## 5 Conclusions  
The EMMENA region is facing many challenges related to climate change, environmental degradation, energy, water scarcity, and hazards. The ongoing development of EO parallel with advancement in the domain of big Earth data has provided the opportunity to better assess and address the various challenges. This work provides an overview of the existing EO applications in the EMMENA region, where 6647 articles were efficiently categorized into the following thematic areas: Atmosphere, water, agriculture, land, disaster risk reduction, cultural heritage, energy, marine safety and security, and other. The big Earth data thematic area was identified as horizontal. A total of 180 articles were further reviewed from the selection of the top 20 highly cited articles per thematic area. The results from the top 20 articles revealed a high research interest in the thematic area of disaster risk reduction with almost two times higher number of citations than the second thematic area (water). The focus of these articles is limited to floods and landslides. The main knowledge gap was the lack of protocols and the development of early warning systems based on EO. The results also revealed limited research in specific EO applications for the water thematic area, which include water body monitoring through radar altimeters and water quality parameter estimation through thermal and optical satellite data. Also, EO research related to cultural heritage (1.4% of the total number of studies) and marine safety and security (0.9% of the total number of studies) was surprisingly rare. The main research interest in the thematic area of atmosphere was related to precipitation estimates, dust, and the impact of coronavirus on air quality. The thematic area of agriculture covered a wide range of EO applications (evapotranspiration estimation, land suitability for agriculture, irrigation mapping, agricultural land loss, crop monitoring, crop production, yield prediction, crop mapping, stem water potential monitoring, and crop water footprint estimation). The study has also identified the top authors, research organizations, and funding agencies for the EMMENA region. Sentinel-2 data (60.8%) and Sentinel-1 data (35.4%) are the most widely used among the Sentinel missions. Similarly, Landsat 8 (83.2%) and Landsat 7 (10.0%) are the most widely used data sources among the Landsat missions. The ongoing development of big Earth data techniques and the increasing availability of satellite EO data will enhance the research capabilities in the aforementioned thematic areas. **Supplementary Materials:** The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/rs15174202/sl](https://www.mdpi.com/article/10.3390/rs15174202/sl)]([https://www.mdpi.com/article/10.3390/rs15174202/sl](https://www.mdpi.com/article/10.3390/rs15174202/sl)), Table S1: List of publications including author name, article title, author keywords and affiliations, times cited, and DOI. **Author Contributions:** Conceptualization, methodology, validation, formal analysis: M.E., S.M., K.T. and K.N. ; investigation, software, resources, data curation: M.E., E.E., K.F. ([PERSON]), K.F. ([PERSON]), G.L., C.T., C.F.P., C.P., M.M. and S.N. ; writing--original draft preparation, M.E. ; writing--review and editing, A.A., G.K., G.S., C.K. and D.H.; visualization, M.E. and S.M. ; supervision, D.H.; project administration, D.H.; funding acquisition, D.H. All authors have read and agreed to the published version of the manuscript. **Funding:** This research was funded by 'EXCELSIOR' project (European Union's Horizon 2020 research and innovation programme), grant number \"857510\".