Satellite Detect Changes of Net Radiation and Its Components over Lake Huron

One of the prerequisites of physically-based models is the knowledge of the spatially distributed net radiation. Net radiation is a key component in assessing the energy balance of the surface and heat fluxes interface the atmosphere. This study examines the spatiotemporal distribution of net radiation (Q*) and its four components: incoming shortwave (K↓), outgoing shortwave (K↑), incoming longwave (L↓), and outgoing longwave (L↑) under all sky conditions across Lake Huron using remotely sensed data. Eleven years (2002-2012 ) of daily visible and thermal data with multi-spatial resolution of 1 km to 5 km were analyzed. Good agreement is found between the 30 minute observed average net radiation and instantaneous estimates made from the satellite data with the correlation coefficient of 0.92 and 0.75 under clear sky and all sky condition respectively. Results showed that Q* and all of its components significantly changed over the study period. Trend analysis revealed that significant decrease of the Q* at the rate of 0.003 Wm-1 d-1 with significantly decrease of shortwave (K↓ and K↑) and significantly increase of longwave (L↓ and L↑). Here, we discuss variations in the seasonal spatial distributions patterns and relationships of these four components to the recent climate change, and present explanations for these phenomena. In spite of change in cloudiness, we also explain some of the likely factors which are possible relate to decline in net radiation.