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Process-level model evaluation: a snow and heat transfer metric

This work defines a metric for evaluation of a specific model snow process, namely, heat transfer through snow into soil. Heat transfer through snow regulates the difference in air temperature versus soil temperature. Accurate representation of the snow heat transfer process is critically important for accurate representation of the current and future state of permafrost. Utilizing this metric, we can clearly identify models that can and cannot reasonably represent snow heat transfer.

Divergence of seafloor elevation and sea level rise in coral reef ecosystems

We report regional-scale erosion of coral reef ecosystems in the Atlantic, Caribbean, and Pacific oceans determined by measuring changes in seafloor elevation. The magnitude of seafloor elevation loss has increased local sea level rise, causing water depths not predicted until near 2100, placing coastal communities at elevated and accelerating risk from hazards such as waves, storms, and tsunamis. Our results have broad implications for coastal resource and safety management.

Accounting for the climate–carbon feedback in emission metrics

Emission metrics such as GWP or GTP are used to put non-CO₂species on aCO₂-equivalentscale. In the fifth IPCC report the metrics are inconsistent, as the climate–carbon feedback is included only for CO₂but not for non-CO₂species. Here, we simulate a new impulse response function for the feedback, and we use it to correct the metrics. For instance, 1 g of CH₄is equivalent to 31 g of CO₂(instead of 28 g) following the corrected GWP100 metric. It is 34 g if other factors are also updated.

Constraining N2O emissions since 1940 using firn air isotope measurements in both hemispheres

Nitrous oxide is the third most important anthropogenic greenhouse gas with an increasing mole fraction. To understand its natural and anthropogenic sources we employ isotope measurements. Results show that while the N₂O mole fraction increases, its heavy isotope content decreases. The isotopic changes observed underline the dominance of agricultural emissions especially at the early part of the record, whereas in the later decades the contribution from other anthropogenic sources increases.

Characterization of the long-term radiosonde temperature biases in the upper troposphere and lower stratosphere using COSMIC and Metop-A/GRAS data from 2006 to 2014

Radiosonde observations (RAOBs) have provided the only long-term global in situ temperature measurements since 1958. In this study, we use Global Positioning System (GPS) radio occultation (RO) temperature data from 2006 to 2014 to characterize the inter-seasonal and interannual variability of temperature biases in the lower stratosphere. Results from this study also demonstrate the feasibility to use RO data to correct RAOB temperature biases for different sensor types.

Drought and flood in the Anthropocene: feedback mechanisms in reservoir operation

There is still little understanding about the dynamics emerging from human–water interactions. As a result, policies and measures to reduce the impacts of floods and droughts often lead to unintended consequences. This paper proposes a research agenda to improve our understanding of human–water interactions, and presents an initial attempt to model the reciprocal effects between water management, droughts, and floods.

Surge dynamics and lake outbursts of Kyagar Glacier, Karakoram

Recent surging of Kyagar Glacier (Karakoram) caused a hazardous ice-dammed lake to form and burst in 2015 and 2016. We use remotely sensed glacier surface velocities and surface elevation to observe dramatic changes in speed and mass distribution during the surge. The surge was hydrologically controlled with rapid summer onset and dramatic termination following lake outburst. Since the surge, the potential outburst hazard has remained high, and continued remote monitoring is crucial.

Manganese in the west Atlantic Ocean in the context of the first global ocean circulation model of manganese

We ran a global ocean model to understand manganese (Mn), a biologically essential element. Our model shows that (i) in the deep ocean, dissolved [Mn] is mostly homogeneous ca. 0.10–0.15 nM. The model reproduces this with a threshold on MnO₂ of 25 pM, suggesting a minimal particle concentration is needed before aggregation and removal become efficient. (ii) The observed distinct hydrothermal signals are produced by assuming both a strong source and a strong removal of Mn near hydrothermal vents.

The European 2015 drought from a climatological perspective

This paper analyses the European summer drought of 2015 from a climatological perspective, including its origin and spatial and temporal development, and how it compares with the 2003 event. It discusses the main contributing factors controlling the occurrence and persistence of the event: temperature and precipitation anomalies, blocking episodes and sea surface temperatures. The results represent the outcome of a collaborative initiative of members of UNESCO’s FRIEND-Water program.

Structural uncertainty in air mass factor calculation for NO2 and HCHO satellite retrievals

Choices and assumptions made to represent the state of the atmosphere introduce an uncertainty of 42 % in the air mass factor calculation in trace gas satellite retrievals in polluted regions. The AMF strongly depends on the choice of a priori trace gas profile, surface albedo data set and the correction method to account for clouds and aerosols. We call for well-designed validation exercises focusing on situations when AMF structural uncertainty has the highest impact on satellite retrievals.

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