#-----------------------------------------------------------------------
#                World Data Center for Paleoclimatology, Boulder 
#                                  and 
#                     NOAA Paleoclimatology Program 
#----------------------------------------------------------------------- 

# NOTE: Please cite original reference when using these data,
# plus the Online Resource and date accessed.

# Original_Source_URL: 
# Archive: Lake sediment
#--------------------
# Contribution_Date
# Date: 03-Jan-2015
#--------------------
# Title
# Study_name: Hudson Lake Gulf of Alaska Lake sediment Midge assemblages
#--------------------
# Investigators
# Investigators: Clegg, Benjamin F. and Kelly, Ryan and Clarke, Gina H. and Walker, Ian R. and Hu, Feng Sheng
#--------------------
# Publication
#       Authors: McKay, N.P. and Kaufman, D.S. 
#       Journal_Name: Nature Scientific Data
#       Published Title: An extended Arctic proxy temperature database for the past 2,000 years 
#       Published Date: August 2014 
#       DOI: 10.1038/sdata.2014.26 
#       Abstract: Robust climate reconstructions of the most recent centuries and millennia are invaluable for placing modern warming in the context of natural variability. Here we present an extended and revised database (version 1.1) of proxy temperature records recently used to reconstruct Arctic temperatures for the past 2,000 years. The datasets are presented in a machine-readable format, and have been extended with the geochronologic data and consistently generated time-uncertain ensembles, which will be useful in future analyses of the influence of geochronologic uncertainty. A revised reconstruction using the included updates and corrections suggests a stronger long-term cooling trend between AD 1 and 1900 than previously reported, although decadal to century variability remains consistent with previous studies. Comparisons with the observational record of temperature suggest that as a whole, the datasets faithfully record temperature variability across the Arctic, especially in northeast Canada and Greenland, where the density of records is highest. 
#--------------------
# Publication
#       Authors: Clegg, Benjamin F. and Kelly, Ryan and Clarke, Gina H. and Walker, Ian R. and Hu, Feng Sheng 
#       Journal Name: Proceedings of the National Academy of Sciences 
#       Published Title: Nonlinear response of summer temperature to Holocene insolation forcing in Alaska 
#       Published Date: 2011 
#       DOI: 10.1073/pnas.1110913108 
#       Abstract: Regional climate responses to large-scale forcings, such as precessional changes in solar irradiation and increases in anthropogenic greenhouse gases, may be nonlinear as a result of complex interactions among earth system components. Such nonlinear behaviors constitute a major source of climate ”surprises„ with important socioeconomic and ecological implications. Paleorecords are key for elucidating patterns and mechanisms of nonlinear responses to radiative forcing, but their utility has been greatly limited by the paucity of quantitative temperature reconstructions. Here we present Holocene July temperature reconstructions on the basis of midge analysis of sediment cores from three Alaskan lakes. Results show that summer temperatures during 10,000–5,500 calibrated years (cal) B.P. were generally lower than modern and that peak summer temperatures around 5,000 were followed by a decreasing trend toward the present. These patterns stand in stark contrast with the trend of precessional insolation, which decreased by  10#--------------------
# Site_Information
#        Site_Name: Hudson Lake
#        Region: Arctic
#        Northernmost Latitude: 61.9
#        Southernmost Latitude: 61.9
#        Easternmost Longitude: -145.66
#        Westernmost Longitude: -145.66
#--------------------
# Data_Collection
#        Collection_Name: Clegg.2011.Hudson Lake
#        Earliest_Year: -837.3
#        Most_Recent_Year: 1996.8
#        Time_Unit: AD
#        Core_Length: 194.5 (in cm)
#--------------------
# Chronology
          lab_id () | depth_top (mm) | depth_bot (mm) | age14C (bp) | age_error (1s) | age (bp) | cal_age_range_old (bp) | cal_age_range_young (2_s) | depth (mm) | thickness (mm)
          NA          0                5                NA            2                -50        NA                       NA                          2.5          5
          124541      860              870              905           40               829        736                      915                         865          10
          120727      880              885              7235          35               8046       7975                     8157                        882.5        5
          124542      1150             1160             1385          35               1301       1262                     1351                        1155         10
          119166      1410             1415             1660          35               1561       1433                     1683                        1412.5       5
          120728      1760             1765             2445          40               2504       2363                     2698                        1762.5       5
