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1. Quantifying chemical weathering rates along a precipitation gradient on Basse-Terre Island, French Guadeloupe: New insight from U-series isotopes in weathering rinds

   https://doi.org/10.1016/j.gca.2016.08.040  

   Engel, Jacqueline M.; Ma, Lin; Sak, Peter B.; Gaillardet, Jerome; Ren, Minghua; Engle, Mark A.; Brantley, Susan L. (December 2016, Geochimica et Cosmochimica Acta)
2. Reconciling chemical weathering rates across scales: Application of uranium-series isotope systematics in volcanic weathering clasts from Basse-Terre Island (French Guadeloupe)

   https://doi.org/10.1016/j.epsl.2019.115874  

   Guo, Jiye; Ma, Lin; Gaillardet, Jerome; Sak, Peter B.; Pereyra, Yvette; Engel, Jacqueline (January 2020, Earth and Planetary Science Letters)
3. The Role of Southeast Asian Island Topography on Indo‐Pacific Climate and Silicate Weathering

   https://doi.org/10.1029/2023PA004672  

   Chiang, John. C. H.; Maffre, Pierre; Swanson‐Hysell, Nicholas L.; Macdonald, Francis A. (March 2024, Paleoceanography and Paleoclimatology)

   Abstract The geography of the Southeast Asian Islands (SEAI) has changed over the last 15 million years, as a result of tectonic processes contributing to both increased land area and high topography. The presence of the additional land area has been postulated to enhance convective rainfall, facilitating both increased silicate weathering and the development of the modern‐day Walker circulation. Using an Earth System Model in conjunction with a climate‐silicate weathering model, we argue instead for a significant role of SEAItopographyfor both effects. SEAI topography increases orographic rainfall over land, through intercepting moist Asian‐Australian monsoon winds and enhancing land‐sea breezes. Large‐scale atmospheric uplift over the SEAI region increases by ∼14% as a consequence of increased rainfall over the SEAI and enhancement through dynamical ocean‐atmosphere feedback. The atmospheric zonal overturning circulation over the Indo‐Pacific increases modestly arising from dynamical ocean‐atmosphere feedback, more strongly over the tropical Indian Ocean. On the other hand, the effect of the SEAI topography on global silicate weathering is substantial, resulting in a ∼109 ppm reduction in equilibriumpCO₂and decrease in global mean temperature by ∼1.7ºC. The chemical weathering increase comes from both enhanced physical erosion rates and increased rainfall due to the presence of SEAI topography. The lowering ofpCO₂by SEAI topography also enhances the Indo‐Pacific atmospheric zonal overturning circulation. Our results support a significant role for the progressive emergence of SEAI topography in global cooling over the last several million years. 

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4. The effect of weathering in runoff-to-groundwater partitioning in the Island of Hawai'i: Perspectives for landscape evolution

   https://doi.org/10.1016/j.epsl.2024.118687  

   Perez-Fodich, Alida; Derry, Louis A; Marçais, Jean; Walter, M Todd (June 2024, Earth and Planetary Science Letters)

   We investigated how runoff-to-groundwater partitioning changes as a function of substrate age and degree of regolith development in the Island of Hawai’i, by modeling watershed-scale hydrodynamic properties for a series of volcanic catchments of different substrate age developed under different climates. In the younger catchments, rainfall infiltrates directly into the groundwater system and surface runoff is minimal, consisting of ephemeral streams flowing on the scale of hours to days. The older catchments show increasing surface runoff, with deeper incision and perennial discharge. We hypothesize that watershed-scale hydrodynamic properties change as a function of their weathering history—the convolution of time and climate: as surfaces age and become increasingly weathered, hydraulic conductivity is reduced, leading to increased runoff-to-recharge ratios. To test this relationship, we calculated both saturated hydraulic conductivity (k) and aquifer thickness (D) using recession flow analysis. We show that the average k in the younger catchments can be between 3 to 6 orders of magnitude larger than in older catchments, whereas modeled D increases with age. Ephemeral streams with zero baseflow at daily timescales cannot be evaluated using the same method. Instead, we calculated the recession constant for two contiguous catchments developed on young ash or lava deposits of different ages. Increasing bedrock age results in slower recession response in these ephemeral streams, which is consistent with decreasing hydraulic conductivity. Our results highlight the role of the weathering history in determining the evolution of watershed-scale hydrologic properties in volcanic catchments. 

