Abstract
El Niño-Southern Oscillation (ENSO) is an important driver of climate and carbon cycle variability in the Amazon. Sea surface temperature (SST) anomalies in the equatorial Pacific drive teleconnections with temperature directly through changes in atmospheric circulation. These circulation changes also impact precipitation and, consequently, soil moisture, enabling additional indirect effects on temperature through land-atmosphere coupling. To separate the direct influence of ENSO SST anomalies from the indirect effects of soil moisture, a mechanism-denial experiment was performed to decouple their variability in the Energy Exascale Earth System Model (E3SM) forced with observed SSTs from 1982 to 2016. Soil moisture variability was found to amplify and extend the effects of SST forcing on eastern Amazon temperature and carbon fluxes in E3SM. During the wet season, the direct, circulation-driven effect of ENSO SST anomalies dominated temperature and carbon cycle variability throughout the Amazon. During the following dry season, after ENSO SST anomalies had dissipated, soil moisture variability became the dominant driver in the east, explaining 67%-82% of the temperature difference between El Niño and La Niña years, and 85%-91% of the difference in carbon fluxes. These results highlight the need to consider the interdependence between temperature and hydrology when attributing the relative contributions of these factors to interannual variability in the terrestrial carbon cycle. Specifically, when offline models are forced with observations or reanalysis, the contribution of temperature may be overestimated when its own variability is modulated by hydrology via land-atmosphere coupling.
| Original language | English |
|---|---|
| Pages (from-to) | 1273-1292 |
| Number of pages | 20 |
| Journal | Journal of Climate |
| Volume | 32 |
| Issue number | 4 |
| DOIs | |
| State | Published - Feb 1 2019 |
Funding
We received funding support from the Reducing Uncertainties in Biogeochemical Interactions through Synthesis and Computation Scientific Focus Area (RUBISCO SFA), which is sponsored by the Regional and Global Model Analysis (RGMA) Program in the Climate and Environmental Sciences Division (CESD) of the Office of Biological and Environmental Research (BER) in the U.S. Department of Energy (DOE) Office of Science. This research used resources from Project m2467 of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility (DE-AC02-05CH11231), and from Project cli106bgc of the Oak Ridge Leadership Computing Facility, which is a DOE Office of Science User Facility (DE-AC05-00OR22725). P.A.L. received funding support from NASA Headquarters under the NASA Earth and Space Science Fellowship Program (NNX16AO38H). J.T.R. and Y.C. received additional funding support from the DOE Office of Science Earth System Modeling Program (DE-SC0006791) and NASA's SMAP and CMS programs. M.S.P. received funding support from the DOE Early Career Program (DESC0012152). M.X. and F.M.H. received additional funding support from the Energy Exascale Earth System Model (E3SM) Project and the Next Generation Ecosystem Experiments-Tropics (NGEE-Tropics) Project, sponsored by BER in the DOE Office of Science. Oak Ridge National Laboratory (ORNL) is managed by UTBattelle, LLC, for the DOE (DE-AC05-00OR22725). GPCP combined precipitation data were provided by the NASA/Goddard Space Flight Center's Laboratory for Atmospheres, which develops and computes the dataset as a contribution to the GEWEX Global Precipitation Climatology Project, from their website at https://precip.gsfc.nasa.gov. CMAP precipitation data were provided by the NOAA/OAR/ESRL PSD, Boulder, Colorado, USA, from their Web site at https://www.esrl.noaa.gov/psd. GRACE terrestrial water storage data are available at http://grace.jpl.nasa.gov, supported by the NASA MEaSUREs Program. CRU TS data were obtained from the University of East Anglia through their website at https://crudata.uea.ac.uk. ERAInterim data were obtained from the European Centre for Medium-Range Weather Forecasts through their website at http://apps.ecmwf.int/datasets. MERRA-2 data were obtained from the Goddard Earth Sciences Data and Information Services Center through their website at https://disc.sci.gsfc.nasa.gov. E3SM output from this experiment is archived on the National Energy Research Scientific Computing Center's High Performance Storage System and is available for download at http://portal.nersc.gov/archive/home/p/plevine/www/data_archive/e3sm_enso. Acknowledgments. We received funding support from the Reducing Uncertainties in Biogeochemical Interactions through Synthesis and Computation Scientific Focus Area (RUBISCO SFA), which is sponsored by the Regional and Global Model Analysis (RGMA) Program in the Climate and Environmental Sciences Division (CESD) of the Office of Biological and Environmental Research (BER) in the U.S. Department of Energy (DOE) Office of Science. This research used resources from Project m2467 of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility (DE-AC02-05CH11231), and from Project cli106bgc of the Oak Ridge Leadership Computing Facility, which is a DOE Office of Science User Facility (DE-AC05-00OR22725). P.A.L. received funding support from NASA Headquarters under the NASA Earth and Space Science Fellowship Program (NNX16AO38H). J.T.R. and Y.C. received additional funding support from the DOE Office of Science Earth System Modeling Program (DE-SC0006791) and NASA’s SMAP and CMS programs. M.S.P. received funding support from the DOE Early Career Program (DESC0012152). M.X. and F.M.H. received additional funding support from the Energy Exascale Earth System Model (E3SM) Project and the Next Generation Ecosystem Experiments–Tropics (NGEE-Tropics) Project, sponsored by BER in the DOE Office of Science. Oak Ridge National Laboratory (ORNL) is managed by UT-Battelle, LLC, for the DOE (DE-AC05-00OR22725). GPCP combined precipitation data were provided by the NASA/Goddard Space Flight Center’s Laboratory for Atmospheres, which develops and computes the dataset as a contribution to the GEWEX Global Precipitation Climatology Project, from their website at https://precip.gsfc.nasa.gov. CMAP precipitation data were provided by the NOAA/OAR/ESRL PSD, Boulder, Colorado, USA, from their Web site at https:// www.esrl.noaa.gov/psd. GRACE terrestrial water storage data are available at http://grace.jpl.nasa.gov, supported by the NASA MEaSUREs Program. CRU TS data were obtained from the University of East Anglia through their website at https://crudata.uea.ac.uk. ERA-Interim data were obtained from the European Centre for Medium-Range Weather Forecasts through their website at http://apps.ecmwf.int/datasets. MERRA-2 data were obtained from the Goddard Earth Sciences Data and Information Services Center through their website at https:// disc.sci.gsfc.nasa.gov. E3SM output from this experiment is archived on the National Energy Research Scientific Computing Center’s High Performance Storage System and is available for download at http://portal.nersc.gov/ archive/home/p/plevine/www/data_archive/e3sm_enso.
| Funders | Funder number |
|---|---|
| DOE Office of Science Earth System Modeling Program | DESC0012152 |
| NGEE-Tropics | |
| U.S. Department of Energy | DE-SC0006791 |
| National Aeronautics and Space Administration | NNX16AO38H |
| Office of Science | DE-AC05-00OR22725, DE-AC02-05CH11231 |
| Biological and Environmental Research | |
| Oak Ridge National Laboratory | |
| Stephen F. Austin State University | |
| National Energy Research Scientific Computing Center | |
| University of East Anglia |
Keywords
- Amazon region
- Atmosphere-land interaction
- ENSO
- Interannual variability
- Land surface model
- Soil moisture