bluuebunny/crossref_metadata_2025 huggingface dataset:
The measurement method of global warming potential based on the infrared absorption spectra and rate constant with the hydroxyl radical
Authors: Lee Bong Jae , Park Sang Hoon
Published: February 2023

Global warming potential (GWP) has been used as an indicator to compare with the greenhouse effect of different gases. Utilized gases, especially, in semiconductor and display manufacturing processes are greenhouse gas with high GWP values. Accordingly, countries and relevant companies are trying to synthesize the alternative gases expressed with low GWP values along with a lot of interest. But GWP values of these hasn’t been presented at any other thesis. Hence it is inevitable to measure GWP of newly gases to compare with climate effect between conventionally used gases and newly gases.
Therefore, this study proposes a measurement method of GWP based on various papers using instrument such as fourier-transform infrared spectroscopy (FT-IR), time of flight- mass spectroscopy (TOF-MS) equipped with the proton transfer reaction (PTR) as a detector and so on. Equation is used in IPCC fifth assessment report to calculate the GWP.

Calculating absorbed cross-sectional area by measuring infrared absorption spectra using FT-IR and by applying to lambert-beer’s law
Applying original pinnock curve (Pinnock et al., 1995) and final pinnock curve using the line-by-line model (Myhre et al., 2006) to calculate the radiative forcing by integrating the calculated absorbed cross-sectional area from first step
Measuring the rate constant when they react with the hydroxyl radical using PTR-MS equipped with the PTR and calculating the atmospheric lifetime based on the constant and tropospheric lifetime of CH3CCl3 as a reference material proposed by WMO (2014)
In accordance with the IPCC fifth assessment report (2013), calculating GWP using the radiative forcing and atmospheric lifetime induced by second and third step, respectively

Acknowledgment:
This work was supported by Korea Environment Industry & Technology Institute (KEITI) through Climate Change R&D Project for New Climate Regime Program, funded by Korea Ministry of Environment (MOE) ( 2022003560008 ).
Minimum rest time for outdoor workers exposed to summer heat stress in South Korea
Authors: Lee Seung-Wook , Park Young-San , Choi Gwangyong
Published: February 2023

Continuous work in high-temperature environments can lead to occupational injuries, illnesses, and even deaths. Thus, mandatory rest time for appropriate heat management programs must be provided for the safety of workers. In this study, we figured out the minimum rest time for the heat safety of outdoor workers in South Korea. To quantitatively calculate the minimum rest time, the wet-bulb globe temperature (WBGT) index estimated by 27 synoptic weather stations in South Korea and the national work-rest regimens were used. We assumed that the minimum rest time is the same as the rest time of the work-rest regimens recommended by the WBGT. To examine the intra-seasonal evolution patterns of the minimum rest time, summer seasons are divided into several sub-periods. The average of the hourly WBGT values during summer months from June to August (2009–2018) shows that outdoor workers with a moderate workload (200–350 kcal/h) are exposed to heat stress during approximately 30% of their daytime working hours (06:00–18:00). In the whole summer period, the minimum rest time required for each hour was about 5 minutes for moderate work. But in the mid-summer period from late July to early August, the daily minimum rest time for moderate workload noticeably increases to 20 minutes of mid-day (11:00–15:00). Regionally, no significant increase in rest time was found in areas with high urbanization rates.
Application of satellite data in air quality management: Lessons learned in India
Authors: Dey Sagnik , Kumar Alok , Katoch Varun , Imam Fahad , Sarkar Debajit , Sharma Kirtika
Published: February 2023

Exposure to ambient PM2.5 is the leading environmental health risk in India. An efficient air quality management plan requires a consistent and long-term database at high spatial and temporal scale. We have developed a satellite-based PM2.5 data for India by filling the gaps in satellite AOD to complement the paucity in ground monitoring. The average population-weighted exposure during 2017-2021 was estimated as 52.5 μg/m3, 18.1% lower than the estimates without adjusting for the sampling gaps. The annually averaged mortality burden attributable to ambient PM2.5 exposure during this period was estimated to be 0.45 million (95% UI: 0.36-0.55), 0.27 million (95% UI: 0.22-0.33) and 0.24 million (95% UI: 0.19-0.28) for low, medium and high sociodemographic index states, respectively. If the sampling gaps in satellite AOD is not filled, the health burden in India would be overestimated by 0.1 million (95% UI: 0.07-0.13).  We demonstrated  use of this satellite data in various air quality management practices. We have delineated 9 to 11 major seasonal air sheds in India using k-means clustering. We have found that the number of days daily PM2.5 exceeding the national standard have decreased during 2017 to 2021 in all air sheds. We have identified the potential sites for future expansion of the ground network under the National Clean Air Program. We examined the representativeness of the existing ground monitors in the non-attainment cities. These lessons learned in India could be valuable for other developing countries with limited or no ground monitoring.   
239Pu concentrations reconstructed using three Antarctic ice cores during 1940-1980 CE
Authors: Shin Jinhwa , Lee Seungmi , Hwang Heejin , Han Yeongcheol
Published: February 2023

