Two catchments amended with snow fences were paired with unaltered controls to investigate the influences of increased snow accumulation on the hydrology, soil thermal regime, and nutrient fluxes from High Arctic headwater catchments, representative of polar desert and mid-moisture vegetative classes at the Cape Bounty Arctic Watershed Observatory (CBAWO). The impact of augmented snow accumulation on the winter soil thermal regime was highly variable during the period studied. Soil temperatures were 8-9°C warmer beneath a drift 54 cm deep compared to ambient snow (10 cm) in the winter of 2006-2007, whereas soil temperatures were not significantly warmer beneath drifts (88 and 50 cm) compared to ambient snow (18 and 35 cm) in the winter of 2007-2008. Departures between air and ground surface temperatures suggest that snow accumulation was insufficient to insulate soils before February 2007-2008 due to late snow accumulation, compared to earlier snow accumulation in September in the winter of 2006-2007. The augmented snow accumulation did not significantly impact the timing of soil thaw in spring or active layer thickness at this site. Greater snow accumulation in the amended catchments altered runoff characteristics, including an extended duration of runoff by 30-80%, a delay in peak flow of ~5 days, and increased runoff ratios. Augmented snow accumulation, resulted in greater fluxes of dissolved organic carbon (DOC), dissolved organic nitrogen (DON), dissolved inorganic carbon (DIC), nitrate (NO3-), ammonium (NH4+) and total inorganic solutes (TIS) in amended catchments relative to control sites. The seasonality of solute fluxes were also affected, with a greater proportion of inorganic solute fluxes occurring in the later portion of the runoff season compared to the controls. Snow accumulation was strong factor in determining total specific solute fluxes, with the magnitude of DOC and DON fluxes also strongly dependent on vegetative class. An active layer detachment that occurred in one of the amended catchments may have contributed to changes in nutrient fluxes, but the precise influence of the active layer detachment could not be differentiated from the combined impact of the disturbance and increased snow accumulation. / Thesis (Master, Geography) -- Queen's University, 2010-09-23 10:36:11.833

Snow Albedo Feedback (SAF) in response to climate change is a process that can amplify the climate warming response to increases in anthropogenic atmospheric CO2 concentrations from the 20th to the 21st Century. Warmer surface air temperature may induce snowmelt and expose darker underlying surfaces which absorb more incoming solar radiation and further increase the ambient temperature. Springtime SAF in the fully Coupled Model Intercomparison Project Phase 3 (CMIP3) models is associated with summertime circulation. However, no clear physical mechanism explaining this link has been found. Furthermore, there is a large intermodel spread in the projection of SAF among the CMIP3 models which is primarily controlled through the parameterization of snow albedo in each model. Limited work was conducted on assessing the response of SAF to that of an isolated controlling parameter such as snow albedo. Here, the uncoupled Geophysical Fluid Dynamics Laboratory Atmospheric Model 2.1 (AM2.1) was used to diagnose SAF in the CMIP3 models by conducting a set of sensitivity experiments with perturbed snow albedo. This was performed to remove indirect external climate factors that may influence SAF and to use the simplified uncoupled model to understand the behaviours exhibited by the complex coupled models. Snow cover extent (SNC) and snow metamorphosis as a function of temperature (TEM) that influences SAF, as well as the knock-on effects of SAF on soil moisture, snow mass, snow melt and circulation were analyzed using both the CMIP3 and AM2.1 models. In addition, it was hypothesized that summertime Land Sea Contrast response to climate change (dLSC) is a physical mechanism that induces summertime circulation patterns in relation to springtime SAF. It is found that the AM2.1 can similarly reproduce SNC and TEM as well as the spread in SAF exhibited in the CMIP3 models. However, no robust link can be determined between SAF and its knock-on effects. Furthermore, the correlation between SAF and dLSC is not significant and thus dLSC is not a physical mechanism that influences the summertime circulation patterns in response to climate change. It is the expectation that these research results can provide an in-depth understanding of the role of SAF among fully coupled GCMs through tests performed by the uncoupled simulation.

