Andes Temperate-Mediterranean Transition 657 Year PDSI Reconstruction ----------------------------------------------------------------------- World Data Center for Paleoclimatology, Boulder and NOAA Paleoclimatology Program ----------------------------------------------------------------------- NOTE: Please cite original reference when using these data, plus the data file URL and date accessed. NAME OF DATA SET: Andes Temperate-Mediterranean Transition 657 Year PDSI Reconstruction LAST UPDATE: 5/2012 (Original receipt by WDC Paleo) CONTRIBUTORS: Christie, D.A., J.A. Boninsegna, M.K. Cleaveland, A. Lara, C. Le Quesne, M.S. Morales, M. Mudelsee, D.W. Stahle, and R. Villalba IGBP PAGES/WDCA CONTRIBUTION SERIES NUMBER: 2012-055 WDC PALEO CONTRIBUTION SERIES CITATION: Christie, D.A., et al. 2012. Andes Temperate-Mediterranean Transition 657 Year PDSI Reconstruction. IGBP PAGES/World Data Center for Paleoclimatology Data Contribution Series # 2012-055. NOAA/NCDC Paleoclimatology Program, Boulder CO, USA. ORIGINAL REFERENCE: Christie, D.A., J.A. Boninsegna, M.K. Cleaveland, A. Lara, C. Le Quesne, M.S. Morales, M. Mudelsee, D.W. Stahle, and R. Villalba. 2011. Aridity changes in the Temperate-Mediterranean transition of the Andes since ad 1346 reconstructed from tree-rings. Climate Dynamics, Vol. 36, Numbers 7-8, pp. 1505-1521, DOI: 10.1007/s00382-009-0723-4 ABSTRACT: The Andes Cordillera acts as regional "Water Towers" for several countries and encompasses a wide range of ecosystems and climates. Several hydroclimatic changes have been described for portions of the Andes during recent years, including glacier retreat, negative precipitation trends, an elevation rise in the 0° isotherm, and changes in regional streamflow regimes. The Temperate-Mediterranean transition (TMT) zone of the Andes (35.5°-39.5°S) is particularly at risk to climate change because it is a biodiversity hotspot with heavy human population pressure on water resources. In this paper we utilize a new tree-ring network of Austrocedrus chilensis to reconstruct past variations in regional moisture in the TMT of the Andes by means of the Palmer Drought Severity Index (PDSI). The reconstruction covers the past 657 years and captures interannual to decadal scales of variability in late spring-early summer PDSI. These changes are related to the north-south oscillations in moisture conditions between the Mediterranean and Temperate climates of the Andes as a consequence of the latitudinal position of the storm tracks forced by large-scale circulation modes. Kernel estimation of occurrence rates reveals an unprecedented increment of severe and extreme drought events during the last century in the context of the previous six centuries. Moisture conditions in our study region are linked to tropical and high-latitude ocean-atmospheric forcing, with PDSI positively related to Nino-3.4 SST during spring and strongly negatively correlated with the Antarctic Oscillation (AAO) during summer. Geopotential anomaly maps at 