scholarly journals Last Millennium Reanalysis with an expanded proxy database and seasonal proxy modeling

2019 ◽  
Vol 15 (4) ◽  
pp. 1251-1273 ◽  
Author(s):  
Robert Tardif ◽  
Gregory J. Hakim ◽  
Walter A. Perkins ◽  
Kaleb A. Horlick ◽  
Michael P. Erb ◽  
...  
Keyword(s):  
Tree Ring ◽  
Ring Width ◽  
Surface Air Temperature ◽  
Severity Index ◽  
Drought Severity ◽  
Last Millennium ◽  
Tree Ring Width ◽  
Forward Models ◽  
Proxy Records ◽  
Northern Latitudes

Abstract. The Last Millennium Reanalysis (LMR) utilizes an ensemble methodology to assimilate paleoclimate data for the production of annually resolved climate field reconstructions of the Common Era. Two key elements are the focus of this work: the set of assimilated proxy records and the forward models that map climate variables to proxy measurements. Results based on an updated proxy database and seasonal regression-based forward models are compared to the LMR prototype, which was based on a smaller set of proxy records and simpler proxy models formulated as univariate linear regressions against annual temperature. Validation against various instrumental-era gridded analyses shows that the new reconstructions of surface air temperature and 500 hPa geopotential height are significantly improved (from 10 % to more than 100 %), while improvements in reconstruction of the Palmer Drought Severity Index are more modest. Additional experiments designed to isolate the sources of improvement reveal the importance of the updated proxy records, including coral records for improving tropical reconstructions, and tree-ring density records for temperature reconstructions, particularly in high northern latitudes. Proxy forward models that account for seasonal responses, and dependence on both temperature and moisture for tree-ring width, also contribute to improvements in reconstructed thermodynamic and hydroclimate variables in midlatitudes. The variability of temperature at multidecadal to centennial scales is also shown to be sensitive to the set of assimilated proxies, especially to the inclusion of primarily moisture-sensitive tree-ring-width records.

scholarly journals Last Millennium Reanalysis with an expanded proxy database and seasonal proxy modeling

2018 ◽  
Author(s):  
Robert Tardif ◽  
Gregory J. Hakim ◽  
Walter A. Perkins ◽  
Kaleb A. Horlick ◽  
Michael P. Erb ◽  
...  
Keyword(s):  
Tree Ring ◽  
Ring Width ◽  
Surface Air Temperature ◽  
Drought Severity ◽  
Last Millennium ◽  
Tree Ring Width ◽  
Forward Models ◽  
Proxy Records ◽  
Skill Scores ◽  
Paleoclimate Data

Abstract. The Last Millennium Reanalysis utilizes an ensemble methodology to assimilate paleoclimate data for the production of annually resolved climate field reconstructions of the Common Era. Two key elements are the focus of this work: the set of assimilated proxy records, and the forward models that map climate variables to proxy measurements. Results based on an extensive proxy database and seasonal regression-based forward models are compared to the prototype reanalysis of Hakim et al. (2016), which was based on a smaller set of proxy records and simpler proxy models formulated as univariate linear regressions against annual temperature. Validation against various instrumental–era gridded analyses shows that the new reconstructions of surface air temperature, 500 hPa geopotential height and the Palmer Drought Severity Index are significantly improved, with skill scores increasing from 10 % to more than 200 %, depending on the variable and verification measure. Additional experiments designed to isolate the sources of improvement reveal the importance of additional proxy records, including coral records for improving tropical reconstructions; tree-ring-width chronologies, including moisture-sensitive trees, for thermodynamic and hydroclimate variables in mid-latitudes; and tree-ring density records for temperature reconstructions, particularly in high northern latitudes. Proxy forward models that account for seasonal responses, and the dual sensitivity to temperature and moisture characterizing tree-ring-width proxies, are also found to be particularly important. Other experiments highlight the beneficial role of covariance localization on reanalysis ensemble characteristics. This improved paleoclimate data assimilation system served as the basis for the production of the first publicly released NOAA Last Millennium Reanalysis.

scholarly journals Growth response of Abies spectabilis to climate along an elevation gradient of the Manang valley in the central Himalayas

2019 ◽  
Vol 31 (6) ◽  
pp. 2245-2254 ◽  
Author(s):  
Samresh Rai ◽  
Binod Dawadi ◽  
Yafeng Wang ◽  
Xiaoming Lu ◽  
Huang Ru ◽  
...  
Keyword(s):  
Tree Ring ◽  
Elevation Gradient ◽  
Ring Width ◽  
Principal Component ◽  
Moisture Stress ◽  
Severity Index ◽  
Forest Growth ◽  
Drought Severity ◽  
Tree Ring Width ◽  
Standard Tree

