler lidars and reduce the signal-to-noise ratio threshold used to discriminate between noise, and cloud or aerosol signals. We show that, for Doppler lidars operating continuously at a number of locations in Finland, the data availability can be increased by as much as 50% after performing this background correction and subsequent reduction in the threshold. The reduction in bias also greatly improves subsequent calculations of turbulent properties in weak signal regimes.
  • Oksanen, Otto; Zliobaite, Indre; Saarinen, Juha; Lawing, A. Michelle; Fortelius, Mikael (2019)
    Aim The links between geo- and biodiversity, postulated by Humboldt, can now be made quantitative. Species are adapted to their environments and interact with their environments by having pertinent functional traits. We aim to improve global ecometric models using functional traits for estimating palaeoclimate and apply models to Pleistocene fauna for palaeoclimate interpretation. Location Global at present day, Pleistocene of Europe for fossil data analysis. Taxa Artiodactyla, Perissodactyla, Proboscidea and Primates. Methods We quantify functional traits of large mammal communities and develop statistical models linking trait distributions to local climate at present day. We apply these models to the fossil record, survey functional traits, and quantitatively estimate climates of the past. This approach to analysing functional relationships between faunal communities and their environments is called ecometrics. Results and main conclusions Here, we present new global ecometric models for estimating mean annual and minimum temperature from dental traits of present day mammalian communities. We also present refined models for predicting net primary productivity. Using dental ecometric models, we produce palaeoclimate estimates for 50 Pleistocene fossil localities in Europe and show that the estimates are consistent with trends derived from other proxies, especially for minimum temperatures, which we hypothesize to be ecologically limiting. Our new temperature models allow us to trace the distribution of freezing and non-freezing ecosystems in the recent past, opening new perspectives on the evolution of cold-adaptive biota as the Pleistocene cooling progressed.
  • Jylhä, Kirsti; Laapas, Mikko; Ruosteenoja, Kimmo; Arvola, Lauri; Drebs, Achim; Kersalo, Juha; Saku, Seppo; Gregow, Hilppa; Hannula, Henna-Reetta; Pirinen, Pentti (2014)
  • Galbrun, Esther; Tang, Hui; Fortelius, Mikael; Zliobaite, Indre (2018)
    As organisms are adapted to their environments, assemblages of taxa can be used to describe environments in the present and in the past. Here, we use a data mining method, namely redescription mining, to discover and analyze patterns of association between large herbivorous mammals and their environments via their functional traits. We focus on functional properties of animal teeth, characterized using a recently developed dental trait scoring scheme. The teeth of herbivorous mammals serve as an interface to obtain energy from food, and are therefore expected to match the types of plant food available in their environment. Hence, dental traits are expected to carry a signal of environmental conditions. We analyze a global compilation of occurrences of large herbivorous mammals and of bioclimatic conditions. We identify common patterns of association between dental traits distributions and bioclimatic conditions and discuss their implications. Each pattern can be considered as a computational biome. Our analysis distinguishes three global zones, which we refer to as the boreal-temperate moist zone, the tropical moist zone and the tropical-subtropical dry zone. The boreal-temperate moist zone is mainly characterized by seasonal cold temperatures, a lack of hypsodonty and a high share of species with obtuse lophs. The tropical moist zone is mainly characterized by high temperatures, high isothermality, abundant precipitation and a high share of species with acute rather than obtuse lophs. Finally, the tropical dry zone is mainly characterized by a high seasonality of temperatures and precipitation, as well as high hypsodonty and horizodonty. We find that the dental traits signature of African rain forests is quite different from the signature of climatically similar sites in North America and Asia, where hypsodont species and species with obtuse lophs are mostly absent. In terms of climate and dental signatures, the African seasonal tropics share many similarities with Central-South Asian sites. Interestingly, the Tibetan plateau is covered both by redescriptions from the tropical-subtropical dry group and by redescriptions from the boreal-temperate moist group, suggesting a combination of features from both zones in its dental traits and climate.
