Annual Precipitation Reconstruction Research Articles

Disentangling seasonal and annual precipitation signals in the tropics over the Holocene: Insights from δD, alkanes and GDGTs

Rainfall seasonality in the tropics has a substantial impact on both ecosystems and human livelihoods. Yet, reconstructions of past rainfall variability have so far generally been unable to differentiate between annual and seasonal precipitation changes. Past variations in seasonality are therefore largely unknown. Here, we disentangle hydrogen isotopic (δD) signals from terrestrial leaf waxes and algae in an 8000-year peat core from Sumatra, which reflect annual versus wet season rainfall signals, respectively. We validate these results using lipid biomarkers by reconstructing vegetation dynamics via n-alkane distributions and peatland hydrological conditions using glycerol dialkyl glycerol tetraethers (GDGTs), as well as biomass burning using levoglucosan concentrations in the core. Finally, we compare our proxy results to a transient climate model simulation (MPI-ESM1.2) to identify the mechanism for seasonality changes. We find that algal δD indicates stronger Indonesian-Australian Summer Monsoon (IASM) precipitation in the Mid-Holocene, between 8 and 4.2 cal ka BP. A period of alternating flooding, droughts and wildfires is reconstructed between 6 and 4.2 cal ka BP, implicating very strong monsoonal precipitation and drying out and burning during a longer and intensified dry season. We attribute this strong rainfall seasonality in the Mid-Holocene mainly to orbitally forced insolation seasonality and a strengthened IASM, consistent with the modeling results. In terms of annual rainfall, terrestrial plant δD, vegetation composition and GDGTs all indicate wetter conditions peaking between 3 and 4.5 cal ka BP, preceded by drier conditions, followed by drastic and rapid drying in the late Holocene from around 2.8 cal ka BP. Our multiproxy annual precipitation reconstruction thereby indicates the wettest overall conditions approximately 1500–2000 years later than a nearby speleothem δ18O record, which instead follows the seasonally biased algal δD in our record. We, therefore, hypothesize that speleothem reconstructions over the Holocene in parts of the tropics with low but significant seasonality may carry a stronger seasonal component than previously suggested. The data presented here contribute with new insights on how isotopic rainfall proxies in the tropics can be interpreted. Our findings resolve the seasonal versus annual components of Holocene rainfall variability in the Indo-Pacific Warm Pool region, highlighting the importance of considering seasonality in rainfall reconstructions.

Terrestrial vegetation and lake aquatic community diversity under climate change during the mid–late Holocene in the Altai Mountains

Using pollen analysis and metabarcoding of plant sedimentary ancient DNA (sedaDNa), we infer the floristic diversity in the vicinity of Lake Balyktukel, Ulagan Plateau, the Altai Mountains, over the last 7 kyr. The SedaDNA method identified 200% more taxa than found by morphological pollen analysis. In particular, it revealed that the dominant tree for the last 7 kyr was Larix rather than Pinus, which was less frequent in the vicinity of Lake Balyktukel. About 7 ka, larch forest mixed with dwarf birch was widespread on the Ulagan Plateau. The period between 5.3 and 3.4 kyr BP was characterized by the maximal spread of larch forest with an understorey cover of Vaccinium vitis-idaea. Pollen-based annual precipitation reconstruction indicates the most humid phase was between 6.95 and 4.3 ka, and generally coincides with maximal phytodiversity. The most bioproductive period of the lake was from 7 to 6 ka. After that, the trophicity of the lake decreased until 4.5 ka. The appearance of Hippuris vulgaris and increase in Ranunculus subgen. Batrachium at about 5.3–5 ka may indicate the extension of shallow-water ecotopes. Between 3.7 and 3.5 ka, the cyanobacterium Anabaena – an indicator of increased organic matter and algal blooms – was widespread. A planktic thermophilic cladoceran Bosmina longirostris appeared after 1.8 ka and colonized the lake, suggesting an increase in lake trophicity. The last 100 years have been characterized by dramatic changes in the cladoceran community reflecting significant warming of climate.

