English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

. Elevation gradients of meteorological variables inmountains are of interest to a number of scientific disciplines and oftenrequired as parameters in modeling frameworks. Measurements of suchgradients on glaciers, however, are particularly scarce and strongly skewedtowards the midlatitudes and valley glaciers. This article adds a tropicalperspective and presents 4 years of overlapping measurements at 5603and 5873 m on Kersten Glacier, Kilimanjaro (East Africa), between 2009 and2013. Mean gradients in near-surface air temperature (T), water vaporpressure (VP), and snow accumulation (ACC) per 100 m elevation are −0.75 ∘C, −0.16 hPa, and -114±16 mm w.e. yr−1,respectively. An intriguing feature is a strong diurnal cycle of the T and VPgradients, which are (depending on season) 2–4 times larger between earlyand late morning than in the hours of weak gradients. The ACC decrease withelevation, furthermore, is mostly the result of a lower recorded frequencyof ACC events at the upper measurement site and not due to contrastingamounts at the two altitudes during events. A novel facet of our study is thelinking of measured on-glacier gradients to a high-resolution atmosphericmodeling data set, which reveals the importance of the mesoscale atmosphericcirculation. A thermally direct circulation is established over the mountainin response to diabatic surface heating or cooling with upslope flow during theday and downslope flow in the night. This persistent circulationcommunicates heat and moisture changes in the lowlands to the higherelevations during morning and early afternoon, which is evident in theadvection patterns of potential temperature and VP, and shapes thetime variability in gradients as recorded by our weather stations on theglacier. A few local processes seem to matter as well (glacier sublimation,turbulent heat fluxes), yet they show a secondary influence only duringlimited time windows. Atmospheric model data also demonstrate that decliningmoist entropy and water vapor fluxes in the summit zone favor formation ofthe negative ACC gradient. The results extend the empirical basis ofelevation gradients in high mountains, in particular over glaciersurfaces, by the unusual case of a slope glacier on an equatorial,free-standing massif. Our measurement–model link, moreover, demonstrates anapproach for future studies to put observations of elevation gradients moresystematically in a multiscale process context.

Mesoscale atmospheric circulation controls of local meteorological elevation gradients on Kersten Glacier near Kilimanjaro summit