During austral summer (DJF) 2017/18, the New Zealand region experienced an unprecedented coupled ocean-atmosphere heatwave, covering area of 4 million km2. Regional average air temperature anomalies over land were +2.2 °C, and sea surface reached +3.7 °C in eastern Tasman Sea. This paper discusses event, including atmospheric oceanic drivers, role anthropogenic warming, terrestrial marine impacts. The heatwave was associated with very low wind speeds, reducing upper ocean mixing allowing...

Abstract Meteorological and glaciological measurements obtained at 5873 m a.s.l. on Kersten Glacier, a slope glacier the southern flanks of Kilimanjaro, are used to run physically‐based mass balance model for period February 2005 January 2006. This shows that net shortwave radiation is most variable energy flux glacier‐atmosphere interface, governed by surface albedo. The majority loss (∼65%) due sublimation (direct conversion snow/ice water vapour), with melting secondary importance....

Abstract Slope glaciers on Kilimanjaro (ca. 5000–6000 m MSL) reached their most recent maximum extent in the late nineteenth century (L19) and have receded since then. This study quantifies climate signal behind recession of Kersten Glacier, which generates information change tropical midtroposphere between L19 present. Multiyear meteorological measurements at 5873 MSL serve to force verify a spatially distributed model glacier’s mass balance (the direct link glacier behavior atmospheric...

Abstract Multi-annual records of glacier surface meteorology and energy balance are necessary to resolve glacier–climate interactions but remain sparse, especially in the Southern Hemisphere. To address this, we present a record from ablation zone Brewster Glacier, New Zealand, between October 2010 September 2012. The mean air temperature was 1.2°C at 1760 m a.s.l., with only moderate difference warmest coldest months (∼8°C). Long-term annual precipitation estimated exceed 6000 mm −1 ,...

Abstract The turbulent sensible and latent heat fluxes are important components of the surface energy balance over glaciers in Southern Alps New Zealand, contributing half available for ablation during large melt events. To calculate these terms confidently glacier mass-balance models it is essential to use appropriate parameterizations roughness atmospheric stability. Eddy covariance measurements at Brewster Glacier were obtained an ice help facilitate assessment calculation fluxes. length...

Abstract The occurrence of extreme precipitation events in New Zealand regularly results devastating impacts to the local society and environment. An automated atmospheric river (AR) detection technique (ARDT) is applied construct a climatology (1979–2019) midlatitude moisture fluxes conducive precipitation. A distinct seasonality exists AR aligning with seasonal variations jet streams. formation Southern Hemisphere winter split enables persist through all seasons northern regions Zealand,...

Recent and long term variations in ice extent on Kilimanjaro are investigated the context of 20th century climate change East Africa. Quickbird satellite data show that areal glaciers is 2.51 km 2 February 2003. To assess glacier retreat two systems identified: (1) plateau (≥5700 m) (2) slope (<5700 m). Vertical wall governs irreversible, changes have not altered their continuous demise. Rapid at beginning implies a strong departure from steady state conditions during this time. This...

Abstract Eddy covariance data collected over a horizontal surface on the largest ice body Kilimanjaro, Tanzania, 26–29 July 2005 were used to assess uncertainty of calculating sublimation with energy balance (SEB) model. Data required for input SEB model obtained from an existing automatic weather station. Surface temperatures that solved iteratively by compute emitted longwave radiation, turbulent heat fluxes using aerodynamic bulk method and subsurface flux. Roughness lengths momentum...

Abstract Broadband radiation schemes (parameterizations) are commonly used tools in glacier mass-balance modelling, but their performance at high altitude the tropics has not been evaluated detail. Here we take advantage of a high-quality 2 year record global ( G ) and incoming longwave L ↓) measured on Kersten Glacier, Kilimanjaro, East Africa, 5873 m a.s.l., to optimize parameterizations ↓. We show that two terms can be related by an effective cloud-cover fraction n eff , so or ↓ modelled...

Abstract. A new and consistent time series of glacier retreat on Kilimanjaro over the last century has been established by re-interpreting two historical maps processing nine satellite images, which removes uncertainty about location extent past present ice bodies. Three-dimensional visualization techniques were used in conjunction with aerial ground-based photography to facilitate interpretation boundaries eight epochs between 1912 2011. The glaciers have retreated from their former 11.40...

