Watamu Reef, Kenya Coral Radiocarbon Data ----------------------------------------------------------------------- World Data Center for Paleoclimatology, Boulder and NOAA Paleoclimatology Program ----------------------------------------------------------------------- NOTE: PLEASE CITE CONTRIBUTORS WHEN USING THIS DATA!!!!! NAME OF DATA SET: Watamu Reef, Kenya Coral Radiocarbon Data LAST UPDATE: 2/2003 (14C values rounded to zero decimal places) CONTRIBUTORS: Nancy Grumet, Tom Guilderson, Rob Dunbar IGBP PAGES/WDCA CONTRIBUTION SERIES NUMBER: 2002-084 SUGGESTED DATA CITATION: Grumet, N., et al., 2002, Watamu Reef, Kenya Coral Radiocarbon Data, IGBP PAGES/World Data Center for Paleoclimatology Data Contribution Series # 2002-084. NOAA/NGDC Paleoclimatology Program, Boulder CO, USA. ORIGINAL REFERENCES: Grumet, N.S., T.P. Guilderson, and R.D. Dunbar, 2002, Meridional Transport in the Indian Ocean Traced by Coral Radiocarbon. J. Marine Research, v.60, No.5, September 2002. Grumet, N.S., T.P. Guilderson, R.D. Dunbar Pre-bomb radiocarbon variability inferred from a Kenyan coral record. Radiocarbon, in press. GEOGRAPHIC REGION: Indian Ocean, coastal Kenya PERIOD OF RECORD: 1947-1987 DESCRIPTION: Watamu Reef, Kenya Coral Radiocarbon Data Watamu Reef, Kenya, Porites Lutea, 3 23' South, 39 52' East, 5m. water depth The data set includes a bimonthly radiocarbon time series derived from a coral record collected off the coast of Kenya in the western Indian Ocean. Radiocarbon analysis was performed at the Center for Accelerator Mass Spectrometry (CAMS) at Lawrence Livermore National Laboratory (LLNL). Oxygen isotope data (not included) was performed at Stanford University Stable Isotope Laboratory and used to develop the chronology. Abstract Ocean circulation in the Indian Ocean is predominantly driven by the monsoon and is responsible for convergence along the equator. As a result, upwelling is primarily restricted to the western boundary where surface waters are anomalously depleted in 14C. Here, we describe aspects of western boundary upwelling based on insights derived from the first coral radiocarbon time-series in the Indian Ocean. The absence of a distinct sub-annual pre-bomb d14C signal suggests that open and coastal upwelling are negligible off the coast of Kenya. Instead, our results suggest that upwelling from the coast of Somalia and possibly Oman are the sources of the depleted seasonal D14C signal. In contrast, the southern hemisphere subtropical gyre provides water enriched in 14C. We demonstrate that the coral D14C time-series is a tracer for meridional transport in the Indian Ocean. The Indian Ocean exhibits a shallow cross-equatorial overturning circulation cell. Our results demonstrate that the Kenyan coral radiocarbon record is responding to a western boundary limb of this cell, similar to that observed in other subtropical oceans. Therefore, while the majority of cross-equatorial transport is in the interior and eastern basin of the Indian Ocean, our results argue that the Somali Current is a distinct pathway for inter-hemispheric water mass exchange. DATA: In keeping with the definition of "high-precision radiocarbon" (<3 per mil, 1-sigma) data have been rounded to zero significant figures. Watamu, Kenya Coral Radiocarbon (per mil) N. Grumet Year D14C per mil 1947.417 -66 1947.58367 -68 1947.75034 -64 1947.91701 -57 1948.08368 -50 1948.25035 -50 1948.41702 -56 1948.58369 -58 1948.75036 -56 1948.91703 -59 1949.0837 -58 1949.25037 -59 1949.41704 -62 1949.58371 -62 1949.75038 -58 1949.91705 -67 1950.08372 -65 1950.25039 -62 1950.41706 -63 1950.58373 -61 1950.7504 -63 1950.91707 -67 1951.08374 -66 1951.25041 -63 1951.41708 -58 1951.58375 -57 1951.75042 -58 1951.91709 -58 1952.08376 -65 1952.25043 -63 1952.4171 -63 1952.58377 -64 1952.75044 -66 1952.91711 -63 1953.08378 -64 1953.25045 -64 1953.41712 -62 1953.58379 -62 1953.75046 -63 1953.91713 -63 1954.0838 -61 1954.25047 -59 1954.41714 -56 1954.58381 -57 1954.75048 -60 1954.91715 -62 1955.08382 -57 1955.25049 -53 1955.41716 -51 1955.58383 -50 1955.7505 -52 1955.91717 -49 1956.08384 -51 1956.25051 -57 1956.41718 -59 1956.58385 -53 1956.75052 -49 1956.91719 -51 1957.08386 -49 1957.25053 -44 1957.4172 -43 1957.58387 -41 1957.75054 -49 1957.91721 -44 1958.08388 -39 1958.25055 -38 1958.41722 -38 1958.58389 -38 1958.75056 -36 1958.91723 -32 1959.0839 -26 1959.25057 -29 1959.41724 -29 1959.58391 -31 1959.75058 -29 1959.91725 -22 1960.08392 -18 1960.25059 -19 1960.41726 -12 1960.58393 -15 1960.7506 -20 1960.91727 -18 1961.08394 -11 1961.25061 -12 1961.41728 1 1961.58395 -2 1961.75062 -1 1961.91729 -4 1962.08396 20 1962.25063 25 1962.4173 25 1962.58397 26 1962.75064 20 1962.91731 14 1963.08398 26 1963.25065 37 1963.41732 52 1963.58399 52 1963.75066 44 1963.91733 43 1964.084 54 1964.25067 64 1964.41734 68 1964.58401 63 1964.75068 57 1964.91735 65 1965.08402 77 1965.25069 77 1965.41736 71 1965.58403 68 1965.7507 68 1965.91737 92 1966.08404 97 1966.25071 91 1966.41738 93 1966.58405 87 1966.75072 80 1966.91739 87 1967.08406 99 1967.25073 98 1967.4174 100 1967.58407 94 1967.75074 90 1967.91741 83 1968.08408 92 1968.25075 99 1968.41742 105 1968.58409 95 1968.75076 88 1968.91743 84 1969.0841 83 1969.25077 86 1969.41744 92 1969.58411 93 1969.75078 90 1969.91745 87 1970.08412 79 1970.25079 83 1970.41746 99 1970.58413 101 1970.7508 102 1970.91747 97 1971.08414 91 1971.25081 91 1971.41748 102 1971.58415 116 1971.75082 113 1971.91749 105 1972.08416 95 1972.25083 104 1972.4175 117 1972.58417 114 1972.75084 109 1972.91751 101 1973.08418 90 1973.25085 95 1973.41752 109 1973.58419 110 1973.75086 110 1973.91753 100 1974.0842 105 1974.25087 109 1974.41754 115 1974.58421 121 1974.75088 114 1974.91755 113 1975.08422 110 1975.25089 107 1975.41756 108 1975.58423 103 1975.7509 98 1975.91757 99 1976.08424 101 1976.25091 106 1976.41758 108 1976.58425 101 1976.75092 94 1976.91759 97 1977.08426 99 1977.25093 104 1977.4176 101 1977.58427 98 1977.75094 94 1977.91761 96 1978.08428 101 1978.25095 106 1978.41762 111 1978.58429 111 1978.75096 104 1978.91763 93 1979.0843 96 1979.25097 102 1979.41764 107 1979.58431 106 1979.75098 103 1979.91765 101 1980.08432 105 1980.25099 108 1980.41766 109 1980.58433 107 1980.751 98 1980.91767 99 1981.08434 104 1981.25101 109 1981.41768 106 1981.58435 100 1981.75102 98 1981.91769 97 1982.08436 91 1982.25103 99 1982.4177 104 1982.58437 101 1982.75104 92 1982.91771 96 1983.08438 91 1983.25105 94 1983.41772 102 1983.58439 94 1983.75106 86 1983.91773 84 1984.0844 88 1984.25107 95 1984.41774 98 1984.58441 97 1984.75108 93 1984.91775 91 1985.08442 92 1985.25109 94 1985.41776 92 1985.58443 92 1985.7511 92 1985.91777 83 1986.08444 88 1986.25111 84 1986.41778 90 1986.58445 90 1986.75112 80 1986.91779 90 1987.08446 79 1987.25113 81