  • Žliobaite, Indrė (2019)
    Fossils are the remains organisms from earlier geological periods preserved in sedimentary rock. The global fossil record documents and characterizes the evidence about organisms that existed at different times and places during the Earth's history. One of the major directions in computational analysis of such data is to reconstruct environmental conditions and track climate changes over millions of years. Distribution of fossil animals in space and time make informative features for such modeling, yet concept drift presents one of the main computational challenges. As species continuously go extinct and new species originate, animal communities today are different from the communities of the past, and the communities at different times in the past are different from each other. The fossil record is continuously increasing as new fossils and localities are being discovered, but it is not possible to observe or measure their environmental contexts directly, because the time is gone. Labeled data linking organisms to climate is available only for the present day, where climatic conditions can be measured. The approach is to train models on the present day and use them to predict climatic conditions over the past. But since species representation is continuously changing, transfer learning approaches are needed to make models applicable and climate estimates to be comparable across geological times. Here we discuss predictive modeling settings for such paleoclimate reconstruction from the fossil record. We compare and experimentally analyze three baseline approaches for predictive paleoclimate reconstruction: (1) averaging over habitats of species, (2) using presence-absence of species as features, and (3) using functional characteristics of species communities as features. Our experiments on the present day African data and a case study on the fossil data from the Turkana Basin over the last 7 million of years suggest that presence-absence approaches are the most accurate over short time horizons, while species community approaches, also known as ecometrics, are the most informative over longer time horizons when, due to ongoing evolution, taxonomic relations between the present day and fossil species become more and more uncertain.
  • Bradter, Ute; Johnston, Alison; Hochachka, Wesley M.; Soultan, Alaaeldin; Brommer, Jon E.; Gaget, Elie; Kalas, John Atle; Lehikoinen, Aleksi; Lindstrom, Ake; Piirainen, Sirke; Pavon-Jordan, Diego; Part, Tomas; Oien, Ingar Jostein; Sandercock, Brett K. (2022)
    The relationships between species abundance or occurrence versus spatial variation in climate are commonly used in species distribution models to forecast future distributions. Under "space-for-time substitution", the effects of climate variation on species are assumed to be equivalent in both space and time. Two unresolved issues of space-for-time substitution are the time period for species' responses and also the relative contributions of rapid- versus slow reactions in shaping spatial and temporal responses to climate change. To test the assumption of equivalence, we used a new approach of climate decomposition to separate variation in temperature and precipitation in Fennoscandia into spatial, temporal, and spatiotemporal components over a 23-year period (1996-2018). We compiled information on land cover, topography, and six components of climate for 1756 fixed route surveys, and we modeled annual counts of 39 bird species breeding in the mountains of Fennoscandia. Local abundance of breeding birds was associated with the spatial components of climate as expected, but the temporal and spatiotemporal climatic variation from the current and previous breeding seasons were also important. The directions of the effects of the three climate components differed within and among species, suggesting that species can respond both rapidly and slowly to climate variation and that the responses represent different ecological processes. Thus, the assumption of equivalent species' response to spatial and temporal variation in climate was seldom met in our study system. Consequently, for the majority of our species, space-for-time substitution may only be applicable once the slow species' responses to a changing climate have occurred, whereas forecasts for the near future need to accommodate the temporal components of climate variation. However, appropriate forecast horizons for space-for-time substitution are rarely considered and may be difficult to reliably identify. Accurately predicting change is challenging because multiple ecological processes affect species distributions at different temporal scales.
  • Granberg, F.; Byggmästar, J.; Nordlund, K. (2020)
    The understanding of materials' behaviour during continuous irradiation is of great interest for utilizing materials in environments where harsh radiation is present, like nuclear power plants. Most power plants, both current and future ones, are based, at least partially, on Fe or FeCr alloys. In this study, we investigate the response of BCC Fe and several FeCr alloys to massively overlapping cascades. The effect of the added chromium on the defect accumulation and defect evolution was studied. Both a bulk setup, for observing the evolution deep inside the material far from grain boundaries and surfaces, and a setup with a nearby open surface, to investigate the effect of a permanent defect sink, were studied. We found that the primary defect production is similar in all materials, and also the build-up before serious overlap is comparable. When cascade overlap starts, we found that different sized clusters are formed in the different materials, depending on the setup. The defect cluster evolution was followed and could be related to the dislocation reactions in the materials. We found that the irradiation mixing was specific to the different chromium concentrations, the low chromium-containing alloy showed ordering, whereas the highest chromium-containing sample showed segregation. (C) 2019 The Authors. Published by Elsevier B.V.