The radioisotope Plutonium-239 (239Pu) was artificially produced to the environment by atmospheric nuclear weapons tests during 1940-1980 CE. Although 239Pu is the most abundant one among isotopes of Plutonium, it exists in Antarctic ice cores at very low level of sub-fg g-1. Accordingly, the historical records of 239Pu fallout in Antarctica have not been well reconstructed. In this study, we determined 239Pu concentrations in three coastal ice cores in Northern Victoria Land, East Antarctica. Discrete samples with sub-annual resolution for the period 1940-1980 CE were analyzed using inductively coupled plasma sector field mass spectrometry (ICP-SFMS) without purification or preconcentration. The fallout records of the three sites showed consistent fluctuations and also agreed with the records recovered from inland dome sites (Hwang et al., 2019), which allowed for constructing an Antarctic composite record. The composite 239Pu record was characterized by two major peaks in 1954 and 1964 CE and a minor peak in 1970s, which could be ascribed to the major atmospheric nuclear test events. Those synchronous 239Pu peaks are expected to serve as useful age markers in other regions in Antarctica, which can improve depth-age relationships of ice core records and enable more precise interregional comparisons. In addition, it will contribute to a more precise comparison of ice core records with reanalysis data back to the 1950s (e.g., ERA5).
Salt rhythmite formation and organic matter enrichment in the Qianjiang Formation, Jianghan Basin, China: Constraints from alternating dry and wet climates
Authors: Taoyuan Ge
Published: February 2023

Jianghan Basin is the largest terrestrial saline lake basin in China, with the largest salinization area in the Paleogene. Research on salt rhythmite formations is crucial for petroleum exploration in salt lake basins. With alternating dry and wet climates, the difference in the organic matter (OM) provenance and enrichment remain controversial. In this study, petrology, element geochemistry, and molecular geochemical analyses were performed for the Qianjiang Formation to determine the depositional environment and provenance of its OM. The response of OM enrichment in the saline lake to the alternating dry and wet climates was reassessed. Three lithofacies associations (LAs) were designated: (1) LA1 was rich in argillaceous dolomite and argillaceous limestone with high total organic carbon (TOC); (2) LA3 was interbedded argillaceous glauberite and argillaceous dolomite with low TOC; (3) LA2 was a mixture of the above minerals with moderate TOC values. LA1 was deposited during desalination with a reducing environment and water stratification. The ∑C21-/∑C22+, C29/C30 hopane and maceral indicate the OM of LA1 derive from algae. Compared with LA1, LA2 was deposited with higher salinity and less algae. LA3 was deposited during intense evaporation, high salinity, and a disturbed environment. The OM sources of LA3 include higher plants and low aquatic organisms. Dry and wet climates control changes in organic enrichment. Hypersalinity is unfavorable to algae but beneficial to preservation. The stratified deep water is conducive to the accumulation of OM. The desalination is a crucial period for organic matter enrichment in the saline lake.
Ice-Inclusion Compounds for Energy Gas Storage
Authors: Cha Minjun
Published: February 2023

Gas hydrates are types of crystalline-inclusion compounds composed by a ‘host’ framework and ‘guest’ molecules. In general, ‘host’ water molecules constitute the hydrogen-bonded host framework, and ‘guest’ molecules, such as methane, ethane, propane, hydrogen, or carbon dioxide, can be encapsulated in the framework structures. Huge amount of gases can be selectively captured in the hydrate structures, and thus; gas hydrates have been received much attention in the energy and environmental fields for gas storage and separation. Here, we introduced the hydrate-forming agents, including cyclic alcohol and amine molecules, for energy gas storage. The guest inclusion behaviors of binary clathrate hydrates were examined by spectroscopic tools, 13C solid-state nuclear magnetic resonance (NMR) spectroscopy and powder X-ray diffraction (PXRD) analysis. The storage capacity of methane gas in the binary clathrate hydrates was also examined. The findings, regarding the inclusion behavior of cyclic molecules in hydrate cages, the storage capacity of methane in hydrate structure, and the thermodynamic stability of the binary clathrate hydrates, may provide fundamental information on the complex nature of host–guest inclusion chemistry and lend useful insights with respect to potential gas hydrates applications for gas storage. 
Responses of peatland development and carbon accumulation to climate change over the past 2500 years in the Arxan region, Northeast China
Authors: Xia Yingfan , Yang Zili , Yu Zicheng
Published: February 2023