500-hPa show that extreme dry years are tightly associated with negative height anomalies in the Ross-Amundsen Seas, in concordance with the strong negative relationship between PDSI and AAO. The twentieth century increase in extreme drought events in the TMT may not be related to ENSO but to the positive AAO trend during late-spring and summer resulting from a gradual poleward shift of the mid-latitude storm tracks. This first PDSI reconstruction for South America demonstrates the highly significant hindcast skill of A. chilensis as an aridity proxy. GEOGRAPHIC REGION: Southern Andes PERIOD OF RECORD: 1346-2002 AD FUNDING SOURCES: Inter-American Institute for Global Change Research (IAI) CRN II #2047, supported by the US National Science Foundation (GEO-0452325), Universidad Austral de Chile (DID-UACh D-2007-07), Chilean Research Council (FONDECYT 1050298 and FONDECYT PDA-24), Chilean Ministry of Planning (ICM project P04-065-F), Argentinean Agency for Promotion of Science (PICTR 02-186). DATA FILE URLS: ftp://ftp.ncdc.noaa.gov/pub/data/paleo/treering/reconstructions/southamerica/andes2011pdsi.txt ftp://ftp.ncdc.noaa.gov/pub/data/paleo/treering/reconstructions/southamerica/andes2011pdsi.xls DESCRIPTION: Reconstruction of Palmer Drought Severity Index (PDSI) for the southern Andes Temperate-Mediterranean Transition zone (~35.5°-39.5°S) for the past 657 years. The reconstruction is based on a six site network of Austrocedrus chilensis tree-ring widths. DATA: Christie et al. 2011 Andes PDSI reconstruction YearAD PDSI 1346 -0.497 1347 0.382 1348 0.72 1349 -1.537 1350 -0.64 1351 1.543 1352 -0.695 1353 -2.98 1354 0.902 1355 1.398 1356 -1.259 1357 0.922 1358 -2.713 1359 -0.258 1360 0.635 1361 0.818 1362 1.785 1363 1.649 1364 0.156 1365 -2.122 1366 0.149 1367 1.401 1368 0.504 1369 1.704 1370 0.941 1371 0.191 1372 -1.652 1373 0.094 1374 3.32 1375 -0.037 1376 -0.897 1377 -1.022 1378 -1.356 1379 1.934 1380 1.562 1381 -2.147 1382 1.421 1383 0.795 1384 -1.811 1385 -0.52 1386 1.453 1387 -0.387 1388 0.55 1389 3.756 1390 0.216 1391 -0.088 1392 -2.529 1393 -0.667 1394 -0.014 1395 -1.234 1396 1.288 1397 3.22 1398 -0.843 1399 -2.704 1400 -1.107 1401 2.578 1402 0.432 1403 -1.487 1404 3.864 1405 -1.88 1406 -0.392 1407 0.497 1408 -0.141 1409 1.288 1410 0.918 1411 -2.374 1412 2.739 1413 1.594 1414 -2.184 1415 -0.638 1416 -1.16 1417 0.734 1418 -1.026 1419 -2.124 1420 0.955 1421 0.308 1422 0.561 1423 0.315 1424 -0.355 1425 0.497 1426 -2.149 1427 -1.089 1428 2.712 1429 -2.855 1430 -3.962 1431 3.714 1432 1.645 1433 -1.324 1434 -1.099 1435 -0.97 1436 -1.629 1437 -1.595 1438 -0.255 1439 -1.178 1440 -0.83 1441 0.599 1442 -0.396 1443 -0.022 1444 0.793 1445 -0.016 1446 -0.258 1447 -0.073 1448 -1.422 1449 -0.324 1450 1.057 1451 -0.551 1452 -0.706 1453 -0.988 1454 0.238 1455 1.256 1456 -2.284 1457 -1.115 1458 0.983 1459 -0.26 1460 -2.434 1461 0.157 1462 3.26 1463 -0.085 1464 -2.184 1465 1.042 1466 1.693 1467 -1.502 1468 0.088 1469 1.111 1470 -1.111 1471 -0.261 1472 -0.844 1473 -0.706 1474 0.494 