  • Breneman, A. W.; Halford, A. J.; Millan, R. M.; Woodger, L. A.; Zhang, X. -J.; Sandhu, J. K.; Capannolo, L.; Li, W.; Ma, Q.; Cully, C. M.; Murphy, K. R.; Brito, T.; Elliott, S. S. (2020)
    We present observations of similar to 10-60 min solar wind dynamic pressure structures that drive large-scale coherent similar to 20-100 keV electron loss from the outer radiation belt. A combination of simultaneous satellite and Balloon Array for Radiation-belt Relativistic Electron Losses (BARREL) observations on 11-12 January 2014 shows a close association between the pressure structures and precipitation as inferred from BARREL X-rays. Specifically, the structures drive radial ExB transport of electrons up to 1 Earth radii, modulating the free electron energy available for low-frequency plasmaspheric hiss growth, and subsequent hiss-induced loss cone scattering. The dynamic pressure structures, originating near the Sun and commonly observed advecting with the solar wind, are thus able to switch on scattering loss of electrons by hiss over a large spatial scale. Our results provide a direct link between solar wind pressure fluctuations and modulation of electron loss from the outer radiation belt and may explain long-period modulations and large-scale coherence of X-rays commonly observed in the BARREL data set. Plain Language Summary The Earth's low-density magnetosphere is a region of enclosed magnetic field lines that contains energetic electrons ranging from eV to MeV energies. These populations can be greatly enhanced in response to solar driving. Following enhancements, energetic electron populations are depleted on timescales of hours to days by various processes. One important depletion process occurs when an electromagnetic plasma wave called plasmaspheric hiss, which exists within a high plasma density region called the plasmasphere and its (occasional) radial extension called the plume, scatters energetic electrons into the atmosphere. In this paper, we show that these hiss waves can be switched on by compressions of the magnetosphere which occur in response to similar to 1 hr long pressure structures in the solar wind. These structures originate at or near the Sun and are very common in the solar wind at 1 AU. The newly excited hiss waves scatter electrons into the atmosphere where they are observed on balloon-borne X-ray detectors. Our results suggest that magnetospheric models that predict the loss of electrons from hiss waves may be improved by consideration of solar wind pressure-driven dynamics.
  • Teerikorpi, Pauliina Elisabet; Sirkiä, Paivi Maria; Laaksonen, Toni (2018)
    Environmental shifts may induce sudden reversals in the relative quality or sexual attractiveness of mates (ecological crossovers) leading to non-directional sexual selection. Studies on such ecological crossovers induced by environmental shifts during the nonbreeding season are particularly rare. We studied the interactive effects between nonbreeding conditions and a male white wing patch on the breeding success of breeding pairs and the local survival of females in a migratory passerine population over a 32-year period. After dry winters, females paired with large-patched males were more likely to survive than those paired with small-patched males, and vice versa after moist winters. Moreover, after dry winters, large-patched males succeeded in attracting females that laid large clutches, while small-patched males bred with females that laid small clutches, and vice versa after moist winters. This phenomenon led to a difference in fledgling numbers only during years with dry winters and high precipitation during the breeding season. The selection on this male trait and its signaling value to females thus depended on a complex interaction between conditions both at the nonbreeding and breeding grounds. We show that it is important to consider conditions during the nonbreeding season when examining the effects of sexual ornaments on fitness.
