From	Tim Osborn	Date	Tue, 05 Oct 1999 16:18:29 +0100
To	Michael E. Mann, imacadam@meto.gov.uk
CC	k.briffa@uea, p.jones@uea
Subject	Briffa et al. series for IPCC figure
Dear Mike and Ian Keith has asked me to send you a timeseries for the IPCC multi-proxy reconstruction figure, to replace the one you currently have. The data are attached to this e-mail. They go from 1402 to 1995, although we usually stop the series in 1960 because of the recent non-temperature signal that is superimposed on the tree-ring data that we use. I haven't put a 40-yr smoothing through them - I thought it best if you were to do this to ensure the same filter was used for all curves. The raw data are the same as used in Briffa et al. (1998), the Nature paper that I think you have the reference for already. They are analysed in a different way, to retain the low-frequency variations. In this sense, it is one-step removed from Briffa et al. (1998). It is not two-steps removed from Briffa et al. (1998), since the new series is simply a *replacement* for the one that you have been using, rather than being one-step further. A new manuscript is in preparation describing this alternative analysis method, the calibration of the resulting series, and their comparison with other reconstructions. We are consdering submitting this manuscript to J. Geophys. Res. when it is ready, but for now it is best cited as: Briffa KR, Osborn TJ, Schweingruber FH, Harris IC and Jones PD (1999) Extracting low-frequency temperature variations from a northern tree-ring density network. In preparation. Keith will be sending you a copy of the manuscript when it is nearer to completion. I have also attached a PS file showing the original Briffa et al. (1998) curve, with annotation of cold years associated with known volcanic eruptions. Overlain on this, you will see a green curve. This is the new series with a 40-yr filter through it. This is just so that you can see what it should look like (***ignore the temperature scale on this figure***, since the baseline is non-standard). With regard to the baseline, the data I've sent are calibrated over the period 1881-1960 against the instrumental Apr-Sep tempratures averaged over all land grid boxes with observed data that are north of 20N. As such, the mean of our reconstruction over 1881-1960 matches the mean of the observed target series over the same period. Since the observed series consists of degrees C anomalies wrt to 1961-90, we say that the reconstructed series also represents degrees C anomalies wrt to 1961-90. One could, of course, shift the mean of our reconstruction so that it matched the observed series over a different period - say 1931-60 - but I don't see that this improves things. Indeed, if the non-temperature signal that causes the decline in tree-ring density begins before 1960, then a short 1931-60 period might yield a more biased result than using a longer 1881-1960 period. If you have any queries regarding this replacement data, then please e-mail me and/or Keith. Best regards Tim Calibrated against observed Apr-Sep temperature over 1881-1960 averaged over all land grid boxes north of 20N Year Reconstructed temperature anomaly (degrees C wrt 1961-90) 1402 -0.283 1403 -0.334 1404 -0.286 1405 -0.350 1406 -0.152 1407 -0.124 1408 -0.220 1409 -0.175 1410 -0.100 1411 -0.129 1412 -0.226 1413 -0.115 1414 -0.386 1415 -0.319 1416 -0.277 1417 -0.136 1418 -0.172 1419 -0.294 1420 -0.280 1421 -0.335 1422 -0.406 1423 -0.312 1424 -0.207 1425 -0.136 1426 -0.354 1427 -0.222 1428 -0.305 1429 -0.322 1430 -0.282 