Diurnal ocean surface layer model validation

The diurnal ocean surface layer (DOSL) model at the Fleet Numerical Oceanography Center forecasts the 24-hour change in a global sea surface temperatures (SST). Validating the DOSL model is a difficult task due to the huge areas involved and the lack of in situ measurements. Therefore, this report details the use of satellite infrared multichannel SST imagery to provide day and night SSTs that can be directly compared to DOSL products. This water-vapor-corrected imagery has the advantages of high thermal sensitivity (0.12 C), large synoptic coverage (nearly 3000 km across), and high spatial resolution that enables diurnal heating events to be readily located and mapped. Several case studies in the subtropical North Atlantic readily show that DOSL results during extreme heating periods agree very well with satellite-imagery-derived values in terms of the pattern of diurnal warming. The low wind and cloud-free conditions necessary for these events to occur lend themselves well to observation via infrared imagery. Thus, the normally cloud-limited aspects of satellite imagery do not come into play for these particular environmental conditions. The fact that the DOSL model does well in extreme events is beneficial from the standpoint that these cases can be associated with the destruction of the surface acoustic duct. This so-called afternoon effect happens as the afternoon warming of the mixed layer disrupts the sound channel and the propagation of acoustic energy

Expansion Potential for Irrigation within the Mississippi Delta Region

17.6 million acres, or 73 percent, of the Mississippi Delta Region is currently cropland and possesses the physical characteristics of slope, texture and soil type which are recommended for irrigation. Economic feasibility of expanding irrigation by flood, furrow and center pivot methods were examined under 24 scenarios representing two sets of crop prices, yield levels, production costs, opportunity costs and six crop rotations. Irrigation was economically feasible for 56 to 100 percent of the cropland across all scenarios. Approximately 88 percent of the cropland can be economically irrigated with flood or furrow in its present form, 8 percent yield highest net returns if furrow irrigated following land forming and 4 percent can be economically irrigated only with center pivot systems

Using Kappenman\u27s Model to Compare the Relative Fishing Power of 42-Foot Shrimp Trawls and 65-Foot Fish Trawls During Summer and Fall in the Western and North-Central Gulf of Mexico

Kappenman’s fishing power correction (FPC) model was used to compare the fishing efficiency between a 42-ft shrimp trawl and a 65-ft fish trawl towed simultaneously at 985 stations by the National Oceanic and Atmospheric Administration ship Oregon II in the western and north-central Gulf of Mexico. The shrimp trawl was consistently more efficient, both summer and fall, and regardless of whether using no./hr or kg/hr to calculate the FPC factors, for four species of fish, three species of crustaceans, and paper scallops. During summer, the shrimp trawl was more efficient, when using FPC factors calculated using no./hr as the catch per unit of effort (CPUE), at catching 13 of the 42 species of fish, 11 of the 12 species of crustaceans, and paper scallops. It was more efficient at catching 18 of the 42 species of fish, 10 of the 12 species of crustaceans, and paper scallops when FPC factors were calculated using kg/hr as the CPUE. In the fall, the shrimp trawl was more efficient, when using no./hr or kg/hr as the CPUE, at catching five species of fish, three species of crustaceans, and paper scallops. Fishing power correction factors were then compared between summer and fall seasons for 42 species of fish and 16 species of invertebrates. During summer, FPC values ranged from a low of 0.15 for Gulf menhaden to 4.94 for shoal flounder; fall FPC values ranged from 0.05 for yellow box crab to 2.52 for broad-striped anchovy. With the exception of three species, when using number of individuals caught per hour as the CPUE, all FPC factors were significantly different between summer and fall catches