Tree-ring reconstruction of March-August drought variability over the past 567 years in the Yajiang region of West Sichuan Plateau, China

We constructed standard tree-ring-width chronology of Picea likiangensis var. rubescens for the Larima sampling site in the Ganzi Prefecture, Sichuan Province, by the single-free detren-ding method. The results showed that there was significant and positive correlation between the tree-ring chronology and March-August 1-month scale standardized precipitation and evapotranspiration index (SPEI1) of Yajiang region. The variation of the March-August SPEI1 sequence for 1942-2008 was reconstructed based on the current and last year sequences of the tree-ring chronology, with an explained variation of 42.8%. The newly reconstructed series mainly represented the variation of SPEI1 in the low-frequency domain over the historical period. Three wet periods were found in 1442-1465, 1516-1601 and 1836-2008, while the two intervals were dry periods for the March-August SPEI1 reconstruction in the Yajiang region of West Sichuan Plateau. There was a significant drying trend in 1456-1762 for the reconstructed sequence, a significant wetting trend in 1455-1762, while the wetting trend was the most significant in 1959-2008. Mutation test showed that the sudden changes from dry to wet for the March-August SPEI1 reconstructions occurred in 1512, 1733, 1767, 1831, 1941, 1957 and 1975, while that in 1684 and 1961 was the opposite. The comparison with surrounding region showed a good coherence of variations in the low-frequency domain among the SPEI1 reconstruction for the Yajiang region, the annual precipitation reconstruction for the northeastern Tibetan Plateau, and the SPEI05 reconstruction for the northern slope of the eastern Qilian Mountains. The reconstructed sequence well represented the variation of the March-August SPEI1 in the northeastern Tibetan Plateau and the southern Qinhai Province.

TWO RECONSTRUCTIONS OF AUGUST–JULY PRECIPITATION FOR CENTRAL NORTHERN ARIZONA FROM TREE RINGS

This study reports two multi-century regional reconstructions of annual precipitation based on Pinus ponderosa and P. edulis from four sites in central northern Arizona. It compares standard regional and time-nested methods to generate reconstructions from 1581–2016 C.E. and 1529–2016 C.E., respectively. The strongest climate relationship is a positive correlation between total ring width and 12-month total precipitation ending in July of the growth year. The chronologies account for 50% of the variance of observed annual precipitation in the regional model and 59%, 60%, and 47% and 35% in the nested models. The two reconstructions are highly correlated (Pearson's correlation r > 0.97, p < 0.001) demonstrating that the reconstructions are highly similar over the period common to both reconstructions, with the nested-models’ advantage of extending the range of the reconstruction. The precipitation reconstructions are significantly correlated (r = 0.66, p < 0.001) with the North American Drought Atlas (NADA).

Rainfall reconstruction for the Karakoram region in Pakistan since 1540 CE reveals out‐of‐phase relationship in rainfall between the southern and northern slopes of the Hindukush‐Karakorum‐Western Himalaya region

AbstractClimate change has influenced the glaciers and water resources in the Hindukush‐Karakorum‐Himalaya region. The relatively short instrumental record of northern Pakistan makes long‐term climate change assessments difficult. In this paper, tree‐ring width chronologies were developed from two stands of spruce species (Picea smithiana) in the Karakoram region of northern Pakistan. The results of the correlation analysis revealed that tree‐ring growth of spruce was limited by annual (June–May) precipitation. Based on the regional chronology, we developed an annual precipitation reconstruction for the period 1540–2016 CE. The precipitation reconstruction equation accounts for 40% of the regional precipitation variance during the instrumental period 1946–2016. Dry episodes with rainfall below the 477‐year average occurred from 1569 to 1577, 1598 to 1612, 1621 to 1621, 1638 to 1654, 1673 to 1680, 1697 to 1720, 1728 to 1739, 1753 to 1761, 1777 to 1793, 1801 to 1840, 1860 to 1874, 1914 to 1932, 1960 to 1985, 1998 to 2011. Wet episodes occurred from 1540 to 1568, 1578 to 1597, 1613 to 1620, 1632 to 1637, 1655 to 1672, 1681 to 1696, 1721 to 1727, 1740 to 1752, 1762 to 1776, 1794 to 1800, 1841 to 1859, 1875 to 1913, 1933 to 1959, 1986 to 1997. Furthermore, the results of spatial correlation analyses show that the reconstructed precipitation represents the regional precipitation variations for northern Pakistan and nearby high‐altitude mountains. The out‐of‐phase relationship in tree‐ring records of the Karakoram region and surrounding areas suggests that the Karakoram was under the control of large‐scale ocean–atmosphere–land circulations on a decadal timescale in the past centuries. In addition, by the comparison between the precipitation reconstruction and the instrumental data, we found that the drought risk of Karakoram has increased in the past 70 years and that extreme events are likely to become more severe and more frequent under the backdrop of climatic warming.