1475 -0.071 1476 -0.413 1477 -1.189 1478 -0.073 1479 0.384 1480 -0.238 1481 -1.307 1482 -1.066 1483 0.431 1484 1.308 1485 0.735 1486 -0.625 1487 1.247 1488 -0.573 1489 0.143 1490 2.873 1491 -1.294 1492 -2.159 1493 1.059 1494 0.54 1495 -1.381 1496 -1.412 1497 -0.368 1498 -0.447 1499 -0.537 1500 -0.001 1501 1.907 1502 -0.662 1503 -2.347 1504 0.635 1505 3.485 1506 -0.026 1507 -0.718 1508 1.181 1509 -1.809 1510 -1.88 1511 1.389 1512 -0.577 1513 -0.81 1514 -0.065 1515 -0.485 1516 1.584 1517 2.407 1518 -0.914 1519 -0.586 1520 0.251 1521 0.006 1522 1.306 1523 -0.48 1524 -2.348 1525 0.216 1526 0.651 1527 -0.433 1528 0.614 1529 -1.842 1530 -1.772 1531 1.436 1532 0.491 1533 1.004 1534 0.033 1535 -0.977 1536 1.63 1537 1.126 1538 -1.585 1539 -2.281 1540 -0.537 1541 0.192 1542 -0.408 1543 0.274 1544 0.659 1545 1.081 1546 -0.51 1547 -1.685 1548 0.402 1549 -0.18 1550 -1.335 1551 -0.461 1552 3.6 1553 0.38 1554 -3.214 1555 -0.973 1556 -1.311 1557 0.063 1558 2.436 1559 2.807 1560 -1.878 1561 -0.657 1562 3.975 1563 2.058 1564 -3.976 1565 -1.339 1566 0.441 1567 -0.395 1568 2.576 1569 2.598 1570 -1.165 1571 2.563 1572 -0.58 1573 -2.409 1574 -0.208 1575 -1.008 1576 -1.193 1577 -0.901 1578 -0.082 1579 -0.134 1580 -0.464 1581 -1.28 1582 -1.619 1583 1.777 1584 2.364 1585 -0.328 1586 0.952 1587 0.495 1588 -3.009 1589 1.347 1590 3.582 1591 -0.824 1592 -1.724 1593 3.948 1594 -0.01 1595 -2.562 1596 1.867 1597 1.78 1598 -1.708 1599 -2.959 1600 2.402 1601 0.615 1602 -1.487 1603 -1.668 1604 0.724 1605 1.793 1606 -0.285 1607 -1.843 1608 0.311 1609 2.756 1610 1.239 1611 -3.251 1612 -2.334 1613 1.741 1614 -1.579 1615 -2.265 1616 0.826 1617 -0.353 1618 -0.175 1619 1.543 1620 0.13 1621 -0.511 1622 1.466 1623 1.174 1624 -3.102 1625 -2.115 1626 0.921 1627 0.732 1628 -0.688 1629 -0.633 1630 0.079 1631 -0.412 1632 0.157 1633 -2.498 1634 -1.401 1635 4.146 1636 1.873 1637 -0.597 1638 0.942 1639 -1.025 1640 -0.391 1641 0.175 1642 1.563 1643 -0.003 1644 -0.5 1645 -1.296 1646 -1.466 1647 0.745 1648 2.701 1649 -2.727 1650 -2.545 1651 0.705 1652 1.036 1653 -0.535 1654 1.556 1655 -0.99 1656 -2.176 1657 -0.499 1658 2.116 1659 0.506 1660 -1.512 1661 -0.52 1662 0.569 1663 -0.767 1664 -2.823 1665 1.141 1666 0.159 1667 -0.857 1668 -1.1 1669 -1.841 1670 2.655 1671 -1.569 1672 -0.66 1673 1.021 1674 -0.066 1675 -0.239 1676 0.742 1677 -1.614 1678 2.274 1679 -0.297 1680 -0.527 1681 -1.197 1682 -2.118 1683 2.787 1684 0.981 1685 -2.569 1686 -0.954 1687 0.247 1688 -0.625 1689 2.791 1690 0.987 1691 -0.798 1692 -2.737 1693 1.05 1694 3.427 1695 0.05 1696 -0.087 1697 1.03 1698 -1.7 1699 -1.463 1700 -0.912 1701 -0.905 1702 -1.035 1703 2.708 1704 1.124 1705 -3.559 1706 2.091 1707 2.236 1708 -0.84 1709 -0.622 1710 0.108 1711 0.968 1712 -1.249 1713 -1.023 1714 1.618 1715 2.418 1716 -0.991 1717 -0.779 1718 -3.323 1719 -1.667 1720 4.739 1721 -1.104 1722 -1.473 1723 1.312 1724 -0.563 1725 -0.645 1726 0.776 1727 -1.064 1728 1.595 1729 -0.68 1730 -0.364 1731 1.717 1732 0.459 1733 -0.857 1734 -0.045 1735 -0.713 1736 0.878 1737 -3.824 1738 