Primary productivity, new productivity, and their relation to carbon flux during two Southern Ocean Gas Exchange tracer experiments

Journal of Geophysical Research: Oceans

Volumn 117, Issue 4, 2012, Pages

  Lance, Veronica P ^a,b,i   Strutton, Peter G ^c,d   Vaillancourt, Robert D ^e   Hargreaves, Bruce R ^f   Zhang, Jia Zhong ^g   Marra, John ^h  

^a International Research Institute for Climate and Society   (United States)

^b SCIENCE SYSTEMS AND APPLICATIONS INC   (United States)

^c UNIVERSITY OF TASMANIA   (Australia)

^d ARC Centre of Excellence for Climate System Science   (Australia)

^e MILLERSVILLE UNIVERSITY   (United States)

^f LEHIGH UNIVERSITY   (United States)

^g ATLANTIC OCEANOGRAPHIC AND METEOROLOGICAL LABORATORY   (United States)

^h CITY UNIVERSITY OF NEW YORK   (United States)

ⁱ NASA GODDARD SPACE FLIGHT CENTER   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

CARBON DIOXIDE; CHLOROPHYLL; NITRATES; OCEANOGRAPHY; PHOTOSYNTHESIS; PHYTOPLANKTON; PRODUCTIVITY; SILICON;

AIR SEA FLUX; ANTARCTIC ZONE; BIOLOGICAL UPTAKE; CARBON BUDGETS; CARBON FLUXES; CHLOROPHYLL CONCENTRATION; F RATIO; GAS EXCHANGE; INORGANIC CARBON; MIXED LAYER; OPEN OCEAN; PHOTOCHEMICAL EFFICIENCY; PRIMARY PRODUCTION; PRIMARY PRODUCTIVITY; RELEASE GAS; SOUTHERN OCEAN; SOUTHWEST ATLANTIC; TRACER EXPERIMENT;

EXPERIMENTS;

AIR-SEA INTERACTION; AMMONIUM; BIOLOGICAL UPTAKE; CARBON BUDGET; CARBON DIOXIDE; CARBON FLUX; CARBON ISOTOPE; CHLOROPHYLL; CONCENTRATION (COMPOSITION); GAS EXCHANGE; INORGANIC CARBON; ION; MIXED LAYER; NITRATE; PRIMARY PRODUCTION;

SOUTHERN OCEAN;

EID: 84859726961     PISSN: None     EISSN: 21699291     Source Type: Journal    
DOI: 10.1029/2011JC007687     Document Type: Article

References (78)