The climate, the fuel and the land use: Long-term regional variability of biomass burning in boreal forests.

The influence of different drivers on changes in North American and European boreal forests biomass burning (BB) during the Holocene was investigated based on the following hypotheses: land use was important only in the southernmost regions, while elsewhere climate was the main driver modulated by changes in fuel type. BB was reconstructed by means of 88 sedimentary charcoal records divided into six different site clusters. A statistical approach was used to explore the relative contribution of (a) pollen-based mean July/summer temperature and mean annual precipitation reconstructions, (b) an independent model-based scenario of past land use (LU), and (c) pollen-based reconstructions of plant functional types (PFTs) on BB. Our hypotheses were tested with: (a) a west-east northern boreal sector with changing climatic conditions and a homogeneous vegetation, and (b) a north-south European boreal sector characterized by gradual variation in both climate and vegetation composition. The processes driving BB in boreal forests varied from one region to another during the Holocene. However, general trends in boreal biomass burning were primarily controlled by changes in climate (mean annual precipitation in Alaska, northern Quebec, and northern Fennoscandia, and mean July/summer temperature in central Canada and central Fennoscandia) and, secondarily, by fuel composition (BB positively correlated with the presence of boreal needleleaf evergreen trees in Alaska and in central and southern Fennoscandia). Land use played only a marginal role. A modification towards less flammable tree species (by promoting deciduous stands over fire-prone conifers) could contribute to reduce circumboreal wildfire risk in future warmer periods.

Tree-ring based annual precipitation reconstruction for the southern Three-River Headwaters region, China

Abstract Tree-ring width standard chronologies were created from Juniperus przewalskii Kom data collected in the southern Three-River Headwaters (TRH) region. Statistical analysis results showed high correlation between the first primary component (PC1) of the four chronologies and instrumental precipitation records during the annual September–August interval. Precipitation of the region was reconstructed for the past 461 years. It was verified that the reconstruction model was stable by split-sample calibration-verification statistics. The reconstruction series revealed 22 extremely dry years and 9 extremely wet years. Results showed relatively dry periods occurred during 1567–1597, 1604–1614, 1641–1656, 1684–1700, 1734–1755, 1817–1830, 1913–1932, 1953–1971, 1990–2005. Relatively wet periods occurred during 1615–1630, 1657–1683, 1701–1733, 1756–1786, 1798–1816, 1844–1855, 1864–1875, 1885–1912, 1933–1952, 1977–1989. Comparison with tree-ring based precipitation reconstructions, and chronologies from surrounding areas provided a high degree of confidence in our reconstruction, and correlated well with the Monsoon Asia Drought Atlas (MADA) dataset in the public section of corresponding grids. The empirical mode decomposition analysis suggests the existence of significant periods with intervals of 2–5, 6–10, 11–18, and 28–60 years. This research contributes to a better understanding of historical variations in precipitation and will aid in future plans to address climate change of the TRH region.

Annual precipitation variation for the southern edge of the Gobi Desert (China) inferred from tree rings: linkages to climatic warming of twentieth century

We developed a new reconstruction of annual precipitation (August–July) for the Helan Mountains near the southern edge of the Gobi Desert, using a regional tree-ring width chronology. The reconstruction explained 52.1 % of the observed precipitation variance during the period 1953–2008. In addition to the new precipitation reconstruction for the Helan Mountains, two previously published annual precipitation reconstructions from the same region were also used to infer the large-scale precipitation signal of the southern edge of the Gobi Desert. Spatial correlation analyses with gridded precipitation data showed that the tree-ring records were indeed able to capture much of the regional interannual precipitation variability. Using principal component analyses on the precipitation reconstructions and documentary records, 29 large-scale dry events were found during the period AD 1760–2006. Many of these dry events have had profound impacts on the people of the study area over the past several centuries. A notably good agreement with a temperature reconstruction for Zhangye suggests that the precipitation of the Gobi Desert has the characteristics of monsoon rainfall variability (wet–warm and cold–dry). Our precipitation reconstruction exhibited a downward trend during the last two decades, a trend also found in northern and eastern China. It might be caused by a weakening of the Asian summer monsoon induced by global warming (especially increased sea surface temperature).

