Xclim

--------------------
Contributors to this version: David Huard (:user:`huard`), Trevor James Smith (:user:`Zeitsperre`), Pascal Bourgault (:user:`aulemahal`), Éric Dupuis (:user:`coxipi`).

Announcements
^^^^^^^^^^^^^
* The default mechanism for computing the Mean Radiant Temperature, a part of the Universal Thermal Climate Index (UTCI) was broken in xclim v0.44.0 and v0.45.0. This has now been fixed by changing the default settings.

New indicators
^^^^^^^^^^^^^^
* ``xclim.indices.snw_storm_days`` computes the number of days with snowfall amount accumulation above a given threshold (default: `10 Kg m-2`). (:pull:`1505`).
* Added ``xclim.indices.wind_power_potential`` to estimate the potential for wind power production given wind speed at the turbine hub height and turbine specifications, along with ``xclim.indices.wind_profile`` to estimate the wind speed at different heights based on wind speed at a reference height. (:issue:`1458`, :pull:`1471`).

New features and enhancements
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
* `xclim` now has a dedicated console command for prefetching testing data from `xclim-testdata` with branch options (e.g.: `$ xclim prefetch_testing_data --branch some_development_branch`). This command can be used to download the testing data to a local cache, which can then be used to run the testing suite without internet access or in "offline" mode. For more information, see the contributing documentation section for `Updating Testing Data`. (:issue:`1468`, :pull:`1473`).
* The testing suite now offers a means of running tests in "offline" mode (using `pytest-socket <https://github.com/miketheman/pytest-socket>`_ to block external connections). This requires a local copy of `xclim-testdata` to be present in the user's home cache directory and for certain `pytest` options and markers to be set when invoked. For more information, see the contributing documentation section for `Running Tests in Offline Mode`. (:issue:`1468`, :pull:`1473`).
* The `SKIP_NOTEBOOKS` flag to speed up docs builds is now documented. See the contributing documentation section `Get Started!` for details. (:issue:`1470`, :pull:`1476`).
* Refactored the indicators page with the addition of a search bar (:issue:`1433`, :pull:`1454`).
* Indicator ``xclim.indices.generic.stats`` now accepts any frequency (previously only `daily`). (:pull:`1498`).
* Added argument `"out_units"` to ``select_resample_op`` to bypass limitations of ``to_agg_units`` in custom indicators. Also, added ``var`` to supported operations in ``to_agg_units``. (:pull:`1498`).
* `adapt_freq_thresh` argument was added `to `sdba`` training functions, to facilitate performing frequency adaptation appropriately in each map block. (:pull:`1407`).
* Standardized indices (``xclim.indices.standardized_precipitation_index`` and ``xclim.indices.standardized_precipitation_evapotranspiration_index``) (:issue:`1270`, :issue:`1416`, :issue:`1474`, :pull:`1311`) were changed:
* Optimized and noticeably faster calculation.
* Can be computed in two steps: first compute fit parameters with ``xclim.indices.stats.standardized_index_fit_params``, then use the output in the standardized indices functions.
* The standardized index values are now clipped to ±8.21. This reflects the ``float64`` precision of the computation when cumulative distributed function values are inverted to a normal distribution and avoids returning infinite values.
* An offset parameter is now available to account for negative water balance values``xclim.indices.standardized_precipitation_evapotranspiration_index``.

Bug fixes
^^^^^^^^^
* Fixed an error in the `pytest` configuration that prevented copying of testing data to thread-safe caches of workers under certain conditions (this should always occur). (:pull:`1473`).
* Coincidentally, this also fixes an error that caused `pytest` to error-out when invoked without an active internet connection. Running `pytest` without network access is now supported (requires cached testing data). (:issue:`1468`).
* Calling a ``sdba.map_blocks``-wrapped function with data chunked along the reduced dimensions will raise an error. This forbids chunking the trained dataset along the distribution dimensions, for example. (:issue:`1481`, :pull:`1482`).
* Optimization of indicators ``huglin_index`` and ``biologically_effective_degree_days`` when used with `dask` and `flox`. As a side effect, the indice functions (i.e. under ``xclim.indices``) no longer mask incomplete periods. The indicators' output is unchanged under the default `"check_missing"` setting (:issue:`1494`, :pull:`1495`).
* Fixed ``xclim.indices.run_length.lazy_indexing`` which would sometimes trigger the loading of auxiliary coordinates. (:issue:`1483`, :pull:`1484`).
* Indicators ``snd_season_length`` and ``snw_season_length`` will return `0` instead of `NaN` if all inputs have a (non-`NaN`) zero snow depth (or water-equivalent thickness). (:pull:`1492`, :issue:`1491`)
* Fixed a bug in the `pytest` configuration that could prevent testing data caching from occurring in systems where the platform-dependent cache directory is not found in the user's home. (:issue:`1468`, :pull:`1473`).
* Fix ``xclim.core.dataflags.data_flags`` variable name generation (:pull:`1507`).
* Remove nonsensical `stat='average'` option for ``mean_radiant_temperature``. (:issue:`1496`, :pull:`1501`).