As one of the soil types, peat is an important soil carbon storage and archive of past environmental changes. Here we used multi-core and multi-proxy records from a peatland near Da’erbin Lake in the Arxan region of Northeast China to reconstruct peatland development and carbon accumulation history and to understand their responses to past climate changes during the last 2500 years. Our macrofossil results show that the peatland was characterized by a sedge-dominated fen from 490 BCE to 1450 CE, changed to a Sphagnum-dominated poor fen or bog with abundant shrubs (mostly Ericaceae) during the period of 1450–1960 CE, and finally became predominated by Sphagnum after 1960 CE. The time-weighted mean apparent carbon accumulation rate (aCAR) from three cores range from 19.5 to 53.0 g C m-2 yr-1 with a mean value of 32.4 g C m-2 yr-1, but increase rapidly to 139.2 g C m-2 yr-1 during last several decades. During the early stage of the past 2500 years, three coring sites that are only 50 m apart were all in the fen phase but they had highly variable peat properties. The fen-bog transition occurred at different times at these sites due to local influences of autogenic process, permafrost dynamics, or fire disturbance. These observations suggest that fens are highly heterogeneous, not only in peat properties but also in ecosystem dynamics. The dramatic increase in aCAR during the late stage of bog phase after 1960 CE cannot be explained entirely by limited decomposition of recently-accumulated peat. Instead, this was likely due to increasing Sphagnum dominance and resultant low decomposition of Sphagnum-derived organic matter, suggesting the important role of vegetation change in controlling carbon accumulation rates. Around the 1990s CE, an increase in allogenic CAR—after removing the age-related long-term autogenic effect—seems to correspond with a period of increase in regional summer precipitation, revealing a sensitive response of ombrotrophic bog ecosystem to climate change at decadal timescale.
On endogenous and exogenous factors controlling the behaviour of the Lusi eruption (Java, Indonesia)
Authors: Miyazawa Masatoshi , Mazzini Adriano , Lupi Matteo
Published: February 2023

The Lusi eruption started on Java Island on the 29th of May 2006, almost two days after a M6.5 earthquake struck Yogyakarta. More than 16 years later, Lusi is still erupting clasts, mud, oil, and surges of thermogenic methane and mantle-derived CO2. Lusi features a geysering behaviour, and its flow rate currently averages 50.000 m3/day with peaking up to 180.000 m3/day during the early phases of the eruption. Previous investigations revealed that at 4.5 km depth, Lusi is connected with the neighbouring volcanic complex that is fueling the eruption site. Observations also show that since 2006, Lusi’s behaviour has been periodically perturbed by seismic events and possibly by neighbouring volcanic eruptions. However, it remains unclear if/how other factors may influence Lusi’s eruptive behaviour. We use a statistical approach comparing flow rate records against a multiparametric database accounting for peak ground velocities and accelerations, tidal phases, Pressure and Temperature atmospheric variations, Geodetic monitoring (subsidence and inflation of the edifice), and faulting. A preliminary investigation of the relationship between daily flow rate and peak ground motion imposed by regional and teleseismic earthquakes shows that large amplitude seismic waves are often associated with increasing the flow rate at Lusi. Results can be fit by a power law. Geodetic monitoring shows a sudden increase in subsidence following major ground accelerations imposed by nearby seismic events and eruptions of neighbouring volcanic systems. Similarly, these events are also consistent with fresh extended fractures around Lusi and/or major breaching and deformations of the tall embankment walls surrounding the eruption site. When considering daily variations and using a higher resolution catalogue accounting for the fluid temperature of Lusi, we find that external factors such as local P/T and tidal events can alter the local temperature of the fluids emitted at the Lusi site.Our results reveal that multiparameter monitoring represents a valuable approach to understanding the dynamics controlling the activity and the evolution of active eruption sites. Results could be useful in identifying potential precursors.
Risk Assessment of Downstream Areas in Case of Earth Dam Failure Using 3D Simulation
Authors: Lee Seulgi , Lee Sungsu
Published: February 2023

Concerns about landslides or dam failures are increasing due to torrential rains, sudden heavy rains, and typhoons caused by global warming. In the 21st century, more than 200 dam and reservoir failures have occurred worldwide, causing enormous damage of human life and property. When a dam or reservoir collapses, a large amount of water and various sizes of earth and rocks are mixed and a debris flow occurs. Debris flows are dangerous because they move quickly and destroy objects in their path. In order to predict the damage caused by these dam and reservoir failures, 3D multiphase flow numerical analysis can be used. This study proposes a downstream risk assessment technique in the event of dam and reservoir failure that predicts downstream damage using a three-dimensional multi-phase flow numerical analysis and evaluates quantitative losses using a building's vulnerability curve against debris flows. This research was supported by Research Program to Solve Urgent Safety Issues of the National Research Foundation of Korea(NRF) funded by the Korean government (Ministry of Science and ICT(MSIT)) (Grant Number : 2021M3E9A1103506)
Simulation setup for atmospheric CH4 concentrations in the ICON-ART Limited Area Mode
Authors: Mamtimin Buhalqem , Rösch Thomas , Roth Franziska , Sunkisala Anusha , Kaiser-Weiss Andrea
Published: February 2023

