xclim.indicators.land package

Land Indicators

Submodules

xclim.indicators.land._snow module

xclim.indicators.land._snow.blowing_snow(snd='snd', sfcWind='sfcWind', *, snd_thresh='5 cm', sfcWind_thresh='15 km/h', window=3, freq='YS-JUL', ds=None)

Blowing snow days (realm: land)

The number of days with snowfall, snow depth, and windspeed over given thresholds for a period of days.

This indicator will check for missing values according to the method “from_context”. Based on indice blowing_snow(). Keywords : snow.

Parameters:

  • snd (str or DataArray) – Surface snow depth. Default : ds.snd. [Required units : [length]]

  • sfcWind (str or DataArray) – Wind velocity Default : ds.sfcWind. [Required units : [speed]]

  • snd_thresh (quantity (string or DataArray, with units)) – Threshold on net snowfall accumulation over the last window days. Default : 5 cm. [Required units : [length]]

  • sfcWind_thresh (quantity (string or DataArray, with units)) – Wind speed threshold. Default : 15 km/h. [Required units : [speed]]

  • window (number) – Period over which snow is accumulated before comparing against threshold. Default : 3.

  • freq (offset alias (string)) – Resampling frequency. See https://pandas.pydata.org/pandas-docs/stable/user_guide/timeseries.html#offset-aliases for available options. Default : YS-JUL.

  • ds (Dataset, optional) – A dataset with the variables given by name. Default : None.

Returns:

{freq}_blowing_snow (DataArray) – Days with snowfall and wind speed at or above given thresholds [days], with additional attributes: description: The {freq} number of days with snowfall over last {window} days above {snd_thresh} and wind speed above {sfcWind_thresh}.

Return type:

xarray.DataArray

xclim.indicators.land._snow.snd_days_above(snd='snd', *, thresh='2 cm', freq='YS-JUL', op='>=', ds=None, **indexer)

Days with snow (depth) (realm: land)

Number of days when the snow depth is greater than or equal to a given threshold.

This indicator will check for missing values according to the method “from_context”. Based on indice snd_days_above(). Keywords : snow.

Parameters:

  • snd (str or DataArray) – Surface snow thickness. Default : ds.snd. [Required units : [length]]

  • thresh (quantity (string or DataArray, with units)) – Threshold snow thickness. Default : 2 cm. [Required units : [length]]

  • freq (offset alias (string)) – Resampling frequency. The default value is chosen for the northern hemisphere. See https://pandas.pydata.org/pandas-docs/stable/user_guide/timeseries.html#offset-aliases for available options. Default : YS-JUL.

  • op ({‘ge’, ‘>=’, ‘>’, ‘gt’}) – Comparison operation. Default: “>=”. Default : >=.

  • ds (Dataset, optional) – A dataset with the variables given by name. Default : None.

  • indexer – Indexing parameters to compute the indicator on a temporal subset of the data. It accepts the same arguments as xclim.indices.generic.select_time(). Required.

Returns:

snd_days_above (DataArray) – Number of days with snow [days], with additional attributes: description: The {freq} number of days with snow depth greater than or equal to {thresh}.

Return type:

xarray.DataArray

xclim.indicators.land._snow.snd_max_doy(snd='snd', *, freq='YS-JUL', ds=None, **indexer)

Day of year of maximum snow depth (realm: land)

Day of the year when snow depth reaches its maximum value.

This indicator will check for missing values according to the method “from_context”. Based on indice snd_max_doy(). Keywords : snow.

Parameters:

  • snd (str or DataArray) – Surface snow depth. Default : ds.snd. [Required units : [length]]

  • freq (offset alias (string)) – Resampling frequency. See https://pandas.pydata.org/pandas-docs/stable/user_guide/timeseries.html#offset-aliases for available options. Default : YS-JUL.

  • ds (Dataset, optional) – A dataset with the variables given by name. Default : None.

  • indexer – Indexing parameters to compute the indicator on a temporal subset of the data. It accepts the same arguments as xclim.indices.generic.select_time(). Required.

