easyclimate.field.teleconnection.index_da¶

Arctic Dipole Anomaly (DA/AD)

Functions¶

calc_index_DA_EOF2_Wu_2006(, lon_dim, lat_dim, ...)

The calculation of monthly mean Arctic Dipole Anomaly (DA/AD) index using empirical orthogonal functions (EOFs) method

Module Contents¶

easyclimate.field.teleconnection.index_da.calc_index_DA_EOF2_Wu_2006(slp_monthly_data: xarray.DataArray, time_range: slice = slice(None, None), lon_dim: str = 'lon', lat_dim: str = 'lat', lat_range: slice = slice(70, 90), time_dim: str = 'time', random_state: int | None = None, solver: Literal['auto', 'full', 'randomized'] = 'auto', solver_kwargs: dict = {}, normalized: bool = True) → xarray.DataArray¶

The calculation of monthly mean Arctic Dipole Anomaly (DA/AD) index using empirical orthogonal functions (EOFs) method

Tip

The second EOF mode of SLP anomaly north of 70°N is Arctic Dipole Anomaly (DA/AD) pattern.

Parameters¶

slp_monthly_data: xarray.DataArray.: The monthly data of sea level pressure (SLP).
time_range: slice, default: slice(None, None).: The time range of seasonal cycle means to be calculated. The default value is the entire time range.
lon_dim: str, default: lon.: Longitude coordinate dimension name. By default extracting is applied over the lon dimension.
lat_dim: str, default: lat.: Latitude coordinate dimension name. By default extracting is applied over the lat dimension.
lat_range: slice, default: slice(20, 90).: The latitude range of computation using EOFs over the Northern Hemisphere. The default value is from \(\mathrm{20^{\circ}N}\) to \(\mathrm{90^{\circ}N}\).
time_dim: str, default: time.: The time coordinate dimension name.
random_state: int, default None.: Seed for the random number generator.
solver: {“auto”, “full”, “randomized”}, default: “auto”.: Solver to use for the EOFs computation.
solver_kwargs: dict, default {}.: Additional keyword arguments to be passed to the EOFs solver.
normalized: bool, default True, optional.: Whether to standardize the index based on standard deviation over time_range.

Returns¶

The monthly mean DA/AD index (xarray.DataArray).

Reference¶

Wu, B., Wang, J., & Walsh, J. E. (2006). Dipole Anomaly in the Winter Arctic Atmosphere and Its Association with Sea Ice Motion. Journal of Climate, 19(2), 210-225. https://doi.org/10.1175/JCLI3619.1
Wu, B., and M. A. Johnson (2007), A seesaw structure in SLP anomalies between the Beaufort Sea and the Barents Sea, Geophys. Res. Lett., 34, L05811, doi: https://doi.org/10.1029/2006GL028333.
Wang, J., J. Zhang, E. Watanabe, M. Ikeda, K. Mizobata, J. E. Walsh, X. Bai, and B. Wu (2009), Is the Dipole Anomaly a major driver to record lows in Arctic summer sea ice extent? Geophys. Res. Lett., 36, L05706, doi: https://doi.org/10.1029/2008GL036706.
1. Zhang, R. Zhang, Mechanisms for low-frequency variability of summer Arctic sea ice extent, Proc. Natl. Acad. Sci. U.S.A. 112 (15) 4570-4575, https://doi.org/10.1073/pnas.1422296112 (2015).
Kapsch, ML., Skific, N., Graversen, R.G. et al. Summers with low Arctic sea ice linked to persistence of spring atmospheric circulation patterns. Clim Dyn 52, 2497–2512 (2019). https://doi.org/10.1007/s00382-018-4279-z
Bi, H., Wang, Y., Liang, Y., Sun, W., Liang, X., Yu, Q., Zhang, Z., & Xu, X. (2021). Influences of Summertime Arctic Dipole Atmospheric Circulation on Sea Ice Concentration Variations in the Pacific Sector of the Arctic during Different Pacific Decadal Oscillation Phases. Journal of Climate, 34(8), 3003-3019. https://doi.org/10.1175/JCLI-D-19-0843.1
Bi, H., Liang, Y., & Chen, X. (2023). Distinct role of a spring atmospheric circulation mode in the Arctic sea ice decline in summer. Journal of Geophysical Research: Atmospheres, 128, e2022JD037477. https://doi.org/10.1029/2022JD037477