Subglacial hydrology directly impacts glacier motion, but few studies have investigated the connections between ice speed and water input on regional scales. Here, we analyze the correlation of glacier surface speed and runoff for 77 glaciers ≥3 km2 (~3070 km2) on the Kenai Peninsula, Alaska, within and between seasons from 2015-2019. Most correlations between monthly/seasonal mean ice speed and cumulative runoff in preceding months/multi-month periods are significant (p<0.05), while correlations for the same months or seasons are generally insignificant or weak indicating seasonally delayed responses of ice speed to runoff. In almost all cases lower-than-average monthly/seasonal ice speeds are associated with higher-than-average runoff in preceding months or multi-month periods. Overall, our results show that runoff can influence ice speed with considerable (multi-month) delays.

Tibetan Plateau (TP) has aroused widely scientific concerns in recent decades owning to its important effects on regional climatic and cryospheric changes, hydrological cycle, and environments. However, our understandings on the chemical and optical properties of aerosols are still limited at those regions. In this study, regional difference of aerosol light absorption properties were explored at three remote TP sites, including Qomolangma Station (QOMS) in the southern TP, Nam Co Station (NamCo) in the central TP, and Waliguan Observatory in the northeastern TP. Although aerosol mass concentration at QOMS was less than half of that at Waliguan, the light absorption coefficient at QOMS was nearly 5 time higher than that at Waliguan, mainly as a result of the high contributions of light-absorbing carbonaceous aerosols in the southern TP from the long-range transported biomass burning emissions of South Asia. An improved method was used to derive the near-realistic absorption Ångström exponent for pure black carbon (BC) particles. BC dominated the light absorption at all wavelengths, whereas brown carbon (BrC) contributed more than 30% of the light absorption at 370 nm at QOMS and ~ 20% at Waliguan and NamCo. The major contributor to BrC light absorption at QOMS was the biomass burning related organic aerosol. Radiative transfer simulations also showed the highest atmospheric radiative forcings at QOMS among the three campaigns. The significant regional differences of aerosol light absorption properties in the TP might be related tightly with the different aerosol sources and chemical processes.

Understanding, predicting, and responding to a rapidly changing Arctic requires sustained observations that capture variability and transformative change of the Arctic systems with all its major components. A key challenge for researchers, Arctic communities, and others tasked with effective responses to such change is to achieve structured coordination of numerous individual observing activities and networks. These have different regional and thematic foci. Many are driven from the bottom-up by research interests, while others are mission-oriented operational networks. The Arctic Observing Summit (AOS) is an effort that seeks to help coordinate such disparate activities and support efforts such as the Sustaining Arctic Observing Networks (SAON) initiative. We report on progress as part of an AOS 2018 working group focused on implementation and optimization of sustained observations. Drawing on the Framework on Ocean Observations, our group identified effective approaches and barriers to integration of different observation requirements and activities/platforms into a coherent observing framework. Case studies for benthic communities, sea ice prediction, and permafrost highlighted the importance of allowing for independently driven activities to coalesce into a uniform framework. This in turn requires clearly defined requirements that ideally serve multiple societal benefits. Such clear definitions also aid private-public partnerships and the development of new observing system business models. Prerequisite to better coordination is a comprehensive, international assessment that describes the current set of systems, community-based networks, sensors, networks, and surveys that are used to observe the Arctic today. Pieces of such an endeavor are starting to emerge, and SAON may serve as a home for integrating and building upon these pieces. Essential to this goal is the development of a knowledge map that collates and connects observing resources to societal benefits, helps identify and prioritize essential variables, data management needs, and critical products and services. The AOS 2018 calls for the launch of an optimization and implementation team of experts that would conduct such an effort under the auspices of SAON. We explore different elements of such a team’s portfolio of tasks.

Glaciers have proven to be a particularly sensitive indicator of climate change, and the impact of glacier melting on downstream water supplies is becoming increasingly important as the world’s population expands and global warming continues. Data scarcity in mountainous catchments, on the other hand, has been a substantial impediment to hydrological process simulation. Therefore, an integrated glacier hydrological process module was introduced for the Soil and Water Assessment Tool Plus model (SWAT+), in which an enhanced temperature-index glacier melt algorithm considering solar radiation was employed to maintain model clarity and favorable performance in this study. Furthermore, SWATplusR was introduced for sensitivity analysis using the Sobol approach, and Integrated Parameter Estimation and Uncertainty Analysis Tool Plus (IPEAT+) was coupled with this enhanced model (SWAT+Glacier) to perform calibration and validation in the Upper Yarkant River (UYR) basin. The result indicated that (i) including glacial-hydrological processes considerably improved simulation precision, with an NSE promotion of 2.6 times and R 2 of 1.7 times greater than the original model; (ii) it is an efficient and feasible way to simulate glacial-hydrological processes with SWAT+Glacier and calibrate it using observed discharge data in data-scarce and glacier melt dominated catchments; and (iii) we discovered that glacier runoff is intensively distributed throughout the summer season, accounts for about 78.5% of the annual glacier runoff, and glacier meltwater provides approximately 52.5% (4.4×10 9m 3) of total runoff in the study area.