Breaking changes
^^^^^^^^^^^^^^^^
* `pytest-socket` is now a required development dependency for running `"offline"` tests or the `"offline"` configuration of the `tox` testing suite. This has been added to the `dev` installation recipe. (:issue:`1468`, :pull:`1473`).
* For better transparency and control in development, the `tox` configuration has been adapted to allow passing of markers directly to the `pytest` call. Positional arguments must be passed to tox after the `--` separator to select/deselect tests (e.g. ``'tox -e py38 -- -m "not slow"'``). (:pull:`1473`).
* For better accuracy, the `tox -e black` recipe has been renamed to `tox -e lint`, as this configuration already included several other linting checks. (:pull:`1473`).
* ``xclim.indices.winter_storm`` renamed to ``xclim.indices.snd_storm_days``. (:pull:`1505`).
* Default threshold in ``xclim.indices.snw_season_{start|length|end}`` changed form `20 kg m-2` to `4 kg m-2`. (:pull:`1505`).
* `xclim` development dependencies now include `ruff`. `pycodestyle` and `pydocstyle` have been replaced by `ruff` and removed from the `dev` installation recipe. (:pull:`1504`).
* The `mf_file` call signature found in ``xclim.ensembles.create_ensemble`` (and ``xclim.ensembles._ens_align_dataset``) has been removed (deprecated since `xclim` v0.43.0). (:pull:`1506`).
* ``xclim.indices.standardized_precipitation_index`` and ``xclim.indices.standardized_precipitation_evapotranspiration_index`` will no longer accept two datasets (data and calibration data). Instead, a single dataset covering both the calibration and evaluation periods is expected. (:issue:`1270`, :pull:`1311`).

Internal changes
^^^^^^^^^^^^^^^^
* Changed "degK" to "K" (used to designate Kelvin units). (:pull:`1475`).
* Added a `pytest` marker (``pytest.mark.requires_internet``) to allow for skipping of tests that depend on remote network calls to function properly. (:pull:`1473`).
* Added handling for `pytest-socket`'s ``SocketBlockedError`` in ``xclim.testing.open_dataset`` when attempting to fetch md5 validation files for cached testing data while explicitly disabling internet sockets. (:issue:`1468`, :pull:`1473`).
* Updated the testing data used in the `analogs.ipynb` notebook to use the testing data now found in `Ouranosinc/xclim-testdata`'s main branch. (`xclim-testdata PR/26 <https://github.com/Ouranosinc/xclim-testdata/pull/26>`_, :pull:`1473`).
* Fixed an issue with automatic labelling that occurs when a Pull Request is made from a forked repository. (:pull:`1479`).
* Changes to the ``.zenodo.json`` file no longer are marked as CI-related changes. (:pull:`1479`).
* GitHub deployment workflows now employs use of deployment environments for workflow security and uses the `Trusted Publisher <https://docs.pypi.org/trusted-publishers/using-a-publisher/>`_ feature to sign and publish the `xclim` wheel and source distributions. (:pull:`1469`).
* Mastodon publishing now uses `chuhlomin/render-template <https://github.com/chuhlomin/render-template>`_ and a standard formatting markdown document to format Mastodon toots. (:pull:`1469`).
* GitHub testing workflows now use `Concurrency` instead of the styfle/cancel-workflow-action to cancel redundant workflows. (:pull:`1487`).
* The `pkg_resources` library has been replaced for the `packaging` library when version comparisons have been performed, and a few warning messages have been silenced in the testing suite. (:issue:`1489`, :pull:`1490`).
* New ``xclim.testing.helpers.assert_lazy`` context manager to assert the laziness of code blocks. (:pull:`1484`).
* Added a fix for the deprecation warnings that `importlib.resources` throws, made backwards-compatible for Python3.8 with `importlib_resources` backport. (:pull:`1485`).
* Added basic keywords on most indicators for easier searching in the docs. Extracted climate indicators API to its own page for faster loading. (:pull:`1502`, :issue:`1433`).
* `nbstripout` now removes 'metadata.kernelspec' in notebook cells. (:pull:`1407`).
* Deprecation wrapper ``xclim.core.utils.deprecated`` are added to help with deprecation warnings. (:pull:`1505`).
* `xclim` now uses `ruff` to format the codebase with `make lint` and `pre-commit`. `flake8` is still used for the time being, solely to enforce docstring linting (with `flake8-rst-docstrings`) and alphabetical `__all__` entries (with `flake8-alphabetize`). (:pull:`1504`).

--------------------
Contributors to this version: David Huard (:user:`huard`), Trevor James Smith (:user:`Zeitsperre`), Pascal Bourgault (:user:`aulemahal`), Juliette Lavoie (:user:`juliettelavoie`), Gabriel Rondeau-Genesse (:user:`RondeauG`), Marco Braun (:user:`vindelico`), Éric Dupuis (:user:`coxipi`).

