Eastern Oregon NOAA Climate Divisions 7 and 8 PDSI and Precipitation Reconstructions, 1705-1979 : Readme file ----------------------------------------------------------------------- NOAA Paleoclimatology Program and World Data Center A for Paleoclimatology ----------------------------------------------------------------------- NOTE: PLEASE CITE ORIGINAL REFERENCE WHEN USING THIS DATA!!!!! NAME OF DATA SET: Eastern Oregon NOAA Climate Divisions 7 and 8 PDSI and Precipitation Reconstructions, 1705-1979 CONTRIBUTORS: Gregg M. Garfin and Malcolm K. Hughes Laboratory of Tree-Ring Research The University of Arizona Tucson, Arizona 85721 520-621-6470 MHUGHES@LTRR.ARIZONA.EDU IGBP PAGES/WDCA CONTRIBUTION SERIES NUMBER: 96-029 SUGGESTED DATA CITATION: Garfin, G. M., and Hughes, M. K., 1996, Eastern Oregon PDSI and Precipitation Reconstructions. International Tree-Ring Data Bank. IGBP PAGES/World Data Center-A for Paleoclimatology Data Contribution Series # 96-029. NOAA/NGDC Paleoclimatology Program, Boulder CO, USA. ORIGINAL REFERENCE: Garfin, G. M., and Hughes, M. K., 1996: Eastern Oregon Divisional Precipitation and Palmer Drought Severity Index from Tree-Rings. Report to the U.S. Forest Service Intermountain Research Station. USDA Forest Service Cooperative Agreement PNW 90-174. LATITUDE AND LONGITUDE: Approximate center of Oregon Division 7: 43°40'N 119°48'W Approximate center of Oregon Division 8: 45°00'N 118°00'W ELEVATION: Varies throughout each division GEOGRAPHIC REGION: Northwestern United States PERIOD OF RECORD: 1705-1979 LIST OF FILES: OR7_8.txt (space delimited ASCII text), Oregon.Readme(this file) VARIABLE NAMES: August Palmer Drought Severity Index (PDSI), Water Year Precipitation (Previous October-Current September) VARIABLE UNITS: PDSI = Index Values; Precipitation = mm DATA PRECISION: PDSI = 0.01; Precipitation = mm (whole numbers) DATA FORMAT: (I4,2F7.2,2I7) Column 1: YEAR Column 2: Oregon division 7 PDSI (D7PDSI) Column 3: Oregon division 8 PDSI (D8PDSI) Column 4: Oregon division 7 precipitation (D7MM) Column 5: Oregon division 8 precipitation (D8MM) DESCRIPTION: These data are reconstructed drought index and precipitation for NOAA Oregon climate divisions 7 and 8, derived from tree-ring data by Gregg M. Garfin and Dr. Malcolm K. Hughes of the Laboratory of Tree-Ring Research, University of Arizona. NOTE: These reconstructions were calibrated using drought sensitive tree-ring chronologies provided by David Meko at the Laboratory of Tree-Ring Research of the University of Arizona. The original reference for these chronologies is Meko, D., E. R. Cook, D. W. Stahle, C. W. Stockton, and M. K. Hughes. 1993. Spatial patterns of tree-growth anomalies in the United States and Southeastern Canada. Journal of Climate. 6(9):1773-1786. Observed divisional climate data were provided by the National Climatic Data Center. These data are referenced in the following publication: NCDC, 1994. Time bias corrected divisional temperature-precipitation-drought index. Documentation for dataset TD-9640. National Oceanic and Atmospheric Administration. Asheville. 12 pp. ADDITIONAL INFORMATION: 1. Chronology sites. Species are coded as follows: JUOC = Juniperus occidentalis, PIJE = Pinus jeffreyi, PIPO = Pinus ponderosa, PSME = Pseudotsuga menziesii. Site Name State Altitude(m) Species Latitude Longitude 1 SPRING CANYON OR 1366 JUOC 44 54'N 118 55'W 2 CASTLE ROCKS OR 1340 PIPO 44 39'N 121 33'W 2 ROBINSON LAKE TRAIL OR 1000 PSME 44 17'N 121 58'W 3 TABLE MOUNTAIN OR 1402 PIPO 44 13'N 118 51'W 4 HORSE RIDGE OR 1146 JUOC 43 58'N 121 04'W 4 FREDRICK BUTTE OR 1494 JUOC 43 35'N 120 27'W 4 COMMITTEE CREEK OR 1486 JUOC 44 10'N 120 14'W 5 CALAMITY CREEK OR 1463 JUOC 43 59'N 118 48'W 6 LITTLE JUNIPER MOUNTAIN OR 1650 JUOC 43 08'N 119 52'W 7 STEEN'S MOUNTAIN OR 1655 JUOC 42 40'N 118 55'W 8 GRASSHOPPER TRAIL ID 1701 JUOC 42 30'N 116 48'W 9 SHARP MOUNTAIN CA 1417 JUOC 41 43'N 121 48'W 10 TIMBERED MOUNTAIN CA 1581 JUOC 41 43'N 120 45'W 11 BLACK CONE CA 2190 PIPO 41 11'N 120 07'W 11 HAGER BASIN RESERVOIR CA 1524 JUOC 41 46'N 120 45'W 11 DALTON RESERVOIR CA 1531 PIPO 41 37'N 120 42'W 12 JACKSON MOUNTAINS NV 2097 JUOC 41 18'N 118 26'W 13 LIKELY MOUNTAIN CA 1760 PIJE 41 09'N 120 34'W METHODS: Linear regression models were used to retrodict precipitation and PDSI values from combinations of tree-ring predictor variables. The following model development strategy was employed: (1) principal components analysis was used to reduce the highly correlated individual tree-ring chronologies to a set of orthogonal predictors, which included information from the maximum number of individual chronologies and were, therefore, determined to be more robust than individual tree-ring chronology predictors; (2) best subsets regression between tree-ring PC predictors and 1931-1979 divisional climate data was used to suggest likely candidate models; (3) models were evaluated based on the following criteria: coefficient of determination (R2), F-statistic, residual analysis, and parsimony; (4)the same process was applied when lagged predictors were added to the best models selected in step 3; (5) the best models were subjected to two tests of verification, i.e., cross-validation based on the PRESS R2 statistic, and correlation with long individual instrumental station and divisional climate records, (6) the most straightforward and easily interpretable models that met the aforementioned criteria were selected. Finally, the reconstructions were compared with other tree-ring reconstructions of Pacific Northwest precipitation and drought.