Returns:

{freq}_snd_max_doy (DataArray) – Day of the year when snow depth reaches its maximum value (day_of_year), with additional attributes: description: The {freq} day of the year when snow depth reaches its maximum value.

Return type:

xarray.DataArray

xclim.indicators.land._snow.snd_season_end(snd='snd', *, thresh='2 cm', window=14, freq='YS-JUL', ds=None)

Snow cover end date (depth). (realm: land)

The first date on which snow depth is below a given threshold for a given number of consecutive days.

This indicator will check for missing values according to the method “from_context”. Based on indice snd_season_end(). Keywords : snow.

Parameters:

  • snd (str or DataArray) – Surface snow thickness. Default : ds.snd. [Required units : [length]]

  • thresh (quantity (string or DataArray, with units)) – Threshold snow thickness. Default : 2 cm. [Required units : [length]]

  • window (number) – Minimum number of days with snow depth below threshold. Default : 14.

  • freq (offset alias (string)) – Resampling frequency. The default value is chosen for the northern hemisphere. See https://pandas.pydata.org/pandas-docs/stable/user_guide/timeseries.html#offset-aliases for available options. Default : YS-JUL.

  • ds (Dataset, optional) – A dataset with the variables given by name. Default : None.

Returns:

snd_season_end (DataArray) – End date of continuous snow depth cover (day_of_year), with additional attributes: description: Day of year when snow depth is below {thresh} for {window} consecutive days.

Return type:

xarray.DataArray

References

Chaumont, Mailhot, Diaconescu, Fournier, and Logan [2017]

xclim.indicators.land._snow.snd_season_length(snd='snd', *, thresh='2 cm', window=14, freq='YS-JUL', ds=None, **indexer)

Snow cover duration (depth). (realm: land)

The season starts when snow depth is above a threshold for at least N consecutive days and stops when it drops below the same threshold for the same number of days.

This indicator will check for missing values according to the method “from_context”. Based on indice snd_season_length(). Keywords : snow.

Parameters:

  • snd (str or DataArray) – Surface snow thickness. Default : ds.snd. [Required units : [length]]

  • thresh (quantity (string or DataArray, with units)) – Threshold snow thickness. Default : 2 cm. [Required units : [length]]

  • window (number) – Minimum number of days with snow depth above and below threshold. Default : 14.

  • freq (offset alias (string)) – Resampling frequency. The default value is chosen for the northern hemisphere. See https://pandas.pydata.org/pandas-docs/stable/user_guide/timeseries.html#offset-aliases for available options. Default : YS-JUL.

  • ds (Dataset, optional) – A dataset with the variables given by name. Default : None.

  • indexer – Indexing parameters to compute the indicator on a temporal subset of the data. It accepts the same arguments as xclim.indices.generic.select_time(). Required.

Returns:

snd_season_length (DataArray) – Snow cover duration [days], with additional attributes: description: The duration of the snow season, starting with at least {window} days with snow depth above {thresh} and ending with at least {window} days with snow depth under {thresh}.

Return type:

xarray.DataArray

References

Chaumont, Mailhot, Diaconescu, Fournier, and Logan [2017]

xclim.indicators.land._snow.snd_season_start(snd='snd', *, thresh='2 cm', window=14, freq='YS-JUL', ds=None)

Snow cover start date (depth). (realm: land)

The first date on which snow depth is greater than or equal to a given threshold for a given number of consecutive days.

This indicator will check for missing values according to the method “from_context”. Based on indice snd_season_start(). Keywords : snow.

Parameters:

  • snd (str or DataArray) – Surface snow thickness. Default : ds.snd. [Required units : [length]]

  • thresh (quantity (string or DataArray, with units)) – Threshold snow thickness. Default : 2 cm. [Required units : [length]]

  • window (number) – Minimum number of days with snow depth above or equal to threshold. Default : 14.

  • freq (offset alias (string)) – Resampling frequency. The default value is chosen for the northern hemisphere. See https://pandas.pydata.org/pandas-docs/stable/user_guide/timeseries.html#offset-aliases for available options. Default : YS-JUL.