1. Ardelan, M. V., O. Holm-Hansen, C. D. Hewes, C. S. Reiss, N. S. Silva, H. Dulaiova, E. Steinnes, and E. Sakshaug (2010), Natural iron enrichment around the Antarctic Peninsula in the Southern Ocean, Biogeosciences, 7, 11-25, doi:10.5194/bg-7-11-2010.
2. Atkinson, A., and M. J. Whitehouse (2000), Ammonium excretion by Antarctic krill Euphausia superba at South Georgia, Limnol. Oceanogr., 45, 55-63, doi:10.4319/lo.2000.45.1.0055. (Pubitemid 30065599)
3. Atkinson, A., and M. J. Whitehouse (2001), Ammonium regeneration by Antarctic mesozooplankton: An allometric approach, Mar. Biol., 139, 301-312, doi:10.1007/s002270100590. (Pubitemid 32824579)
4. Atkinson, A., M. J. Whitehouse, J. Priddle, G. C. Cripps, P. Ward, and M. A. Brandon (2001), South Georgia, Antarctica: A productive, cold water, pelagic ecosystem, Mar. Ecol. Prog. Ser., 216, 279-308, doi:10.3354/meps216279. (Pubitemid 32731503)
5. Balch, W. M., D. T. Drapeau, B. C. Bowler, E. Lyczskowski, E. S. Booth, and D. Alley (2011), The contribution of coccolithophores to the optical and inorganic carbon budgets during the Southern Ocean Gas Exchange Experiment: New evidence in support of the "Great Calcite Belt" hypothesis, J. Geophys. Res., 116, C00F06, doi:10.1029/2011JC006941.
6. Behrenfeld, M. J., A. J. Bale, Z. S. Kolber, J. Aiken, and P. G. Falkowski (1996), Confirmation of iron limitation of phytoplankton photosynthesis in the equatorial Pacific Ocean, Nature, 383, 508-511, doi:10.1038/ 383508a0.
7. Behrenfeld, M. J., K. Worthington, R. M. Sherrell, F. P. Chavez, P. Strutton, M. McPhaden, and D. M. Shea (2006), Controls on tropical Pacific Ocean productivity revealed through nutrient stress diagnostics, Nature, 442, 1025-1028, doi:10.1038/nature05083. (Pubitemid 44330257)
8. Blain, S., et al. (2001), A biogeochemical study of the island mass effect in the context of the iron hypothesis: Kerguelen Islands, Southern Ocean, Deep Sea Res., Part I, 48, 163-187, doi:10.1016/S0967-0637(00)00047-9.
9. Blain, S., et al. (2007), Effect of natural iron fertilization on carbon sequestration in the Southern Ocean, Nature, 446, 1070-1074, doi:10.1038/ nature05700. (Pubitemid 46676050)
10. Brzezinski, M. A., D. M. Nelson, V. M. Franck, and D. E. Sigmon (2001), Silicon dynamics within an intense open-ocean diatom bloom in the Pacific sector of the Southern Ocean, Deep Sea Res., Part II, 48, 3997-4018, doi:10.1016/S0967-0645(01)00078-9. (Pubitemid 34029728)
11. Brzezinski, M. A., J. L. Jones, and M. S. Demarest (2005), Control of silica production by iron and silicic acid during the Southern Ocean Iron Experiment (SOFeX), Limnol. Oceanogr., 50, 810-824, doi:10.4319/10.2005.50.3. 0810. (Pubitemid 40764368)
12. Coale, K. H., S. E. Fitzwater, R. M. Gordon, K. S. Johnson, and R. T. Barber (1996), Control of community growth and export production by upwelled iron in the equatorial Pacific Ocean, Nature, 379, 621-624, doi:10.1038/ 379621a0.
13. Coale, K. H., et al. (2004), Southern Ocean iron enrichment experiment: Carbon cycling in high- and low-Si waters, Science, 304, 408-414, doi:10.1126/science.1089778. (Pubitemid 38495931)
14. Cochlan, W. P. (2008), Nitrogen uptake in the Southern Ocean, in Nitrogen in the Marine Environment, edited by D. G. Capone et al., pp. 569-596, Elsevier, Burlington, Mass., doi:10.1016/B978-0-12-372522-6.00012-8
15. Cochlan, W. P., and R. M. Kudela (2006), The Southern Ocean Iron Enrichment Experiment: The nitrogen uptake response, in Report of the 2004 Workshop on In Situ Iron Enrichment Experiments in the Eastern and Western Subarctic Pacific, PICES Sci. Rep. 31, edited by S. Takeda and C. S.Wong, pp. 26-31,North Pac. Mar. Sci. Organ., Victoria, B. C. Canada.