1431 -0.143 1432 -0.212 1433 -0.234 1434 -0.076 1435 -0.309 1436 -0.411 1437 -0.122 1438 -0.272 1439 -0.159 1440 -0.330 1441 -0.160 1442 -0.105 1443 -0.080 1444 -0.308 1445 -0.138 1446 -0.317 1447 -0.270 1448 -0.301 1449 -0.357 1450 -0.137 1451 -0.183 1452 -0.207 1453 -0.485 1454 -0.265 1455 -0.358 1456 -0.241 1457 -0.199 1458 -0.366 1459 -0.397 1460 -0.252 1461 -0.230 1462 -0.252 1463 -0.209 1464 -0.174 1465 -0.174 1466 -0.280 1467 -0.256 1468 -0.256 1469 -0.222 1470 -0.237 1471 -0.094 1472 -0.122 1473 -0.056 1474 -0.320 1475 -0.376 1476 -0.133 1477 -0.075 1478 0.037 1479 -0.161 1480 -0.379 1481 -0.513 1482 -0.286 1483 -0.354 1484 -0.327 1485 -0.208 1486 -0.125 1487 -0.380 1488 -0.193 1489 -0.245 1490 -0.466 1491 -0.244 1492 -0.146 1493 -0.278 1494 -0.394 1495 -0.526 1496 -0.275 1497 -0.264 1498 -0.233 1499 -0.169 1500 -0.128 1501 -0.415 1502 -0.306 1503 0.011 1504 -0.013 1505 -0.378 1506 -0.226 1507 -0.428 1508 -0.192 1509 -0.312 1510 -0.157 1511 -0.162 1512 -0.188 1513 -0.135 1514 -0.418 1515 -0.258 1516 -0.381 1517 -0.134 1518 -0.180 1519 -0.166 1520 -0.035 1521 -0.384 1522 -0.302 1523 -0.541 1524 -0.371 1525 -0.183 1526 -0.289 1527 -0.224 1528 -0.247 1529 -0.432 1530 -0.291 1531 -0.467 1532 -0.343 1533 -0.586 1534 -0.183 1535 -0.417 1536 -0.350 1537 -0.257 1538 -0.451 1539 -0.398 1540 -0.497 1541 -0.406 1542 -0.584 1543 -0.448 1544 -0.317 1545 -0.312 1546 -0.289 1547 -0.114 1548 -0.459 1549 -0.335 1550 -0.009 1551 -0.074 1552 -0.047 1553 -0.207 1554 -0.285 1555 -0.116 1556 -0.141 1557 -0.419 1558 -0.174 1559 -0.465 1560 -0.287 1561 -0.169 1562 -0.231 1563 -0.270 1564 -0.347 1565 -0.116 1566 -0.202 1567 -0.278 1568 -0.445 1569 -0.488 1570 -0.465 1571 -0.434 1572 -0.674 1573 -0.324 1574 -0.493 1575 -0.273 1576 -0.623 1577 -0.483 1578 -0.521 1579 -0.551 1580 -0.473 1581 -0.436 1582 -0.382 1583 -0.345 1584 -0.280 1585 -0.565 1586 -0.409 1587 -0.580 1588 -0.530 1589 -0.534 1590 -0.354 1591 -0.377 1592 -0.407 1593 -0.337 1594 -0.591 1595 -0.459 1596 -0.436 1597 -0.475 1598 -0.152 1599 -0.134 1600 -0.381 1601 -1.169 1602 -0.403 1603 -0.414 1604 -0.472 1605 -0.393 1606 -0.564 1607 -0.529 1608 -0.822 1609 -0.789 1610 -0.617 1611 -0.681 1612 -0.670 1613 -0.364 1614 -0.733 1615 -0.428 1616 -0.698 1617 -0.479 1618 -0.485 1619 -0.524 1620 -0.706 1621 -0.671 1622 -0.714 1623 -0.662 1624 -0.387 1625 -0.566 1626 -0.671 1627 -0.665 1628 -0.759 1629 -0.654 1630 -0.379 1631 -0.466 1632 -0.330 1633 -0.377 1634 -0.521 1635 -0.222 1636 -0.265 1637 -0.252 1638 -0.396 1639 -0.382 1640 -0.400 1641 -1.152 1642 -1.067 1643 -1.092 1644 -0.649 1645 -0.588 1646 -0.632 1647 -0.554 1648 -0.368 1649 -0.572 1650 -0.215 1651 -0.317 1652 -0.529 1653 -0.268 1654 -0.343 1655 -0.400 1656 -0.372 1657 -0.332 1658 -0.359 1659 -0.182 1660 -0.260 1661 -0.258 1662 -0.433 1663 -0.433 1664 -0.353 1665 -0.440 1666 -0.837 1667 -0.857 1668 -0.816 1669 -0.779 1670 -0.871 1671 -0.463 1672 -0.434 1673 -0.631 1674 -0.663 1675 -0.870 1676 -0.523 1677 -0.670 1678 -0.794 1679 -0.768 1680 -0.701 1681 -0.380 1682 -0.518 1683 -0.364 1684 -0.369 1685 -0.688 1686 -0.178 1687 -0.481 1688 -0.351 1689 -0.229 1690 -0.254 1691 -0.221 1692 -0.545 1693 -0.263 1694 -0.316 1695 -0.955 1696 -0.816 1697 -0.687 1698 -1.054 1699 -1.005 1700 -0.630 1701 -0.818 1702 -0.510 1703 -0.377 1704 -0.420 1705 -0.527 1706 -0.328 1707 -0.257 1708 -0.465 1709 -0.493 1710 -0.288 1711 -0.344 1712 -0.345 1713 -0.242 1714 -0.390 1715 -0.305 1716 -0.390 1717 -0.309 1718 -0.270 1719 -0.194 1720 -0.110 1721 -0.427 1722 0.005 1723 -0.193 1724 -0.249 1725 -0.497 1726 -0.381 1727 -0.241 1728 -0.133 