Geomorphologic and paleoclimatic evidence of Holocene glaciation on Mount Olympus, Greece

This study investigates the possibility of Holocene glaciation on Mount Olympus (Greece) with a respective local temperature–precipitation equilibrium line altitude (TP-ELA) at c. 2200 m a.s.l., based on geomorphologic and paleoclimatic evidence. At present, the local TP-ELA is situated above the mountain’s summit ( c. 2918 m a.s.l.), but permanent snowfields and ice bodies survive within Megala Kazania cirque between c. 2400 and c. 2300 m a.s.l., because of the cirque’s maritime setting that results from its close proximity ( c. 18 km) to the Aegean Sea and of the local topographical controls. The snow and ice bodies occupied a considerably larger area and attained a stabilization phase between AD 1960 and 1980, also manifested from aerial photographs, a period characterized by increased winter precipitation ( Pw) with subsequent TP-ELA depression to c. 2410 m a.s.l. Mid- to late-20th-century Pw and TP-ELA variations exhibit negative correlations with the winter North Atlantic Oscillation index (NAOw) at annual and multidecadal (30 years) timescales. Late Holocene (AD 1680–1860) reconstructed summer mean temperatures were lower by Ts &lt; 1.1°C in relation to the reference period between AD 1960 and 1980 and were also superimposed to negative NAOw phases, thus bracketing this time interval as a favorable one to glacial formation and/or advance. Millennial-scale annual precipitation reconstructions at the hypothesized TP-ELA ( c. 2200 m a.s.l.) point the period between 8 and 4 kyr BP as another glacier-friendly candidate. The mid-Holocene rather simplistic sequence of potential glacial advance phase was disturbed by short-lived cold climatic deteriorations, well-documented over the northern Aegean region that may partly explain the multicrested shape of the highest ( c. 2200 m a.s.l.) morainic complex of Megala Kazania cirque.

설악산 지역의 Tree-ring 자료를 이용한 연 강수량 재생성

The purpose of this research is reconstruction of annual precipitation based on Tree-ring series at Seorak mountain and examine its effectiveness. To do so we performed nonlinear time series characteristics test of Tree-ring series and reconstructed annual precipitation of Gangneung from 1687 to 1911 using Artificial neural network and Nonlinear autoregressive exogeneous input (NARX) model which reflects stochastic properties. As a result, Tree-ring series at Seorak Mountain shows nonlinear time series property and reconstructed annual precipitation series drawn from NARX is similar in statistical characteristics of observed annual time series.

August to July Precipitation from Tree Rings in the Forest-Steppe Zone of Central Siberia (Russia)

ABSTRACT The goal of this research report is to describe annual precipitation reconstruction from Pinus sylvestris trees on three sites in the Abakan region, located in the Minusinsk Depression, at the confluence of the Yenisei and Abakan Rivers, Russia. The study was performed during the 4th annual international summer course “Tree Rings, Climate, Natural Resources and Human Interaction” held in Abakan, 5-19 August 2013. The reconstruction, for the 12-month total precipitation ending in July of the growth year, is based on a reliable and replicable statistical relationship between precipitation and tree-ring growth, and shows climate variability on both interannual and interdecadal time scales. The regional tree-ring chronology accounts for 56% of the variance of observed annual precipitation in a linear regression model, with the strongest monthly precipitation signal concentrated in May and June of the current growing season. Composite 500 mb height-anomaly maps suggest that the tree-ring data from thi...

Precipitation anomalies in Eastern-Central Iowa from 1640 – Present

Summary The Midwest has experienced several extreme hydrologic events over the last few decades, including severe drought events in 1988, 1989 and most recently in 2012. The economic impact of drought on the Midwest, specifically on the state of Iowa, is particularly substantial because of the region’s reliance on agriculture. The Midwest drought in 2012 lead to decreased crop yield across most of Iowa and record high temperatures throughout the growing season (April–October). However, the severity of this and other recent extreme hydrologic events are better understood when placed in the context of multiple centuries of Midwest hydroclimatic variability. In this study we combine a 350 year tree ring reconstruction of annual precipitation from 17 archives in Eastern-Central Iowa to a shorter-term instrumental record from 43 COOP precipitation stations. We analyze precipitation anomalies between 1640 and 2013 and report the return rates of specific drought and pluvial events. The results show that the last 20 years in Iowa have been the wettest 20-year period on record, including the only three years which are 3 or more standard deviations wetter than the (1640–2013) mean. The 1990–2013 period coincides with previously reported increases in annual precipitation and extreme precipitation events, along with decreases in drought severity and spatial extent. The 2012 drought was the driest anomaly over the last 20 years. However, the event was not anomalous with respect to the entire 373 year record and had a return period of approximately 6 years.