16. Del Castillo, C. E., and R. L. Miller (2011), Horizontal and vertical distributions of colored dissolved organic matter during the Southern Ocean Gas Exchange Experiment, J. Geophys. Res., 116, C00F07, doi:10.1029/ 2010JC006781.
17. Dugdale, R. C., and J. J. Goering (1967), Uptake of new and regenerated forms of nitrogen in primary productivity, Limnol. Oceanogr., 12, 196-206, doi:10.4319/lo.1967.12.2.0196.
18. Dugdale, R. C., and F. P. Wilkerson (1986), The use of 15N to measure nitrogen uptake in eutrophic oceans: Experimental considerations, Limnol. Oceanogr., 31, 673-689, doi:10.4319/lo.1986.31.4.0673.
19. Dugdale, R. C., F. P. Wilkerson, and H. J. Minas (1995), The role of a silicate pump in driving new production, Deep Sea Res., Part I, 42, 697-719, doi:10.1016/0967-0637(95)00015-X. (Pubitemid 26449910)
20. Eppley, R. W., and B. J. Peterson (1979), Particulate organic matter flux and planktonic new production in the deep ocean, Nature, 282, 677-680, doi:10.1038/282677a0. (Pubitemid 10257612)
21. Franck, V. M., M. A. Brzezinski, K. H. Coale, and D. M. Nelson (2000), Iron and silicic acid concentrations regulate Si uptake north and south of the Polar Frontal Zone in the Pacific sector of the Southern Ocean, Deep Sea Res., Part II, 47, 3315-3338, doi:10.1016/S0967-0645(00)00070-9. (Pubitemid 32039890)
22. Goeyens, L., P. Tréguer, M. E. M. Baumann, W. Baeyens, and F. Dehairs (1995), The leading role of ammonium in the nitrogen uptake regime of Southern Ocean marginal ice zones, J. Mar. Syst., 6, 345-361, doi:10.1016/0924-7963(94)00033-8.
23. Gordon, A. L. (1967), Structure of Antarctic Waters Between 20°W and 170°W, Antarct. Map Folio Ser., vol. 6, Am. Geogr. Soc., Brooklyn, N. Y.
24. Hamme, R. C., et al. (2012), Dissolved O2/Ar and other methods reveal rapid changes in productivity during a Lagrangian experiment in the Southern Ocean, J. Geophys. Res., 117, C00F12, doi:10.1029/ 2011JC007046.
25. Hinz, D. J., M. C. Nielsdóttir, R. E. Korb, M. J. Whitehouse, A. J. Poulton, C. M. Moore, E. P. Achterberg, and T. S. Bibby (2012), Responses of microplankton community structure to iron addition in the Scotia Sea, Deep Sea Res., Part II, 59-60, 36-46, doi:10.1016/j.dsr2.2011.08.006.
26. Hiscock, M. R., et al. (2003), Primary productivity and its regulation in the Pacific sector of the Southern Ocean, Deep Sea Res., Part II, 50, 533-558, doi:10.1016/S0967-0645(02)00583-0. (Pubitemid 36339256)
27. Ho, D. T., et al. (2011a), Southern Ocean Gas Exchange Experiment: Setting the stage, J. Geophys. Res., 116, C00F08, doi:10.1029/ 2010JC006852.
28. Ho, D. T., R. Wanninkhof, P. Schlosser, D. S. Ullman, D. Hebert, and K. F. Sullivan (2011b), Toward a universal relationship between wind speed and gas exchange: Gas transfer velocities measured with 3He/SF6 during the Southern Ocean Gas Exchange Experiment, J. Geophys. Res., 116, C00F04, doi:10.1029/2010JC006854.
29. Holeton, C. L., et al. (2005), Physiological state of phytoplankton communities in the Southwest Atlantic sector of the Southern Ocean, as measured by fast repetition rate fluorometry, Polar Biol., 29, 44-52, doi:10.1007/s00300-005-0028-y. (Pubitemid 41778797)
30. Hooker, S. B., et al. (2005), The second SeaWiFS HPLC Analysis Round- Robin Experiment (SeaHARRE-2), Rep. NASA/TM-2005-212785, NASA Sci. and Tech. Inf. Program Off., Hanover, Md.
31. Jeffrey, S. W., R. F. C. Mantoura, and S. W. Wright (Eds.) (1997), Phytoplankton Pigments in Oceanography: Guidelines to Modern Methods, Monogr. Oceanogr. Methodol. Ser., vol. 10, U.N. Educ. Sci. and Cult. Organ., Paris.
32. Johnson, Z. I., R. Shyam, A. E. Ritchie, C. Mioni, V. P. Lance, J. W. Murray, and E. R. Zinser (2010), The effect of iron- and light-limitation on phytoplankton communities of deep chlorophyll maxima of the western Pacific Ocean, J. Mar. Res., 68, 283-308, doi:10.1357/002224010793721433.