An experimental setup within ICON (ICOsahedral Non-hydrostatic)-ART (Aerosols and Reactive Trace gases) has been  carried out to simulate the atmospheric CH4 concentration over Europe during the investigation period from 01 May 2018 to 30 June 2018.Modelling CH4 in the Limited Area Mode (Europe, 6.5 x 6.5 km), the model requires as accurate as possible initial and boundary atmospheric conditions as well as spatially highly resolved emissions. Temporal resolved emissions are to be included in the next step. While the intial data denote here the state of the atmosphere (meteorological and CH4 concentration fields) at the start of the model run, the boundary conditions shall denote the data in the lateral boundary zone where the model is forced by the meteorological and CH4 concentration data outside the domain. We have used DWD's operational numerical weather prediction output as meteorological boundary conditions. The Copernicus Atmosphere Monitoring Service (CAMS) provides the necessary initial and boundary CH4 data, which are made applicable  for the ICON-ART before the model run in Limited Area Mode. The regional CH4 emissions for Europe have been  provided by TNO and are processed with the ART module.  Since CAMS uses a vertical coordinate of a hybrid sigma-pressure system, the data had been horizontally and vertically interpolated to the height based SLEVE coordinate system of ICON. The sectorial CH4 emissions for Europe and for Germany were mapped separately to the target ICON grid by preprocessing the corresponding reported methane emissions of various sectors (resulting in 36 distinct methane variables in the model). The 50 largest point emissions from each sector are treated separately, smaller point emissions are treated together with the area emissions.To run a hourly experimental setup for two month the Basic Cycling environment (BACY) tool was used. The fields for meteorological parameters were initialized daily by using the DWD's operational data, while the atmospheric CH4 concentrations are taken from the previous ICON-ART CH4 simulation results (e.g., the 24 h CH4 forecast from the previous day). Then, the merged concentration fields for meterological conditions and atmospheric methane are used as “DWD first guess”, which served for a daily start of the simulation process in the ICON-ART Limited Area Mode. In order to compare the model results and measurements from the Integrated Carbon Observation System (ICOS) stations, the model equivalents have been extracted at the locations of the  ICOS montoring stations  using the “Model Equivalent Calculator”.In this work, the ICON-ART CH4 simulation setup for Limited Area Mode (Europe) was forced by ICON meteorology and CAMS CH4 boundary data and had been started daily by the merged “DWD first guess”. These are shown to be a useful method to simulate the CH4 atmospheric concentrations at the regional scale.
An open-field multifactor experiment to simulate extreme climate events for observation of soils and plants
Authors: Kim Gwang-Jung , Jo Heejae , Cho Min Seok , Noh Nam Jin , Han Seung Hyun , Son Yowhan
Published: February 2023

Extreme climate events, generally defined as inordinately hotter, drier, or wetter compared to the historical period, are showing an increasing trend in terms of their frequency, intensity, and magnitude. They can impair the recovery system of plants, and thus, there is a need to understand their effects on plants. Here, we constructed a temperature and precipitation manipulation system to simulate extreme climate events for plants in the open field in April, 2020. We applied a factorial combination of three temperature levels (control, +3 °C, and +6 °C) and three precipitation levels (control, drought, and heavy rainfall) with six replicates (i.e., 54 plots of 1.5 m × 1.0 m) from April to June, 2020. Infrared heaters were adopted for simulating extreme heat since they are able to provide a realistic heating mechanism. The targeted temperature was automatically maintained by the data loggers and relays. For the extreme drought simulation, automatic rainout shelters intercepted ambient rainfall, closing only when detecting rainfall to avoid a disturbance of light absorption and passive warming. The rainfall simulator sprayed water from a height of 1.6 m above the ground using spraying nozzles and, the spraying time and pressure were set by the hooked-up pump and control panel to generate realistic rainfall. An infrared thermometer and a soil moisture and temperature sensor per plot measured the soil surface temperature and soil water content, respectively. As a result, the infrared heaters increased the mean soil surface temperature (°C ± standard error) by 2.7 ± 0.2 and 5.7 ± 0.5 in the +3 °C and +6 °C plots, respectively, compared to that in the control. The rainout shelter and rainfall simulator successfully produced extreme drought and heavy rainfall conditions, showing higher mean soil water contents (vol. %) of 4.44 ± 0.01 in the drought plots and 8.45 ± 0.03 in the heavy rainfall plots than that in the control (7.19 ± 0.03). Our multifactor manipulation system can provide a mechanistic understanding of the combined extreme stresses on soils and plants (e.g., soil microbial activity, seed germination, and growth of seedlings) through the comparison between the impact of single and multiple factors. Furthermore, the system has the advantage of applying diverse intensities of extreme climate events without restrictions on regions and scenarios by altering the settings of data loggers or the control panel. The system in this study can aid in investigating and modeling the mechanisms between extreme climate events, and soils and plants.Acknowledgment: This study was carried out with the support of the National Research Foundation, Republic of Korea (Project No. 2022R1A2C1011309) and Korea Forest Service (Project No. 2020181A00-2222-BB01).
How much does diabatic heating affect storm track activity?
Authors: Nakamura Noboru
Published: February 2023