An Ensemble Weighting Approach for Dendroclimatology: Drought Reconstructions for the Northeastern Tibetan Plateau

Traditional detrending methods assign equal mean value to all tree-ring series for chronology developments, despite that the mean annual growth changes in different time periods. We find that the strength of a tree-ring model can be improved by giving more weights to tree-ring series that have a stronger climate signal and less weight to series that have a weaker signal. We thus present an ensemble weighting method to mitigate these potential biases and to more accurately extract the climate signals in dendroclimatology studies. This new method has been used to develop the first annual precipitation reconstruction (previous August to current July) at the Songmingyan Mountain and to recalculate the tree-ring chronology from Shenge site in Dulan area in northeastern Tibetan Plateau (TP), a marginal area of Asian summer monsoon. The ensemble weighting method explains 31.7% of instrumental variance for the reconstructions at Songmingyan Mountain and 57.3% of the instrumental variance in the Dulan area, which are higher than those developed using traditional methods. We focus on the newly introduced reconstruction at Songmingyan Mountain, which showsextremely dry (wet) epochs from 1862–1874, 1914–1933 and 1991–1999 (1882–1905). These dry/wet epochs were also found in the marginal areas of summer monsoon and the Indian subcontinent, indicating the linkages between regional hydroclimate changes and the Indian summer monsoon.

A 250-year annual precipitation reconstruction and drought assessment for Cyprus from Pinus brutia Ten. tree-rings

Precipitation around Cyprus, a relatively small island, is generally consistent in year-to-year variation in all dimensions except amplitude, with the higher elevations in the west generally receiving more precipitation. An annual record of precipitation was found in tree-rings of the predominant pine species, Pinus brutia Ten., which grows from the lower foothills up to 1400 m in altitude across the island. Tree-ring chronologies from four sites in west-central Cyprus are used here to reconstruct the annual September to August precipitation and a drought record for AD 1830-2006, with the drought reconstruction extending back to 1756. A minimum of 40% of the variance in annual precipitation and drought occurrence is explained by the variance in the tree-ring widths in all cases. Our drought assessment indicates that, on average, annual droughts occur once every 5 years and sustained droughts, 2-6 years in length, have occurred in small clusters of time, from 1806-1824, 1915-1934 and 1986-2000, when the winter North Atlantic Oscillation was in a predominantly positive phase. These results suggest that a sustained drought period has a mean return time probability of one in 70-100 years. This study provides the first long-term annual precipitation reconstruction and drought assessment at low to mid-elevations for Cyprus and will aid in future plans for drought mitigation.

Tree‐ring‐based annual precipitation reconstruction for the Hexi Corridor, NW China: consequences for climate history on and beyond the mid‐latitude Asian continent

An annual (July to June) precipitation reconstruction for the period AD 1760–2010 was developed from a Picea crassifolia regional tree‐ring chronology from two sites in the northern mountainous region of the Hexi Corridor, NW China. This reconstruction explains 52.1% of the actual precipitation variance during the period 1951 to 2010. Spatial correlations with gridded land‐surface data reveal that our reconstruction contains a strong regional precipitation signal for the Hexi Corridor and for the southern margin of the Badain Jaran Desert. Significant spectral peaks were identified at 31.9, 11.1, 8.0, 7.0, 3.2, 2.6 and 2.2 years. A large‐scale comparison indicates that our reconstruction is more consistent with climate records of a Westerly‐dominated Central Asia, and that the Westerlies have a greater impact on the precipitation in this region than the Asian summer monsoon. Our reconstructed precipitation series is significantly correlated with sea‐surface temperature (SST) in the tropical Atlantic Ocean (positive), the tropical Indian Ocean (positive), the western tropical Pacific Ocean (positive), and the western North Pacific Ocean (negative). The spatial correlation patterns between our precipitation reconstruction and SSTs of the Atlantic and Pacific Oceans suggest a connection between regional precipitation variations and the high‐mid‐latitude northern atmospheric circulations (Westerlies and Asian summer monsoon).