Abstract The Himalayas are characterized by a broad gradient of bioclimatic zones along their elevation. However, less is known how forest growth responds to climatic change along elevation. In this study, four standard tree-ring width chronologies of Himalayan fir (Abiesspectabilis) were developed, spanning 142–649 years along an elevation gradient of 3076–3900 m a.s.l. Principal component analysis classified the four chronologies into two groups; the ones at lower elevations (M1 and M2) and higher elevations (M3 and M4) show two distinct growth trends. Radial growth is limited by summer (June–August) precipitation at M3, and by precipitation during spring (March–May) and summer at M4. It is limited by spring temperatures and winter precipitation (December–February) at M1. Tree-ring width chronologies also significantly correlate with winter and spring Palmer Drought Severity Index (PDSI) at M1, and with summer PDSI at M3 and M4. Thus, Himalayan fir growth at high elevations is mainly limited by moisture stress rather than by low temperatures. Furthermore, the occurrence of missing rings coincides with dry periods, providing additional evidence for moisture limitation of Himalayan fir growth.

scholarly journals Development of a Larix principis-rupprechtii tree-ring width chronology and its climatic signals for the southern Greater Higgnan Mountains

2018 ◽  
Vol 45 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Tongwen Zhang ◽  
Shulong Yu ◽  
Yujiang Yuan ◽  
Liping Huang ◽  
Shengxia Jiang
Keyword(s):  
Tree Ring ◽  
Ring Width ◽  
Low Frequency ◽  
Northern China ◽  
Severity Index ◽  
Drought Severity ◽  
Mountainous Area ◽  
Tree Ring Width ◽  
Large Area ◽  
Climatic Signals

Abstract Forty-one living larch (Larix principis-rupprechtii) trees collected from two sampling sites in 1310–1530 m a.s.l. in the southern Greater Higgnan Mountains in the northeastern China are used to develop a regional tree-ring width chronology. The credible chronology spans 185 years from 1830 to 2014. The results of correlation analyses indicate that moisture is the main climatic factor controlling radial growth of larch trees in this mountainous area. Spatial correlation proves that the regional tree-ring width chronology contains climatic signals representative for a large area including the eastern Mongolian Plateau and Nuluerhu Mountains. A comparison between the newly developed chronology and a May–July Palmer Drought Severity Index (PDSI) reconstruction for the Ortindag Sand Land reveals similar variations, particularly in the low-frequency domain. The tree-ring records also capture a severe and sustained drying trend recorded in the 1920s across a wide area of northern China.

scholarly journals The 600-mm precipitation isoline distinguishes tree-ring-width responses to climate in China

2018 ◽  
Vol 6 (2) ◽  
pp. 359-368 ◽  
Author(s):  
Yu Liu ◽  
Huiming Song ◽  
Changfeng Sun ◽  
Yi Song ◽  
Qiufang Cai ◽  
...  
Keyword(s):  
Tree Ring ◽  
Large Scale ◽  
Ring Width ◽  
Severity Index ◽  
Annual Precipitation ◽  
Drought Severity ◽  
Climate Variations ◽  
Tree Ring Width ◽  
Past Climate ◽  
Tree Ring Data

AbstractThe numerous temperature and precipitation reconstructions in China based on tree-ring-width data have played significant roles in furthering the understanding of past climate changes. However, the geographical variability in the responses of trees to climate variations in China remains largely undetermined. Here, we describe an important spatial boundary in the response of trees to climate variations, namely the 600-mm annual precipitation isoline. We found that, to the north of this line, tree-ring widths are usually positively correlated with precipitation and negatively correlated with growing-season temperature. To the south of this line, the tree-ring widths respond positively to temperature, and winter half-year temperatures are the main reconstructed parameters, especially on the third topographical step of China. We also found that precipitation reconstructions based on tree-ring data and the Palmer Drought Severity Index almost exclusively fall in the region of the 200- to 600-mm annual precipitation isolines, not other regions. Our findings indicate that, when using multiple tree-ring-width chronologies for large-scale past climate reconstructions, the climatic signal of each tree-ring-width series should be carefully considered.

scholarly journals A 424-year tree-ring-based Palmer Drought Severity Index reconstruction of <i>Cedrus deodara</i> D. Don from the Hindu Kush range of Pakistan: linkages to ocean oscillations

2020 ◽  
Vol 16 (2) ◽  
pp. 783-798
Author(s):  
Sarir Ahmad ◽  
Liangjun Zhu ◽  
Sumaira Yasmeen ◽  
Yuandong Zhang ◽  
Zongshan Li ◽  
...  
Keyword(s):  
Tree Ring ◽  
Palmer Drought Severity Index ◽  
Southern Oscillation ◽  
Ring Width ◽  
Severity Index ◽  
Drought Severity ◽  
Mountain Range ◽  
Cedrus Deodara ◽  
Hindu Kush ◽  
Drought Severity Index