Announcements
^^^^^^^^^^^^^
* `xclim` now uses `platformdirs` to write `xclim-testdata` to the user's cache directory. Dynamic paths are now used to cache data dependent on the user's operating system. Developers can now safely delete the ``.xclim-testdata`` folder in their home directory without affecting the functionality of `xclim`. (:pull:`1460`).

New indicators
^^^^^^^^^^^^^^
* Variations of already existing indices: ``xclim.indices.snd_max`` and ``xclim.indices.frost_free_spell_max_length``. (:pull:`1443`, :issue:`1386`).

New features and enhancements
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
* Added ``ensembles.hawkins_sutton`` method to partition the uncertainty sources in a climate projection ensemble. (:issue:`771`, :pull:`1262`), along with a notebook example. (:pull:`1466`).
* New function ``xclim.core.calendar.convert_doy`` to transform day-of-year data between calendars. Also accessible from ``convert_calendar`` with ``doy=True``. (:issue:`1283`, :pull:`1406`).
* New ``xclim.units.declare_relative_units`` to enable relative unit checks. This was applied to most "generic" indices. (:pull:`1414`).
* Added new function ``xclim.sdba.properties.std`` to calculate the standard deviation of a variable over all years at a given time resolution. (:pull:`1445`).
* Amended the documentation of ``xclim.sdba.properties.trend`` to document already existing functionality of calculating the return values of ``scipy.stats.linregress``. (:pull:`1445`).
* Add support for setting optional variables through the ``ds`` argument. (:issue:`1432`, :pull:`1435`).
* New ``xclim.core.calendar.is_offset_divisor`` to test if a given freq divides another one evenly (:pull:`1446`).
* Missing value objects now support input timeseries of quarterly and yearly frequencies (:pull:`1446`).
* Missing value checks enabled for all "generic" indicators (``return_level``, ``fit`` and ``stats``) (:pull:`1446`).

Bug fixes
^^^^^^^^^
* Fix ``kldiv`` docstring so the math formula renders to HTML. (:issue:`1408`, :pull:`1409`).
* Fix the registry entries of "generic" indicators. (:issue:`1423`, :pull:`1424`).
* Fix ``jetstream_metric_woollings`` so it uses the ``vertical`` coordinate identified by `cf-xarray`, instead of ``pressure`` (:issue:`1421`, :pull:`1422`).
* Add logic to handle coordinates in decreasing order, or for longitudes defined from 0-360 instead of -180 to 180. (:issue:`1429`, :pull:`1430`).
* Fix virtual indicator attribute assignment causing individual indicator's realm to be ignored. (:issue:`1425`, :pull:`1426`).
* Fixes the ``raise_flags`` argument of ``xclim.core.dataflags.data_flags`` so that an `Exception` is only raised when some checkups fail. (:issue:`1456`, :pull:`1457`).
* Fix ``xclim.indices.generic.get_zones`` so that `bins` can be given as input without error. (:pull:`1455`).

Internal changes
^^^^^^^^^^^^^^^^
* Tolerance thresholds for error in ``test_stats::test_fit`` have been relaxed to allow for more variation in the results. Previously untested ``*_moving_yearly_window`` functions are now tested. (:issue:`1400`, :pull:`1402`).
* Increased the guess of number of quantiles needed in `ExtremeValues`. (:pull:`1413`).
* Tolerance thresholds for error in ``test_processing::test_adapt_freq`` have been relaxed to allow for more variation in the results. (:issue:`1417`, :pull:`1418`).
* Added ``"streamflow"`` to the list of known variables. (:pull:`1431`).
* Refactoring of index backend calculations. (:pull:`1443`, :issue:`1386`):
* Use ``xclim.indices.generic.select_resample_op`` for ``{tg|tn|tx}_{max|mean|min}`` , ``max_1day_precipitation_amount``, ``{snw|snd}_max``
* Directly use ``{cold|hot}_spell_max_length`` in ``maximum_consecutive_{frost|tx}_days``
* ``xclim.indices.generic.select_resample_op`` now gives an output with the correct units (``xclim.core.units.to_agg_units`` is used internally).
* Shuffle autogenerated documentation files into distinct folders that can be easily cleaned using Makefile. (:pull:`1449`).
* Some docstring adjustments to existing classes. (:pull:`1449`).
* The `pre-commit` dependency `identify` now associates Jupyter Notebooks as JSON files. `pre-commit` is now set to ignore JSON-formatting of notebooks. (:pull:`1449`).
* Added a helper module ``_finder`` in the notebooks folder so that the working directory can always be found, with redundancies in place to prevent scripts from failing if the helper file is not found. (:pull:`1449`).
* Added a manual cache-cleaning workflow (based on `GitHub cache-cleaning example <https://docs.github.com/en/actions/using-workflows/caching-dependencies-to-speed-up-workflows#managing-caches>`_), triggered when a branch has been merged. (:pull:`1462`).
* Added a workflow for posting updates to the xclim Mastodon account (using `cbrgm/mastodon-github-action <https://github.com/cbrgm/mastodon-github-action>`_, triggered when a new version is published. (:pull:`1462`).
* Refactor base indicator classes and fix misleading inheritance of ``return_level``. (:issue:`1263`, :pull:`1446`).