We examine regional and seasonal variations of extratropical storm tracks and their maintenance in terms of a column-mean local wave activity budget.  Seasonal climatology of wave activity in ERA5 reveals spatial and temporal variations of storm tracks in both hemispheres broadly consistent with previous studies based on other metrics. The seasonal-mean budget consists of horizontal convergence of wave activity fluxes, input from the surface (the upward Eliassen-Palm flux), a small storage, and the residual. When averaged hemispherically, surface injection of wave activity due to baroclinic instability and forced stationary waves is balanced by a negative residual (dissipation) due to mixing and radiative damping.However, the budget terms show considerable zonal, meridional and seasonal variations, especially in the Northern Hemisphere. Wave activity migrates downstream from a source region to a sink, where the residual is negative and largely balanced by flux convergence. In addition to the surface sources in the regions of strong baroclinicity, the residual term, though negative on average, shows significant positive values where cloud water abounds, suggesting diabatic (and/or nonquasigeostrophic) sources of wave activity.By reconstructing the budget driven by a fixed transport velocity and damping rate evaluated from the seasonal climatology but suppressing the positive residual values, we estimate the impact of diabatic sources on the mean wave activity. It is found that the diabatic sources contribute to 26% and 20%, respectively, of North Atlantic and North Pacific storm track activities in winter, 28% of wave activity over the Pacific Northwest in summer, and 34% of activity in the Indo-western Pacific sector of the austral storm track in summer.
Regional and tele-connected impacts of the Tibetan Plateau surface darkening
Authors: Tang Shuchang , Vlug Anouk , Piao Shilong , Li Fei , Wang Tao , Krinner Gerhard , Li Laurent Z. X. , Wang Xuhui , Wu Guangjian , Li Yue , Zhang Yuan , Lian Xu , Yao Tandong
Published: February 2023

Despite knowledge of the presence of the Tibetan Plateau (TP) in reorganizing large-scale atmospheric circulation, it remains unclear how surface albedo darkening over TP will impact local glaciers and remote Asian monsoon systems. Here, we use a coupled land-atmosphere global climate model and a glacier model to address these questions. Under a high-emission scenario, TP surface albedo darkening will increase local temperature by 0.24 K by the end of this century. This warming will strengthen the elevated heat pump of TP, increasing South Asian monsoon precipitation while exacerbating the current “South Flood-North Drought” pattern over East Asia. The albedo darkening-induced climate change also leads to an accompanying TP glacier volume loss of 6.9%, which further increases to 25.2% at the equilibrium, with a notable loss in western TP. Our findings emphasize the importance of land-surface change responses in projecting future water resource availability, with important implications for water management policies.
The Changes of Hailuogou Glacier in the Southeastern Tibetan Plateau and the Impacts on Glacier Dynamics from the Mechanical Ablation
Authors: Xu Shuyang , Fu Ping , Quincey Duncan , Feng Meili , Marsh Stuart , Liu Qiao , Jia Tian
Published: February 2023

Glaciers in the Tibetan Plateau are melting at an unprecedented rate in the context of global warming. Hailuogou (HLG) Glacier, a rapidly receding temperate land-terminating glacier in the southeastern Tibetan Plateau, has been observed to lose mass partly through ice frontal mechanical ablation (i.e., ice collapse).In this study, we present analysis from Uncrewed Aerial Vehicles (UAV) surveys conducted over nine field campaigns to the HLG Glacier, providing evidence of glacier change and frontal ice collapse between 2017 and 2021. Structure from Motion with Multi-View Stereo was applied to produce multi-temporal Digital Surface Models (DEMs) and orthophoto mosaics, from which geomorphological maps and DEMs of Difference were derived to quantify the changes of the glacier snout and the ice loss from frontal ice collapse. Based on that, a linear correlation of Area-Volume for frontal ice collapse was subsequently built. Planet images were used to identify additional ice collapse events (i.e., 2017 to 2021) and to extract time-sequenced glacier extents. ASTER-derived DEMs generated by NASA Ames Stereo Pipeline (ASP) were then differenced to calculate the ice volume changes in the period. Combined with frontal ice collapse events identified from Planet, the contribution of that to the glacier mass balance can be estimated from the established Area-Volume correlation.These analyses reveal that at the margins of the glacier terminus retreated 132.1 m over the period of analysis, and that in the area specifically affected by collapsing (i.e., the glacier collapsed terminus), it retreated 236.4 m. Overall the volume lost in the terminal area was of the order of 184.61 ± 10.32 x 104 m3, within which the volume change due to observed collapsing events comprises approximately 28%. We show that ice volume changes at the terminus due to a single ice collapse event may exceed the interannual level of volume change, and the daily volume of ice loss due to ice calving exceeds the seasonal and interannual level by a factor of ~ 2.5 and 4. The contribution to the mass balance change of the entire glacier that is attributed to frontal ice collapse is limited (i.e., ranges from 0.48% to 1.12% from 2017 to 2021). However, the mechanical ablation (e.g., frontal ice collapse and subglacial/englacial conduit’s roof collapse) has probably changed the way of losing ice mass to some extent.Our results suggest that the evolution of the HLG Glacier terminus is dominantly controlled by the frontal ice collapse. The projection of the recession rate of the HLG Glacier may well be underestimated if based on surface mass balance alone, as the frontal ice collapsing might be more frequent and larger under the context of warming. If the future evolution of glaciers such as HLG Glacier is to be robustly predicted, the contribution of mechanical ablation should be accounted for by numerical models.
SST-driven changes in cloud radiative heating in RCEMIP models and observations
Authors: Gasparini Blaž , Voigt Aiko , Mandorli Giulio , Stubenrauch Claudia
Published: February 2023

