Freezing rain is an especially hazardous type of adverse weather and is frequently observed in Churchill, Manitoba. The goals of this study were to assess the climatology of freezing rain in Churchill, assess the synoptic climatology of the Hudson Bay region using a multi-level synoptic classification scheme, assess the relationships between the synoptic climate and freezing rain events, and assess the trends in synoptic types and to discuss the implications of climate change in relation to the expected changes in freezing rain. For the years 1953 thru 2009, freezing rain was observed during 796 hours, an average of approximately 15 hours per year. A 34-type multi-level synoptic classification consisting of five NCEP/NCAR reanalysis datasets was constructed. Type-20 was associated with a majority of the freezing rain cases. More research is needed to understand how climate change may impact the timing, frequency and intensity of freezing rain in Churchill.

Two series of experiments have been carried out to study the relative contributions of both dry deposition wash off and crown leaching, including H<SUP>+ </SUP>-cation exchange, to the change in chemistry of rain passing over the leaves of Sitka spruce (<i>Picea sitchensis</i> (Bong.) Carr.). In the first experiments detached needles and small trees were washed under several conditions with artificial acid rain water, following various pretreatments. Increases in Na and Mg in the canopy drip were found to be due, predominantly, to washed off dry deposition whereas about 50% of the K and Ca increases on washing with solutions of pH less than 4 were considered to be due to leaching of neutral salts and H<SUP>+ </SUP>-cation exchange. In a second series of experiments the unidirectional membrane fluxes of ions across the needle surface were studied by compartmental analysis, using <SUP>36</SUP>Cl, <SUP>45</SUP>Ca and <SUP>42</SUP>K. There appears to be a net loss of all these elements when artificial rain water solution of pH 4.3 was used for elution. Neutral salt leaching over 24 h may result in as much as 5% of total K present in needle being lost, making it the most readily leached cation. Ca is not readily available for exchange as it is bound within the vacuole and cell wall. It was determined that about 15% of total Ca is available for exchange, of which 1.5-3% is considered to be leached as neutral salts. The elution of <SUP>45</SUP>Ca from needles attached to twigs suggested that leached Ca may be readily replaced by movement from the translocation stream to the cytoplasm. Although Cl in canopy drip is generally considered to be due predominantly to washed off dry deposition, about 12.5% of the total Cl content of needles was estimated to be leached over 24 h.

The main objective of this work was to determine the quantum yields for the production of alkoxy radicals via the near U-V photolysis of alkyl nitrites. Alkoxy radical reactions, including their isomerization, are important in both clear and polluted atmospheres. Alkyl nitrites were used as a photolytic source of alkoxy radicals (1). The extent of the of photolysis for the nitrites was determined by measuring the yield of either ketone or aldehyde product produced from the decomposition of the alkoxy radical, as a result of the dissociation of the nitrite concerned. Experiments were carried out at elevated temperatures (393K) in order to ensure that every alkoxy radical that was formed, dissociated via reaction (3), rather than recombine with nitric oxide to reform the nitrite (2). Care was taken to search for any other products via the primary step. RONO = (+ hv) RO &43 NO (1); RO + NO &61 RONO (2); RO = Products (Ketone or Aldehyde) (3) The experimental determination of azomethane, t-butyl, s-butyl, t-pentyl and 2-pentyl nitrite molecular electronic absorption spectrums were carried out using ultraviolet and near ultraviolet spectrophotometry (U.V.). Spectrophotometric measurements were made using certain nitrite pressure at 393 K with a 9.3 cm length cell. The average absorption at each nanometer of 5 runs were plotted against the absorption range (328 - 383 nm). The absorption cross section (σ) and the absorption rate (J_a) for the azomethane and the four nitrites were measured and calculated in the range 328 - 283 nm and at 393 K.

Effects of acid rain on the dry weight, nitrogen and sulfur content of radish plants were determined. They were exposed to distilled water acidified with a 7:3 ratio of sulfuric acid and nitric acid and adjusted to pH levels 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, and 5.7. A control group, exposed to distilled water only, was also used. Four hundred plants, divided in eight groups, were grown under laboratory conditions. At four, seven and ten week intervals, an equal number of plants of each pH level were removed from the soil.Plants exposed to water of lower pH values were found to be significantly higher (p < .05) in dry weight, percentage of nitrogen, and weight of sulfur per plant than crops at more neutral pH levels. The increased weight may be due to the greater availability of nitrates and sulfates at lower pH levels. These compounds probably contributed to better growth and greater dry weight of the plants at low pH levels.

