This report summarizes a practical algorithm to estimate the momentum and scalar transfer in the atmospheric surface layer over water basins, where the wave field can be considered generated by the local wind. The algorithm needs only wind speed, air temperature and humidity and water surface temperature data, but takes into account the wave state of the water surface. The wave state dependence of the surface roughness lengths and the wave induced momentum are estimated using similarity expressions linking the wave spectral peak characteristics (if not known) to the wind speed and the fetch. The effects of stability, capillary waves, and laminar limit for low wind speeds are also considered. Some examples of the calculated transfer coefficients are shown in different wind speed and stability conditions, as functions of the fetch and compared with literature data. Two applications of the routine are also described in the fields of meteorology and environmental pollution respectively. The first is an application over buoy data, that points out two strong convective conditions over the ocean related to strongly perturbed weather. The second shows the result of coupling the routine with a multimedia chemical transfer model: the pollutant concentrations are different from those obtained using constant averaged air-water transfer coefficients when the correlation between local meteorology and air pollution is taken into account.
Estimation of air-sea transfer coefficients: routine description and applications
Martano P;
2002
Abstract
This report summarizes a practical algorithm to estimate the momentum and scalar transfer in the atmospheric surface layer over water basins, where the wave field can be considered generated by the local wind. The algorithm needs only wind speed, air temperature and humidity and water surface temperature data, but takes into account the wave state of the water surface. The wave state dependence of the surface roughness lengths and the wave induced momentum are estimated using similarity expressions linking the wave spectral peak characteristics (if not known) to the wind speed and the fetch. The effects of stability, capillary waves, and laminar limit for low wind speeds are also considered. Some examples of the calculated transfer coefficients are shown in different wind speed and stability conditions, as functions of the fetch and compared with literature data. Two applications of the routine are also described in the fields of meteorology and environmental pollution respectively. The first is an application over buoy data, that points out two strong convective conditions over the ocean related to strongly perturbed weather. The second shows the result of coupling the routine with a multimedia chemical transfer model: the pollutant concentrations are different from those obtained using constant averaged air-water transfer coefficients when the correlation between local meteorology and air pollution is taken into account.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