The interactions of ice particles with radiative fluxes in tropical high clouds substantially alter the heating structure within the atmosphere, also known as cloud radiative heating (CRH). CRH influences the upper-tropospheric temperature structure and thus modulates the strength and position of tropical and extratropical circulations. Moreover, it influences the life cycle of tropical high clouds through longwave destabilization of the cloud layer and lifting of clouds by absorption of both shortwave and longwave radiation by ice crystals. A possible change of CRH, for example, due to global warming, can substantially alter the tropical climate.Despite a large body of work that has explored interactions between clouds and radiation, responses of CRH to global warming remain largely unknown. We therefore use idealized SAM cloud-resolving model simulations, the RCEMIP multimodel dataset, and a 15-year-long satellite-derived CRH dataset to explore changes in CRH under different sea surface temperatures.To a first approximation, the upper tropospheric CRH shifts nearly isothermally to a higher altitude level following a surface warming. In addition, upper-tropospheric CRH in 27 of the 32 analyzed models increase by 0.5 to 10%/K, with a mean value of about 3%/K. Interestingly, the CRH increases despite decreases in upper tropospheric ice water content and cloud fraction. The increase in CRH can be to a large extent explained by an increase in atmospheric transmissivity due to a 2-3 km vertical shift of high clouds, in an environment with decreased air density. Similarly, all models simulate an increase in the upper tropospheric clear-sky radiative cooling in warmer conditions.Additionally, the CRH response to surface warming can be largely predicted by assuming a nearly isothermal vertical shift of upper tropospheric CRH profiles (as per the fixed anvil temperature hypothesis) following a warmer moist adiabat and by considering the increase in CRH magnitude due to changes in atmospheric density. Therefore, if we know the CRH of a reference climate state, we can, to a good approximation, estimate its response to surface warming.The modeled CRH vertical shift and increase are confirmed by a 15-year-long satellite-derived tropical CRH dataset. The years with the highest SSTs lead to the most positive CRH that is shifted to higher levels, similarly to what is simulated by RCEMIP models.
Relative phase analysis for volcanic tremor detection and source location
Authors: Barajas Andres , Shapiro Nikolai Shapiro
Published: February 2023

The analysis of highly coherent seismic signals produced during tremor episodes has been recently gained interest as a mean to study the structure of volcanic systems, and the underlying physical mechanism producing its activity. Volcanic tremor signals usually appear with a non-impulsive gradual onset and can last for long periods of time, ranging from hours to months, during which individual waves cannot be recognized. The lack of identifiable arrivals during tremor episodes and the long duration of the registered signals, renders ineffective classical methods based on the analysis of the travel times, making difficult the location of its sources. We present observations showing that during tremor episodes, the relative phase of inter-station cross-correlations is approximately constant, which is directly linked to the stability of the source position and mechanism. We propose a new method to identify the relative phase stability (and therefore, wavefield coherence) in recordings obtained from a seismic network, that can also be applied to recordings from a single pair of stations. Then, we use a new approach based on the relative phase measurements to find the position of the source of a tremor episode in 2015 at the Klyuchevskoy Volcanic Group.  In general, we show several of the advantages of extracting information from the relative phase as opposed from methods relying on the identification of arrival phases.
Rainwater canopy flowpath estimated by raindrop measurements
Authors: Nanko Kazuki , Keim Richard , Hudson Sean , Ebato Munehiro , Levia Delphis
Published: February 2023

Water flowpaths caused by incident rainfall onto forest canopy surfaces have a notable effect on the water budgets and chemistry of wooded ecosystems. The objective of this work was to use drop-size distributions in throughfall to identify canopy flowpaths at the intra-event scale and across the phenological transition from leafed to leafless states for a set of three American beech (Fagus grandifolia Ehrh.) trees and konara oak (Quercus serrata Murray) in a multilayered canopy.Simultaneous measurements of raindrops and throughfall drops by laser disdrometers were analyzed during the transition from leafed to leafless phenophases. Throughfall was partitioned into free throughfall, splash throughfall, and canopy drip with four drop size classes. The partitioning was based on the difference of drop size distributions between open rainfall and throughfall.Throughfall drop size distributions and volume of each throughfall type varied at both intra-event and inter-event scales. As for American beech, smaller canopy drips, <5.5 mm in diameter, were initiated earlier in rain events, whereas more rainfall accumulation was necessary to generate larger canopy drips, >5.5 mm in diameter. Smaller canopy drips were more dominant in the leafed phenophase when some structurally-mediated woody surface drip points were more muted. These results suggested throughfall from foliar surfaces generated smaller-sized canopy drip with shorter residence time, whereas throughfall from structurally-mediated woody surface drip points generated larger-sized canopy drip with longer residence time. There was also an increase in both free throughfall and splash droplets from leafed to leafless states, consistent with increased canopy gaps and direct interaction with woody surfaces in the leafless state.Similar analysis was conducted for konara oak. More rainfall accumulation was necessary to generate larger canopy drips as with the American beech, but the amount of the larger canopy drips was stable after generation during rain events compared with smaller canopy drips. Thus, the fluctuation of throughfall amount was correlated with that of the amount of smaller canopy drips.Based on the results, a conceptualization of the genesis and development of leaf and branch flowpaths in canopies is proposed.This research was supported by JSPS KAKENHI (Grant numbers JP21K05837, JP17KK0159, JP15H05626). A part of the study is published in Nanko et al. (2022) in Journal of Hydrology (doi: 10.1016/j.jhydrol.2022.128144).
Investigating the Correlation between the Characteristics of Seismic Activity and Environmental Variables in Taiwan
Authors: Chen Yi-Ho , Lin Yuan-Chien
Published: February 2023