  • ds (Dataset, optional) – A dataset with the variables given by name. Default : None.

Returns:

snd_season_start (DataArray) – Start date of continuous snow depth cover (day_of_year), with additional attributes: description: Day of year when snow depth is above or equal to {thresh} for {window} consecutive days.

Return type:

xarray.DataArray

References

Chaumont, Mailhot, Diaconescu, Fournier, and Logan [2017]

xclim.indicators.land._snow.snd_storm_days(snd='snd', *, thresh='25 cm', freq='YS-JUL', ds=None, **indexer)

Winter storm days (realm: land)

Number of days with snowfall depth accumulation greater or equal to threshold (default: 25 cm).

This indicator will check for missing values according to the method “from_context”. Based on indice snd_storm_days(). Keywords : snow.

Parameters:

  • snd (str or DataArray) – Surface snow depth. Default : ds.snd. [Required units : [length]]

  • thresh (quantity (string or DataArray, with units)) – Threshold on snowfall depth accumulation require to label an event a snd storm. Default : 25 cm. [Required units : [length]]

  • freq (offset alias (string)) – Resampling frequency. See https://pandas.pydata.org/pandas-docs/stable/user_guide/timeseries.html#offset-aliases for available options. Default : YS-JUL.

  • ds (Dataset, optional) – A dataset with the variables given by name. Default : None.

  • indexer – Indexing parameters to compute the indicator on a temporal subset of the data. It accepts the same arguments as xclim.indices.generic.select_time(). Required.

Returns:

{freq}_snd_storm_days (DataArray) – Days with snowfall depth at or above a given threshold [days], with additional attributes: description: The {freq} number of days with snowfall depth accumulation above {thresh}.

Return type:

xarray.DataArray

Notes

Snowfall accumulation is estimated by the change in snow depth.

xclim.indicators.land._snow.snd_to_snw(snd='snd', *, snr=None, const='312 kg m-3', out_units=None, ds=None)

Surface snow amount (realm: atmos)

Based on indice snd_to_snw().

Parameters:

  • snd (str or DataArray) – Snow depth. Default : ds.snd. [Required units : [length]]

  • snr (quantity (string or DataArray, with units)) – Snow density. Default : None. [Required units : [mass]/[volume]]

  • const (quantity (string or DataArray, with units)) – Constant snow density const is only used if snr is None. Default : 312 kg m-3. [Required units : [mass]/[volume]]

  • out_units (str) – Desired units of the snow amount output. If None, output units simply follow from snd * snr. Default : None.

  • ds (Dataset, optional) – A dataset with the variables given by name. Default : None.

Returns:

snw (DataArray) – Approximation of daily snow amount from snow depth and density (surface_snow_amount) [kg m-2], with additional attributes: description: The approximation of daily snow amount from snow depth and density.

Return type:

xarray.DataArray

Notes

The estimated mean snow density value of 312 kg m-3 is taken from Sturm et al. [2010].

References

Sturm, Taras, Liston, Derksen, Jonas, and Lea [2010]

xclim.indicators.land._snow.snow_depth(snd='snd', *, freq='YS', ds=None, **indexer)

Mean snow depth (realm: land)

Mean of daily snow depth.

This indicator will check for missing values according to the method “from_context”. Based on indice snow_depth(). Keywords : snow.

Parameters:

  • snd (str or DataArray) – Mean daily snow depth. Default : ds.snd. [Required units : [length]]

  • freq (offset alias (string)) – Resampling frequency. See https://pandas.pydata.org/pandas-docs/stable/user_guide/timeseries.html#offset-aliases for available options. Default : YS.

  • ds (Dataset, optional) – A dataset with the variables given by name. Default : None.

  • indexer – Indexing parameters to compute the indicator on a temporal subset of the data. It accepts the same arguments as xclim.indices.generic.select_time(). Required.

Returns:

snow_depth (DataArray) – Mean of daily snow depth (surface_snow_thickness) [cm], with additional attributes: cell_methods: time: mean over days; description: The {freq} mean of daily mean snow depth.

