Land Evaporation

This project aims to generate long-term, global land evaporation records derived from satellite observations that align with community requirements.

Background

Land evaporation is a critical variable at the intersection between water, carbon, and energy cycles. It governs water availability for ecosystems, agriculture, and society, while playing a key role in climate regulation. Land evaporation cools the surface by using energy that would otherwise heat up the atmosphere. This makes Land evaporation especially important during extreme events like droughts and heatwaves, where it modulates temperature and stress. It also influences major climate processes – such as the water vapour, cloud, and lapse rate feddbacks – shaping local weather and regional climate dynamics.

However, despite its importance, land evaporation remains one of the most uncertain components of the global water cycle. This is due to difficulties to observe it directly across large scales, the sparse distribution of ground stations - especially in the Global South - and the challenges of accurately modelling the influence of its complex drivers.

Advances in satellite remote sensing and physical modelling now make it possible to estimate land evaporation and its main components (i.e., transpiration, interception loss, and bare soil evaporation) with unprecedented accuracy and coverage. The ESA’s Climate Change Initiative (CCI) Land Evaporation project will leverage these advances to deliver a long-term, global dataset of land evaporation tailored to scientific requirements and policy needs.

This dataset will improve our understanding of land–climate interactions, support climate model evaluation, and inform water resource management and climate adaptation strategies. With E recently recognised by ESA and GCOS as an Essential Climate Variable (ECV), this project will provide the data needed to address a key gap in our climate observation capabilities.

Aims and objectives

The main objective of this project is to enhance the ESA CCI ECV portfolio by developing a long-term, high-accuracy Evaporation dataset, including its main components, and the partitioning between surface latent and sensible heat fluxes.

The specific objectives are to:

• establish the needs and requirements of the climate science and climate service communities
• develop a state-of-the-art land evaporation algorithm
• implement a processing system to generate and deliver the CCI Land Evaporation products
• ensure the accuracy, reliability, and usability of CCI Land Evaporation products
• assess the suitability of CCI Land Evaporation products for various climate and hydrometeorological applications

Project plan

The project is divided into six work packages and two processing cycles:

• WP1 | Requirement Analysis: Define user and climate data needs through consultation and review.
• WP2 | Algorithm Development: Develop and refine a modular algorithm to estimate land evaporation and quantify uncertainty.
• WP3 | System Development: Build a full processing system to generate and distribute consistent long-term datasets.
• WP4 | Product Validation: Validate datasets against observations and benchmarks to ensure accuracy and reliability.
• WP5 | Product Assessment: Test usability through case studies and gather feedback from scientific and stakeholder communities.
• WP6 | Project Management: Coordinate activities, reporting, and communication to ensure efficient project delivery.