        Since Taiwan is located at the Pacific Ring of Fire, seismic activity of varying magnitudes occurs almost every day. Among them, some of these seismic activities have in turn caused severe disasters, resulting in loss of personal property, casualties and damage to important public facilities. Therefore, investigating the long-term spatiotemporal pattern of seismic activities is a crucial task for understanding the causes of seismic activity and to predict future seismic activity, in order to carry out disaster prevention measures in advance. Previous studies mostly focused on the causes of single seismic events on the small spatiotemporal scale. In this study, the data from 1987 to 2020 are used, including seismic events from the United States Geological Survey (USGS), the ambient environmental factors such as daily air temperature from Taiwan Central Weather Bureau (CWB) and daily sea surface temperature data from National Oceanic and Atmospheric Administration (NOAA). Then the temperature difference between the land air temperature and the sea surface temperature (SST) to the correlation between the occurrence of seismic activities and the abnormal occurrence of temperature difference are compared. The results show that lots of seismic activities often have positive and negative anomalies of temperature difference from 21 days before to 7 days after the seismic event. Moreover, there is a specific trend of temperature difference anomalies under different magnitude intervals. In the magnitude range of 2.5 to 4 and greater than 6, almost all of the seismic events have significant anomalous differences in the temperature difference between land air temperature and SST compared with no seismic events. This study uncovers anomalous frequency signatures of seismic activities and temperature differences between land air temperature and SST. The significant difference in temperature difference between seismic events and non-seismic events was compared by using statistical analysis. Additionally, the deep neural network (DNN) of deep learning model, logistic regression and random forest of machine learning model was used to identify whether there will be a seismic event under different magnitude intervals. It is hoped that it can provide relevant information for the prediction of future seismic activity, to more accurately prevent disasters that may be caused by seismic activity.
Assessment of the Long-term Temporal Resilience of the Indian Terrestrial Ecosystems: Insights into the Country-scale Drivers
Authors: Chakraborty Abhishek , Muddu Sekhar , Rao Lakshminarayana
Published: February 2023

The knowledge of the long-term resilience of Indian terrestrial ecosystems is essential in the background of massive land-use conversion to croplands, intensification of irrigation, and the enhanced climate change signals over the past few decades. Previous assessments of Indian ecosystem resilience were limited by a smaller temporal span, lack of consideration for the sub-annual ecosystem transitions, and non-aridity-based stressors of the loss of resilience of ecosystems (Sharma and Goyal, 2017, Glob Chang Biol; Kumar and Sharma, 2023, J Environ Manage). This study aims towards a comprehensive understanding of the resilience of Indian terrestrial ecosystems through monthly scale assessment considering the driving role of the stressors in a standalone and compound manner.The study utilizes ecosystem water use efficiency (WUE) as a state variable to assess the resilience of Indian ecosystems. WUE, produced from the FLUXCOM RS+METEO gross primary productivity (GPP) and evapotranspiration (ET) datasets at a monthly scale (WUEe=GPP/ET) from 1950 to 2010 (Jung et al., 2019, Sci Data; Tramontana et al., 2016, Biogeosciences), is a metric to quantify the strength of the coupling between terrestrial water and carbon cycles. Further lag-1 autocorrelation time series (AC(1)) is produced by evaluating the Kendall tau correlations for each pixel's residual component of the decomposed time series of WUE (excluding the impacts of trends and seasonal cycles). Such higher-order statistical assessments have been used earlier to quantify the loss of resilience (Smith et al., 2022, Nat Clim Change; Boulton et al., 2022, Nat Clim Change). We conduct the AC(1) analysis for resilience for India's six homogeneous meteorological regions, the eight major river basins, and the biome scale. We further consider the impacts of different forms of aridity on the loss of resilience: atmospheric aridity, hydrological aridity, and soil moisture aridity, individually and in a compound pattern. We also assess the loss of resilience at a seasonal scale (winter, summer, monsoon, post-monsoon) for the two major anthropogenic influences on Indian ecosystems: intensity of irrigation and groundwater fluctuations. This study attempts at a holistic understanding of the loss of resilience through its quantification and impacts of drivers, which could help the policymakers to identify the hotspots of loss of resilience and the significant perturbations to the resilience of Indian terrestrial ecosystems.
The last glacial cycle transiently simulated with a coupled climate-ice sheet model
Authors: Pöppelmeier Frerk , Joos Fortunat , Stocker Thomas F.
Published: February 2023