Breaking changes
^^^^^^^^^^^^^^^^
* Fix and adapt ``percentile_doy`` for an error raised by xarray > 2023.7.0. (:issue:`1417`, :pull:`1450`).
* `integral` replaces `prod` and `delta_prod` as possible input in ``xclim.core.units.to_agg_units`` (:pull:`1443`, :issue:`1386`).

--------------------
Contributors to this version: Éric Dupuis (:user:`coxipi`), Trevor James Smith (:user:`Zeitsperre`), Pascal Bourgault (:user:`aulemahal`), Ludwig Lierhammer (:user:`ludwiglierhammer`), David Huard (:user:`huard`).

Announcements
^^^^^^^^^^^^^
* `xclim: xarray-based climate data analytics` has been published in the Journal of Open Source Software (`DOI:10.21105/joss.05415 <https://doi.org/10.21105/joss.05415>`_). Users can now make use of the `Cite this repository` button in the sidebar for academic purposes. Many thanks to our core developers and user base for their fine contributions over the years! (:issue:`95`, :pull:`250`).
* `xclim` now officially supports Python3.11. (:pull:`1388`).

New indicators
^^^^^^^^^^^^^^
* Several new indices and indicators:
* ``snowfall_{frequency | intensity}`` for calculating the {percentage of | mean snowfall intensity on} days with snowfall above a threshold. (:issue:`1352`, :pull:`1358`)
* ``{sfcWind | sfcWindmax}_{max | mean | min}`` for calculating the {max | mean | min} daily {mean | max} wind speed. (:issue:`1352`, :pull:`1358`)
* ``{precip | liquid_precip | solid_precip}_average}`` for calculating the mean daily {total precipitation | liquid precipitation | solid precipitation } amount. (:issue:`1352`, :pull:`1358`)
* ``{cold | dry}_spell_max_length`` for calculating maximum length of {cold | dry} spell events. (:issue:`1352`, :pull:`1359`).
* ``dry_spell_frequency`` for calculating total number of dry spells. (:issue:`1352`, :pull:`1359`).
* ``hardiness_zones`` with supported methods `"usda"` (USA) and `"anbg"` (Australia) for calculating hardiness classifications from climatologies. (:issue:`1290`, :pull:`1396`).
* New indicator ``late_frost_days`` for calculating the number of days where the daily minimum temperature is below a threshold over a given time period. (:issue:`1352`, :pull:`1361`).

New features and enhancements
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
* ``xclim.sdba.processing.escore`` performance was improved with a faster runtime (:pull:`1360`).
* New generic function (``flux_and_rate_converter``) converting flux to a rate (and vice-versa) using a density. ``snw_to_snd`` and ``snd_to_snw`` were refactored using this function. (:issue:`1352`, :pull:`1358`)
* New function (``prsn_to_prsnd``) to convert snowfall flux ([mass] / [area] / [time]) to snowfall rate ([length] / [time]) using snow density ([mass] / [volume]). (:issue:`1352`, :pull:`1358`)
* New variables: Snowfall rate ``prsnd`` and surface maximum wind speed ``sfcWindmax``. (:issue:`1352`, :pull:`1358`).
* Docstring for ``freq`` links to pandas offset aliases documentation. (:issue:`1310`, :pull:`1392`).
* New function ``xclim.indces.run_length.extract_events`` for determining runs whose starting and stopping points are defined through run length conditions. (:pull:`1256`).
* Stats functions `frequency_analysis` now takes `method` parameter to select other fitting methods such as PWM or MOM. (:issue:`1168`, :pull:`1398`).
* ``xclim.indices.frost_days`` now accepts an ``**indexer`` parameter for calculating frost days over a temporal subset of the given dataset. (:issue:`1352`, :pull:`1361`).
* New function ``xclim.indices.generic.get_zones`` attributing a histogram bin index (a zone) to each value in an input array. (:issue:`1290`, :pull:`1396`).

Bug fixes
^^^^^^^^^
* Fixed a bug in ``xclim.core.calendar.time_bnds`` when using ``DataArrayResample`` objects, caused by an upstream change in xarray 2023.5.0. (:issue:`1368`, :pull:`1377`).
* ``ensembles.change_significance`` will returns NaNs when the input values are all NaNs, instead of failing. (:issue:`1379`, :pull:`1380`).
* Accelerated import of xclim by caching the compilation of `guvectorize` functions. (:pull:`1378`).
* Fixed many issues with ``xclim.indices.helpers.cosine_of_solar_zenith_angle``, the signature changed. (:issue:`1110`, :pull:`1399`).

