Xclim

--------------------
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`).

--------------------
Contributors to this version: Trevor James Smith (:user:`Zeitsperre`), Pascal Bourgault (:user:`aulemahal`), David Huard (:user:`huard`), Juliette Lavoie (:user:`juliettelavoie`).

New features and enhancements
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
* Virtual modules can add variables to ``xclim.core.utils.VARIABLES`` through the new `variables` section of the yaml files. (:issue:`1129`, :pull:`1231`).
* ``xclim.core.units.convert_units_to`` can now perform automatic conversions based on the standard name of the input when needed. (:issue:`1205`, :pull:`1206`).
- Conversion from amount (thickness) to flux (rate), using ``amount2rate`` and ``rate2amount``.
- Conversion from amount to thickness for liquid water quantities, using the new ``amount2lwethickness`` and ``lwethickness2amount``. This is similar to the implicit transformations enabled by the "hydro" unit context.
- Passing ``context='infer'`` will activate the "hydro" context if the source or the target are DataArrays with a standard name that is compatible, as decided by the new ``xclim.core.units.infer_context`` function.
* New `generic` indicator realm. Now holds indicators previously meant for streamflow analysis in the `land` realm: `fit`, `return_level` (previously `freq_analysis`) and `stats`. (:issue:`1130`, :pull:`1225`).
* Thresholds and other quantities passed as parameters of indicators can now be multi-dimensional `DataArray`s. `xarray` broadcasting mechanisms will apply. These parameters are now annotated as "Quantity" in the signatures (``xclim.core.utils.Quantity``), instead of "str" as before. Attributes where such thresholds where included will now read "<an array>" (french: "<une matrice>") for these new cases. Multi-dimensional quantities are still largely unsupported, except where documented in the docstring. (:issue:`1093`, :pull:`1236`).

Breaking changes
^^^^^^^^^^^^^^^^
* Rewrite of ``xclim.core.calendar.time_bnds``. It should now be more resilient and versatile, but all ``cftime_*`` and ``cfindex_*`` functions were removed. (:issue:`74`, :pull:`1207`).
* `hydro` context is not always enabled, as it led to unwanted unit conversions. Unit conversion operations now need to explicitly declare the `hydro` context to support conversions from `kg / m2 /s` to `mm/day`. (:issue:`1208`, :pull:`1227`).
* Many previously deprecated indices and indicators have been removed from `xclim` (:pull:`1228`), with replacement indices/indicators suggested as follows:
- ``xclim.indicators.atmos.fire_weather_indexes`` → ``xclim.indicators.atmos.cffwis_indices``
- ``xclim.indices.freshet_start`` → ``xclim.indices.first_day_temperature_above``
- ``xclim.indices.first_day_above`` → ``xclim.indices.first_day_temperature_above``
- ``xclim.indices.first_day_below`` → ``xclim.indices.first_day_temperature_below``
- ``xclim.indices.tropical_nights`` → ``xclim.indices.tn_days_above``
- ``xclim.indices.generic.degree_days`` → ``xclim.indices.generic.cumulative_difference``
* The following *modules* have been removed (:pull:`1228`):
- `xclim.indices.fwi` → functions migrated to `xclim.indices.fire`
- `xclim.subset` (mock submodule) → functions migrated to `clisops.core.subset`
* Indicators ``standardized_precipitation_index`` and ``standardized_precipitation_evapotranspiration_index`` will now require ``pr_cal`` and ``wb_cal`` as keyword arguments only. (:pull:`1236`).
* The internal object ``PercentileDataArray`` has been removed. (:pull:`1236`).
* The ``xclim.testing.utils.get_all_CMIP6_variables`` and ``xclim.testing.utils.update_variable_yaml`` function were removed as the former was extremely slow and unusable. (:pull:`1258`).
* The wind speed input of ``atmos.potential_evapotranspiration`` and ``atmos.water_budget`` was renamed to ``sfcWind`` (capital W) as this is the correct CMIP6 name. (:pull:`1258`).
* Indicator `land.stats`, `land.fit` and `land.freq_analysis` are now deprecated and will be removed in version 0.43. They are being phased out in favor of generic indicators `generic.stats`, `generic.fit` and `generic.return_level` respectively. (:issue:`1130`, :pull:`1225`).

Bug fixes
^^^^^^^^^
* The weighted ensemble statistics are now performed within a context in order to preserve data attributes. (:issue:`1232`, :pull:`1234`).
* The `make docs` Makefile recipe was failing with an esoteric error. This has been resolved by splitting the `linkcheck` and `docs` steps into separate actions. (:issue:`1248`. :pull:`1251`).
* The setup step for `pytest` needed to be addressed due to the fact that files were being accessed/modified by multiple tests at a time, causing segmentation faults in some tests. This has been resolved by splitting functions into those that fetch or generate test data (under `xclim.testing.tests.data`) and the fixtures that supply accessors to them (under `xclim.testing.tests.conftest`). (:issue:`1238`, :pull:`1254`).
* Relaxed the expected output for ``test_spatial_analogs[friedman_rafsky]`` to support expected results from `scikit-learn` 1.2.0.
* The MBCn example in documentation has been fixed to properly imitate the source. (:issue:`1249`, :pull:`1250`).
* Streamflow indicators relying on indices defined in `xclim.indices.stats` were not checking input variable units. These indicators will now raise an error if input data units are not m^3/s. (:issue:`1130`, :pull:`1225`).
* Adjusted some documentation examples were not being rendered properly. (:issue:`1264`, :pull:`1266`).

Internal changes
^^^^^^^^^^^^^^^^
* Minor adjustments to GitHub Actions workflows (newest Ubuntu images, updated actions version, better CI triggering). (:pull:`1221`).
* Pint units `context` added to various operations, tests and `Indicator` attributes. (:issue:`1208`, :pull:`1227`).
* Updated article from Alavoine & Grenier (2022) within documentation. Many article reference URLs have been updated to use HTTPS where possible. (:issue:`1246`, :pull:`1247`).
* Added relevant variable dataflag checks for potential evaporation, convective precipitation, and air pressure at sea level. (:pull:`1241`).
* Documentation restructured to include `ReadMe` page (as `About`) with some minor changes to documentation titles. (:pull:`1233`).
* `xclim` development build now uses `nbqa` to effectively run black checks over notebook cells. (:pull:`1233`).
* Some `tox` recipes (``opt-slow``, ``conda``) are temporarily deactivated until a `tox>=4.0`-compatible `tox-conda` plugin is released. (:pull:`1258`).
* A notebook (``extendingxclim.ipynb``) has been updated to remove mentions of obsolete `xclim.subset` module. (:pull:`1258`).
* Merge of sdba documentation from the module and the rst files, some cleanup and addition of a section referring to GitHub issues. (:pull:`1230`).