Here are some suggestions on how to find accessible and numerically processed global vegetation data:

1. **NASA Earthdata:** NASA provides a wealth of environmental data, including vegetation-related information. The MODIS (Moderate Resolution Imaging Spectroradiometer) dataset, available through NASA's Earthdata platform, offers global vegetation indices such as NDVI (Normalized Difference Vegetation Index) that can be processed numerically. You can access this data in various formats, including HDF, which can be converted for use in SPSS.

Website: https://earthdata.nasa.gov/

2. **UN Food and Agriculture Organization (FAO):** The FAO maintains datasets related to vegetation and land cover. The Global Land Cover SHARE dataset (GLC-SHARE) is a global land cover dataset that includes information on vegetation. While it may require some data processing, it is a valuable resource for your research.

Website: http://www.fao.org/geonetwork/srv/en/metadata.show?id=37196

3. **Global Vegetation Monitoring (GVM) Project:** The GVM project provides access to global vegetation datasets, including the GIMMS NDVI dataset, which covers several decades. These datasets are commonly used in ecological and environmental research and can be processed for use in SPSS.

Website: http://www.ntsg.umt.edu/project/gvm

4. **European Space Agency (ESA):** The ESA offers various Earth observation datasets, including vegetation-related data. The Climate Change Initiative (CCI) Land Cover project provides global land cover information, including vegetation, in formats suitable for scientific analysis.

Website: https://www.esa-landcover-cci.org/

5. **Data Repositories:** Consider exploring data repositories and archives such as the World Bank's DataBank, which provides access to environmental and climate-related datasets. While the focus may not be solely on vegetation, you can find relevant data.

Website: https://databank.worldbank.org/

6. **Collaboration with Remote Sensing Experts:** Collaborating with experts in remote sensing and geospatial analysis can be beneficial. They can help you access and process vegetation data for your specific research needs.

7. **Data Conversion Tools:** If you find data in formats not directly compatible with SPSS, consider using data conversion tools or software to transform the data into a usable format. Tools like R or Python can be helpful for this purpose.

8. **Consult Local Universities or Research Institutions:** Local universities or research institutions in your region or in regions of interest may have access to relevant vegetation data or can guide you on where to find it.

When working with global environmental data, it's essential to ensure that the datasets are up-to-date and cover the regions of interest for your research.