No description available.

Mountain precipitation, as a major component of global ecology and culture, requires diverse observation-based distribution studies to improve process characterisation and so enhance environmental management and understanding. Analysis of data from an array of precipitation gauges within the nationally important, and internationally extreme, mountainous Lake Pukaki catchment in New Zealand has been undertaken in an effort to provide such a study, while also improving local hydrological understanding. An objective observation based undercatch-corrected 1971-2000 average annual precipitation distribution has been prepared for the mountainous Lake Pukaki catchment, New Zealand. Precipitation records from 58 gauges at 51 sites, augmented with 10 new gauges, were used in preparation of the distribution. The assessed undercatch correction of 17 % across the catchment indicates that mountain hydrological investigations in New Zealand that use precipitation data and yet do not consider undercatch will be in considerable error. The average annual distribution confirms the existence of high precipitation magnitudes and horizontal gradients in the catchment in comparison with other mountain regions around the world. The high magnitude is unusual when its position in the lee of the principal orographic divide is considered indicating rare precipitation distribution processes occur in the region. Consideration of river flows, glacial change and evaporation led to a confirmation of the gauge derived average catchment precipitation. Precipitation to wind direction relationships identified the predominant westerly wind to be the primary precipitation generating direction with large magnitude events biased towards the northerly direction. All directions from the eastern side of the mountain divide had the lowest frequency and daily precipitation magnitude. Derivation of wind-classed precipitation distributions identified a distinctive south east to north west precipitation gradient for all wind directions, most severe for the north west direction and least severe for the easterly direction. Precipitation extent was greatest for the northerly direction and least for the south south westerly. The wind-classed distributions enable the estimation of daily precipitation likelihood and magnitude at any location in the catchment based on knowledge of the synoptic wind flow direction and precipitation at just one reference site. Improved river flow and lake inflow estimates resulted from the use of wind classed daily precipitation estimates validating the quality of the wind classed distributions. From 1939 to 2000 there has been no statistically significant trend in precipitation magnitudes, frequencies, or extremes in the catchment. At Aoraki/Mt Cook village, in the upper catchment, there have been significant increases in magnitude, frequency and extremes associated with the phase change of the Interdecadal Pacific Oscillation (IPO) in 1978. This change can be explained by the increase in strength of westerly winds for the different IPO phases but not by a change in frequency of different wind directions. In the lower catchment the IPO relationship is of an opposite sense to that observed in the upper catchment, indicating that the areas operate under two different climate regimes with different precipitation controls. The significant relationship to the IPO phase indicates that it is more important than climate warming in terms of future precipitation distribution in the Lake Pukaki catchment, and by extension the Southern Alps. The distributions prepared provide a valuable tool for operational and academic hydrological applications in the region. In addition, they provide a valuable characterisation of the precipitation in a Southern Hemisphere mid-latitude lee to predominant westerlies glacierized mountain catchment. From this standpoint they highlight the contrast to Northern Hemisphere mountain precipitation distributions commonly used in model validation studies, thereby providing an extension of locations with which to refine orographic precipitation process understanding.

Thesis (M.S. - Watershed Management)--University of Arizona. / Includes bibliographical references.

Thesis (M.S. - Watershed Management)--University of Arizona. / Includes bibliographical references.

Thesis (Ph. D. - Watershed Management)--University of Arizona. / Includes bibliographical references.

Thesis (M.S.)--University of Nevada, Reno, 2007. / "August, 2007." Includes bibliographical references (leaves 143-147). Online version available on the World Wide Web.

Thesis (M. Sc.)--University of Canterbury, 2008. / Typescript (photocopy). Includes bibliographical references (leaves 45-52). Also available via the World Wide Web.

Thesis (M.S. in biological and agricultural engineering)--Washington State University, December 2008. / Title from PDF title page (viewed on Apr. 10, 2009). "Department of Biological Systems Engineering." Includes bibliographical references (p. 16-21).