Internal changes
^^^^^^^^^^^^^^^^
* In order to ensure documentation can be rebuilt at a later time, errors raised by `sphinx` linkcheck are now set to be ignored when building the documentation. (:pull:`1375`).
* With the publication of `xclim`, the code repository now offers a `CITATION.cff` configuration for users to properly cite the software (APA formatted and raw BibTeX) for academic purposes. (:issue:`95`, :pull:`250`).
* Logging messages emitted when redefining units via `pint` (caused by `logging` interactions with dependencies) have been silenced. (:issue:`1373`, :pull:`1384`).
* Fixed some annotations and `dev` recipe dependencies issues to allow for the development of xclim inside a python3.11 environment. (:issue:`1376`, :pull:`1381`).
* The deprecated `mamba-org/provision-with-micromamba` GitHub Action has been replaced with `mamba-org/setup-micromamba`. (:pull:`1388`).
* `xclim` GitHub CI workflows now run builds against Python3.11. (:pull:`1388`).
* In indices, verify that all parameters of type `Quantified` that have a default value have their dimension declared. (:issue:`1293`, :pull:`1393`).
* Updated `roy_extremeprecip_2021` to the newly published paper. (:pull:`1394`).
* Two new GitHub CI Actions have been added to the existing Workflows (:pull:`1390`):
* `actions/add-to-project`: Automatically adds issues to the `xclim` project.
* `saadmk11/github-actions-version-updater`: Updates GitHub Action versions in all Workflows (triggered monthly).
* Added `method` parameter to `frequency_analysis` and `fa`. (:issue:`1168`, :pull:`1398`).

Breaking changes
^^^^^^^^^^^^^^^^
* Signature of `hot_spell_{frequency | max_length | total_length}` : `thresh_tasmax` modified to `thresh`. (:issue:`1352`, :pull:`1359`).

--------------------
Contributors to this version: Trevor James Smith (:user:`Zeitsperre`), Ludwig Lierhammer (:user:`ludwiglierhammer`), Pascal Bourgault (:user:`aulemahal`), Juliette Lavoie (:user:`juliettelavoie`), Alexis Beaupré (:user:`Beauprel`), Éric Dupuis (:user:`coxipi`).

Announcements
^^^^^^^^^^^^^
* `xclim` has passed the peer-review process and been officially accepted as a project associated with both `pyOpenSci <https://www.pyopensci.org>`_ and `PANGEO <https://pangeo.io/>`_. Additionally, `xclim` has been accepted to be published in the `Journal of Open Source Software <https://joss.theoj.org/>`_. Our review process can be consulted here: `PyOpenSci Software Review <https://github.com/pyOpenSci/software-review/issues/73>`_. (:pull:`1350`).

New features and enhancements
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
* New ``xclim.sdba`` measure ``xclim.sdba.measures.taylordiagram``. (:pull:`1360`).

New indicators
^^^^^^^^^^^^^^
* ``ensembles.change_significance`` now supports the Brown-Forsythe test. (:pull:`1292`).

Bug fixes
^^^^^^^^^
* Fixed a bug in the `pyproject.toml` configuration that excluded the changelog (`CHANGES.rst`) from the packaged source distribution. (:pull:`1349`).
* When summing an all-`NaN` period with `resample`, `xarray` v2023.04.0 now returns `NaN`, whereas earlier versions returned `0`. This broke ``fraction_over_precip_thresh``, but is now fixed. (:pull:`1354`, :issue:`1337`).
* In ``xclim.sdba``'s Quantile Delta Mapping algorithm, the quantiles of the simulation to adjust were computed slightly differently than when creating the adjustment factor. The ``xclim.sdba.utils.rank`` function has been fixed to return "percentage-ranks" (quantiles) in the proper range. (:issue:`1334`, :pull:`1355`).
* The radiation converters (``longwave_upwelling_radiation_from_net_downwelling`` and ``shortwave_upwelling_radiation_from_net_downwelling``) were hard-coded to redefine output units as `W m-2`, regardless of input units, so long as unit dimensions checks cleared. Units are now set directly from inputs. (:issue:`1365`, :pull:`1366`).

Breaking changes
^^^^^^^^^^^^^^^^
* Many previously deprecated indices and indicators have been removed from `xclim` (:pull:`1318`), with replacement indicators suggested as follows:
* ``xclim.indicators.atmos.first_day_above`` -> ``xclim.indicators.atmos.first_day_{tn | tg | tx}_above``
* ``xclim.indicators.atmos.first_day_below`` -> ``xclim.indicators.atmos.first_day_{tn | tg | tx}_below``
* ``xclim.indicators.land.continuous_snow_cover_end`` -> ``xclim.indicators.land.snd_season_end``
* ``xclim.indicators.land.continuous_snow_cover_start`` -> ``xclim.indicators.land.snd_season_start``
* ``xclim.indicators.land.fit`` -> ``xclim.indicators.generic.fit``
* ``xclim.indicators.land.frequency_analysis`` -> ``xclim.indicators.generic.return_level``
* ``xclim.indicators.land.snow_cover_duration`` -> ``xclim.indicators.land.snd_season_length``
* ``xclim.indicators.land.stats`` -> ``xclim.indicators.generic.stats``
* ``xclim.indices.continuous_snow_cover_end`` -> ``xclim.indices.snd_season_end``
* ``xclim.indices.continuous_snow_cover_start`` -> ``xclim.indices.snd_season_start``
* ``xclim.indices.snow_cover_duration`` -> ``xclim.indices.snd_season_length``
* Several `_private` functions within ``xclim.indices.fire._cffwis`` that had been exposed publicly have now been rendered as hidden functions. Affected functions are: ``_day_length``, ``_day_length_factor``, ``_drought_code``, ``_duff_moisture_code``, ``_fine_fuel_moisture_code``, ``_overwintering_drought_code``. (:pull:`1159`, :pull:`1369`).

