Comprehensive Validation of the Prithvi WxC FM Through Atmospheric Process Analysis

Weather Foundation Models in general represent a significant advancement in computational weather prediction by leveraging data-driven techniques to improve accuracy and speed. This study evaluates the Prithvi WxC foundation model for weather and climate by systematically assessing its adherence to fundamental physical constraints governing atmospheric processes. While traditional model validation primarily focuses on error statistics of modeled fields, this work takes a more comprehensive approach, incorporating a series of process-based tests to ensure the model's consistency with key atmospheric principles.

We first test the model's compliance with conservation of mass, ensuring that it respects the fundamental principle that mass is neither created nor destroyed within the atmosphere. Next, we examine the model's representation of geostrophic balance, critical for large-scale flow, by evaluating the relationship between the pressure gradient and the Coriolis force. The hypsometric equation is also applied to assess the vertical consistency of the model’s simulations, verifying that changes in pressure are appropriately related to temperature and height. To further evaluate large-scale flow dynamics, we analyze the model’s consistency with thermal wind relations, ensuring that temperature gradients are correctly reflected in the vertical wind profile. Finally, we tested our model on radiative and convective parameterization by comparing its performance of convection to established methods in conventional weather models, testing its ability to properly simulate convective processes. 

The results of these tests highlight the Prithvi WxC model's strengths and areas for improvement in terms of physical consistency. By adhering to these atmospheric principles, the findings of this study offer valuable insights into how the model can be refined, enhancing its potential applications in both weather forecasting and climate research.