Update index.md

Author: valentina-s

ohw25/tutorials-index/index.md

@@ -30,7 +30,9 @@ The following tutorials will be presented live during the **US sessions**, and w
 ### Wednesday, August 28th
 [Boris Shapkin](https://de.linkedin.com/in/boris-shapkin) - [**Using LLMs and AI Agents with Climate and Ocean Data**]()
 
-[Kristen Thyng](https://www.linkedin.com/in/kristen-thyng) - [**Visualization**]()
+[Kristen Thyng](https://www.linkedin.com/in/kristen-thyng) - [**Visualization**]() 
+
+[Joe Hamman](https://joehamman.com/about/) - **Advanced xarray and icechunk with ICESat2 data** (optional with [ICESat-2 Hackweek](https://2025.hackweek.io/))
 
 ### Thursday, August 29th
 [Valentina Staneva](https://valentina-s.github.io/) - [**Reproducible Workflows**]()
@@ -43,6 +45,6 @@ Finally, each year we offer brief sessions on non-coding aspects of computationa
 - OHW Fellows - **Science Talks**
 - [Hafeez Oladejo](https://www.linkedin.com/in/hafeez-oladejo-a55b06167)  - **AI Assisted Programming Discussion** following a tutorial on LLMs.
 - [Alex Kerney](https://github.com/abkfenris) - [**Stresses in the geosciences**](https://github.com/oceanhackweek/ohw-tutorials/tree/OHW25/02-Wed/README.md), an open discussion about mental health in the geosciences.
-- [Joe Hamman](https://joehamman.com/about/) - **Advanced xarray and icechunk with ICESat2 data** (optional with [ICESat-2 Hackweek](https://2025.hackweek.io/))
+