With rising concern about flooding and water pollution in the Red River and particularly in Lakes Manitoba and Winnipeg in recent years, building rain gardens in cities may become one solution with considerable potential for improving water quality. The literature illustrated the many benefits that can be provided by a rain garden system, not only aesthetically pleasing gardens with educational and biodiversity values, but they also can reduce storm water pollution and flooding in downstream water bodies. In order to address questions of public understanding and perceptions of their usefulness so as to better promote future implementation, the study examined social feedback about rain gardens through a survey at Ecole St Avila, an elementary school in Winnipeg. The findings from the survey indicated that the largest obstacles for rain garden development are funding and the lack of knowledge by the public.

Freezing rain is an especially hazardous type of adverse weather and is frequently observed in Churchill, Manitoba. The goals of this study were to assess the climatology of freezing rain in Churchill, assess the synoptic climatology of the Hudson Bay region using a multi-level synoptic classification scheme, assess the relationships between the synoptic climate and freezing rain events, and assess the trends in synoptic types and to discuss the implications of climate change in relation to the expected changes in freezing rain. For the years 1953 thru 2009, freezing rain was observed during 796 hours, an average of approximately 15 hours per year. A 34-type multi-level synoptic classification consisting of five NCEP/NCAR reanalysis datasets was constructed. Type-20 was associated with a majority of the freezing rain cases. More research is needed to understand how climate change may impact the timing, frequency and intensity of freezing rain in Churchill.

Altitudinal zonation of rain forests was investigated on Bukit Belalong (913m), Brunei. Mean annual rainfall was 4100mm at 45m and 5500mm at 913m. Mean annual temperatureswere 25.7°C (45m) and 21.8°C (913m). Three 0.25ha plots were set up at each of three altitudes. At 200m and 500m there was evergreen lowland rain forest and at 850m there was lower montane rain forest (LMRF). The Dipterocarpaceae had the highest proportion of basal area throughout, but their importance declined in the LMRF where the Fagaceae, Myrtaceae and Lauraceae were increasingly important. Soils in the LMRF were more organic and had higher concentrations of total nitrogen and phosphorus and the soils from 500m were the most acid and least base saturated. Rates of nitrogen mineralisation and soil concentrations of inorganic nitrogen did not differ significantly among altitudes. The rates (t ha-1 yr-1) of total small litterfall and leaf litterfall were significantly lower in the LMRF (10.6 and 7.9 at 200m; 10.5 and 7.9 at 500m; 8.3 and 6.0 at 850m). Litterfall nutrient concentrations were similar among altitudes, but smaller quantities of litterfall nutrients were cycled at 850m. The mass (t ha-1) of the small litter layer was similar throughout (5.2 at 200m; 6.1 at 500m; 5.2 at 850m) but leaf litter kL values were lower at 850m (2.4 at 200m; 2.4 at 500m; 2.0 at 850m). Fine root (<5mm) mass (t ha-1) in the top 100cm of soil was 8.3 (200m); 12.0 (500m); 10.6 (850m). Rates (t ha-1 yr-1) of fine root growth (estimated by ingrowth bags) were 0.9 (200m); 2.2 (500m); 0.5 (850m). A bioassay experiment using rice was made at 30m and 913m. Nutrients were more limiting in the montane soil, but climate was of overriding importance for rice growth. It seems that the LMRF is not nutrient limited and the lower temperatures at 850m are the primary cause of the change in species composition and reduction of stature there.

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It is argued that for many regions of the earth, ground based remote sensing techniques for rainfall measurement are impractical due to their cost and limited range of coverage. Global rainfall estimates must therefore be provided largely by satellites, particularly those exploiting atmospheric windows in the visible/IR and microwave regimes. / A 2-D pattern matching technique using visible and IR data is proposed and its accuracy investigated. Because these wavelengths respond primarily to cloud and not rain sized drops, significant accuracy may be achieved in rain areas, but not directly in amounts. However, when long term average rain rates for raining areas are used, errors of (TURN) (+OR-) 49% for 10('5) km('2) are achieved. This compares favorably with other techniques based on cloud life histories. / Microwave radiometer-based techniques are also investigated and are found to be fundamentally limited in accuracy ((TURN) (+OR-) 70%) by the large variations in the (unknown) effective rain layer height. However, useful accuracy ((TURN) (+OR-) 20%) may be obtained over large areas ((TURN) 10('5) km('2)), provided that the long term average effective rain layer height is known. It is argued that a once or twice daily satellite rain estimate is insufficient for either accurate estimates of daily accumulation or for samples of climatological rain rates. A hybrid microwave satellite-vis/IR technique is therefore proposed in order to solve the temporal resolution problem without the necessity of orbiting many microwave radiometers. This technique would take advantage of the high ( 1/2 hour) temporal resolution of the vis/IR data and could achieve accuracies of (TURN) (+OR-) 20% for 12 hour accumulations over 10('5) km('2) provided that the mean effective rain layer height is known. The practical implementation of such a technique will ultimately depend on the relative difficulty of measuring the mean effective rain layer height, and the mean rain rate for raining areas as well as the availability of appropriate sensor platforms.