Sea surface roughness

These parameters are some of the most important needed for developing an aerosol model, but by no means all of them. Most likely, temperature of the sea surface and air, height of the mixing layer, and sea surface roughness also need to be known. 

Duntley, S. Q. et al. 1970, Atmospheric Limitations on Remote Sensing of Sea Surface Roughness by Means of Reflected Daylight, Final Report, Contract NAS-12-2126, NASA, Ames Research Center. 

One key factor for tropical diazotrophs may be water temperature. For example, the distribution of Trkhodesmium spp. is roughly limited by the 20°C isotherm, and other planktonic cyanobacteria are likewise primarily tropical or subtropical in distribution. MetabolicaUy active populations of Trkhodesmium have been observed at 18.3°C in the North Atlantic (McCarthy and Carpenter, 1979), but activity was low, and substantial growth is typically not seen until water temperature exceeds 20°C (Carpenter, 1983a,b). Moreover, water temperature co-varies inversely with surface nutrient concentrations (Kamykowski and Zentara, 1986). Indeed, in previous studies we have used sea surface temperature as a proxy for oligotrophic waters in order to estimate the areal range of Trkhodesmium (Capone et al., 2005). 

Following Zhang and McPhaden (1995), the important contribution of latent heat fluxes increases with the increase in sea surface temperature (SST). This holds true for moderate ranges in the SST, the wind speed, and the humidity difference between the surface air and the saturation humidity observed at the sea surface of the North Atlantic. This means, however, that latent heat fluxes and associated fluctuations in air temperature should be roughly in... 

Figure 11.7 shows the climatologic surface salinity 1900-2005 ofthe Baltic Sea from the BALTIC atlas, provided in Chapter 20. The permanent entrainment of salt from lower layers into the surface water forms a stable NE-SW salinity gradient during the surface water renewal period of about 30 years (Meier and Kauker, 2003 Meier et al., 2006 Feistel et al., 2006a). The excess freshwater input of about 500km /year causes a comparable export of brackish water (Knudsen, 1900 Matthaus, 2006) with salinity of about 8 g/kg, as visible in the Arkona Basin, Fig. 11.7. Thus, the Baltic Sea exports about 4 Gt of salt per year, and imports the same amount on average (Feistel and Feistel, 2006). Divided by the sea surface area of almost 400 000 km, a rough estimate of the mean apparent vertical salt transport is...

One of the most important findings of these studies and parallel laboratory efforts was that surface wave roughness (a parameter that can be remotely-sensed) was found to correlate well with gas-transfer rates across the air-sea interface (Frew et al. 1995, Hara et al. 1995). Results obtained in both laboratory and field experiments indicate that the range of wavelengths pertinent to gas transport may be restricted to wavelengths of millimetres to centimetres. While the correlation between surface roughness and gas transport is robust under differing environmental conditions, the specific mechanisms of interfacial transport have yet to be adequately elucidated and are the topic of recent research (e.g., McKenna 2004). 

It should also be noted that satellite-borne SAR images do not allow the detection of oil spills, if the sea surface is too rough or too smooth, i.e., in the case of winds below 2 m s"1 and above 15 m s 1. Last, not least, at present, satellites SAR images are unable to identify the pollution culprit (i.e., the name of the ship that polluted) satellite can at best identify the position of the probable pollution culprit. 

Fig. 7. Variation of SAR intensity (arbitrary units) along sections normal to the spill shown in Figure la at the distances of 2.7 km (7a, top) and 34.5 km (7b, bottom) from point B (from west to east), with cross-track average of 1 km and along-track average of 50 m. The decreased SAR intensity in the spill area is due to the damping of the small-scale roughness of the sea surface. The solid lines show average radar backscatter of the sea surface west (1) and east (2) of the spill, and in the spill area (3). The length of line 4 characterizes the width of the spill...

Prom these figures, the dependency of temporal residual currents on the wind is also clear. Since the sea surface has not so many obstacles compared with that of the land and the roughness is also smaller than the land, the sea wind is often... 

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