DOI: 10.5061/dryad.1rn8pk16q
title: ENSO’s changing grip on Bering Sea ice: The emerging control of the North Pacific meridional mode

description: Bering Sea winter sea ice (BSWI), vital for regional climate, ecosystem,
 and livelihoods, is significantly influenced by El Niño-Southern
 Oscillation (ENSO). Here we identify a shift in the ENSO-BSWI
 relationship. Pre-mid-1990s, traditional eastern Pacific ENSO dominated,
 driving a positive ENSO-BSWI linkage; Post-mid-1990s, more frequent
 central Pacific (CP) ENSO events reversed this relationship to negative.
 Observations and model experiments show CP El Niño coupled with
 positive-phase North Pacific Meridional Mode (NPMM) redirects
 poleward-propagating Rossby wave trains, enhancing Bering Sea southerlies.
 This suppresses ice advection, intensifies warm air intrusion, and reduces
 sea ice cover (SIC). Strengthened CP ENSO-NPMM coupling and heightened
 NPMM variability amplify this teleconnection, increasing its influence on
 winter SIC by 38.9% versus NPMM alone. Our findings underscore the growing
 role of subtropical and tropical Pacific climate interactions in subarctic
 sea ice variability and highlight the need for improved climate models
 that capture ENSO diversity, NPMM dynamics, and subtropical-subarctic
 teleconnections.
description: # ENSO’s changing grip on Bering Sea ice: The emerging control of the
 North Pacific meridional mode Dataset DOI:
 [10.5061/dryad.1rn8pk16q](10.5061/dryad.1rn8pk16q) ## Description of the
 data and file structure To examine the impact of anomalous surface winds
 on SIC, three ocean general circulation model (OGCM) experiments were
 conducted using the Parallel Ocean Program version 2 (POP2) within the
 Community Earth System Model version 1.2.2 (CESM1.2.2). These experiments
 consist of one control simulation (CTRL) and two sensitivity simulations
 (southerly and northerly wind experiments). The CTRL simulation is forced
 by global monthly climatological 10-meter winds, implemented with the
 G_NORMAL_YEAR component sets. The sensitivity experiments are identical to
 the CTRL, except that observed southerly or northerly wind anomalies are
 prescribed within the region spanning 160°E–160°W and 50°N–70°N from
 January to December. The surface wind anomalies are applied based on the
 partial regression pattern of JFM1 surface winds over the Bering Sea onto
 the normalized JJA0 Niño4 index during 1995-2021, without amplitude
 scaling. All OGCM experiments were integrated over 35 years, with the
 ensemble mean of the last 30 years used for analysis in this study. ###
 Files and variables #### File: data.zip File: data.zip contains two
 folders (pop_bs_south, pop_bs_north). Each folder includes *.ctl and .dat
 files (comp_aice_30case_320x384_JFM, comp_shf_30case_320x384_JFM,
 comp_transixy_30yr_320x384_JFM). The **.ctl files serve as descriptor
 files for the binary *.dat files. The dataset has a horizontal grid
 resolution of 320 points in the zonal direction (x) and 384 points in the
 meridional direction (y). The temporal average is the JFM (January,
 February, March) seasonal mean. **Description:**  `pop_bs_south`: Ensemble
 mean differences in SIC, surface heat flux (sensible heat flux (SHF),
 latent heat flux (LHF), net shortwave radiation (NSWR), net longwave
 radiation (NLWR), and net surface heat flux (Qnet)) and sea ice mass
 transport between the southerly winds experiment and CTRL. `pop_bs_north`:
 Ensemble mean differences in SIC, surface heat flux (sensible heat flux
 (SHF), latent heat flux (LHF), net shortwave radiation (NSWR), net
 longwave radiation (NLWR), and net surface heat flux (Qnet)) and sea ice
 mass transport between the northerly winds experiment and CTRL. 1\.
 "The file pair comp_aice_30case_320x384_JFM.[ctl|dat] "
 represents: `Ensemble mean difference`: The difference in sea ice
 concentration (SIC, variable aice) between the northerly/southerly winds
 experiment and the control (CTRL). `Statistical significance`: The
 corresponding values from a significant t-test (variable ttest)." 2\.
 "The file pair comp_shf_30case_320x384_JFM.[ctl|dat] "
 represents: ` Ensemble mean difference`: The difference in surface heat
 flux components (variable shf) between the northerly/southerly winds
 experiment and the control (CTRL). The five tdef values correspond to the
 following fluxes:  (*1) Latent Heat Flux (LHF)* (*2) Sensible Heat Flux
 (SHF)* (*3) Net Shortwave Radiation (NSWR)* *(4) Net Longwave Radiation
 (NLWR)* *(5) Net Surface Heat Flux (Qnet)*  `Statistical significance`:
 The corresponding values from a significant t-test (variable ttest). 3\.
 "comp_transixy_30yr_320x384_JFM.[ctl|dat]" represents:
  `Ensemble mean difference`: The difference in monthly means of ice mass
 transport on East side (variable transix) and monthly means of ice mass
 transport on North side (variable transiy) between the northerly/southerly
 winds experiment and the control (CTRL).  `Statistical significance`: The
 corresponding values from a significant t-test (variable ttest). Values
 where ttest &gt; 0 signify that the ensemble mean difference is
 statistically significant at the ≥90% confidence level. 
 
 #### Methods This dataset is the post-processed CESM model outputs of the
 northerly/southerly winds experiment and the control (CTRL). All the
 results were processed by the GrADS （Grid Analysis and Display System）.
 **Usage notes** The data descriptor file, commonly referred to as a
 control file and identified by its .ctl extension, is a plain-text file
 that contains all the necessary metadata to interpret its companion raw
 binary data file (.dat). This metadata includes the path to the data file,
 grid definition, time axis details, horizontal coordinates, vertical
 levels, and a list of variables with their units, effectively allowing the
 .ctl file to act as the header for the separate binary dataset, similar to
 a self-describing format like NetCDF. To open and view this data, the free
 and open-source software GrADS (Grid Analysis and Display System) can be
 used; it reads the .ctl file to load the corresponding .dat file, enabling
 users to interactively inspect, subset, and visualize the data.