Internal changes
^^^^^^^^^^^^^^^^
* The testing suite has been adjusted to ensure calls are made to existing functions using non-deprecated syntax. The volume of warnings emitted during testing has been significantly reduced. (:pull:`1318`).
* In order to follow best practices and reduce the installed size of the `xclim` wheel, the `tests` folder containing the testing suite has been split from the package and placed in the top-level of the code repository. (:issue:`1348`, :pull:`1349`, suggested from `PyOpenSci Software Review <https://github.com/pyOpenSci/software-review/issues/73>`_). Submodules that were previously called within ``xclim.testing.tests`` have been refactored as follows:
* ``xclim.testing.tests.data`` → ``xclim.testing.helpers``
* ``xclim.testing.tests.test_sdba.utils`` → ``xclim.testing.sdba_utils``
* Added a "Conventions" section to the README. (:issue:`1342`, :pull:`1351`).
* New helper function ``xclim.testing.helpers.test_timeseries`` for generating timeseries objects with specified variable names and units. (:pull:`1356`).
* `tox` recipes and documentation now refer to the official build of `SBCK`, available on PyPI. (:issue:`1362`, :pull:`1364`).
* Excluded some URLs from `sphinx linkcheck` that were causing issues on ReadTheDocs. (:pull:`1364`).
* Tagged versions of `xclim-testdata` now follow a `calendar-based versioning <https://calver.org/>`_ scheme for easier determination of compatibility between `xclim` and testing data. (:pull:`1367`, `xclim-testdata discussion <https://github.com/Ouranosinc/xclim-testdata/pull/24>`_).
* `flake8`, `pycodestyle`, and `pydocstyle` checks have been significantly changed in order to clean up the code base of redundant ` noqa` markers. Linting checks for Makefile and `tox` recipes have been synchronized as well. (:pull:`1369`).
* `flake8` plugin `flake8-alphabetize` has been added to development recipes in order to check order of `__all__` entries and Exceptions. (:pull:`1369`).
* Corrected translations of ``cold_spell_{frequency | days}`` (:pull:`1372`).

--------------------
Contributors to this version: Trevor James Smith (:user:`Zeitsperre`), Juliette Lavoie (:user:`juliettelavoie`), Éric Dupuis (:user:`coxipi`), Pascal Bourgault (:user:`aulemahal`).

Announcements
^^^^^^^^^^^^^
* `xclim` now supports testing against tagged versions of `Ouranosinc/xclim-testdata <https://github.com/Ouranosinc/xclim-testdata>`_ in order to support older versions of `xclim`. For more information, see the `Contributing Guide <https://xclim.readthedocs.io/en/stable/contributing.html>`_ for more details. (:pull:`1339`).
* `xclim v0.42.0` will be the last version to explicitly support Python3.8. (:issue:`1268`, :pull:`1344`).

New features and enhancements
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
* Two previously private functions for selecting a day of year in a time series when performing calendar conversions are now exposed. (:issue:`1305`, :pull:`1317`). New functions are:
* ``xclim.core.calendar.yearly_interpolated_doy``
* ``xclim.core.calendar.yearly_random_doy``
* `scipy` is no longer pinned below v1.9 and `lmoments3>=1.0.5` is now a core dependency and installed by default with `pip`. (:issue:`1142`, :pull:`1171`).
* Fix bug on number of bins in ``xclim.sdba.properties.spatial_correlogram``. (:pull:`1336`)
* Add `resample_before_rl` argument to control when resampling happens in `maximum_consecutive_{frost|frost_free|dry|tx}_days` and in heat indices (in `_threshold`) (:issue:`1329`, :pull:`1331`)
* Add ``xclim.ensembles.make_criteria`` to help create inputs for the ensemble-reduction methods. (:issue:`1338`, :pull:`1341`).

New indicators
^^^^^^^^^^^^^^
* Rain season index implemented (default parameters for West Africa). (:issue:`842`, :pull:`1256`)

Bug fixes
^^^^^^^^^
* Warnings emitted from regular usage of some indices (``snowfall_approximation`` with ``method="brown"``, ``effective_growing_degree_days``) due to successive ``convert_units_to`` calls within their logic have been silenced. (:pull:`1319`).
* Fixed a bug that prevented the use of the `sdba_encode_cf` option with xarray 2023.3.0 (:pull:`1333`).
* Fixed bugs in ``xclim.core.missing`` and ``xclim.sdba.base.Grouper`` when using pandas 2.0. (:pull:`1344`).

