LAUSR

To achieve a smooth transition between algorithms for "clear" water and "turbid" water, we propose a single formula to calculate the input parameter (ip) used for empirical retrieval of absorption coefficients (a) or chlorophyll concentration ([Chl]) from remote-sensing reflectance (Rrs). This formula for ip takes the ratio of the maximum Rrs in the blue-green bands to the sum of Rrs(green) and the scaled Rrs in the red and infrared bands (termed as ipMax-Sum). We found that, compared to the widely used OC4-type formula for ip, ipMax-Sum can improve the coefficient of determination from ∼0.88 to 0.99 for absorption coefficient at 440 nm [a(440)] in ∼0.01-20.0  m-1 ([Chl] ∼0.01-500  mg m-3). Especially, the sensitivity of ipMax-Sum to the change in a(440) is about five times greater than that of OC4-type for a(440)>∼1.0  m-1 ([Chl]>∼10  mg m-3). These results indicate an advantage of ipMax-Sum for generating robust and seamless a(440) or [Chl] from clear to highly turbid waters. The inclusion of such a scheme in a quasi-analytical algorithm is also presented.