Understanding climate variability from millennial to glacial-interglacial timescales remains challenging due to the complex and non-linear feedbacks between ice, ocean, and atmosphere. Although the ever-increasing number of reconstructions has helped to form compelling hypotheses for the evolution of ocean and atmosphere circulation or ice sheet extent over the last glacial cycle, climate models, required for systematically testing these hypotheses, struggle to dynamically and comprehensively simulate such long time periods as a result of the large computational costs. Here, we therefore coupled a dynamical ice sheet model to the Bern3D Earth system model of intermediate complexity, that allows for simulating multiple glacial-interglacial cycles in reasonable time. To test the fully-coupled model, we explore the climate evolution over the entire last glacial cycle in a transient simulation forced by the orbital configuration and greenhouse gas and aerosol concentrations. We are able to simulate Global Mean Surface Temperature (GMST) in fair agreement with reconstructions exhibiting a gradual cooling trend since the last interglacial that is interrupted by two more rapid cooling events during the early Marine Isotope Stage (MIS) 4 and Last Glacial Maximum (LGM). The glacial-interglacial GMST and mean ocean temperature differences are 5 °C and 1.6 °C, respectively. Ice volume shows pronounced variability on orbital timescales mirroring northern hemispheric summer insolation. From early MIS3 to the LGM ice volume roughly doubles in good agreement with recent sea-level reconstructions. The Atlantic overturning circulation shows larger variability during the relatively warm MIS5 than during the cooler MIS3, however we note that Dansgaard-Oeschger events are not intrinsically simulated in our setup. At the LGM the Atlantic overturning has a strength of about 14 Sv, which is a reduction by about one quarter compared to the pre-industrial. We thus demonstrate that the new coupled model is able to realistically simulate glacial-interglacial cycles, which allows as to systematically investigate the sensitivities to parameters such as equilibrium climate sensitivity or aerosol radiative forcing during the last glacial cycle.
Volcanic and Seismic source Modelling (VSM) - An open tool for geodetic data modelling
Authors: Trasatti Elisa
Published: February 2023

Natural processes and anthropogenic activities often generate changes in the stress state of the crust, and, consequently, measurable surface deformation. Volcanic activity produces surface displacements as a result of phenomena including magma recharge/deployment and migration, and fluid flow. The accurate measurement of surface deformation is one of the most relevant parameters to measure tectonic stress accumulation and for studying the seismic cycle. Improved monitoring capabilities also capture surface deformations related to coastal erosion and its connection to climate change, landslides and deep seated gravitational slopes, and other hydrogeological hazards. In addition, anthropogenic activity such as mining and water pumping cause measurable soil displacement.Ground deformations are measured by space and terrestrial techniques, reaching sub-millimetric accuracy. Synthetic Aperture Radar (SAR) satellites have been quickly developing in the last decades. GNSS data allows to map nearly 3D deformation patterns, but often the network consists of few benchmarks. The joint use of SAR and GNSS data compensate the intrinsic limitations of each technique. Levelling measures the geodetic height of a benchmark. Borehole dilatometers and clinometers provide derivative measurements of the surface displacements.Theoretical models of deformation sources are commonly employed to investigate the surface displacements observed, for example, in volcanic areas or related to a seismic event. A volcanic source can be represented by a confined part of crust with a certain shape inflating/deflating because of a change in the internal magma/gas pressure. The static seismic source is ideally represented by a tabular discontinuity in the crust undergoing relative movement of both sides. Furthermore, gas reservoir exploitation, water pumping and soil consolidation, can be represented using the same models.Volcanic and Seismic source Modelling (VSM) is an open-source Python tool to model ground deformation detected by satellite and terrestrial geodetic techniques. It allows the user to choose one or more geometrical sources as forward model among sphere, spheroid, ellipsoid, fault, and sill. It supports geodetic from several techniques: interferometric SAR, GNSS, levelling, Electro-optical Distance Measuring, tiltmeters and strainmeters. Two sampling algorithms are available, one is a global optimization algorithm based on the Voronoi cells and the second follows a probabilistic approach to parameters estimation based on the Bayes theorem. VSM can be executed as Python script, in Jupyter Notebook environments or by its Graphical User Interface. Its broad applications range from high level research to teaching, from single studies to near real-time hazard estimates. Potential users range from early career scientists to experts. It is freely available on GitHub (https://github.com/EliTras/VSM). In this contribution I show the functionalities of VSM and test cases.
Laminar transport and turbulent cascades in downslope rotating gravity currents.
Authors: Rétif Sévan , Negretti Maria-Eletta , Wirth Achim , Tassigny Axel
Published: February 2023

We present experimental results from large-scale laboratory experiments of rotating downslope gravity currents intruding into a two-layer stratified ambient performed in the Coriolis Rotating Platform in Grenoble. By means of PIV velocity and conductivity data for the density measurement, we show that mixing occurs mostly on the slope area during the descent rather than once the current has penetrated the stratified ambient, where the Richardson number remains above the stability threshold of 1/4. Looking at the time evolution of the vertical density profile in the stratified receiving ambient, two distinct mixing regimes can be identified, the first issued by laminar transport through Ekman dynamics, the second by turbulent transport due to intermittent cascading events. Vertical density gradients reveal a linear piece-wise dependence on the density anomaly, highlighting an advection-diffusion process as proposed by the theoretical model of Munk & Wunsch (1998). If the gravity current flow is laminar on the slope, the structure shows a linear variation of the density with depth ; For the turbulent transport regime characterized by intermittent cascades, an exponential shape is rather observed. The shape of the density structure allows to estimate bulk mixing coefficients and entrainment velocities at the top and the bottom of the intruding gravity current, which can be further compared to oceanographic observational data.