  • Silvonen, Soila; Niemistö, Juha; Myyryläinen, Jerry Olavi; Kinnunen, Outi Kaarina; Huotari, Simo; Nurminen, Leena; Horppila, Jukka; Jilbert, Tom (2022)
    Hypolimnetic withdrawal provides a way to remove phosphorus (P) from eutrophic lakes, but the method is still rarely combined with water treatment for capturing this P. Thus, little is known about the chemical interactions of P and other elements upon the treatment of hypolimnetic lake water. We investigated these chemical processes in a hypolimnetic withdrawal and treatment system (HWTS) in which hypolimnetic water is first led into a treatment unit for dissolved P (dP) precipitation and subsequently filtered before being circulated back into the lake. We studied three different field-scale treatment unit setups and water treatments (aeration only, aeration + calcium hydroxide (Ca(OH)(2)), aeration + biopolymer) to compare their effectiveness for dP removal and the geochemical properties of the resulting precipitate. In the aeration only treatment, most of the dissolved iron (dFe) (91-95%) and dP (71-91%) were removed when sand filters were used. The addition of Ca (OH)(2) and biopolymer enhanced Fe flocculation, leading to more effective removal of dFe (d99-100%) and dP (88-95%) from the water. Regardless of the water treatment method, dP was always precipitated by amorphous Fe oxides formed in the hypolimnetic water upon aeration. The P content of the resulting precipitates was somewhat lower than expected (2 439-4 145 mg kg(-1)), which may be linked to chemical interactions between Fe and other components in the hypolimnetic water, such as organic matter. The precipitates also contained some heavy metals such as copper and zinc. We conclude that all the tested water treatments were effective in removing dP from hypolimnetic water, but the enhanced precipitation by the addition of treatment chemicals is beneficial when a mesh or other rapid filtration method is used, or when there is only negligible accumulation of dFe in the hypolimnion of the treated lake. Depending on the water treatment method and the water chemistry of the treated lake, the precipitate may have potential for nutrient recycling, although it may sometimes require preliminary processing to enhance bioavailability for plants and to reduce the concentration of heavy metals.
  • Zhang, Rui; Maltari, Riku; Guo, Ming; Kontro, Jussi; Eronen, Aleksi; Repo, Timo (2020)
    More than 90 % of global lignin production comes from Kraft pulp mills but due to shortage of economical viable methods to valorise lignin, it is commonly burned for energy. Therefore, finding new routes to utilize Kraft lignin (KL) as a renewable raw material for the chemical industry is of significant economic and environmental importance. Herein we report a novel, two-step procedure for facile synthesis of vanillin from technical KL by combining solvent fractionation and catalytic oxidation reaction. From the studied green solvents, 1-propanol was the most attractive for one-step, single solvent fractionation as it afforded uniform, low molecular weight lignin fractions (Mw=1300 g·mol−1, Mn=580 g·mol−1) with yield of 46 wt%. Using this homogeneous lignin as a raw material, CuSO4 catalyzed oxidation reaction proceeds smoothly, and under optimized conditions a high vanillin yield of 10.9 wt% was achieved. The method reported herein is promising as it facilitates straightforward and high yield vanillin synthesis from commercially available technical KL.
  • Aikio, A. T.; Pitkanen, T.; Honkonen, I.; Palmroth, M.; Amm, O. (2013)
  • Moiseev, Dmitry; Lautaportti, Susanna; Alku, Laura; Tabakova, Ksenia; O'Connor, Ewan; Leskinen, Matti; Kulmala, Markku (2019)
    Abstract: Eleven years of dual-polarization weather radar data, complemented by satellite and lidar observations, were used to investigate the origin of areas of localized intensification of precipitation spotted in the vicinity of Helsinki-Vantaa airport. It was observed that existing precipitation is enhanced locally on spatial scales from a few kilometers to several tens of kilometers. The precipitation intensity in these localized areas was 6-14 times higher than the background large-scale precipitation rate. Surface observations and dual-polarization radar data indicate that snowflakes within the ice portion of the falling precipitation in the intensification regions are larger and more isotropic than in the surrounding precipitation. There appears to be an increase in the ice particle number concentration within the intensification region. The observed events were linked to arriving or departing air traffic. We advocate that the mechanism responsible for intensification is aircraft-produced ice particles boosting the aggregation growth of snowflakes. Plain Language Summary: By analyzing 11 years of dual-polarization weather radar observations in the Helsinki region, we have discovered that airplanes landing in or departing from the Helsinki-Vantaa airport could locally increase precipitation rate by as much as 14 times. The observed phenomenon is related to the hole-punch clouds, which are also forming with the help of airplanes. The reported observations allow us to have a better understanding of precipitation formation processes that take place in ice and mixed phase clouds. They show that falling ice crystals from upper clouds could seed lower clouds and therefore increase rain or snowfall intensity through the process called snowflake aggregation. During snowflake aggregation bigger faster falling particles are formed by ice particles colliding and sticking together.