Breaking changes
^^^^^^^^^^^^^^^^
* The call signatures for ``xclim.ensembles.create_ensemble`` and ``xclim.ensembles._base._ens_align_dataset`` have been deprecated. Calls to these functions made with the original signature will emit warnings. Changes will become breaking in `xclim>=0.43.0`.(:issue:`1305`, :pull:`1317`). Affected variable:
* `mf_flag` (bool) -> `multifile` (bool)
* The indice and indicator for ``last_spring_frost`` has been modified to use ``tasmin`` by default, reflecting its docstring and literature definition (:issue:`1324`, :pull:`1325`).
* following indices now accept the `op` argument for modifying the threshold comparison operator (:pull:`1325`):
* ``snw_season_length``, ``snd_season_length``, ``growing_season_length``, ``frost_season_length``, ``frost_free_season_length``, ``rprcptot``, ``daily_pr_intensity``
* In order to support older environments, `pandas` is now conditionally pinned below v2.0 when installing `xclim` on systems running Python3.8. (:pull:`1344`).

Bug fixes
^^^^^^^^^
* ``xclim.indices.run_length.last_run`` nows works when ``freq`` is not ``None``. (:issue:`1321`, :pull:`1323`).

Internal changes
^^^^^^^^^^^^^^^^
* Added `xclim` to the `ouranos Zenodo community <https://zenodo.org/communities/ouranos/>`_ . (:pull:`1313`).
* Significant documentation adjustments. (:issue:`1305`, :pull:`1308`):
* The CONTRIBUTING page has been moved to the top level of the repository.
* Information concerning the licensing of xclim is clearly indicated in README.
* `sphinx-autodoc-typehints` is now used to simplify call signatures generated in documentation.
* The SDBA module API is now found with the rest of the User API documentation.
* `HISTORY.rst` has been renamed `CHANGES.rst`, to follow `dask`-like conventions.
* Hyperlink targets for individual `indices` and `indicators` now point to their entries under `API` or `Indices`.
* Module-level docstrings have migrated from the library scripts directly into the documentation RestructuredText files.
* The documentation now includes a page explaining the reasons for developing `xclim` and a section briefly detailing similar and related projects.
* Markdown explanations in some Jupyter Notebooks have been edited for clarity
* Removed `Mapping` abstract base class types in call signatures (`dict` variables were always expected). (:pull:`1308`).
* Changes in testing setup now prevent ``test_mean_radiant_temperature`` from sometimes causing a segmentation fault. (:issue:`1303`, :pull:`1315`).
* Addressed a formatting bug that caused `Indicators` with multiple variables returned to not be properly formatted in the documentation. (:issue:`1305`, :pull:`1317`).
* `tox` now include `sbck` and `eofs` flags for easier testing of dependencies. CI builds now test against `sbck-python` master. (:pull:`1328`).
* `upstream` CI tests are now run on push to master, at midnight, and can also be triggered via `workflow_dispatch`. Failures from upstream build will open issues using `xarray-contrib/issue-from-pytest-log`. (:pull:`1327`).
* Warnings from set ``_version_deprecated`` within Indicators now emit ``FutureWarning`` instead of ``DeprecationWarning`` for greater visibility. (:pull:`1319`).
* The `Graphics` section of the `Usage` notebook has been expanded upon while grammar and spelling mistakes within the notebook-generated documentation have been reduced. (:issue:`1335`, :pull:`1338`, suggested from `PyOpenSci Software Review <https://github.com/pyOpenSci/software-review/issues/73>`_).
* The Contributing guide now lists three separate subsections to help users understand the gains from optional dependencies. (:issue:`1335`, :pull:`1338`, suggested from `PyOpenSci Software Review <https://github.com/pyOpenSci/software-review/issues/73>`_).

--------------------
Contributors to this version: Trevor James Smith (:user:`Zeitsperre`), Pascal Bourgault (:user:`aulemahal`), Ludwig Lierhammer (:user:`ludwiglierhammer`), Éric Dupuis (:user:`coxipi`).

New features and enhancements
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
* New properties ``xclim.sdba.properties.decorrelation_length`` and ``xclim.sdba.properties.transition_probability``. (:pull:`1252`)

New indicators
^^^^^^^^^^^^^^
* New indices and indicators for converting from snow water equivalent to snow depth (``snw_to_snd``) and snow depth to snow water equivalent (``snd_to_snw``) using snow density [kg/m^3]. (:pull:`1271`).
* New indices and indicators for determining upwelling radiation (`shortwave_upwelling_radiation_from_net_downwelling` and `longwave_upwelling_radiation_from_net_downwelling`; CF variables `rsus` and `rlus`) from net and downwelling radiation (shortwave: `rss` and `rsds`; longwave: `rls` and `rlds`). (:pull:`1271`).
* New indice and indicator ``{snd | snw}_season_{length | start | end}`` which generalize ``snow_cover_duration`` and ``continuous_snow_cover_{start | end}`` to allow using these functions with variable `snw` (:pull:`1275`).
* New indice and indicator (``dryness_index``) for estimating soil humidity classifications for winegrowing regions (based on Riou et al. (1994)). (:issue:`355`, :pull:`1235`).
* ``ensembles.change_significance`` now supports Mann-whitney U-test and flexible ``realization``. (:pull:`1285`).

