The results of metal analyses carried out on surficial sediment samples collected in the coastal waters of southwest New Brunswick and the Broughton Archipelago in British Columbia have been used to investigate the use of heavy metals as tracers of salmon farm wastes. New Brunswick in particular has seen rapid expansion of open cage salmon aquaculture in recent years. While techniques have been developed to identify benthic impacts directly beneath the cages, no method has been developed to determine the fate of dispersed wastes. We show that Zn and Cu, two elements associated with aquaculture operations, can be used to identify farm wastes in sediments at some distance from the cage sites. Geochemical normalization for grain size is needed in order to see the small tracer signals. Excess Zn and Cu levels are found in the sediment at varying distances from the salmon cages in depositional areas in southwest New Brunswick and in the Broughton Archipelago. Evidence that links these observations to salmon aquaculture development is described.

The high resolution infrared spectrometer AIRS was launched on the NASA AQUA platform in May 2002. This paper documents briefly some of the characteristics, potential and initial experience with AIRS data in the ECMWF forecasting system. Section 1 outlines the instrument characteristics and the hoped for potential for improvements to NWP skill to be gained from high resolution measurements. Section 2 outlines the scheme adopted for detecting the presence of cloud in the data and section 3 describes the observed error characteristics of the AIRS data, especially the biases present and possible strategies for handling these. Section 4 presents results of assimilation of AIRS radiances and finally section 5 outlines areas of immediate and future research aimed at optimising the use of these exciting new data. 1. THE AIRS INSTRUMENT AIRS is an infrared spectrometer with nominal spectral resolution of around 1 cm on board the AQUA spacecraft along with an AMSU-A instrument. Measurements are made from around 3.7 to 15.5 microns with a gap in the longwave side of the 6 micron water vapour band. The ground IFOV is approximately 12x7 Km with 9 soundings per AMSU-A IFOV. This makes it comparable to the HIRS instrument apart from the spectral resolution and therefore number of channels; 19 for HIRS and 2378 for AIRS. The Metop high resolution sounder IASI will have ~8000 channels at 3-4 times the spectral resolution (~0.3 cm) but is otherwise comparable. HIRS, AIRS and IASI all have channel NeDT values from around 0.2 to 0.4 K. The rationale for flying the AIRS/IASI instruments is to obtain higher vertical resolution soundings than that obtainable from the HIRS and AMSU like radiometers. Most of this increase in resolution arises from the increased spectral sampling rather than from the somewhat narrower weighting functions obtained as a result of better spectral resolution. This is illustrated in figure 1 which shows at the top, the temperature jacobians for the AIRS (left) and HIRS (right) instruments. The jacobians for AIRS are seen to be comparable, but much more numerous (despite only 324 being shown, see section 4) than HIRS. The lower two plots in figure 1 show the averaging kernels expected from the two instruments. These are the response (in a 1Dvar retrieval) of the estimated vertical temperature for a give delta function error in the retrieval a priori profile. For the HIRS, it is clearly seen that perturbations are spread widely across the troposphere and that perhaps 2-3 separate pieces of information on the tropospheric temperature are available. The plot for AIRS shows much narrower kernels indicating significantly better resolution. Note that this simulation is somewhat optimistic in that it assumes a cloud-free scene but also pessimistic in that only the 324 channel subset of the data is used here. The hope for AIRS/IASI in NWP is that this improved vertical resolution can be successfully utilised in NWP models. Figure 1. Temperature Jacobians and averaging kernels for AIRS and HIRS