Abstract. The rate of global warming has led to persistent drought. It is considered to be the preliminary factor affecting socioeconomic development under the background of the dynamic forecasting of the water supply and forest ecosystems in West Asia. However, long-term climate records in the semiarid Hindu Kush range are seriously lacking. Therefore, we developed a new tree-ring width chronology of Cedrus deodara spanning the period of 1537–2017. We reconstructed the March–August Palmer Drought Severity Index (PDSI) for the past 424 years, going back to 1593 CE. Our reconstruction featured nine dry periods (1593–1598, 1602–1608, 1631–1645, 1647–1660, 1756–1765, 1785–1800, 1870–1878, 1917–1923, and 1981–1995) and eight wet periods (1663–1675, 1687–1708, 1771–1773, 1806–1814, 1844–1852, 1932–1935, 1965–1969, and 1990–1999). This reconstruction is consistent with other dendroclimatic reconstructions in West Asia, thereby confirming its reliability. The multi-taper method and wavelet analysis revealed drought variability at periodicities of 2.1–2.4, 3.3, 6.0, 16.8, and 34.0–38.0 years. The drought patterns could be linked to the large-scale atmospheric–oceanic variability, such as the El Niño–Southern Oscillation, Atlantic Multidecadal Oscillation, and solar activity. In terms of current climate conditions, our findings have important implications for developing drought-resistant policies in communities on the fringes of the Hindu Kush mountain range in northern Pakistan.

scholarly journals Independent Aridity and Drought Pieces of Evidence Based on Meteorological Data and Tree Ring Data in Southeast Banat, Vojvodina, Serbia

Atmosphere ◽  
2019 ◽  
Vol 10 (10) ◽  
pp. 586 ◽  
Author(s):  
Milivoj B. Gavrilov ◽  
Wenling An ◽  
Chenxi Xu ◽  
Milica G. Radaković ◽  
Qingzhen Hao ◽  
...  
Keyword(s):  
Tree Ring ◽  
Air Temperature ◽  
Meteorological Data ◽  
Ring Width ◽  
Surface Air Temperature ◽  
Aridity Index ◽  
Precipitation Trend ◽  
Positive Temperature ◽  
Tree Ring Width ◽  
Tree Ring Data

In this study, aridity data and tree ring data were collected in Northern Serbia, in Southeast (SE) Banat, a subregion within Vojvodina, and Vojvodina at large. They were each investigated independently. The De Martonne Aridity Index and the Forestry Aridity Index are derived from examining the relationship between precipitation and surface air temperature data sets sourced from seven meteorological stations in SE Banat, and from 10 meteorological stations located in Vojvodina as a whole. Vojvodina is a large territory and used as the control area, for the period 1949–2017. The Palmer Drought Severity Index was derived for the period 1927–2016, for both SE Banat and the totality of Vojvodina. The results of the Tree Ring Width Index were obtained from samples collected in or around the villages of Vlajkovac and Šušara, both located in SE Banat, for the period 1927–2017. These tree ring records were compared with three previous aridity and drought indices, and the meteorological data on the surface air temperature and the precipitation, with the objective being to evaluate the response of tree growth to climate dynamics in the SE Banat subregion. It was noted that the significant positive temperature trends recorded in both areas were too insufficient to trigger any trends in aridity or the Tree Ring Width Index, as neither displayed any change. Instead, it appears that these climatic parameters only changed in response to the precipitation trend, which remained unchanged during the investigated period, rather than in response to the temperature trend. It appears that the forest vegetation in the investigated areas was not affected significantly by climate change in response to the dominant temperature increase.

scholarly journals Last 1100 yr of precipitation variability in western central Asia as revealed by tree-ring data from the Pamir-Alay

2018 ◽  
Vol 91 (1) ◽  
pp. 81-95 ◽  
Author(s):  
Magdalena Opała-Owczarek ◽  
Tadeusz Niedźwiedź
Keyword(s):  
Central Asia ◽  
Tree Ring ◽  
Tree Growth ◽  
Palmer Drought Severity Index ◽  
Ring Width ◽  
Severity Index ◽  
Drought Severity ◽  
Mountainous Area ◽  
Transfer Function Method ◽  
Tree Ring Data

AbstractWe developed a 1108 yr chronology of tree-ring widths, based on 64 Himalayan pencil juniper (Juniperus semiglobosa Regel) trees, for the Pamir-Alay Mountains, central Asia. Dendroclimatological analysis demonstrates that precipitation has significant effects on tree growth in the semiarid mountainous area of northwestern Tajikistan located on the edge of the great midlatitude Karakum and Kyzylkum deserts. The highest level of linear correlation (r=0.67) is observed between tree growth and seasonalised winter (previous December–February) precipitation. Our studies also show that moisture (precipitation/Palmer Drought Severity Index) from the previous June to the current September was the dominant climatic factor accounting for interannual variations in tree-ring width, suggesting that this should be considered in climate reconstruction. Using the transfer function method, we reconstructed the region’s drought history over the period AD 908–2015. The results of this moisture reconstruction showed that the most recent millennium was characterised by series of dry and wet stages. The driest periods occurred before 1000, 1200–1250, and at the end of the eighteenth century and beginning of the nineteenth century. The wettest conditions existed in 1650–1700 and after 1990.