Return type:

xarray.DataArray

xclim.indicators.land._snow.snow_melt_we_max(snw='snw', *, window=3, freq='YS-JUL', ds=None)

Maximum snow melt (realm: land)

The water equivalent of the maximum snow melt.

This indicator will check for missing values according to the method “from_context”. Based on indice snow_melt_we_max(). Keywords : snow.

Parameters:

  • snw (str or DataArray) – Snow amount (mass per area). Default : ds.snw. [Required units : [mass]/[area]]

  • window (number) – Number of days during which the melt is accumulated. Default : 3.

  • freq (offset alias (string)) – Resampling frequency. See https://pandas.pydata.org/pandas-docs/stable/user_guide/timeseries.html#offset-aliases for available options. Default : YS-JUL.

  • ds (Dataset, optional) – A dataset with the variables given by name. Default : None.

Returns:

{freq}_snow_melt_we_max (DataArray) – Maximum snow melt (change_over_time_in_surface_snow_amount) [kg m-2], with additional attributes: description: The {freq} maximum negative change in melt amount over {window} days.

Return type:

xarray.DataArray

xclim.indicators.land._snow.snw_days_above(snw='snw', *, thresh='4 kg m-2', freq='YS-JUL', op='>=', ds=None, **indexer)

Days with snow (amount) (realm: land)

Number of days when the snow amount is greater than or equal to a given threshold.

This indicator will check for missing values according to the method “from_context”. Based on indice snw_days_above(). Keywords : snow.

Parameters:

  • snw (str or DataArray) – Surface snow amount. Default : ds.snw. [Required units : [mass]/[area]]

  • thresh (quantity (string or DataArray, with units)) – Threshold snow amount. Default : 4 kg m-2. [Required units : [mass]/[area]]

  • freq (offset alias (string)) – Resampling frequency. The default value is chosen for the northern hemisphere. See https://pandas.pydata.org/pandas-docs/stable/user_guide/timeseries.html#offset-aliases for available options. Default : YS-JUL.

  • op ({‘ge’, ‘>=’, ‘>’, ‘gt’}) – Comparison operation. Default: “>=”. Default : >=.

  • ds (Dataset, optional) – A dataset with the variables given by name. Default : None.

  • indexer – Indexing parameters to compute the indicator on a temporal subset of the data. It accepts the same arguments as xclim.indices.generic.select_time(). Required.

Returns:

snw_days_above (DataArray) – Number of days with snow [days], with additional attributes: description: The {freq} number of days with snow amount greater than or equal to {thresh}.

Return type:

xarray.DataArray

xclim.indicators.land._snow.snw_max(snw='snw', *, freq='YS-JUL', ds=None, **indexer)

Maximum snow amount (realm: land)

The maximum snow amount equivalent on the surface.

This indicator will check for missing values according to the method “from_context”. Based on indice snw_max(). Keywords : snow.

Parameters:

  • snw (str or DataArray) – Snow amount (mass per area). Default : ds.snw. [Required units : [mass]/[area]]

  • freq (offset alias (string)) – Resampling frequency. See https://pandas.pydata.org/pandas-docs/stable/user_guide/timeseries.html#offset-aliases for available options. Default : YS-JUL.

  • ds (Dataset, optional) – A dataset with the variables given by name. Default : None.

  • indexer – Indexing parameters to compute the indicator on a temporal subset of the data. It accepts the same arguments as xclim.indices.generic.select_time(). Required.

Returns:

{freq}_snw_max (DataArray) – Maximum snow amount equivalent (surface_snow_amount) [kg m-2], with additional attributes: description: The {freq} maximum snow amount equivalent on the surface.

Return type:

xarray.DataArray

xclim.indicators.land._snow.snw_max_doy(snw='snw', *, freq='YS-JUL', ds=None, **indexer)

Day of year of maximum snow amount (realm: land)

The day of year when snow amount equivalent on the surface reaches its maximum.

This indicator will check for missing values according to the method “from_context”. Based on indice snw_max_doy(). Keywords : snow.