33. Joubert, W. R., S. J. Thomalla, H. N. Waldron, M. I. Lucas, M. Boye, F. A. C. Le Moigne, F. Planchon, and S. Speich (2011), Nitrogen uptake by phytoplankton in the Atlantic sector of the Southern Ocean during late austral summer, Biogeosciences, 8, 2947-2959, doi:10.5194/bg-8-2947- 2011.
34. Kolber, Z., J. Zehr, and P. Falkowski (1988), Effects of growth irradiance and nitrogen limitation on photosynthetic energy conversion in photosystem II, Plant Physiol., 88, 923-929, doi:10.1104/pp.88.3.923.
35. Kolber, Z. S., O. Prasil, and P. G. Falkowski (1998), Measurements of variable chlorophyll fluorescence using fast repetition rate techniques: Defining methodology and experimental protocols, Biochim. Biophys. Acta, Bioenerg., 1367, 88-106, doi:10.1016/S0005-2728(98)00135-2. (Pubitemid 28451586)
36. Korb, R. E., M. J. Whitehouse, A. Atkinson, and S. E. Thorpe (2008), Magnitude and maintenance of the phytoplankton bloom at South Georgia: A naturally iron-replete environment, Mar. Ecol. Prog. Ser., 368, 75-91, doi:10.3354/meps07525.
37. Korb, R. E., M. J. Whitehouse, P. Ward, M. Gordon, H. J. Venables, and A. J. Poulton (2012), Regional and seasonal differences in microplankton biomass, productivity, and structure across the Scotia Sea: Implications for the export of biogenic carbon, Deep Sea Res., Part II, 59-60, 67-77, doi:10.1016/j.dsr2. 2011.06.006.
38. Lance, V. P. (2007), Functional effects of iron availability on phytoplankton photophysiology in high nutrient, low chlorophyll ocean environments, Ph.D. thesis, pp. 216, Duke Univ., Beaufort, N. C.
39. Lee, Z., et al. (2011), An assessment of optical properties and primary production derived from remote sensing in the Southern Ocean (SO GasEx), J. Geophys. Res., 116, C00F03, doi:10.1029/2010JC006747.
40. Leynaert, A., P. Tréguer, C. Lancelot, and M. Rodier (2001), Silicon limitation of biogenic silica production in the equatorial Pacific, Deep Sea Res., Part I, 48, 639-660, doi:10.1016/S0967-0637(00)00044-3. (Pubitemid 32100457)
41. Lindley, S. T., and R. T. Barber (1998), Phytoplankton response to natural and experimental iron addition, Deep Sea Res., Part II, 45, 1135-1150, doi:10.1016/S0967-0645(98)00014-9. (Pubitemid 28503892)
42. Lippemeier, S., P. Hartig, and F. Colijn (1999), Direct impact of silicate on the photosynthetic performance of the diatom Thalassiosira weissflogii assessed by on- and off-line PAM fluorescence measurements, J. Plankton Res., 21, 269-283, doi:10.1093/plankt/21.2.269. (Pubitemid 29332221)
43. Lipschultz, F., N. R. Bates, C. A. Carlson, and D. A. Hansell (2002), New production in the Sargasso Sea: History and current, Global Biogeochem. Cycles, 16(1), 1001, doi:10.1029/2000GB001319.
44. Marchetti, A., D. E. Varela, V. P. Lance, Z. Johnson, M. Palmucci, M. Giordano, and E. V. Armbrust (2010), Iron and silicic acid effects on phytoplankton productivity, diversity, and chemical composition in the central equatorial Pacific Ocean, Limnol. Oceanogr., 55, 11-29, doi:10.4319/lo.2010.55. 1.0011.
45. Moore, J. K., and M. R. Abbott (2002), Surface chlorophyll concentrations in relation to the Antarctic Polar Front: Seasonal and spatial patterns from satellite observations, J. Mar. Syst., 37, 69-86, doi:10.1016/S0924-7963(02) 00196-3. (Pubitemid 35343512)
46. Moore, J. K., M. R. Abbott, J. G. Richman, and D. M. Nelson (2000), The Southern Ocean at the last glacial maximum: A strong sink for atmospheric carbon dioxide, Global Biogeochem. Cycles, 14, 455-475, doi:10.1029/1999GB900051.
