‘NO’ as a conservative tracer in the Weddell Sea

The salinity maximum of the Warm Deep Water advecting into the Weddell Sea lies about 200 m below the temperature maximum and an NO minimum. The NO minimum is horizontally as well as vertically resolved on two sections towards the eastern and southern coast of the Weddell Sea, one towards Cap Norvegia, the other towards the Filchner Ice Shelf, whereas the temperature and salinity maxima are horizontally resolved on the former section only. Thus NO is a valuable complementary tool in studying the boundary current along the coast of the Weddell Sea. The NO signal indicates a non-continuity within the boundary current, as the minimum in the downstream section (less than 480 μmol kg⁻¹ ) is deeper than the upstream one ( more than 490 μmol kg⁻¹). The temperature maximum as well as the NO minimum descend from a depth of about 400 m in the Cap Norvegia section to about 600 m in the Filchner Ice Shelf section, the salinity maximum being correspondingly lowered. A plot of NO vs. salinity shows a continuous mixing line between Warm Deep Water and the freshest part of the Winter Water interval, thus essentially displaying Winter Water as itself lying on a mixing line. This indicates that Warm Deep Water is being advected well into the winter surface layer.     

Lateral coherence of longitudinal wind components in strong winds

A combination of lateral coherence measurements of wind speed at five locations suggests that the decay constant is a monotonically increasing function of the ratio of separation to height, under neutral conditions.     

Trace metal levels in coastal sea water investigation of Danish waters

The concentration levels of Cd (25 ng l^?1), Cu (0.45 μg l^?1), Ni (0.48 μg l^?1), Fe (0.2–7.0 μg l^?1), Pb (40 ng l^?1) and Zn (0.80 μg l^?1) have been determined in the Danish Sounds and in the Kattegat. Different sampling techniques have been used and analyses have been carried out separately by two different investigators, both using freon-extraction followed by determination by atomic absorption spectrometry (a.a.s.). Except for iron, found mainly in the particulate phase, the metals are found predominantly in a dissolved and labile (extractable) form. The results are compared with trace metal levels found in the two main water masses entering the Kattegat—the North Sea and the Baltic Sea.     

The convergence of harmonic reduction to an internal sphere

The boundary value problem of physical geodesy has been solved with the use of a harmonic reduction down to an internal sphere using a discrete procedure. (For gravity cf. Bjerhammar 1964 and for the potential cf. Bjerhammar 1968). This was a finite-dimensional approach mostly with one-to-one correspondence between observations and unknowns on the sphere. Earlier studies were made with the use of surface elements (on the sphere) with constantgravity. Integration over the surface elements was replaced by a discrete approach with the use of the distance to a point in the centre of the surface element. See Bjerhammar (1968) and (1969). This approach was later presented as a “reflexive prediction” technique for a weakly stationary stochastic process. Bjerhammar (1974, 1976). Krarup (1969) minimized the L²-norm of the potential on the internal sphere. It will here be proved that the two solutions are identical for a proper choice of the radii of the internal spheres. The proof is given for a spherical earth with selected choice of “carrier points”. The convergence problem is discussed. The L²-norm solution is found convergent for the fully harmonic case. Uniform convergence is obtained in the non-harmonic case with the use of the original procedure applied in accordance with the theorems of Keldych-Lavrentieff and Yamabe.     

The Uppsala urban meteorology project

An extensive urban meteorology project in Uppsala, Sweden, is described. The city itself is considered suitable as a kind of model city, being almost circular, having sharp urban/rural boundaries and being situated in a relatively flat area. The project incorporates numerous measurements. A main station with a 100-m mast is situated at the NE urban/rural border. Its instrumentation consists of a slow-response (profile) system and a turbulence system. The profile instrumentation is described in detail. In addition to the main station, the project comprises: measurements from two 14-m masts, one on the top of a centrally located building, the other mobile; pilot balloon ascents; tethered balloon soundings, car-borne temperature traverses etc. Some preliminary results are presented: analyses of wind profiles from the mast and three-dimensional heat island studies.     