  • Räty, Olle; Räisänen, Jouni; Bosshard, Thomas; Donnelly, Chantal (2018)
    In this paper, the ability of two joint bias correction algorithms to adjust biases in daily mean temperature and precipitation is compared against two univariate quantile mapping methods when constructing projections from years 1981-2010 to early (2011-2040) and late (2061-2090) 21st century periods. Using both climate model simulations and the corresponding hydrological model simulations as proxies for the future in a pseudo-reality framework, these methods are inter-compared in a cross-validation manner in order to assess to what extent the more sophisticated methods have added value, particularly from the hydrological modeling perspective. By design, bi-variate bias correction methods improve the inter-variable relationships in the baseline period. Cross-validation results show, however, that both in the early and late 21st century conditions the additional benefit of using bi-variate bias correction methods is not obvious, as univariate methods have a comparable performance. From the evaluated hydrological variables, the added value is most clearly seen in the simulated snow water equivalent. Although not having the best performance in adjusting the temperature and precipitation distributions, quantile mapping applied as a delta change method performs well from the hydrological modeling point of view, particularly in the early 21st century conditions. This suggests that retaining the observed correlation structures of temperature and precipitation might in some cases be sufficient for simulating future hydrological climate change impacts.
  • Uusheimo, Sari; Tulonen, Tiina; Huotari, Jussi; Arvola, Lauri (2020)
    Agriculture contributes significantly to phosphorus and nitrogen loading in southern Finland. Climate change with higher winter air temperatures and precipitation may also promote loading increase further. We analyzed long-term nutrient trends (2001-2020) based on year-round weekly water sampling and daily weather data from a boreal small agricultural watershed. In addition, nutrient retention was studied in a constructed sedimentation pond system for two years. We did not find any statistically significant trends in weather conditions (temperature, precipitation, discharge, snow depth) except for an increase in discharge in March. Increasing trends in annual concentrations were found for nitrate, phosphate, and total phosphorus and total nitrogen. In fact, phosphate concentration increased in every season and nitrate concentration in other seasons except in autumn. Total phosphorus and total nitrogen concentrations increased in winter as well and total phosphorus also in summer. Increasing annual loading trend was found for total phosphorus, phosphate, and nitrate. Increasing winter loading was found for nitrate and total nitrogen, but phosphate loading increased in winter, spring, and summer. In the pond system, annual retention of total nitrogen was 1.9-4.8% and that of phosphorus 4.3-6.9%. In addition, 25-40% of suspended solids was sedimented in the ponds. Our results suggest that even small ponds can be utilized to decrease nutrient and material transport, but their retention efficiency varies between years. We conclude that nutrient loading from small boreal agricultural catchments, especially in wintertime, has already increased and is likely to increase even further in the future due to climate change. Thus, the need for new management tools to reduce loading from boreal agricultural lands becomes even more acute.
  • Marke, Tobias; Crewell, Susanne; Schemann, Vera; Schween, Jan H.; Tuononen, Minttu (2018)
    Low-level-jet (LLJ) periods are investigated by exploiting a long-termrecord of ground-based remote sensing Doppler wind lidar measurements supported by tower observations and surface flux measurements at the Julich Observatory for Cloud Evolution (JOYCE), a midlatitude site in western Germany. LLJs were found 13% of the time during continuous observations over more than 4 yr. The climatological behavior of the LLJs shows a prevailing nighttime appearance of the jets, with a median height of 375 m and a median wind speed of 8.8 ms(-1) at the jet nose. Significant turbulence below the jet nose only occurs for high bulk wind shear, which is an important parameter for describing the turbulent characteristics of the jets. The numerous LLJs (16% of all jets) in the range of wind-turbine rotor heights below 200 m demonstrate the importance of LLJs and the associated intermittent turbulence for wind-energy applications. Also, a decrease in surface fluxes and an accumulation of carbon dioxide are observed if LLJs are present. A comprehensive analysis of an LLJ case shows the influence of the surrounding topography, dominated by an open pit mine and a 200-m-high hill, on the wind observed at JOYCE. High-resolution large-eddy simulations that complement the observations show that the spatial distribution of the wind field exhibits variations connected with the orographic flow depending on the wind direction, causing high variability in the long-term measurements of the vertical velocity.
