Sentinel Asia: Earth Observation–Enabled Disaster Response and Resilience in the Asia-Pacific

Sentinel Asia is a voluntary regional cooperation framework established in 2006 under the Asia-Pacific Regional Space Agency Forum (APRSAF) to support disaster management through satellite Earth observation (EO) data. By coordinating the capabilities of space agencies, data analysis institutions, and disaster management authorities, Sentinel Asia enables rapid, on-demand access to EO-derived information for emergency response across the Asia-Pacific region. This mechanism allows countries and regions without their own Earth observation satellites to benefit from timely satellite-based information during disasters.

Since its establishment, Sentinel Asia has supported more than 500 emergency observation activations in over 30 countries and regions, addressing a wide range of natural hazards including floods, earthquakes, landslides, volcanic eruptions, and wildfires. Through the timely provision of actionable, decision-ready information, Sentinel Asia directly supports disaster response operations by helping authorities assess impacts, prioritize actions, allocate resources, and coordinate national and international assistance. The initiative remains fully operational and continues to strengthen disaster response and resilience across the region through sustained international collaboration and capacity building.

Countries in the Asia-Pacific region face a diverse range of natural hazards that can cause large-scale human and economic losses. Disaster management agencies often operate under time pressure, uncertainty, and incomplete information, especially during the early stages of an emergency. Cloud cover, limited ground access, and damaged infrastructure can further complicate situational awareness.

Sentinel Asia was established to address these challenges by ensuring that disaster response organizations have rapid access to reliable EO information, regardless of national technical capacity. By fostering international cooperation and data sharing, Sentinel Asia helps bridge resource gaps and strengthens regional disaster resilience. The initiative supports decision-makers who require clear, trusted information to act quickly and confidently in high-stakes situations.

Sentinel Asia operates as an on-demand emergency response service. When a disaster occurs, authorized disaster management agencies submit an observation request through the Sentinel Asia coordination mechanism. Satellite data are then acquired, processed, analyzed, and converted into decision-ready information products.

The resulting EO products are tailored to the needs of operational users. Rather than raw imagery, users receive interpreted maps and visualizations that clearly delineate affected areas and potential impacts. These products are designed to be easily understood and rapidly integrated into emergency response workflows, even by non-specialist users.

The Sentinel Asia initiative is underpinned by a broad, multi-national collaboration involving space agencies, disaster management authorities, research institutions, and international organizations across the Asia-Pacific region. Sentinel Asia operates under the framework of the Asia-Pacific Regional Space Agency Forum (APRSAF), with the Japan Aerospace Exploration Agency (JAXA) serving as the executive secretariat and the Asian Disaster Reduction Center (ADRC) acting as the primary coordination hub for emergency observation requests. The Joint Project Team (JPT) comprises more than one hundred member organizations, including national space agencies, data analysis institutions, and governmental disaster management agencies from over 30 countries and regions.

Earth observation data used within Sentinel Asia are contributed by participating space agencies designated as Data Provider Nodes (DPNs). These include, among others, JAXA (Japan), the Indian Space Research Organisation (ISRO), the Korea Aerospace Research Institute (KARI), Thailand’s Geo-Informatics and Space Technology Development Agency (GISTDA), the Taiwan Space Agency (TASA), the Mohammed Bin Rashid Space Centre (MBRSC, United Arab Emirates), the Philippine Space Agency (PhilSA), the Space Technology Institute-Vietnam Academy of Science and Technology (STI-VAST), Center for Remote Imaging, the Sensing and Processing (CRISP), and the JSC National Company Kazakhstan Gharysh Sapary (KGS). These agencies provide satellite data on a voluntary basis to support emergency response activities across the region.

Sentinel Asia makes use of a diverse constellation of Earth observation satellites, encompassing both optical and Synthetic Aperture Radar (SAR) sensors. Satellite missions supporting Sentinel Asia emergency observations include ALOS-2 (JAXA), Cartosat-2S&3 and Resourcesat-2&2A (ISRO), FORMOSAT-5 (TASA), Thaichote/THEOS-1&2 (GISTDA), KhalifaSat (MBRSC), and DIWATA-2, NovaSAR-1 (PhilSA), DS-EO(CRISP), and Kazeosat-1&2 (KGS). The availability of SAR data is particularly critical for disaster monitoring in conditions of persistent cloud cover or during nighttime operations, such as during monsoon-related flooding or tropical cyclones.

Satellite imagery acquired through these missions is processed and interpreted by Data Analysis Nodes (DANs), which include universities, research institutes, and specialized analysis centers across the region. By combining observations from multiple satellite missions and agencies, Sentinel Asia enhances temporal coverage, spatial resolution, and the robustness of disaster-related information. This multi-source, collaborative observation approach ensures continuity of data supply and builds confidence in the derived information products used by disaster management authorities for time-critical decision-making.

Since its establishment, Sentinel Asia has delivered substantial and measurable benefits for disaster response and resilience across the Asia‑Pacific region. To date, the initiative has supported more than 500 emergency observation activations, addressed a broad spectrum of natural hazards and supported response activities in over 30 countries and regions.

In terms of hazard type, the majority of Sentinel Asia activations have been related to hydrometeorological disasters, particularly flood events, reflecting their high frequency and wide spatial impact across the region. Flood-related activations account for well over half of all emergency observations, including flooding, flash floods, and inundation associated with tropical cyclones and monsoon rainfall. These activations have been critical for mapping flood extent, identifying isolated communities, and prioritizing emergency response actions.

Geological hazards, including earthquakes and landslides, represent a significant secondary portion of activations. Earthquake-related observations have supported rapid damage assessment in both urban and rural settings, while landslide monitoring has been particularly important in mountainous and high‑rainfall regions, where secondary hazards often follow major storms or seismic events.

Sentinel Asia has also been activated for volcanic eruptions, supporting ash plume monitoring, lava flow mapping, and exclusion zone management, as well as for wildfires, where EO-based products have been used to assess burn extent and support firefighting and recovery planning. In addition, a smaller number of activations have addressed other hazard types, such as storm-related coastal flooding and environmental accidents, demonstrating the flexibility of the Sentinel Asia mechanism.

Beyond the numbers, the accumulated impact of these activations lies in their operational value. The repeated use of Sentinel Asia products has enabled disaster management authorities to act more quickly and confidently, even in situations where ground information is unavailable or unreliable.

For example, in September 2024, Typhoon Yagi affected Lao PDR, Myanmar, the Philippines, Thailand, and Viet Nam. In response, disaster management organizations in each country, along with the Centre for Humanitarian Assistance on Disaster Management (AHA Centre), requested emergency observations from Sentinel Asia. By utilizing satellite data and flood extent maps provided by Sentinel Asia, the AHA Centre was able to enhance the planning for emergency response operations in a timely manner.

Over time, the initiative has strengthened institutional trust in EO based decision support, enhanced technical capacity among participating agencies, and reinforced regional cooperation in disaster risk reduction. Through its Joint Project Team framework, Sentinel Asia continues to play a vital role in protecting lives and livelihoods and improving resilience across the Asia Pacific region.