Annual regional precipitation variations from a 700 year tree‑ring record in south Tibet, western China

CR Climate Research Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials CR 53:25-41 (2012) - DOI: https://doi.org/10.3354/cr01081 Annual regional precipitation variations from a 700 year tree‑ring record in south Tibet, western China Jingjing Liu1, Bao Yang1,2,*, Kai Huang1, Dmitry M. Sonechkin3 1Key Laboratory of Desert and Desertification, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, 730000 Lanzhou, PR China 2MOE Key Laboratory of West China’s Environmental System College of Earth and Environment Sciences, Lanzhou University, 730000 Lanzhou, PR China 3P. P. Shirshov Oceanology Institute, Russian Academy of Sciences, Nakhimowskii Prospect 36, Moscow 117997, Russia *Email: yangbao@lzb.ac.cn ABSTRACT: Newly measured tree-ring series from 114 living and dead cypress Cupressus gigantea were collected from 2 high-elevation sites in the Langxian region in south Tibet, western China. Combined with 2 previous ring-width data sets from southern Tibet, the composite chronology correlated at 0.563 with instrumental precipitation over the 1961−2009 period. The low-frequency component of the chronology shows a higher correlation of 0.77 with instrumental data. We reconstructed the annual precipitation (July−June) from A.D. 1300 to 2010 for southern Tibet based on the scaling method. Wet conditions occurred in 1342−1391, 1383−1387, 1408−1423, 1453−1458, 1473−1492, 1508−1524, 1657−1667, 1701−1731, 1742−1768, 1781−1788, 1854−1868, 1917−1933, and 1994−2006, whereas dry years prevailed during 1388−1407, 1424−1452, 1459−1472, 1493−1507, 1525−1656, 1668−1700, 1732−1741, 1769−1780, 1789−1853, 1869−1916, and 1934−1993. Spatial correlation revealed that the annual precipitation reconstruction contained a strong regional precipitation signal for the southern Tibetan Plateau (TP). Coherent moisture variations on the southern TP over the past 700 yr were identified by comparison with other tree-ring-based drought reconstructions of the nearby regions. The reconstructed series showed that high (low) precipitation periods on the southern TP corresponded with dry (wet) spells on the northern TP during most of the past 500 yr, suggesting the influence of different moisture sources from the Westerlies and the south Asian summer monsoon on the northern and southern TP, respectively. The possible mechanism was related to the shift of the convergence shear line and a teleconnection of the North Atlantic Oscillation (NAO) through controlling moisture via the Westerlies. KEY WORDS: Tree ring · Climate change · Tibetan Plateau · Westerlies · South Asian summer monsoon · North Atlantic Oscillation Full text in pdf format PreviousNextCite this article as: Liu J, Yang B, Huang K, Sonechkin DM (2012) Annual regional precipitation variations from a 700 year tree‑ring record in south Tibet, western China. Clim Res 53:25-41. https://doi.org/10.3354/cr01081 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in CR Vol. 53, No. 1. Online publication date: May 24, 2012 Print ISSN: 0936-577X; Online ISSN: 1616-1572 Copyright © 2012 Inter-Research.

A 1000-year reconstruction of summer precipitation from Ireland: Calibration of a peat-based palaeoclimate record

