From 65c90df49118c99895d494e111f4191461557757 Mon Sep 17 00:00:00 2001 From: Erik van Sebille Date: Thu, 25 Jun 2026 07:32:08 +0200 Subject: [PATCH 1/6] First draft of v4-preview blog post --- src/posts/parcels-v4preview/index.md | 31 ++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+) create mode 100644 src/posts/parcels-v4preview/index.md diff --git a/src/posts/parcels-v4preview/index.md b/src/posts/parcels-v4preview/index.md new file mode 100644 index 0000000..77acea1 --- /dev/null +++ b/src/posts/parcels-v4preview/index.md @@ -0,0 +1,31 @@ +--- +title: 'Parcels v4.0-preview is available! 🚀' +date: '2026-08-01' +authors: + - name: Erik van Sebille + github: erikvansebille + - name: Nick Hodgskin + github: VeckotheGecko + - name: Joe Schoonover + github: fluidnumericsJoe +summary: 'Parcels v4.0-preview is now available, bringing exciting new features and improvements to the Parcels framework.' +--- + +We are very excited to announce that Parcels v4-preview is now available for performing Lagrangian simulations in hydrodynamic flows. Parcels v4 is a complete redesign of the [Parcels code](https://parcels-code.org) and is designed to be more flexible and extensible than previous versions. + +Parcels v4 is pure python code, so that it can leverage the full power of the [Pangeo ecosystem](https://pangeo.io/) of geoscience python tools such as xarray, dask and zarr. Particle advection and interpolation are now vectorised operations, which improves performance and makes [particle-particle interactions](https://docs.parcels-code.org/en/main/user_guide/examples/tutorial_interaction.html) easier to implement. + +Key improvements of Parcels v4 are + +1. Support for [unstructured grids](https://docs.parcels-code.org/en/main/user_guide/examples/explanation_grids.html). +2. More flexibility in writing Kernels (including [using python functions in Kernels](https://docs.parcels-code.org/en/main/user_guide/examples/tutorial_gsw_density.html) .and support for writing output in a Kernel) +3. Support for [user-defined interpolators](https://docs.parcels-code.org/en/main/user_guide/examples/explanation_interpolation.html). +4. More robust and flexible support for [nested grids](https://docs.parcels-code.org/en/main/user_guide/examples/tutorial_nestedgrids.html). + +We have also changed the [output format to `parquet`](https://docs.parcels-code.org/en/main/getting_started/tutorial_output.html#reading-the-output-file), which is a tabular format and therefore more efficient and flexible for storing large datasets. + +See the full migration guide from Parcels v3 to v4 [here](https://docs.parcels-code.org/en/main/user_guide/v4-migration.html). + +Note that Parcels v4-preview is not a stable release yet, and we are still working on improving the performance of the framework and adding new features. We welcome feedback from the community, and encourage users to try out the new version and [report any issues or suggestions](https://github.com/Parcels-Code/parcels/issues). + +Funded by the [WarmWorld ELPHE project](https://www.geomar.de/en/research/ongoing-projects/project-details/prj/376612?cHash=449a07d057ea0d890287bd2b8ca26e8b) funded by the German Federal Ministry for Research, Technology and Space (BMFTR) and the [NWO Vici project “Tracing Marine Macroplastics by Unraveling the Ocean’s Multiscale Transport Processes”](https://www.nwo.nl/en/projects/vic222025), the development of Parcels v4 started in September 2025 and was a collaboration between the [GEOMAR Helmholtz Centre for Ocean Research Kiel](https://www.geomar.de/en/), [FluidNumerics](https://www.fluidnumerics.com/) and the [University of Utrecht](https://www.uu.nl/en) in the Netherlands. The development was led by Nick Hodgskin, Joe Schoonover and Erik van Sebille, with contributions from many others, including Willi Rath, Daniel Lizarbe, and Michael Denes. From f78bef07cd51b0d67cdbe624834fa02bc41d0090 Mon Sep 17 00:00:00 2001 From: Erik van Sebille Date: Thu, 25 Jun 2026 17:46:33 +0200 Subject: [PATCH 2/6] Capitalising package names --- src/posts/parcels-v4preview/index.md | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/src/posts/parcels-v4preview/index.md b/src/posts/parcels-v4preview/index.md index 77acea1..317d102 100644 --- a/src/posts/parcels-v4preview/index.md +++ b/src/posts/parcels-v4preview/index.md @@ -13,12 +13,12 @@ summary: 'Parcels v4.0-preview is now available, bringing exciting new features We are very excited to announce that Parcels v4-preview is now available for performing Lagrangian simulations in hydrodynamic flows. Parcels v4 is a complete redesign of the [Parcels code](https://parcels-code.org) and is designed to be more flexible and extensible than previous versions. -Parcels v4 is pure python code, so that it can leverage the full power of the [Pangeo ecosystem](https://pangeo.io/) of geoscience python tools such as xarray, dask and zarr. Particle advection and interpolation are now vectorised operations, which improves performance and makes [particle-particle interactions](https://docs.parcels-code.org/en/main/user_guide/examples/tutorial_interaction.html) easier to implement. +Parcels v4 