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5. Data from: The role of Southeast Asian island topography on Indo-Pacific climate and silicate weathering

   https://doi.org/10.6078/D1271P  

   Chiang, John; Maffre, Pierre (January 2023, Dryad)

   The modern configuration of the South East Asian Islands (SEAI) evolved over the last fifteen million years, as a result of subduction, arc magmatism, and arc-continent collisions, contributing to both increased land area and high topography.  The presence of the additional land area has been postulated to enhance convective rainfall, facilitating both increased silicate weathering and the development of the modern-day Walker circulation.  Using an Earth System Model in conjunction with a climate-silicate weathering model, we argue instead for a significant role of SEAI topography for both effects.  This dataset archives model output used in this investigation, including simulations using the Community Earth System Model version 1.2, and the climate-silicate weathering model GEOCLIM. All data are in Netcdf format, and were generated either by the Community Earth System Model 1.2 (Hurrell et al. 2013) or the climate-silicate weathering model GEOCLIM (Park et al. 2020).  Model output is organized into 4 tar files: 1) B1850C5.tar Contains model output for the fully coupled CESM1.2 runs, for 2D fields and for 3D pressure vertical velocity (W) between 10S-10N.  Monthly mean data for years 41-110 of the simulations.   Naming convention is No SEAI topography: B1850C5_noSEAItopo_y41-110.nc and B1850C5_noSEAItopo_W_y41-110.nc 50% SEAI topography: B1850C5_0.5SEAItopo_y41-110.nc and B1850C5_0.5SEAItopo_W_y41-110.nc 100% SEAI topography: B1850C5_y41-110.nc and B1850C5_W_y41-110.nc 150% SEAO topogaphy: B1850C5_1.5SEAItopo_y41-110.nc and B1850C5_1.5SEAItopo_W_y41-110.nc 2) E1850C5.tar Contains model output for the slab ocean CESM1.2 runs, for 2D fields and for 3D pressure vertical velocity (W) between 10S-10N.  Monthly mean data for years 21-50 of the simulations.  Naming convention is No SEAI topography: E1850C5_noSEAItopo_y21-50.nc and E1850C5_noSEAItopo_W_y21-50.nc 50% SEAI topography: E1850C5_0.5SEAItopo_y21-50.nc and E1850C5_0.5SEAItopo_W_y21-50.nc 100% SEAI topography: E1850C5_y21-50.nc and E1850C5_W_y21-50.nc 150% SEAO topogaphy:  E1850C5_1.5SEAItopo_y21-50.nc and E1850C5_1.5SEAItopo_W_y21-50.nc 3) GEOCLIM.tar Contains model output from the climate-silicate weathering model GEOCLIM.  Data is provided for all 573 parameter combinations.  All values are climatological annual means. All files contain these variables: GMST: global mean surface temperature (in K) atm_CO2_level: atmospheric pCO2 (in ppm) degassing: globally-integrated CO2 flux (in mol/yr) The files ending with 1xCO2.nc also contain these spatial fields: lithology fraction: fraction of land covered by a lithology class erosion: Regolith erosion rate (m/yr) weathering: Ca-Mg weathering rate (mol/m^2/yr) E1850C5_1xCO2.nc - GEOCLIM output using the Modern SEAI simulation as input, and for CO2 fixed to 286.7ppm.  E1850C5_noSEAI_1xCO2.nc - GEOCLIM output using the no SEAI simulation as input, and for CO2 fixed to 286.7ppm.  E1850C5_noSEAItopo_1xCO2.nc - GEOCLIM output using the flat SEAI simulation as input, and for CO2 fixed to 286.7ppm.  E1850C5_noSEAI_equil.nc - GEOCLIM output using the no SEAI simulation as input, and CO2 adjusted so that system is in carbon flux equilibrium.   E1850C5_noSEAItopo_flatSEAIslope_equil.nc - GEOCLIM output using the flat SEAI simulation as input, and CO2 adjusted so that system is in carbon flux equilibrium.   4) Surface.tar Contains land fraction and surface geopotential fields for the modern SEAI (Landfrac.nc) and no SEAI (Landfrac_noSEAI.nc) simulations References Hurrell, J.W., Holland, M.M., Gent, P.R., Ghan, S., Kay, J.E., Kushner, P.J., Lamarque, J.F., Large, W.G., Lawrence, D., Lindsay, K. and Lipscomb, W.H., 2013. The community earth system model: a framework for collaborative research. Bulletin of the American Meteorological Society, 94(9), pp.1339-1360. Park, Y., Maffre, P., Goddéris, Y., Macdonald, F.A., Anttila, E.S. and Swanson-Hysell, N.L., 2020. Emergence of the Southeast Asian islands as a driver for Neogene cooling. Proceedings of the National Academy of Sciences, 117(41), pp.25319-25326. 

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