1729 -0.261 1730 -0.633 1731 -0.723 1732 -0.426 1733 -0.371 1734 -0.104 1735 -0.373 1736 -0.330 1737 -0.206 1738 -0.557 1739 -0.291 1740 -0.734 1741 -0.594 1742 -0.808 1743 -0.378 1744 -0.372 1745 -0.418 1746 -0.501 1747 -0.150 1748 -0.389 1749 -0.328 1750 -0.168 1751 -0.343 1752 -0.227 1753 -0.218 1754 -0.377 1755 -0.328 1756 -0.221 1757 -0.259 1758 -0.431 1759 -0.340 1760 -0.335 1761 -0.261 1762 -0.466 1763 -0.291 1764 -0.473 1765 -0.378 1766 -0.212 1767 -0.429 1768 -0.544 1769 -0.343 1770 -0.341 1771 -0.265 1772 -0.547 1773 -0.421 1774 -0.048 1775 -0.289 1776 -0.186 1777 -0.288 1778 -0.178 1779 -0.550 1780 -0.339 1781 -0.251 1782 -0.164 1783 -0.757 1784 -0.142 1785 -0.141 1786 -0.179 1787 -0.432 1788 -0.207 1789 -0.235 1790 -0.612 1791 -0.163 1792 -0.086 1793 -0.023 1794 -0.030 1795 -0.243 1796 -0.028 1797 -0.565 1798 -0.049 1799 -0.228 1800 -0.287 1801 -0.413 1802 -0.117 1803 0.020 1804 0.036 1805 -0.094 1806 -0.251 1807 -0.089 1808 -0.241 1809 -0.460 1810 -0.582 1811 -0.353 1812 -0.459 1813 -0.545 1814 -0.458 1815 -0.588 1816 -0.855 1817 -0.861 1818 -0.629 1819 -0.680 1820 -0.289 1821 -0.351 1822 -0.159 1823 -0.246 1824 -0.276 1825 -0.263 1826 -0.140 1827 -0.293 1828 -0.033 1829 -0.087 1830 -0.173 1831 -0.045 1832 -0.621 1833 -0.660 1834 -0.141 1835 -0.647 1836 -0.775 1837 -0.771 1838 -0.359 1839 -0.267 1840 -0.144 1841 -0.077 1842 -0.337 1843 -0.435 1844 -0.101 1845 -0.412 1846 0.106 1847 -0.079 1848 -0.346 1849 -0.393 1850 -0.261 1851 -0.165 1852 -0.100 1853 -0.174 1854 -0.138 1855 -0.418 1856 -0.250 1857 -0.538 1858 -0.126 1859 -0.195 1860 -0.231 1861 -0.029 1862 -0.555 1863 -0.303 1864 -0.407 1865 -0.256 1866 -0.437 1867 -0.413 1868 -0.119 1869 -0.321 1870 -0.213 1871 -0.352 1872 -0.163 1873 -0.183 1874 -0.372 1875 -0.247 1876 -0.487 1877 -0.192 1878 0.120 1879 -0.152 1880 -0.346 1881 -0.184 1882 -0.200 1883 -0.183 1884 -0.717 1885 -0.534 1886 -0.485 1887 -0.281 1888 -0.261 1889 -0.153 1890 -0.341 1891 -0.313 1892 -0.138 1893 -0.301 1894 -0.134 1895 -0.128 1896 -0.241 1897 -0.016 1898 0.065 1899 -0.574 1900 -0.218 1901 -0.049 1902 -0.287 1903 -0.142 1904 -0.205 1905 -0.308 1906 -0.034 1907 -0.412 1908 -0.048 1909 -0.214 1910 -0.147 1911 -0.194 1912 -0.631 1913 -0.161 1914 -0.294 1915 -0.074 1916 -0.277 1917 -0.297 1918 -0.460 1919 -0.013 1920 -0.272 1921 -0.114 1922 -0.036 1923 -0.305 1924 -0.141 1925 -0.258 1926 -0.115 1927 -0.198 1928 -0.018 1929 -0.161 1930 0.086 1931 0.104 1932 0.081 1933 -0.057 1934 0.007 1935 -0.037 1936 -0.019 1937 0.060 1938 0.163 1939 -0.075 1940 0.113 1941 -0.200 1942 0.128 1943 0.053 1944 -0.080 1945 0.059 1946 -0.016 1947 -0.188 1948 -0.038 1949 -0.107 1950 -0.269 1951 -0.100 1952 -0.118 1953 0.161 1954 -0.235 1955 -0.127 1956 -0.308 1957 -0.194 1958 -0.308 1959 -0.224 1960 0.076 1961 -0.104 1962 -0.289 1963 -0.173 1964 -0.479 1965 -0.474 1966 -0.171 1967 -0.200 1968 -0.599 1969 -0.355 1970 -0.353 1971 -0.328 1972 -0.563 1973 -0.262 1974 -0.336 1975 -0.507 1976 -0.558 1977 -0.363 1978 -0.698 1979 -0.289 1980 -0.612 1981 -0.195 1982 -0.522 1983 -0.234 1984 -0.335 1985 -0.423 1986 -0.430 1987 -0.424 1988 -0.161 1989 -0.286 1990 -0.275 1991 -0.169 1992 -0.175 1993 -0.341 1994 -0.320 Attachment Converted: "c:\eudora\attach\Briffa et al.ps" Dr Timothy J Osborn | phone: +44 1603 592089 Senior Research Associate | fax: +44 1603 507784 Climatic Research Unit | e-mail: t.osborn@uea.ac.uk School of Environmental Sciences | web-site: University of East Anglia __________| http://www.cru.uea.ac.uk/~timo/ Norwich NR4 7TJ | sunclock: UK | http://www.cru.uea.ac.uk/~timo/sunclock.htm