Abstract The role of atmospheric rivers (ARs) for extreme ablation and snowfall is examined at Brewster Glacier in the Southern Alps, site longest glacier mass balance record New Zealand. By global standards, Zealand strongly impacted by ARs. Here it shown first time (in Zealand) that ARs contribute to thus overall. Vertically integrated water vapor transport (IVT) exceeds 1,600 (800) kg·m −1 ·s largest (snowfall) events, marking these as very strong proximity freezing threshold during...

Abstract An end of summer snowline (EOSS) photographic dataset for Aotearoa New Zealand contains over four decades equilibrium line altitude (ELA) observations more than 50 index glaciers. This provides an opportunity to create a climatological ELA reference series that has several applications. Our work screened out EOSS sites had low temporal coverage and also removed limited when the official survey did not take place. Snowline data from 41 glaciers in were retained included normalised...

Marine heatwaves (MHWs) are extreme ocean temperature events that can have wide-ranging and pervasive effects on marine species ecosystems. However, studies of MHW characteristics drivers primarily focus open-ocean environments, rather than the nearshore coastal (<10 km from coast, <50 m depth). This is despite waters sustaining significant commercial, recreational, customary fisheries aquaculture activities highly susceptible to impacts MHWs. The two longest (>50 year)...

Abstract Micrometeorological data collected from an automatic weather station over a total of 85 days during the summer 2007/2008 in ablation zone (1770 m a.s.l.) Brewster Glacier, New Zealand, were used to determine main atmospheric processes controlling magnitude and variability daily ablation. During field season, was measured modelled using energy balance model (EBM) degree‐day (DDM). Calculation glacier EBM revealed that net radiation provided largest source for (52%). The turbulent...

Abstract The occurrence of maximum precipitation amounts ( P max ) on tropical high mountains at mid elevations is well documented (spatial variability), but little known about the temporal variability in different elevation zones. present study targets this issue by combining various types observations and around Kilimanjaro (East Africa, 5895 m a.s.l.) with mesoscale atmospheric modelling. In observations, vertical moisture profiles air masses approaching mountain clearly differ during...

Abstract. In New Zealand, direct measurements of mass balance are sparse due to the inaccessibility glaciers in Southern Alps and logistical difficulties associated with maintaining a record. order explore benefit remotely sensed imaging monitor Alps, this research assesses relationship between glacier surface albedo derived from Moderate Resolution Imaging Spectroradiometer (MODIS) observations using glaciological method on Brewster Glacier over 2005–2013 period. We confirm that minimum...

ABSTRACT Recognising the scarcity of glacier mass-balance data in Southern Hemisphere, a measurement programme was started at Brewster Glacier Alps New Zealand 2004. Evolution regime over 11 years recorded means there are differences spatial density obtained. To ensure temporal integrity dataset new geostatistical approach is developed to calculate mass balance. Spatial co-variance between elevation and snow depth allows digital model be used co-kriging develop index ( SDI ). By capturing...

Abstract. As climate change is projected to alter both temperature and precipitation, snow-controlled mid-latitude catchments are expected experience substantial shifts in their seasonal regime, which will have direct implications for water management. In order provide authoritative projections of impacts, the uncertainty inherent all components modelling chain needs be accounted for. This study assesses potential impacts on hydro-climate a headwater sub-catchment New Zealand's largest...

Abstract. The effect of clouds on glacier surface energy balance (SEB) has received increased attention in the last decade, but how interact with other meteorological forcing to influence mass (SMB) is not as well understood. This paper resolves SEB and SMB at a site ablation zone Brewster Glacier over 22-month period, using high-quality radiation data carefully evaluate terms define clear-sky overcast conditions. A fundamental change cloudy conditions was driven by effective sky emissivity...

ABSTRACT Clouds are important features of many high‐altitude and glaciated areas, yet detecting their presence specifying effects on incoming shortwave ( SW ↓), longwave LW ↓) net all‐wave radiation Rnet ) remains challenging in these environments. These limitations hamper efforts to understand atmospheric controls glacier surface mass balance SMB the Southern Alps New Zealand, as both cloud airmass forcing accompanies key synoptic . Multi‐year datasets four‐component broadband from two...

Insufficient availability of weather stations recording air temperature is a common problem in many alpine regions. The low station density combined with the high variability means that interpolated fields based on simple or more complex interpolation techniques are unlikely to be representative real patterns temperature. In this study, novel method was developed tackle problem, following initial investigation lapse rate study domain: Clutha catchment, New Zealand. Owing series complexities...