scholarly journals Changes in the Tree-Ring Width-Derived Cumulative Normalized Difference Vegetation Index over Northeast China during 1825 to 2013 CE

Forests ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 241
Author(s):  
Ruoshi Liu ◽  
Yi Song ◽  
Yu Liu ◽  
Xuxiang Li ◽  
Huiming Song ◽  
...  
Keyword(s):  
Tree Ring ◽  
Vegetation Index ◽  
Normalized Difference Vegetation Index ◽  
Climatic Factors ◽  
Eastern China ◽  
Ring Width ◽  
Terrestrial Ecosystems ◽  
Vegetation Coverage ◽  
Drought Severity ◽  
Tree Ring Width

Vegetation coverage is very important in terrestrial ecosystems and climate systems. However, the observational record of the normalized difference vegetation index (NDVI), which started in the 1980s when satellites became widely used, is too short to investigate the history of variation in vegetation coverage beyond the modern observation period. Here, we present a 189 y vegetation coverage series based on a total of 349 Mongolian pine (Pinus sylvestris var. mongolica Litv) cores from seven locations from the central–western Da Hinggan Mountains (CW–DHM), northeastern China. We found a significant relationship between tree-ring width and the regional cumulative normalized difference vegetation index (CNDVI). The correlation between the ring-width chronology and the regional June–July CNDVI (CNDVIJJ) was significant, with r = 0.68 (n = 32, p < 0.001) and an explained variance of 45.8% (44.0% after the adjustment for the loss of the degree of freedom). On this basis, we designed a transfer function to reconstruct the CNDVIJJ for the CW–DHM region from 1825 to 2013 CE (Common Era). During the last 189 years, there were 28 years with high CNDVIJJ values, and another 28 years with low values. We also observed CNDVIJJ fluctuations at the inter-annual and decadal time scales, including eight low value periods and nine high value periods. Based on our analysis, the variation in CNDVI is associated with climatic factors, such as temperature, precipitation and the Palmer Drought Severity Index (PDSI), which combines both temperature and precipitation. From 1950 to 2002 CE, the CNDVI showed a noticeable decreasing trend in the CW–DHM region, whereas after 2003 CE, the CNDVI exhibited an apparent increase, which has also been observed in southern Central Siberia, eastern Mongolia and northeastern and eastern China, indicating that the CNDVI change in the CW–DHM is related to climate change in the local region and in some parts of Asia.

DENDROCLIMATOLOGICAL STUDIES OF PICEA LIKIANGENSIS AND TSUGA DUMOSA IN LIJIANG, CHINA

IAWA Journal ◽  
2009 ◽  
Vol 30 (4) ◽  
pp. 435-441 ◽  
Author(s):  
Gaiai Guo ◽  
Zong-Shan Li ◽  
Qi-Bin Zhang ◽  
Ke-Ping Ma ◽  
Conglong Mu
Keyword(s):  
Tree Ring ◽  
Environmental Variability ◽  
Ring Width ◽  
Correlation Coefficients ◽  
Severity Index ◽  
Drought Severity ◽  
Tree Ring Chronology ◽  
Late 20Th Century ◽  
Moisture Condition ◽  
Individual Trees

Expansion of climate proxy records over space is needed for improving our knowledge of past climate variability. Here we report on a 112-year tree-ring chronology of Picea likiangensis (Franch.) E.Pritz. and a 165- year tree-ring chronology of Tsuga dumosa (D.Don) Eichler for the Lijiang area, northwestern Yunnan, China. Mean correlation coefficients of tree-ring width series among individual trees are 0.48 for P. likiangensis and 0.45 for T. dumosa, indicating a growth response to common environmental variability. Analysis of climate-growth relationships shows that the radial growth of P. likiangensis is mainly negatively correlated with temperature from December of the prior growth year to May of the growth year, and that of T. dumosa is mainly positively correlated with precipitation of January and May in the growth year. We further found that the chronology of T. dumosa can be used to reconstruct the May-June Palmer Drought Severity Index. The reconstruction shows that major wet periods occurred in the 1860s, 1910s and 1940s, and drought periods in 1892–1905, 1914–1924 and 1928–1938. The moisture condition of the late 20th century is characterized by a near-normal state from the 1950s to the 1970s and an increasing trend from 1982 to 2003.

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