Distribution Of Solar Radiation Transmission And Heating Rate Of Yellow Sea In Spring

The transmission of solar energy through the upper ocean is essential for quantification and the modeling of the upper ocean thermodynamics and primary production. The solar radiation can be partitioned into two domains:shortwave radiation and infrared radiation (separated at 700nm). Because of the enormously large attenuation, mostly infrared radiation is lost in the upper 3 meter, also, the attenuation is invariable to the changes of water constituents. Unlike the attenuation for infrared radiation, the shortwave radiation can transmit through much deeper water and heat the water directly, but the attenuation is closely relatated with the water inherent optical property (IOP).This paper will analyze the solar energy transmission in the Yellow Sea in 3 different conditions:midday without cloud, midday with cloud, morning without cloud. The shortwave radiation is simulated by the MOMO tool which IOP input is the ACS data measured in the Yellow Sea in the Spring of 2006, and the infrared radiation is calculated by the mature model. The influences of IOP, cloud, zenith angle are also introduced.Under the same environment conditions, the solar radiation only depends on the shortwave radiation,so the distributions of transmission and heating rate coincide with shortwave radiation transmission. The solar radiation transmission would be lower and heating rate would be higher in the area where shortwave radiation transmission is relatively lower. In the regions of Subei shallow, Shandong peninsula and the center of the South Yellow Sea, the shortwave radiation transmissions are relatively lower at the same depth.One main influence factor of shortwave radiation transmission is water inherent optical property (absorption and scattering). As the single scattering albedo is larger than 0.6 in Yellow Sea, shortwave radiation is mainly determined by scattering. In the areas of Subei shallow and Shandong peninsula, there is a lot of suspended mineral, so water scattering is the key influence factor, while in other areas absorption cannot be ignored. At the center area of the Yellow Sea, the shortwave radiation transmission is also lower than neighboring area due to the high absorption of phytoplankton.If the sky is cloudy, the transmission of shortwave radiation and infrared radiation are both lower than the transmission of clear condition, however, due to cloud changing the solar spectral shape, the ratio of shortwave radiation to the total solar radiation is promoted, so the transmission of solar radiation is larger than the environment without cloud, and the largest difference is 0.042. The solar radiation reaching the sea surface in cloudy sky is 197.9 W/m2, which is smaller than 926.5 W/ m2 (the clear sky) by 78.64%, and the radiation heating rate in cloudy environment is smaller than in clear sky in the degree of 78%-82%.In the morning the zenith angle (45°) is larger than 25°at noon, then the transmission of shortwave radiation is smaller than at noon, and the transmission of infrared radiation is smaller slightly too, so the transmission of total radiation is also smaller. The zenith angle changes the solar transmission mainly through changing shortwave radiation transmission. Also, the solar radiation reaching the sea surface in the morning is 684.7W/m2, which is less than at noon, so the radiation heating rate is smaller than that at noon, and the difference is about 25%-30% in all depths.