On the geodetic boundary value problem for a fixed boundary surface—A satellite approach

Employing satellite-geometrical methods, the physical surface of the earth may be assumed to be known, while gravity measurements yield thelength of the gravity vector (including contributions from rotation). The problem then is to determine gravitational potential from such gravity observations. The corresponding linearized problem is an oblique derivative problem. The problem was discussed by Almqvist (1959), Koch (1970, 1971) and Koch and Pope (1972). Our presentation gives proofs for the existence (and uniqueness) of the solution in the non-linear case. The general implicit function theorem (in Banach spaces) is used to provewellposedness at least when data are close to given standard values (closeness is defined either in terms of Hölder or Sobolev norms). Iterative methods for solution by linear operators are given. The linearized problem is solved by harmonic reduction to an internal sphere in a generalization of the method by the first author for the Stokes problem. Also deflections of the vertical are treated.     

Solution of the altimetry-gravimetry problem

Unique solvability of the altimetry-gravimetry problem is proved for general ocean configurations and for models which are close to the classical Stokes model provided that a zero-degree component is removed from both gravity anomaly and disturbed potential. Data and solutions are to belong to suitable Sobolev spaces. The theory of pseudodifferential operators plays an important part in the proof. Finite element methods for numerical computations are suggested and convergence rates are estimated. Holota (1980, 1981a, b, 1982) has proved wellposedness of the problem without constraints for small continents by variational methods. The present paper yields wellposedness without any constraints when the diameter of the continental area is smaller than 62°.6. There are strong indications, very disturbing considering the amount of work spent on the method for the last two decades, that the direct least squares approach is unstable for mixed sets of data.     

ON THE SENSITIVITY OF PRECIPITATION FORECASTS TO THE MOIST PHYSICS AND THE HORIZONTAL RESOLUTION OF NUMERICAL MODEL

The impacts of the enhanced model's moist physics and horizontal resolution upon the QPFs(quantitative precipitation forecasts)are investigated by applying the HIRLAM(high resolutionlimited area model)to the summer heavy-rain cases in China.The performance of the control run,for which a 0.5°×0.5°grid spacing and a traditional“grid-box supersaturation removal+Kuo typeconvective paramerization”are used as the moist physics,is compared with that of the sensitivityruns with an enhanced model's moist physics(Sundqvist scheme)and an increased horizontalresolution(0.25°×0.25°),respectively.The results show:(1)The enhanced moist physics scheme(Sundqvist scheme),by introducing the cloud watercontent as an additional prognostic variable and taking into account briefly of the microphysicsinvolved in the cloud-rain conversion,does bring improvements in the model's QPFs.Althoughthe deteriorated QPFs also occur occasionally,the improvements are found in the majority of thecases,indicating the great potential for the improvement of QPFs by enhancing the model's moistphysics.(2)By increasing the model's horizontal resolution from 0.5°×0.5°,which is already quitehigh compared with that of the conventional atmospheric soundings,to 0.25°×0.25°without thesimultaneous enhancement in model physics and objective analysis,the improvements in QPFs arevery limited.With higher resolution,although slight amelioration in locating the rainfall centersand in resolving some finer structures of precipitation pattern are made,the number of the mis-predicted fine structures in rainfall field increases with the enhanced model resolution as well.     

Sediment pollution in the Vågen,Bergen harbour,Norway

Recent sediments in the Vågen, Bergen harbour, are subjected to injection of untreated sewage from around 15,000 person equivalent. Here the distribution of trace elements is mapped in surface and subsurface sediments. Selected trace-element concentrations decrease from the inner towards the outer Vågen. These concentration gradients do not correlate with minerogenic grain size. Linear correlation, combined with enriched sediment trace elements, are used to infer sources for these elements and possible reasons for their enrichment. (1) Frequent use of dental amalgam might be related to the enrichments of and correlation between Ag, Cu, Hg and Sn in surficial sediments pre-1994. (2) Enrichment and correlation of Cu/Zn may be related to the commercial and private use of anti-fouling boat-paint. Further, tributyltin is suggested as a source of Sn enrichment. (3) Increased traffic in the city of Bergen with gasoline combustion and car-wheel wear-off release Pb and Zn. (4) Hg and Pb might have been atmospherically supplied due to the combustion of coal in a nearby gas plant pre-1985. (5) No correlation is observed between enriched Vågen trace metals and bedrock element composition of the surrounding mountains, indicating a minor supply from erosion.