47. Mosseri, J., B. Queguiner, L. Armand, and V. Cornet-Barthaux (2008), Impact of iron on silicon utilization by diatoms in the Southern Ocean: A case study of Si/N cycle decoupling in a naturally iron-enriched area, Deep Sea Res., Part II, 55, 801-819, doi:10.1016/j.dsr2.2007.12.003.
48. Nelson, D. M., M. A. Brzezinski, D. E. Sigmon, and V. M. Franck (2001), A seasonal progression of Si limitation in the Pacific sector of the Southern Ocean, Deep Sea Res., Part II, 48, 3973-3995, doi:10.1016/S0967- 0645(01)00076-5. (Pubitemid 34029727)
49. Olson, R. J. (1980), Nitrate and ammonium uptake in Antarctic waters, Limnol. Oceanogr., 25, 1064-1074, doi:10.4319/lo.1980.25.6.1064.
50. Orsi, A. H., T. Whitworth, and W. D. Nowlin (1995), On the meridional extent and fronts of the Antarctic Circumpolar Current, Deep Sea Res., Part I, 42, 641-673, doi:10.1016/0967-0637(95)00021-W. (Pubitemid 26462963)
51. Parkhill, J. P., G. Maillet, and J. J. Cullen (2001), Fluorescence-based maximal quantum yield for PSII as a diagnostic of nutrient stress, J. Phycol., 37, 517-529, doi:10.1046/j.1529-8817.2001.037004517.x. (Pubitemid 32827868)
52. Pollard, R. T., M. I. Lucas, and J. F. Read (2002), Physical controls on biogeochemical zonation in the Southern Ocean, Deep Sea Res., Part II, 49, 3289-3305, doi:10.1016/S0967-0645(02)00084-X. (Pubitemid 34674081)
53. Pollard, R., R. Sanders, M. Lucas, and P. Statham (2007), The Crozet natural iron bloom and Export experiment (CROZEX), Deep Sea Res., Part II, 54, 1905-1914, doi:10.1016/j.dsr2.2007.07.023. (Pubitemid 47588914)
54. Pollard, R. T., et al. (2009), Southern Ocean deep-water carbon export enhanced by natural iron fertilization, Nature, 457, 577-580, doi:10.1038/ nature07716.
55. Priddle, J., et al. (2003), Biogeochemistry of a Southern Ocean plankton ecosystem: Using natural variability in community composition to study the role of metazooplankton in carbon and nitrogen cycles, J. Geophys. Res., 108(C4), 8082, doi:10.1029/2000JC000425.
56. Richardson, T. L., and G. A. Jackson (2007), Small phytoplankton and carbon export from the surface ocean, Science, 315, 838-840, doi:10.1126/ science.1133471.
57. Rönner, U., F. Sorensson, and O. Holmhansen (1983), Nitrogen assimilation by phytoplankton in the Scotia Sea, Polar Biol., 2, 137-147, doi:10.1007/BF00448963.
58. Sabine, C. L., R. A. Feely, G. C. Johnson, P. G. Strutton, M. F. Lamb, and K. E. McTaggart (2004), A mixed layer carbon budget for the GasEx- 2001 experiment, J. Geophys. Res., 109, C08S05, doi:10.1029/ 2002JC001747.
59. Sabine, C. L., R. A. Feely, G. C. Johnson, P. G. Strutton, V. P. Lance, M. D. DeGrandpre, and L. W. Juranek (2010), A carbon mass balance for the Southern Ocean GasEx experiment, Eos Trans. AGU, 91(26), Ocean Sci. Meet. Suppl., Abstract IT54D-07.
60. Sarmiento, J. L., and N. Gruber (2006), Ocean Biogeochemical Dynamics, 503 pp., Princeton Univ. Press, Princeton, N. J.
61. Sosik, H. M., and R. J. Olson (2002), Phytoplankton and iron limitation of photosynthetic efficiency in the Southern Ocean during late summer, Deep Sea Res., Part I, 49, 1195-1216, doi:10.1016/S0967-0637(02) 00015-8.
62. Strutton, P. G., F. P. Chavez, R. C. Dugdale, and V. Hogue (2004), Primary productivity in the central equatorial Pacific (3S 130°W) during GasEx- 2001, J. Geophys. Res., 109, C08S06, doi:10.1029/2003JC001790. (Pubitemid 39437399)
63. Suggett, D. J., C. M. Moore, A. E. Hickman, and R. J. Geider (2009), Interpretation of fast repetition rate (FRR) fluorescence: Signatures of phytoplankton community structure versus physiological state, Mar. Ecol. Prog. Ser., 376, 1-19, doi:10.3354/meps07830.
64. Tarling, G. A., P. Ward, A. Atkinson, M. A. Collins, and E. J. Murphy (2012), DISCOVERY 2010: Spatial and temporal variability in a dynamic polar ecosystem, Deep Sea Res., Part II, 59-60, 1-13, doi:10.1016/j. dsr2.2011.10.001.