Calibration of proxy climate records is well-established for annually resolved proxies such as tree rings, but it has not been attempted for non-annually resolved proxies such as those from peatland surface wetness records. Several previous studies have suggested that peatland surface wetness is primarily driven by warm season moisture balance and implied a potential for producing calibrated records of deficit or precipitation. This paper presents a high-resolution testate amoebae analysis of a peat record from central Ireland covering the last c.1000 years, and provides the first attempt to produce a calibrated record of past precipitation from a peat record. Past water table depth was reconstructed using a transfer function applied to contiguous samples for the top 1m of the profile. The chronology was constrained by a series of radiocarbon ages (including ‘bomb-spike’ ages) and spheroidal carbonaceous particles. Correlations between reconstructed water tables and meteorological records (1958–1995) of precipitation and deficit were strongly positive and were used to reconstruct precipitation and deficit from the last 1000 years. Validation using earlier meteorological records was hampered by very low peat accumulation rates, but suggested the summer precipitation and deficit reconstructions were more robust than a reconstruction of annual precipitation. The summer precipitation reconstruction suggests that the period AD1400–1850 experienced higher summer rainfall than for much of both the preceding 400 years and the last 150 years. The change in regime from low to high summer rainfall may be attributed to changes in the summer North Atlantic Oscillation. Combined with tree ring and speleothem records of winter NAO, this suggests a major change in seasonality of precipitation in far western Europe between the Medieval Climate Anomaly and the Little Ice Age. The MCA was characterised by dry summers and wet winters, whilst the LIA had wet summers and dry winters. Calibration of peat surface wetness records using meteorological records holds much potential for the future and may lead to improved insights into seasonal precipitation and water balance changes. This study was limited by slow accumulation rates leading to low temporal resolution for the late 19th and early 20th century part of the record. Further development of the technique will require more highly temporally resolved records of change over the whole of the instrumental time period to allow a full calibration and validation approach to be applied.

Tree-ring-based annual precipitation reconstruction in Kalaqin, Inner Mongolia for the last 238 years

A tree-ring-width chronology of Pinus tabulaeformis from Kalaqin, Inner Mongolia was developed using modern dendrochronological techniques. Based on the results of correlation function analysis, the total precipitation from the previous August to current July was reconstructed for 1771–2008 AD with an explained variance of 49.3%. The reconstruction correlated well with the dryness/wetness series derived from historical documents, as well as the precipitation reconstruction of the Chifeng-Weichang region. There were eight intervals with greater precipitation than the average (associated with the strong East Asian summer monsoon) and seven intervals lower than the average (weak monsoon). A power spectrum analysis showed that there were 120 a, 80 a, 8 a and 2 a periodicities.

Rainfall history for the Hexi Corridor in the arid northwest China during the past 620 years derived from tree rings

AbstractWe present a 620‐year long ring width record from the middle Qilian Mountains, where it is presently controlled by the Westerlies. The chronology was developed from Qilian juniper (Sabina przewalskii) growing at sites near the western distribution limit of the species in the northern Qilian Mountains, Gansu Province, China. A linear regression model between ring width and annual (July to June) precipitation accounts for 34.9% of the observed instrumental precipitation variance during the period 1952 to 2007. Spatial correlation analyses between the reconstruction and gridded precipitation data shows that the annual precipitation reconstruction captures regional climatic variations over the Qilian Mountains and the nearby Hexi Corridor. We also show the scaled standard chronology adjusted to the mean and variance of the instrumental data. Relatively wet periods are identified for AD 1390–1413, 1425–1450, 1530–1649, 1792–1920, 1937–1949 and 1980–1985. Dry conditions prevailed during AD 1414–1424, 1451–1529, 1650–1791, 1921–1936, 1950–1979 and 1986–2007. In comparison with the regression‐based reconstruction, the scaled reconstruction indicates considerably wetter conditions during 1390–1413, 1425–1450, 1570–1630 and 1790–1920. The interval AD 1451–1529 was the most intense and longest drought epoch in the Hexi Corridor over the past six centuries. This drought was not only recorded in the Qilian Mountains but also occurred in northern and eastern China. It might be caused by a substantial weakening of the Asian summer monsoon induced by the joint effects of solar and volcanic activities at that time. Our results also suggest that the Hexi Corridor was under the control of the Asian monsoon circulation on inter‐decadal to centennial timescales in the past centuries. Copyright © 2010 Royal Meteorological Society

Annual precipitation reconstruction since AD 775 based on tree rings from the Qilian Mountains, northwestern China

AbstractA millennium‐long tree‐ring‐width chronology from the middle Qilian Mountains in northwestern China has been used to reconstruct annual precipitation variation (from the prior August to current July) since AD 775. The reconstruction explains 37.8% of variance of the observed data. Based on the mean and standard deviation of the reconstructed series, several prolonged severe dry and wet periods were indentified: drought spells in AD 1144–1154 (11 years) and 1925–1932 (8 years) and wet spells in AD 985–999 (15 years), 1089–1097 (9 years) and 1979–1991 (12 years). Both multi‐taper spectral analysis (MTM) and wavelet analysis suggest that periods of the reconstructed precipitation are consistent with those associated with the Asian Summer Monsoon and perhaps solar activity. Copyright © 2010 Royal Meteorological Society