Parameters:

  • snw (str or DataArray) – Surface snow amount. Default : ds.snw. [Required units : [mass]/[area]]

  • freq (offset alias (string)) – Resampling frequency. See https://pandas.pydata.org/pandas-docs/stable/user_guide/timeseries.html#offset-aliases for available options. Default : YS-JUL.

  • ds (Dataset, optional) – A dataset with the variables given by name. Default : None.

  • indexer – Indexing parameters to compute the indicator on a temporal subset of the data. It accepts the same arguments as xclim.indices.generic.select_time(). Required.

Returns:

{freq}_snw_max_doy (DataArray) – Day of year of maximum daily snow amount equivalent (day_of_year), with additional attributes: description: The {freq} day of year when snow amount equivalent on the surface reaches its maximum.

Return type:

xarray.DataArray

xclim.indicators.land._snow.snw_season_end(snw='snw', *, thresh='4 kg m-2', window=14, freq='YS-JUL', ds=None)

Snow cover end date (amount). (realm: land)

The first date on which snow amount is below a given threshold for a given number of consecutive days.

This indicator will check for missing values according to the method “from_context”. Based on indice snw_season_end(). Keywords : snow.

Parameters:

  • snw (str or DataArray) – Surface snow amount. Default : ds.snw. [Required units : [mass]/[area]]

  • thresh (quantity (string or DataArray, with units)) – Threshold snow amount. Default : 4 kg m-2. [Required units : [mass]/[area]]

  • window (number) – Minimum number of days with snow water below threshold. Default : 14.

  • freq (offset alias (string)) – Resampling frequency. The default value is chosen for the northern hemisphere. See https://pandas.pydata.org/pandas-docs/stable/user_guide/timeseries.html#offset-aliases for available options. Default : YS-JUL.

  • ds (Dataset, optional) – A dataset with the variables given by name. Default : None.

Returns:

snw_season_end (DataArray) – End date of continuous snow amount cover (day_of_year), with additional attributes: description: Day of year when snow amount is below {thresh} for {window} consecutive days.

Return type:

xarray.DataArray

References

Chaumont, Mailhot, Diaconescu, Fournier, and Logan [2017]

xclim.indicators.land._snow.snw_season_length(snw='snw', *, thresh='4 kg m-2', window=14, freq='YS-JUL', ds=None, **indexer)

Snow cover duration (amount). (realm: land)

The season starts when the snow amount is above a threshold for at least N consecutive days and stops when it drops below the same threshold for the same number of days.

This indicator will check for missing values according to the method “from_context”. Based on indice snw_season_length(). Keywords : snow.

Parameters:

  • snw (str or DataArray) – Surface snow amount. Default : ds.snw. [Required units : [mass]/[area]]

  • thresh (quantity (string or DataArray, with units)) – Threshold snow amount. Default : 4 kg m-2. [Required units : [mass]/[area]]

  • window (number) – Minimum number of days with snow amount above and below threshold. Default : 14.

  • freq (offset alias (string)) – Resampling frequency. The default value is chosen for the northern hemisphere. See https://pandas.pydata.org/pandas-docs/stable/user_guide/timeseries.html#offset-aliases for available options. Default : YS-JUL.

  • ds (Dataset, optional) – A dataset with the variables given by name. Default : None.

  • indexer – Indexing parameters to compute the indicator on a temporal subset of the data. It accepts the same arguments as xclim.indices.generic.select_time(). Required.

Returns:

snw_season_length (DataArray) – Snow cover duration [days], with additional attributes: description: The duration of the snow season, starting with at least {window} days with snow amount above {thresh} and ending with at least {window} days with snow amount under {thresh}.

Return type:

xarray.DataArray

References

Chaumont, Mailhot, Diaconescu, Fournier, and Logan [2017]

xclim.indicators.land._snow.snw_season_start(snw='snw', *, thresh='4 kg m-2', window=14, freq='YS-JUL', ds=None)

Snow cover start date (amount). (realm: land)

The first date on which snow amount is greater than or equal to a given threshold for a given number of consecutive days.

This indicator will check for missing values according to the method “from_context”. Based on indice snw_season_start(). Keywords : snow.

