easyclimate.field.air_sea_interaction.index_iobm

Indian Ocean Basin mode (IOBM) Index

Functions

calc_index_IOBM_1point(, lon_range, lon_dim, lat_dim, ...)	The calculation of monthly mean Indian Ocean Basin mode (IOBM) index is constructed by following method:
calc_index_IOBM_EOF1(, lon_range, lon_dim, lat_dim, ...)	The calculation of monthly mean PNA index using rotated empirical orthogonal functions (REOFs) method over the entire Northern Hemisphere:

Module Contents

easyclimate.field.air_sea_interaction.index_iobm.calc_index_IOBM_1point(sst_monthly_data: xarray.DataArray, time_range: slice = slice(None, None), lon_range: slice = slice(40, 110), lon_dim: str = 'lon', lat_dim: str = 'lat', time_dim: str = 'time', normalized: bool = False) → xarray.DataArray

The calculation of monthly mean Indian Ocean Basin mode (IOBM) index is constructed by following method:

The SSTA averaged over the tropical Indian Ocean (40°E-100°E, 20°S-20°N) or (40°E-110°E, 20°S-20°N).

Parameters

sst_monthly_data: xarray.DataArray.

The monthly sea surface temperature (SST) dataset.

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_range: slice, default: slice(40, 110).

The range of longitude to calculate the IOBM index. Common choices include slice(40, 110) and slice(40, 100).

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.

time_dim: str, default: time.

The time coordinate dimension name.

normalized: bool, default True, optional.

Whether to standardize the index based on standard deviation over time_range.

Returns

The monthly mean IOBM index (xarray.DataArray).

Reference

• (40°E-100°E, 20°S-20°N)

  1. Wu, Y., Tang, Y. Seasonal predictability of the tropical Indian Ocean SST in the North American multimodel ensemble. Clim Dyn 53, 3361–3372 (2019).

  2. Xie, S., Hu, K., Hafner, J., Tokinaga, H., Du, Y., Huang, G., & Sampe, T. (2009). Indian Ocean Capacitor Effect on Indo–Western Pacific Climate during the Summer following El Niño. Journal of Climate, 22(3), 730-747.

  3. Wang, J., Liu, Y., Cheng, F., Song, C., Li, Q., Ding, Y., and Xu, X (2023). Potential modulation of Indian Ocean basin mode on the interdecadal variations of summer precipitation over the East Asian monsoon boundary zone, EGUsphere [preprint].

• (40°E-110°E, 20°S-20°N)

  1. Yang, J., Q. Liu, S.-P. Xie, Z. Liu, and L. Wu (2007), Impact of the Indian Ocean SST basin mode on the Asian summer monsoon, Geophys. Res. Lett., 34, L02708

  2. Sun, Y., Zhu, Z., Yang, Y. et al. Decadal change in the connection between the Pacific–Japan pattern and the Indian Ocean SST basin mode. Clim Dyn (2024).

easyclimate.field.air_sea_interaction.index_iobm.calc_index_IOBM_EOF1(sst_monthly_data: xarray.DataArray, time_range: slice = slice(None, None), lon_range: slice = slice(40, 110), lon_dim: str = 'lon', lat_dim: str = 'lat', 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 PNA index using rotated empirical orthogonal functions (REOFs) method over the entire Northern Hemisphere:

Parameters

sst_monthly_data: xarray.DataArray.

The monthly sea surface temperature (SST) dataset.

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_range: slice, default: slice(40, 110).

The range of longitude to calculate the IOBM index. Common choices include slice(40, 110) and slice(40, 100).

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.

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 IOBM index (xarray.DataArray).

Reference

• (40°E-100°E, 20°S-20°N)

  1. Wu, Y., Tang, Y. Seasonal predictability of the tropical Indian Ocean SST in the North American multimodel ensemble. Clim Dyn 53, 3361–3372 (2019).

  2. Xie, S., Hu, K., Hafner, J., Tokinaga, H., Du, Y., Huang, G., & Sampe, T. (2009). Indian Ocean Capacitor Effect on Indo–Western Pacific Climate during the Summer following El Niño. Journal of Climate, 22(3), 730-747.

  3. Wang, J., Liu, Y., Cheng, F., Song, C., Li, Q., Ding, Y., and Xu, X (2023). Potential modulation of Indian Ocean basin mode on the interdecadal variations of summer precipitation over the East Asian monsoon boundary zone, EGUsphere [preprint].

• (40°E-110°E, 20°S-20°N)

  1. Yang, J., Q. Liu, S.-P. Xie, Z. Liu, and L. Wu (2007), Impact of the Indian Ocean SST basin mode on the Asian summer monsoon, Geophys. Res. Lett., 34, L02708

  2. Sun, Y., Zhu, Z., Yang, Y. et al. Decadal change in the connection between the Pacific–Japan pattern and the Indian Ocean SST basin mode. Clim Dyn (2024).

See also

get_EOF_model