Allgemeine Meteorologie

Liljequist, Gösta H.

doi:10.1007/978-3-322-90603-8

Cited by 19 publications

(7 citation statements)

References 0 publications

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“…(2) The albedo on ice walls of the outer margin is increased to 0.75 in the east-north-east sector (between 45°and 90°; clockwise) and the southwest sector (between 200°and 250°; clockwise) in order to account for the advection of relatively moist air, as reflected in the spatial distribution of annual precipitation with two maxima in these aspects of the mountain [Coutts, 1969]. Advection of moist air leads to formation of hoar frost on objects facing the flow of the moist air mass, a typical and well-known process in mountain meteorology [e.g., Liljequist and Cehak, 1994;Whiteman, 2000], and one we observed on Kibo. In the combined model, the higher albedo not only expresses increased reflectivity of solar radiation on the affected ice walls but again parameterizes other factors, e.g., changed small-scale cloud conditions in this case.…”

Section: Resultsmentioning

confidence: 99%

Solar‐radiation‐maintained glacier recession on Kilimanjaro drawn from combined ice‐radiation geometry modeling

2003

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In the context of investigating modern glacier recession on Kilimanjaro, which began around 1880, this study addresses the glacier regime of the vertical ice walls that typically form the margins of Kilimanjaro's summit glaciers. These walls have suffered a continuous lateral retreat during the twentieth century. To evaluate the role of solar radiation in maintaining glacier recession on Kilimanjaro, a radiation model is applied to an idealized representation of the 1880‐ice cap. The combined process‐based model calculates the spatial extent and geometry of the ice cap for various points in time after 1880. Support for input data and fundamental assumptions are provided by an automatic weather station that has operated on the summit's Northern Icefield since February 2000. Even in a simple climatic scenario only forced with an annual cycle of clouds, the basic evolution in spatial distribution of ice bodies on the summit is modeled well. The Northern and Southern Icefields form in characteristic east‐west orientation, which verifies the basic idea behind the model. Forcing the model with further climate‐related phenomena improves the results. It then additionally reproduces the Eastern Icefield, the third big ice entity on the summit. This study qualitatively demonstrates that solar radiation is the main climatic parameter maintaining modern glacier recession on Kilimanjaro summit, but also suggests that retreat on the inner ice cap margin might have been supported by a secondary energy source. The need for additional field measurements is emphasized in order to better understand the complex processes of glacier‐climate interaction on Kilimanjaro.

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Section: Resultsmentioning

confidence: 99%

Solar‐radiation‐maintained glacier recession on Kilimanjaro drawn from combined ice‐radiation geometry modeling

2003

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“…If the input to the reservoir j , given by precipitation minus evaporation, is a random series, which is assumed to be fulfilled for Δ t = 1 month, then it has been shown [ Klemeš , 1978] that Q j is an AR(1) process with autocorrelation a j = l/( k j + 1). In a river network, owing to the spatial variations of rainfall [ Liljequist and Cehak , 1984; Shah et al , 1996] and storage properties (soil), the runoff at a point on the river is not from a single reservoir but rather a cascade [ Klemeš , 1974] of reservoirs, one feeding the next. For example, runoff at point 3 in Figure 1 is (for Δ t large against the flow time) given by the aggregated runoff contributions from reservoirs above that point, Q (3) = ∑ j =1,…, m Q j .…”

Section: Hypothesismentioning

confidence: 99%

Long memory of rivers from spatial aggregation

Mudelsee

2007

Water Resources Research

117

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[1] Long memory is a hydrological property that can lead to prolonged droughts or the temporal clustering of extreme floods in a river. Analyses of 28 long (up to 145 years), continuous instrumental runoff series from six European, American, and African rivers reveal that this effect increases downstream. Simulations reproduce the increase qualitatively and show that a river network aggregates short-memory precipitation and converts it into long-memory runoff. In view of projected changes in climate and the hydrological cycle, these findings show that decadal-scale variations in drought or flood risk can be predicted for individual rivers, with higher predictability downstream. Spatial aggregation may also explain the emergence of long memory in other networks, such as the brain or those formed by computers.

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“…Rigi. Observations of the specific humidity and the pseudoequivalent potential temperature, O e , which are good indicators of air mass identity (Liljequist (1974), Haltiner and Martin (1957)), showed that no major air mass change occurred between the pre-cloud and in-cloud sampling periods. A small change in air mass was observed during the pre-cloud sampling period.…”

Section: Aerosol and Gas Scavenging: A Case Studymentioning

confidence: 99%

In-cloud scavenging of gases and aerosols at a mountain site in Central Switzerland

et al. 1992

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An in-cloud scavenging case study of the major ions (NH4+, 5042-and NO3-) determining the cloudwater composition at a mountain site (1620 m.a.s.i.) is presented. A comparison between in-cloud measurements of the cloudwater composition, liquid water content, gas concentrations and aerosol concentrations and pre-cloud gas and aerosol concentrations yields the following results. Cloudwater concentrations resulted from scavenging of about half of the available NH3, aerosol NH4+, aerosol NO3-, and aerosol SO42-. Approximately a third of the SO 2 was scavenged by the cloudwater and oxidized to SO42-. Cloud acidity during the first two hours of cloud interception (pH 3.24) was determined mostly by the scavenged gases (NH 3, SO 2, and HNO3); aerosol contributions to the acidity were found to be small. Observations of gas and aerosol concentrations at three elevations prior to several winter precipitation events indicated that NH 3 concentrations are typically half (12 -80 %) of the total (gas and aerosol) N (-III) concentrations. HNO 3 typically is present at much lower concentrations (1 -55 %) than aerosol NO3-. Concentrations of SO 2 are a substantial component of total sulfur, with concentrations averaging 60 % (14 -76 %) of the total S (IV and VI).

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Allgemeine Meteorologie

Cited by 19 publications

References 0 publications

Solar‐radiation‐maintained glacier recession on Kilimanjaro drawn from combined ice‐radiation geometry modeling

Solar‐radiation‐maintained glacier recession on Kilimanjaro drawn from combined ice‐radiation geometry modeling

Long memory of rivers from spatial aggregation

In-cloud scavenging of gases and aerosols at a mountain site in Central Switzerland

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