Parameters:

  • snw (str or DataArray) – Surface snow amount. Default : ds.snw. [Required units : [mass]/[area]]

  • thresh (quantity (string or DataArray, with units)) – Threshold snow amount. Default : 4 kg m-2. [Required units : [mass]/[area]]

  • window (number) – Minimum number of days with snow amount above or equal to threshold. Default : 14.

  • freq (offset alias (string)) – Resampling frequency. See https://pandas.pydata.org/pandas-docs/stable/user_guide/timeseries.html#offset-aliases for available options. Default : YS-JUL.

  • ds (Dataset, optional) – A dataset with the variables given by name. Default : None.

Returns:

snw_season_start (DataArray) – Start date of continuous snow amount cover (day_of_year), with additional attributes: description: Day of year when snow amount is above or equal to {thresh} for {window} consecutive days.

Return type:

xarray.DataArray

References

Chaumont, Mailhot, Diaconescu, Fournier, and Logan [2017]

xclim.indicators.land._snow.snw_storm_days(snw='snw', *, thresh='10 kg m-2', freq='YS-JUL', ds=None, **indexer)

Winter storm days (realm: land)

Number of days with snowfall amount accumulation greater or equal to threshold (default: 10 kg m-2).

This indicator will check for missing values according to the method “from_context”. Based on indice snw_storm_days(). Keywords : snow.

Parameters:

  • snw (str or DataArray) – Surface snow amount. Default : ds.snw. [Required units : [mass]/[area]]

  • thresh (quantity (string or DataArray, with units)) – Threshold on snowfall amount accumulation require to label an event a snw storm. Default : 10 kg m-2. [Required units : [mass]/[area]]

  • freq (offset alias (string)) – Resampling frequency. See https://pandas.pydata.org/pandas-docs/stable/user_guide/timeseries.html#offset-aliases for available options. Default : YS-JUL.

  • ds (Dataset, optional) – A dataset with the variables given by name. Default : None.

  • indexer – Indexing parameters to compute the indicator on a temporal subset of the data. It accepts the same arguments as xclim.indices.generic.select_time(). Required.

Returns:

{freq}_snw_storm_days (DataArray) – Days with snowfall amount at or above a given threshold [days], with additional attributes: description: The {freq} number of days with snowfall amount accumulation above {thresh}.

Return type:

xarray.DataArray

Notes

Snowfall accumulation is estimated by the change in snow amount.

xclim.indicators.land._snow.snw_to_snd(snw='snw', *, snr=None, const='312 kg m-3', out_units=None, ds=None)

Surface snow depth (realm: atmos)

Based on indice snw_to_snd().

Parameters:

  • snw (str or DataArray) – Snow amount. Default : ds.snw. [Required units : [mass]/[area]]

  • snr (quantity (string or DataArray, with units)) – Snow density. Default : None. [Required units : [mass]/[volume]]

  • const (quantity (string or DataArray, with units)) – Constant snow density const is only used if snr is None. Default : 312 kg m-3. [Required units : [mass]/[volume]]

  • out_units (str) – Desired units of the snow depth output. If None, output units simply follow from snw / snr. Default : None.

  • ds (Dataset, optional) – A dataset with the variables given by name. Default : None.

Returns:

snd (DataArray) – Approximation of daily snow depth from snow amount and density (surface_snow_thickness) [m], with additional attributes: description: The approximation of daily snow depth from snow amount and density.

Return type:

xarray.DataArray

Notes

The estimated mean snow density value of 312 kg m-3 is taken from Sturm et al. [2010].

References

Sturm, Taras, Liston, Derksen, Jonas, and Lea [2010]

xclim.indicators.land._streamflow module

Streamflow indicator definitions.

xclim.indicators.land._streamflow.base_flow_index(q='q', *, freq='YS', ds=None)

Base flow index (realm: land)

Minimum of the 7-day moving average flow divided by the mean flow.

This indicator will check for missing values according to the method “from_context”. Based on indice base_flow_index(). Keywords : streamflow hydrology.