0.664 1739 1.715 1740 -1.221 1741 1.069 1742 2.466 1743 -1.431 1744 -0.312 1745 -2.363 1746 -2.62 1747 -1.18 1748 1.572 1749 5.077 1750 1.74 1751 -3.458 1752 -2.894 1753 0.763 1754 -0.746 1755 1.714 1756 3.411 1757 -1.36 1758 -2.017 1759 -0.884 1760 3.296 1761 0.296 1762 -0.032 1763 1.209 1764 -4.728 1765 0.115 1766 4.539 1767 -2.476 1768 -1.476 1769 -1.602 1770 0.33 1771 -0.06 1772 1.449 1773 2.458 1774 -0.225 1775 -3.346 1776 -1.421 1777 4.989 1778 -1.069 1779 -3.118 1780 -0.56 1781 0.522 1782 -1.018 1783 -0.022 1784 -0.239 1785 -0.504 1786 0.666 1787 -3.426 1788 -0.415 1789 2.399 1790 2.63 1791 -3.653 1792 -0.048 1793 1.608 1794 -0.947 1795 1.153 1796 -0.181 1797 -1.583 1798 -1.555 1799 -0.41 1800 1.236 1801 0.277 1802 -0.504 1803 0.295 1804 0.258 1805 -0.406 1806 -0.93 1807 -2.569 1808 -0.041 1809 2.725 1810 1.036 1811 -0.032 1812 0.278 1813 -1.981 1814 0.052 1815 2.207 1816 -2.112 1817 1.394 1818 0.083 1819 -1.388 1820 0.51 1821 -1.726 1822 2.357 1823 3.701 1824 1.672 1825 -1.432 1826 -1.657 1827 -0.389 1828 -2.814 1829 3.348 1830 2.447 1831 -3.865 1832 -2.543 1833 3.48 1834 5.062 1835 -3.748 1836 -2.571 1837 3.476 1838 1.531 1839 -3.629 1840 -0.345 1841 -2.852 1842 -0.129 1843 3.188 1844 1.294 1845 -2.953 1846 -0.259 1847 -1.607 1848 2.089 1849 1.715 1850 -0.511 1851 1.614 1852 2.157 1853 -3.647 1854 -0.42 1855 -0.53 1856 -1.977 1857 3.136 1858 0.885 1859 -2.873 1860 -0.978 1861 -0.568 1862 -0.77 1863 -0.565 1864 -0.782 1865 -1.133 1866 -2.013 1867 -0.384 1868 2.6 1869 0.647 1870 0.349 1871 -0.633 1872 0.912 1873 -1.317 1874 -1.073 1875 0.593 1876 -0.97 1877 -2.592 1878 2.745 1879 2.158 1880 -0.377 1881 -1.09 1882 0.284 1883 -0.847 1884 -1.626 1885 2.379 1886 2.796 1887 -0.763 1888 -1.584 1889 -0.425 1890 -1.171 1891 -0.656 1892 0.001 1893 -2.29 1894 1.764 1895 2.149 1896 -2.529 1897 1.106 1898 3.304 1899 -0.866 1900 -0.97 1901 0.003 1902 -0.328 1903 0.635 1904 2.37 1905 -1.74 1906 -1.454 1907 0.258 1908 1.445 1909 -0.666 1910 -1.741 1911 -0.186 1912 3.284 1913 -4.033 1914 -1.302 1915 2.185 1916 0.608 1917 -2.145 1918 -0.072 1919 1.385 1920 4.626 1921 -0.66 1922 -1.612 1923 0.723 1924 -3.232 1925 0.215 1926 0.097 1927 -2.436 1928 1.534 1929 0.682 1930 2.19 1931 -1.654 1932 -2.666 1933 5.069 1934 -0.351 1935 -1.159 1936 -1.509 1937 0.219 1938 -0.253 1939 -1.046 1940 2.297 1941 2.227 1942 -0.689 1943 -3.858 1944 -2.191 1945 3.134 1946 2.143 1947 -2.225 1948 -1.255 1949 -2.556 1950 1.256 1951 2.91 1952 -1.695 1953 -1.175 1954 -0.881 1955 0.128 1956 1.633 1957 -2.769 1958 -0.3 1959 -0.71 1960 0.048 1961 -2.185 1962 -4.29 1963 1.22 1964 2.553 1965 1.369 1966 1.397 1967 0.216 1968 1.504 1969 -1.011 1970 0.656 1971 0.777 1972 -1.243 1973 -2.017 1974 -0.572 1975 1.548 1976 0.935 1977 1.042 1978 -3.653 1979 0.617 1980 2.463 1981 -0.647 1982 0.345 1983 -2.497 1984 -0.146 1985 0.987 1986 2.359 1987 -0.809 1988 0.33 1989 -1.925 1990 -1.091 1991 2.752 1992 3.004 1993 0.555 1994 -1.667 1995 -1.741 1996 2.214 1997 0.094 1998 -3.391 1999 -2.53 2000 1.323 2001 -0.311 2002 0.8