65. Trathan, P. N., M. A. Brandon, and E. J. Murphy (1997), Characterization of the Antarctic Polar Frontal Zone to the north of South Georgia in summer 1994, J. Geophys. Res., 102, 10,483-10,497, doi:10.1029/ 97JC00381. (Pubitemid 27457514)
66. Tréguer, P., and G. Jacques (1992), Dynamics of nutrients and phytoplankton, and fluxes of carbon, nitrogen and silicon in the Antarctic Ocean, Polar Biol., 12, 149-162, doi:10.1007/BF00238255. (Pubitemid 23403228)
67. U.S. Joint Global Ocean Flux Study Antarctic Environment and Southern Ocean Process Study (USJGOFS AESOPS) (2003), US JGOFS AESOPS Niskin Bottle Data, http://usjgofs.whoi.edu/jg/serv/jgofs/merged-objects/ US-JGOFS/Southern-Ocean/ bottle-southern.brev0, Woods Hole Oceanogr. Inst., Woods Hole, Mass.
68. Venables, H., and C. M. Moore (2010), Phytoplankton and light limitation in the Southern Ocean: Learning from high-nutrient, high-chlorophyll areas, J. Geophys. Res., 115, C02015, doi:10.1029/2009JC005361.
69. Welschmeyer, N. A. (1994), Fluorometric analysis of chlorophyll-A in the presence of chlorophyll-b and pheopigments, Limnol. Oceanogr., 39, 1985-1992, doi:10.4319/lo.1994.39.8.1985.
70. Whitehouse, M. J., J. Priddle, P. N. Trathan, and M. A. Brandon (1996), Substantial open-ocean phytoplankton blooms to the north of South Georgia, South Atlantic, during summer 1994, Mar. Ecol. Prog. Ser., 140, 187-197, doi:10.3354/meps140187.
71. Whitehouse, M. J., J. Priddle, and M. A. Brandon (2000), Chlorophyll/ nutrient characteristics in the water masses to the north of South Georgia, Southern Ocean, Polar Biol., 23, 373-382, doi:10.1007/s003000050458. (Pubitemid 30343074)
72. Whitehouse, M. J., A. Atkinson, P. Ward, R. E. Korb, P. Rothery, and S. Fielding (2009), Role of krill versus bottom-up factors in controlling phytoplankton biomass in the northern Antarctic waters of South Georgia, Mar. Ecol. Prog. Ser., 393, 69-82, doi:10.3354/meps08288.
73. Whitehouse, M. J., A. Atkinson, R. E. Korb, H. J. Venables, D. W. Pond, and M. Gordon (2012), Substantial primary production in the land-remote region of the central and northern Scotia Sea, Deep Sea Res., Part II, 59-60, 47-56, doi:10.1016/j.dsr2.2011.05.010.
74. Zhang, J. Z. (2000), Shipboard automated determination of trace concentrations of nitrite and nitrate in oligotrophic water by gas-segmented continuous flow analysis with a liquid waveguide capillary flow cell, Deep Sea Res., Part I, 47, 1157-1171, doi:10.1016/S0967-0637(99)00085-0. (Pubitemid 30168051)
75. Zhang, J. Z., P. B. Ortner, C. J. Fischer, and L. Moore (1997), Determination of ammonia in estuarine and coastal waters by gas segmented continuous flow colorimetric analysis, in Methods for the Determination of Chemical Substances in Marine and Estuarine Environmental Matrices, 2nd ed., pp. 349.0-01-349.0-16, U.S. Environ. Prot. Agency, Cincinnati.
76. Zhang, J. Z., C. J. Fischer, and P. B. Ortner (2000), Comparison of open stubular cadmium reactor and packed cadmium column in automated gas-segmented continuous flow nitrate analysis, Int. J. Environ. Anal. Chem., 76, 99-113, doi:10.1080/03067310008034123. (Pubitemid 30244623)
77. Zhang, J. Z., C. J. Fischer, and P. B. Ortner (2001a), Continuous flow analysis of phosphate in natural waters using hydrazine as a reductant, Int. J. Environ. Anal. Chem., 80, 61-73, doi:10.1080/03067310108044386. (Pubitemid 32965049)
78. Zhang, J. Z., R. Wanninkhof, and K. Lee (2001b), Enhanced new production observed from the diurnal cycle of nitrate in an oligotrophic anticyclonic eddy, Geophys. Res. Lett., 28, 1579-1582, doi:10.1029/ 2000GL012065. (Pubitemid 32575985)