Parameters:
Returns:

base_flow_index (DataArray) – Base flow index, with additional attributes: description: Minimum of the 7-day moving average flow divided by the mean flow.

Return type:

xarray.DataArray

Notes

Let \(\mathbf{q}=q_0, q_1, \ldots, q_n\) be the sequence of daily discharge and \(\overline{\mathbf{q}}\) the mean flow over the period. The base flow index is given by:

\[\frac{\min(\mathrm{CMA}_7(\mathbf{q}))}{\overline{\mathbf{q}}}\]

where \(\mathrm{CMA}_7\) is the seven days moving average of the daily flow:

\[\mathrm{CMA}_7(q_i) = \frac{\sum_{j=i-3}^{i+3} q_j}{7}\]
xclim.indicators.land._streamflow.doy_qmax(da='da', *, freq='YS', ds=None, **indexer)

Day of year of the maximum streamflow (realm: land)

This indicator will check for missing values according to the method “from_context”. Based on indice select_resample_op(). With injected parameters: op=<function doymax at 0x7f5b19676e80>, out_units=None. Keywords : streamflow hydrology.

Parameters:

  • da (str or DataArray) – Input data. Default : ds.da. [Required units : [discharge]]

  • freq (offset alias (string)) – Resampling frequency defining the periods as defined in Resampling. See https://pandas.pydata.org/pandas-docs/stable/user_guide/timeseries.html#offset-aliases for available options. Default : YS.

  • ds (Dataset, optional) – A dataset with the variables given by name. Default : None.

  • indexer – Time attribute and values over which to subset the array. For example, use season=’DJF’ to select winter values, month=1 to select January, or month=[6,7,8] to select summer months. If not indexer is given, all values are considered. Required.

Returns:

q{indexer}_doy_qmax (DataArray) – Day of the year of the maximum streamflow over {indexer}, with additional attributes: description: Day of the year of the maximum streamflow over {indexer}.

Return type:

xarray.DataArray

xclim.indicators.land._streamflow.doy_qmin(da='da', *, freq='YS', ds=None, **indexer)

Day of year of the minimum streamflow (realm: land)

This indicator will check for missing values according to the method “from_context”. Based on indice select_resample_op(). With injected parameters: op=<function doymin at 0x7f5b19676f20>, out_units=None. Keywords : streamflow hydrology.

Parameters:

  • da (str or DataArray) – Input data. Default : ds.da. [Required units : [discharge]]

  • freq (offset alias (string)) – Resampling frequency defining the periods as defined in Resampling. See https://pandas.pydata.org/pandas-docs/stable/user_guide/timeseries.html#offset-aliases for available options. Default : YS.

  • ds (Dataset, optional) – A dataset with the variables given by name. Default : None.

  • indexer – Time attribute and values over which to subset the array. For example, use season=’DJF’ to select winter values, month=1 to select January, or month=[6,7,8] to select summer months. If not indexer is given, all values are considered. Required.

Returns:

q{indexer}_doy_qmin (DataArray) – Day of the year of the minimum streamflow over {indexer}, with additional attributes: description: Day of the year of the minimum streamflow over {indexer}.

Return type:

xarray.DataArray

xclim.indicators.land._streamflow.rb_flashiness_index(q='q', *, freq='YS', ds=None)

Richards-Baker Flashiness Index (realm: land)

Measurement of flow oscillations relative to average flow, quantifying the frequency and speed of flow changes.

This indicator will check for missing values according to the method “from_context”. Based on indice rb_flashiness_index(). Keywords : streamflow hydrology.

Parameters:
Returns:

rbi (DataArray) – Richards-Baker Flashiness Index, with additional attributes: description: {freq} of Richards-Baker Index, an index measuring the flashiness of flow.

Return type:

xarray.DataArray

Notes

Let \(\mathbf{q}=q_0, q_1, \ldots, q_n\) be the sequence of daily discharge, the R-B Index is given by:

\[\frac{\sum_{i=1}^n |q_i - q_{i-1}|}{\sum_{i=1}^n q_i}\]

References

Baker, Richards, Loftus, and Kramer [2004]