          120729      2120             2125             2870          35               2993       2885                     3132                        2122.5       5
          124543      2380             2390             3320          60               3549       3416                     3690                        2385         10
          124544      2660             2680             3660          70               3988       3785                     4202                        2670         20
          120730      2980             2985             3815          35               4204       4097                     4380                        2982.5       5
          119169      3450             3455             4480          35               5165       4982                     5284                        3452.5       5
          124545      3570             3580             4650          120              5361       4979                     5592                        3575         10
          124546      3980             3990             5710          40               6496       6412                     6625                        3985         10
          124547      4140             4150             5920          140              6754       6437                     7136                        4145         10
          124548      4320             4330             6990          45               7824       7707                     7927                        4325         10
          124549      4480             4490             7740          70               8516       8411                     8684                        4485         10
          124550      4590             4600             8040          180              8923       8494                     9400                        4595         10
          119167      4830             4835             11620         35               13454      13350                    13601                       4832.5       5
          119168      5125             5130             11400         150              13268      12991                    13596                       5127.5       5
#--------------------
# Variables
# Data line variables format:  9 components, and a 10th for climate-sensitive variables: what, material, error, units, seasonality, archive, detail, method, C or N for Character or Numeric data, direction of relation to climate (positive or negative)
## depth_cm	 depth, , , cm, , ,middle of sample, ,N 
## depthUpper_cm	 depth, , , cm, , ,top of sample, ,N 
## depthLower_cm	 depth, , , cm, , ,bottom of sample, ,N 
## year_AD	 age, , , AD, , ,middle of sample, Bacon ,N 
## yearYoung_AD	 age, , , AD, , ,top of sample, Bacon ,N 
## yearOld_AD	 age, , , AD, , ,bottom of sample, Bacon ,N 
## temp_C	 Temperature,midges,,deg C,Jul,Paleolimnology,,WA-PLS,N,positive
#--------------------
# Data
# Missing_Values: NA
# Age Ensembles archived at Clegg.2011.Hudson Lake_AgeEnsemble.nc 
#depth_cm	depthUpper_cm	depthLower_cm	year_AD	yearYoung_AD	yearOld_AD	temp_C	
3.5	 3.0	 4.0	 1996.80	 1998.30	 1995.30	 12.4427
6.5	 6.0	 7.0	 1982.85	 1986.00	 1979.70	 11.8305
9.5	 9.0	 10.0	 1963.95	 1967.10	 1960.80	 11.9809
11.0	 10.5	 12.0	 1952.00	 1956.40	 1943.20	 12.1493
13.0	 12.5	 14.0	 1934.40	 1938.80	 1925.60	 12.6840
16.0	 15.5	 17.0	 1906.30	 1911.55	 1895.80	 11.7884
21.0	 20.5	 22.0	 1852.90	 1858.60	 1841.80	 12.2451
29.5	 29.0	 30.0	 1755.25	 1761.10	 1749.40	 11.8630
31.5	 31.0	 32.0	 1732.55	 1738.20	 1726.90	 11.6209
33.5	 33.0	 34.0	 1710.05	 1715.70	 1704.40	 11.8002
39.5	 39.0	 40.0	 1639.85	 1645.70	 1634.00	 12.1686
41.5	 41.0	 42.0	 1616.50	 1622.40	 1610.60	 11.7739
43.5	 43.0	 44.0	 1592.95	 1598.80	 1587.10	 12.1870
49.5	 49.0	 50.0	 1521.85	 1527.80	 1515.90	 11.7845
51.5	 51.0	 52.0	 1499.05	 1504.70	 1493.40	 12.1440
53.5	 53.0	 54.0	 1476.50	 1482.10	 1470.90	 12.3654
56.5	 56.0	 57.0	 1442.55	 1448.20	 1436.90	 12.0741
59.5	 59.0	 60.0	 1407.90	 1413.70	 1402.10	 11.6462
73.5	 73.0	 74.0	 1246.70	 1252.20	 1241.20	 12.3892
81.5	 81.0	 82.0	 1155.20	 1160.80	 1149.60	 11.3719
86.0	 85.5	 86.5	 1101.90	 1108.75	 1095.10	 11.7572
96.5	 96.0	 97.0	 948.95	 956.50	 941.40	 11.8965
99.5	 99.0	 100.0	 903.40	 910.90	 895.90	 11.6004
101.5	 101.0	 102.0	 872.30	 880.10	 864.50	 11.5167
103.5	 103.0	 104.0	 840.85	 848.60	 833.10	 12.4180
106.5	 106.0	 107.0	 793.80	 801.70	 785.90	 11.6817
109.5	 109.0	 110.0	 746.40	 754.30	 738.50	 11.9513
111.5	 111.0	 112.0	 716.15	 723.70	 708.60	 12.0283
116.5	 116.0	 117.0	 644.20	 650.50	 637.90	 11.6253
127.0	 126.5	 127.5	 515.30	 521.60	 509.15	 12.1099
131.5	 131.0	 132.0	 460.60	 466.70	 454.50	 11.8080
133.5	 133.0	 134.0	 436.35	 442.40	 430.30	 11.8162
137.0	 136.5	 137.5	 394.90	 400.75	 389.05	 12.3465
147.0	 146.5	 147.5	 222.80	 234.85	 210.75	 12.1149
149.5	 149.0	 150.0	 162.75	 174.60	 150.90	 11.7374
151.5	 151.0	 152.0	 114.10	 126.30	 101.90	 11.9071
151.5	 151.0	 152.0	 114.10	 126.30	 101.90	 11.7977
157.0	 156.5	 157.5	 -20.30	 -7.90	 -32.70	 12.0760
159.5	 159.0	 160.0	 -82.15	 -69.80	 -94.50	 12.2780
164.0	 163.5	 164.5	 -193.80	 -181.25	 -206.35	 12.4379
169.0	 168.5	 169.5	 -318.90	 -306.35	 -331.40	 12.4789
175.0	 174.5	 176.0	 -464.50	 -452.35	 -484.10	 12.1902
186.0	 185.5	 186.5	 -653.30	 -645.55	 -661.00	 12.0892
198.0	 197.5	 198.5	 -837.30	 -829.75	 -844.90	 12.2841