is pure python code, so that it can leverage the full power of the [Pangeo ecosystem](https://pangeo.io/) of geoscience python tools such as Xarray, Dask and Zarr. Particle advection and interpolation are now vectorised operations, which improves performance and makes [particle-particle interactions](https://docs.parcels-code.org/en/main/user_guide/examples/tutorial_interaction.html) easier to implement. Key improvements of Parcels v4 are 1. Support for [unstructured grids](https://docs.parcels-code.org/en/main/user_guide/examples/explanation_grids.html). -2. More flexibility in writing Kernels (including [using python functions in Kernels](https://docs.parcels-code.org/en/main/user_guide/examples/tutorial_gsw_density.html) .and support for writing output in a Kernel) +2. More flexibility in writing Kernels (including [using python functions in Kernels](https://docs.parcels-code.org/en/main/user_guide/examples/tutorial_gsw_density.html) and support for writing output in a Kernel) 3. Support for [user-defined interpolators](https://docs.parcels-code.org/en/main/user_guide/examples/explanation_interpolation.html). 4. More robust and flexible support for [nested grids](https://docs.parcels-code.org/en/main/user_guide/examples/tutorial_nestedgrids.html). From 4f5521fd5b8f3ca0aa731e815fa1131a14d13ced Mon Sep 17 00:00:00 2001 From: Erik van Sebille Date: Thu, 25 Jun 2026 17:48:43 +0200 Subject: [PATCH 3/6] Update src/posts/parcels-v4preview/index.md Co-authored-by: Nick Hodgskin <36369090+VeckoTheGecko@users.noreply.github.com> --- src/posts/parcels-v4preview/index.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/src/posts/parcels-v4preview/index.md b/src/posts/parcels-v4preview/index.md index 317d102..234195d 100644 --- a/src/posts/parcels-v4preview/index.md +++ b/src/posts/parcels-v4preview/index.md @@ -15,7 +15,7 @@ We are very excited to announce that Parcels v4-preview is now available for per Parcels v4 is pure python code, so that it can leverage the full power of the [Pangeo ecosystem](https://pangeo.io/) of geoscience python tools such as Xarray, Dask and Zarr. Particle advection and interpolation are now vectorised operations, which improves performance and makes [particle-particle interactions](https://docs.parcels-code.org/en/main/user_guide/examples/tutorial_interaction.html) easier to implement. -Key improvements of Parcels v4 are +Key improvements include: 1. Support for [unstructured grids](https://docs.parcels-code.org/en/main/user_guide/examples/explanation_grids.html). 2. More flexibility in writing Kernels (including [using python functions in Kernels](https://docs.parcels-code.org/en/main/user_guide/examples/tutorial_gsw_density.html) and support for writing output in a Kernel) From 25ac29c7c20563abc832542eb5db2d2ad40aa16c Mon Sep 17 00:00:00 2001 From: Erik van Sebille Date: Thu, 25 Jun 2026 17:49:44 +0200 Subject: [PATCH 4/6] Update src/posts/parcels-v4preview/index.md Co-authored-by: Nick Hodgskin <36369090+VeckoTheGecko@users.noreply.github.com> --- src/posts/parcels-v4preview/index.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/src/posts/parcels-v4preview/index.md b/src/posts/parcels-v4preview/index.md index 234195d..c3d5364 100644 --- a/src/posts/parcels-v4preview/index.md +++ b/src/posts/parcels-v4preview/index.md @@ -26,6 +26,6 @@ We have also changed the [output format to `parquet`](https://docs.parcels-code. See the full migration guide from Parcels v3 to v4 [here](https://docs.parcels-code.org/en/main/user_guide/v4-migration.html). -Note that Parcels v4-preview is not a stable release yet, and we are still working on improving the performance of the framework and adding new features. We welcome feedback from the community, and encourage users to try out the new version and [report any issues or suggestions](https://github.com/Parcels-Code/parcels/issues). +Note that Parcels v4.0 is an early release to gather user feedback and should not be considered stable. We welcome feedback from the community, and encourage users to try out the new version and [report any issues or suggestions](https://github.com/Parcels-Code/parcels/issues). Once incorporating this feedback, improving performance, and implementing a few outstanding features, we aim to release a stable version of Parcels. Funded by the [WarmWorld ELPHE project](https://www.geomar.de/en/research/ongoing-projects/project-details/prj/376612?cHash=449a07d057ea0d890287bd2b8ca26e8b) funded by the German Federal Ministry for Research, Technology and Space (BMFTR) and the [NWO Vici project “Tracing Marine Macroplastics by Unraveling the Ocean’s Multiscale Transport Processes”](https://www.nwo.nl/en/projects/vic222025), the development of Parcels v4 started in September 2025 and was a collaboration between the [GEOMAR Helmholtz Centre for Ocean Research Kiel](https://www.geomar.de/en/), [FluidNumerics](https://www.fluidnumerics.com/) and the [University of Utrecht](https://www.uu.nl/en) in the Netherlands. The development was led by Nick Hodgskin, Joe Schoonover and Erik van Sebille, with contributions from many others, including Willi Rath, Daniel Lizarbe, and Michael Denes. From f831cfd44d9fdef42d854431a380e82007df256a Mon Sep 17 00:00:00 2001 From: Erik van Sebille Date: Thu, 25 Jun 2026 17:50:41 +0200 Subject: [PATCH 5/6] Update src/posts/parcels-v4preview/index.md Co-authored-by: Nick Hodgskin <36369090+VeckoTheGecko@users.noreply.github.com> --- src/posts/parcels-v4preview/index.