Images of Fiji using MODIS 250 and 500 m bands

 

Mati Kahru, mkahru@ucsd.edu

 

Explanation: shown here are 2 types of images, generated from atmospherically corrected MODIS data.

  • RGB = a true color like image using band 1 (620-670 nm) for Red, band 3 (459-479 nm) for Blue, and band 4 (545-565 nm) for Green.
  • Reflectance = Combined reflectance by bottom and materials in the water calculated by subtracting band 2 (841-876 nm) reflectance from band 1 (620-670 nm) reflectance.
  • More details on processing of the MODIS data can be found in: Kahru et al., MODIS detects a devastating algal bloom in Paracas Bay, Peru, EOS, Trans. AGU, Vol. 85, N45, p. 465-472, 2004
  • Two periods (January-March of 2000 and 2004) are compared to detect any possible changes due to coral bleaching, etc. Bleached corals should have higher reflectance. However, the potential influence of water depth due to different tidal cycle has not been eliminated.

 

2000 January-March

 

MOD02QKM.A2000058.2230, RGB RGB, Large Reflectance

 

MOD02QKM.A2000065.2235, RGB RGB, Large Reflectance

 

MOD02QKM.A2000067.2225, RGB RGB, Large Reflectance

 

MOD02QKM.A2000074.2230, RGB RGB, Large Reflectance

 

MOD02QKM.A2000081.2235, RGB RGB, Large Reflectance

 

MOD02QKM.A2000083.2235, RGB RGB, Large Reflectance

 

MOD02QKM.A2000090.2235, RGB RGB, Large Reflectance

 

 

2004 January-March

 

MOD02QKM.A2004037.2215, RGB RGB, Large Reflectance

 

MOD02QKM.A2004053.2215, RGB RGB, Large Reflectance

 

MOD02QKM.A2000062.2210, RGB RGB, Large Reflectance

 

MOD02QKM.A2004076.2220, RGB RGB, Large Reflectance

 

MOD02QKM.A2004078.2210, RGB RGB, Large Reflectance

 

 

 

Map of reef areas for time series analysis

 

 

 

Reflectance of reef areas 1 and 2 in 2000 and 2004.

Each point is a median reflectance (MODIS band1 band2)

for the selected reef area.