Breaking changes
^^^^^^^^^^^^^^^^
* `xclim` testing default behaviours have been changed (:issue:`1295`, :pull:`1297`):
* Running `$ pytest` will no longer use `pytest-xdist` distributed testing be default (can be set with ``-n auto|logical|``. Coverage is also no longer gathered/reported by default.
* Running `$ tox` will now set `pytest-xdist` to use ``-n logical`` processes (with a max of 10).
* Default behaviour for testing is to no longer always fetch `xclim-testdata`. If testdata is found in ``$HOME/.xclim_testing_data``, files will be copied to individual processes, otherwise, will be fetched as needed.
* Environment variables evaluated when running pytest have been changed (:issue:`1295`, :pull:`1297`):
* For testing against specific branches of `xclim-testdata`: ``MAIN_TESTDATA_BRANCH`` -> ``XCLIM_TESTDATA_BRANCH``
* The option to skip fetching of testdata (``SKIP_TEST_DATA``) has been removed
* A new environment variable (``XCLIM_PREFETCH_TESTING_DATA``) is now available to gather `xclim-testdata` before running test ensemble (default: `False`).
* Environment variables are now passed to `tox` on execution.

Bug fixes
^^^^^^^^^
* ``build_indicator_module_from_yaml`` now accepts a ``reload`` argument. When re-building a module that already exists, ``reload=True`` removes all previous indicator before creating the new ones. (:issue:`1192`,:pull:`1284`).
* The test for french translations of official indicators was fixed and translations for CFFWIS indices, FFDI, KDBI, DF and Jetstream metric woollings have been added or fixed. (:pull:`1271`).
* ``use_ufunc`` in ``windowed_run_count`` is now supplied with argument ``freq`` to warn users that the 1d method does not support resampling after run length operations (:issue:`1279`, :pull:`1291`).
* ``{snd|snw}_max_doy`` now avoids an error due to `xr.argmax` when there are all-NaN slices. (:pull:`1277`).

Internal changes
^^^^^^^^^^^^^^^^
* `xclim` has adopted `PEP 517 <https://peps.python.org/pep-0517/>`_ and `PEP 621 <https://peps.python.org/pep-0621/>`_ (``pyproject.toml`` using the `flit <https://flit.pypa.io/en/stable/>`_ backend) to replace the legacy ``setup.py`` used to manage package organisation and building. Many tooling configurations that already supported the ``pyproject.toml`` standard have been migrated to this file. CI and development tooling documentation has been updated to reflect these changes. (:pull:`1278`, suggested from `PyOpenSci Software Review <https://github.com/pyOpenSci/software-review/issues/73>`_).
* Documentation source files have been moved around to remove some duplicated image files. (:pull:`1278`).
* Coveralls GitHub Action removed as it did not support ``pyproject.toml``-based configurations. (:pull:`1278`).
* Add a remark about how `xclim`'s CFFWIS is different from the original 1982 implementation. (:issue:`1104`, :pull:`1284`).
* Update CI runs to use Python3.9 when examining upstream dependencies. Replace `setup-conda` action with `provision-with-micromamba` action. (:pull:`1286`).
* Update CI runs to always use `tox~=4.0` and the `latest` virtual machine images (now `ubuntu-22.04`). (:pull:`1288`, :pull:`1297`).
* `SBCK` installation command now points to the official development repository. (:pull:`1288`).
* Some references in the BibTeX were updated to point to better resources. (:pull:`1288`).
* Add a GitHub CI workflow for performing dependency security review scanning. (:pull:`1287`).
* Grammar and spelling corrections were applied to some docstrings. (:pull:`1271`).
* Added `[radiation]` (`[power] / [area]`) to list of defined acceptable units. (:pull:`1271`).
* Updated testing data used to generate the `atmosds` dataset to use more reproducibly-converted ERA5 data, generated with the `miranda` Python package. (:pull:`1269`).
* Updated testing dependencies to use `pytest-xdist>=3.2`, allowing for the new `--dist=worksteal` scheduler for distributing the pool of remaining tests across workers after individual workers have exhausted their own queues. (:pull:`1235`).
* Adding infer context to the unit conversion in of the training of ExtremeValues. (:pull:`1299`).
* Added `sphinxcontrib-svg2pdfconverter` for converting SVG graphics within documentation to PDF-compatible images. (:pull:`1296`).
* README badges for supported Python versions and repository health have been added. (:issue:`1304`, :pull:`1307`).