Reanalysis products are datasets that provide comprehensive and consistent records of past weather and climate conditions. They are created by combining observations from various sources, such as weather stations, satellites, and buoys, with numerical models to fill in gaps and provide a more complete picture of historical weather patterns. These datasets are used by researchers to analyze and study long-term climate trends, validate model simulations, and improve our understanding of the Earth's climate system. Reanalysis products are constantly updated and refined with new data and improved modeling techniques to provide accurate and reliable historical climate information for scientific research and applications.