  • Lawson, John; Schultz, David M.; Vaughan, Geraint; Kirshbaum, Daniel J. (2013)
  • Kalliokoski, Milla; Kilpua, Emilia; Osmane, Adnane; Jaynes, Allison N.; Turner, Drew L.; George, Harriet; Turc, Lucile; Palmroth, Minna (2022)
    Coronal mass ejection driven sheath regions are one of the key drivers of drastic outer radiation belt responses. The response can however be significantly different based on the sheath properties and the associated inner magnetospheric wave activity. We performed two case studies on the effects of sheaths on outer belt electrons of various energies using data from the Van Allen Probes. One sheath caused a major geomagnetic disturbance and the other had only a minor impact. We especially investigated the phase space density (PSD) of seed, core, and ultrarelativistic electrons to determine the dominant energization and loss processes taking place during the events. Both sheaths produced substantial variation in the electron fluxes from tens of kiloelectronvolts up to ultrarelativistic energies. The responses were however the opposite: the geoeffective sheath mainly led to enhancement, while the nongeoeffective one caused a depletion throughout most of the outer belt. The case studies highlight that both inward and outward radial transport driven by ultra-low frequency waves played an important role in both electron energization and loss. Additionally, PSD radial profiles revealed a local peak that indicated significant acceleration to core energies by chorus waves during the geoeffective event. The distinct responses and different mechanisms in action during these events were related to the timing of the peaked solar wind dynamic pressure causing magnetopause compression, and the differing levels of substorm activity. The most remarkable changes in the radiation belt system occurred in key sheath sub-regions near the shock and the ejecta leading edge.
  • Abera, Temesgen Alemayehu; Heiskanen, Janne Hermanni; Pellikka, Petri Kauko Emil; Maeda, Eduardo Eiji (2018)
    Climate–vegetation interaction can be perturbed by human activities through deforestation and natural extreme climatic events. These perturbations can affect the energy and water balance, exacerbating heat stress associated with droughts. Such phenomena are particularly relevant in the Horn of Africa, given its economic and social vulnerability to environmental changes. In this paper, we used 16-year time series (2001–2016) of remotely sensed environmental data with the objective of 1) clarifying how rainfall–vegetation interaction affects land surface temperature (LST) seasonality across the Horn of Africa, and 2) evaluating how this interaction affects LST anomalies during forest loss and drought events. Our results showed that vegetation seasonality follows rainfall modality patterns in 81% of the region. On the other hand, seasonality of daytime LST was negatively related to vegetation greenness patterns across ecoregions, and rainfall modality. LST varied more strongly in grasslands and shrublands than over other vegetation classes. Comparison of LST before and after forest loss in three selected areas (two in Ethiopia and one in Kenya) revealed an annual average increase in LST of 0.7 °C, 1.8 °C, and 0.2 °C after climate variability correction, respectively. The average increase in LST was relatively high and consistent during dry months (1.5 °C, 3 °C, and 0.6 °C). As expected, the rainfall anomalies during droughts (2010/2011, 2015, and 2016) were positively correlated with vegetation greenness anomalies. Nonetheless, the degree with which vegetation cover is affected by extreme rainfall events has a strong influence in regulating the impact of droughts on temperature anomalies. This highlights the importance of vegetation resilience and land cover management in regulating the impact of extreme events.
  • Wen, Yanjun; Fang, Xiuqi; Liu, Yang; Li, Yikai (2019)
    Grain price volatility during historical periods is regarded as an important indicator of the impact of climate change on economic system, as well as a key link to adjust food security and social stability. The present study used the wheat prices in Baoding Prefecture, China, during 1736-1850 to explore connections between climatic transition and grain price anomalies in the North China Plain. The main findings were as follows: (1) The grain price change showed an apparent correspondence with climatic transition. The period 1781-1820 was a transition phase, with more extremes and decreased precipitations when the climate shifted from a warm phase to a cold one. Corresponding with the climatic transition, the grain price during 1781-1820 was characterized by that the mean of the original grain price series was significantly higher (lower) than the previous (later) phase, and the variance and anomaly amplitude of the detrended grain price series was the highest during 1736-1850. (2) The correspondence between grain price extremes and drought events occurred in phases. Five grain price extremes occurred following drought events during 1781-1810, while extreme droughts were the direct cause of the grain price spike during 1811-1820. (3) Social stability affected by climate change also played an important role in the grain price spike between 1811 and 1820. Paralleling the pathway of "precipitation-grain production-grain price", climate change could have an impact on grain price via the pathway of "precipitation-grain production-grain price-famine-uprising-grain price", as shown during the Tianli Uprising in 1813. These findings could contribute to an improved understanding of the interaction between climate change and human society during the historical period.