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# Sea Ice Indicators
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Sea ice concentration and extent indicators for polar climate analysis and marine applications. These indicators are crucial for Arctic and Antarctic climate monitoring, shipping route planning, and marine ecosystem assessment.
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## Capabilities
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### Sea Ice Area and Extent
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Basic sea ice metrics for polar climate monitoring and trend analysis.
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```python { .api }
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def sea_ice_area(sic, freq="YS"):
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"""
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Total sea ice area from sea ice concentration.
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Parameters:
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- sic: xr.DataArray, daily sea ice concentration data (0-1 or %)
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- freq: str, resampling frequency (default "YS" for yearly)
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Returns:
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xr.DataArray: Total sea ice area
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"""
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def sea_ice_extent(sic, thresh="15%", freq="YS"):
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"""
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Sea ice extent (area with concentration above threshold).
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Parameters:
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- sic: xr.DataArray, daily sea ice concentration data
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- thresh: str or float, concentration threshold (default "15%")
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- freq: str, resampling frequency
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Returns:
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xr.DataArray: Sea ice extent
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"""
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def sic_mean(sic, freq="YS"):
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"""
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Mean sea ice concentration over specified period.
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Parameters:
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- sic: xr.DataArray, daily sea ice concentration data
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- freq: str, resampling frequency
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Returns:
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xr.DataArray: Mean sea ice concentration
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"""
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def sic_max(sic, freq="YS"):
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"""
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Maximum sea ice concentration over specified period.
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Parameters:
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- sic: xr.DataArray, daily sea ice concentration data
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- freq: str, resampling frequency
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Returns:
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xr.DataArray: Maximum sea ice concentration
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"""
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```
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### Sea Ice Threshold Indicators
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Threshold-based sea ice metrics for extreme ice conditions analysis.
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```python { .api }
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def sic_days_above(sic, thresh="15%", freq="YS"):
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"""
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Number of days with sea ice concentration above threshold.
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Parameters:
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- sic: xr.DataArray, daily sea ice concentration data
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- thresh: str or float, concentration threshold (default "15%")
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- freq: str, resampling frequency
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Returns:
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xr.DataArray: Number of days above threshold
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"""
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def sic_days_below(sic, thresh="15%", freq="YS"):
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"""
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Number of days with sea ice concentration below threshold.
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Parameters:
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- sic: xr.DataArray, daily sea ice concentration data
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- thresh: str or float, concentration threshold (default "15%")
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- freq: str, resampling frequency
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Returns:
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xr.DataArray: Number of days below threshold
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"""
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def ice_free_days(sic, thresh="15%", freq="YS"):
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"""
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Number of ice-free days (concentration below threshold).
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Parameters:
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- sic: xr.DataArray, daily sea ice concentration data
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- thresh: str or float, ice-free threshold (default "15%")
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- freq: str, resampling frequency
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Returns:
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xr.DataArray: Number of ice-free days
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"""
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```
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### Sea Ice Season Indicators
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Sea ice seasonality metrics for understanding ice formation and melt patterns.
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```python { .api }
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def sea_ice_season_start(sic, thresh="15%", window=5, freq="YS"):
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"""
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Start date of sea ice season.
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Parameters:
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- sic: xr.DataArray, daily sea ice concentration data
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- thresh: str or float, concentration threshold (default "15%")
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- window: int, minimum number of consecutive days (default 5)
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- freq: str, resampling frequency
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Returns:
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xr.DataArray: Ice season start day of year
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"""
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def sea_ice_season_end(sic, thresh="15%", window=5, freq="YS"):
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"""
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End date of sea ice season.
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Parameters:
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- sic: xr.DataArray, daily sea ice concentration data
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- thresh: str or float, concentration threshold (default "15%")
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- window: int, minimum number of consecutive days (default 5)
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- freq: str, resampling frequency
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Returns:
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xr.DataArray: Ice season end day of year
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"""
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def sea_ice_season_length(sic, thresh="15%", window=5, freq="YS"):
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"""
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Length of sea ice season.
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Parameters:
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- sic: xr.DataArray, daily sea ice concentration data
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- thresh: str or float, concentration threshold (default "15%")
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- window: int, minimum number of consecutive days (default 5)
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- freq: str, resampling frequency
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Returns:
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xr.DataArray: Ice season length in days
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"""
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```
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## Usage Examples
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### Basic Sea Ice Analysis
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```python
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import xarray as xr
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import xclim.seaIce as xcs
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# Load sea ice concentration data
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sic = xr.open_dataset("sea_ice.nc").siconc # Concentration in %
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# Calculate basic sea ice metrics
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ice_area = xcs.sea_ice_area(sic, freq="YS")
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ice_extent = xcs.sea_ice_extent(sic, thresh="15%", freq="YS")
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mean_conc = xcs.sic_mean(sic, freq="YS")
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```
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### Sea Ice Seasonality
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```python
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# Analyze ice season timing and duration
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season_start = xcs.sea_ice_season_start(
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sic, thresh="15%", window=7, freq="YS"
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)
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season_end = xcs.sea_ice_season_end(
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sic, thresh="15%", window=7, freq="YS"
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)
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season_length = xcs.sea_ice_season_length(
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sic, thresh="15%", window=7, freq="YS"
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)
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# Count ice-free days
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ice_free = xcs.ice_free_days(sic, thresh="15%", freq="YS")
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```
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### Threshold Analysis
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```python
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# Days with significant ice cover
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ice_days = xcs.sic_days_above(sic, thresh="50%", freq="YS")
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# Days with minimal ice
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low_ice_days = xcs.sic_days_below(sic, thresh="30%", freq="YS")
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```