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/src/posts/parcels-v4preview/index.md b/src/posts/parcels-v4preview/index.md index c3d5364..189e6f9 100644 --- a/src/posts/parcels-v4preview/index.md +++ b/src/posts/parcels-v4preview/index.md @@ -22,7 +22,7 @@ Key improvements include: 3. Support for [user-defined interpolators](https://docs.parcels-code.org/en/main/user_guide/examples/explanation_interpolation.html). 4. More robust and flexible support for [nested grids](https://docs.parcels-code.org/en/main/user_guide/examples/tutorial_nestedgrids.html). -We have also changed the [output format to `parquet`](https://docs.parcels-code.org/en/main/getting_started/tutorial_output.html#reading-the-output-file), which is a tabular format and therefore more efficient and flexible for storing large datasets. +We have also changed the [output format to `parquet`](https://docs.parcels-code.org/en/main/getting_started/tutorial_output.html#reading-the-output-file), which is a tabular format more suited for writing and reading trajectory data. See the full migration guide from Parcels v3 to v4 [here](https://docs.parcels-code.org/en/main/user_guide/v4-migration.html). From 698f6e91729ced6dbd9ed709d22f260019bfb7ad Mon Sep 17 00:00:00 2001 From: Erik van Sebille Date: Thu, 25 Jun 2026 17:52:01 +0200 Subject: [PATCH 6/6] Update index.md --- src/posts/parcels-v4preview/index.md | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/src/posts/parcels-v4preview/index.md b/src/posts/parcels-v4preview/index.md index 189e6f9..f76da0a 100644 --- a/src/posts/parcels-v4preview/index.md +++ b/src/posts/parcels-v4preview/index.md @@ -13,7 +13,7 @@ summary: 'Parcels v4.0-preview is now available, bringing exciting new features We are very excited to announce that Parcels v4-preview is now available for performing Lagrangian simulations in hydrodynamic flows. Parcels v4 is a complete redesign of the [Parcels code](https://parcels-code.org) and is designed to be more flexible and extensible than previous versions. -Parcels v4 is pure python code, so that it can leverage the full power of the [Pangeo ecosystem](https://pangeo.io/) of geoscience python tools such as Xarray, Dask and Zarr. Particle advection and interpolation are now vectorised operations, which improves performance and makes [particle-particle interactions](https://docs.parcels-code.org/en/main/user_guide/examples/tutorial_interaction.html) easier to implement. +With this release - Parcels is a pure Python package that leverages the full power of the [Pangeo ecosystem](https://pangeo.io/) of geoscience python tools such as Xarray, Dask and Zarr. Particle advection and interpolation are now vectorised operations, which improves performance and makes [particle-particle interactions](https://docs.parcels-code.org/en/main/user_guide/examples/tutorial_interaction.html) easier to implement. Key improvements include: @@ -26,6 +26,6 @@ We have also changed the [output format to `parquet`](https://docs.parcels-code. See the full migration guide from Parcels v3 to v4 [here](https://docs.parcels-code.org/en/main/user_guide/v4-migration.html). -Note that Parcels v4.0 is an early release to gather user feedback and should not be considered stable. We welcome feedback from the community, and encourage users to try out the new version and [report any issues or suggestions](https://github.com/Parcels-Code/parcels/issues). Once incorporating this feedback, improving performance, and implementing a few outstanding features, we aim to release a stable version of Parcels. +Note that Parcels v4-preview is an early release to gather user feedback and should not be considered stable. We welcome feedback from the community, and encourage users to try out the new version and [report any issues or suggestions](https://github.com/Parcels-Code/parcels/issues). Once incorporating this feedback, improving performance, and implementing a few outstanding features, we aim to release a stable version of Parcels. Funded by the [WarmWorld ELPHE project](https://www.geomar.de/en/research/ongoing-projects/project-details/prj/376612?cHash=449a07d057ea0d890287bd2b8ca26e8b) funded by the German Federal Ministry for Research, Technology and Space (BMFTR) and the [NWO Vici project “Tracing Marine Macroplastics by Unraveling the Ocean’s Multiscale Transport Processes”](https://www.nwo.nl/en/projects/vic222025), the development of Parcels v4 started in September 2025 and was a collaboration between the [GEOMAR Helmholtz Centre for Ocean Research Kiel](https://www.geomar.de/en/), [FluidNumerics](https://www.fluidnumerics.com/) and the [University of Utrecht](https://www.uu.nl/en) in the Netherlands. The development was led by Nick Hodgskin, Joe Schoonover and Erik van Sebille, with contributions from many others, including Willi Rath, Daniel Lizarbe, and Michael Denes.