I am analyzing Landsat data around Lagos, Nigeria going back to 1990 which includes Landsat 8, 7, and 5. I am using Google Earth Engine's code editor to access and clean the images. I am trying to get yearly composites and have been successful for Landsat 7 and 8. But I am finding incredibly spotty coverage for Landsat 5. To illustrate, the code below (Google Earth Engine code) compares the size of the resulting image collections for Landsat 7 and Landsat 5. For both Tier 1 and Tier 2 Landsat 5 has drastically fewer images. I believe both LS-5 and LS-7 circle roughly every 2 weeks so I don't understand the difference in data availability.
I am new to Earth Engine and satellite data.
// Get Landsat 5 and 7 over region of interest and print Collection size var pt = ee.Geometry.Point(3.657968670903074, 6.691009458317496); var ls7Collection_T1 = ee.ImageCollection("LANDSAT/LE07/C01/T1").filterBounds(pt); var ls5Collection_T1 = ee.ImageCollection("LANDSAT/LT05/C01/T1").filterBounds(pt); var ls7Collection_T2 = ee.ImageCollection("LANDSAT/LE07/C01/T2").filterBounds(pt); var ls5Collection_T2 = ee.ImageCollection("LANDSAT/LT05/C01/T2").filterBounds(pt); print("LS 5 (tier 1) collection size is: ", ls5Collection_T1.size()); print("LS 7 (tier 1) collection size is: ", ls7Collection_T1.size()); print("LS 5 (tier 2) collection size is: ", ls5Collection_T2.size()); print("LS 7 (tier 2) collection size is: ", ls7Collection_T2.size());