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 plays a key role in the water, carbon, and energy cycles. In recognition of its significant role in the climate and the need for systematic monitoring, the Global Climate Observing System (GCOS) include it as one of the Essential Climate Variable (ECV).

Land evaporation regulates water availability and cools the surface by consuming heat. This can have knock on effects on ecosystems, agriculture, and society, and influence extreme events such as droughts and heatwaves. Through feedbacks involving water vapour, clouds, and atmospheric stability, land evaporation can also shape regional climate patterns.

Despite its importance, land evaporation remains an uncertain component of the global water cycle. Challenges stem from limited direct observations at large scales, sparse ground station coverage - particularly in the Global South - and the complexity of modelling its many interacting 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.

This project, as part of ESA’s Climate Change Initiative (CCI), is leveraging satellite observations to deliver a long-term, global dataset of land evaporation tailored to scientific requirements and policy needs.

The dataset will improve our understanding of land–climate interactions, support climate model evaluation, and inform water resource management and climate adaptation strategies.

Aims and objectives

The main objective of this project is to address GCOS-requirements of the land evaporation ECV by developing a long-term, robust satellite-derived data products, including those for 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.