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"Berg, Peter"
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Strong increase in convective precipitation in response to higher temperatures
The intensity of extreme precipitation rises faster than the rate of increase in the atmosphere’s water-holding capacity. A combination of radar and rain gauge measurements over Germany with synoptic observations and temperature records reveals that convective precipitation, for example from thunderstorms, dominates events of extreme precipitation.
Precipitation changes can affect society more directly than variations in most other meteorological observables
1
,
2
,
3
, but precipitation is difficult to characterize because of fluctuations on nearly all temporal and spatial scales. In addition, the intensity of extreme precipitation rises markedly at higher temperature
4
,
5
,
6
,
7
,
8
,
9
, faster than the rate of increase in the atmosphere’s water-holding capacity
1
,
4
, termed the Clausius–Clapeyron rate. Invigoration of convective precipitation (such as thunderstorms) has been favoured over a rise in stratiform precipitation (such as large-scale frontal precipitation) as a cause for this increase
4
,
10
, but the relative contributions of these two types of precipitation have been difficult to disentangle. Here we combine large data sets from radar measurements and rain gauges over Germany with corresponding synoptic observations and temperature records, and separate convective and stratiform precipitation events by cloud observations. We find that for stratiform precipitation, extremes increase with temperature at approximately the Clausius–Clapeyron rate, without characteristic scales. In contrast, convective precipitation exhibits characteristic spatial and temporal scales, and its intensity in response to warming exceeds the Clausius–Clapeyron rate. We conclude that convective precipitation responds much more sensitively to temperature increases than stratiform precipitation, and increasingly dominates events of extreme precipitation.
Journal Article
Weather warning archives reveal spatio-temporal hot spots of compound natural hazards
Individual natural hazards may be combined in different ways, leading to cascading or co-occurring effects, turning them into compound hazards. However, assessment of individual as well as compound hazards is often hampered by short or incomplete observational records of actual hazards, and records of various hazards that do not easily combine. In this study we propose an alternative way to detect potential risk of compound natural hazards via archived severe weather warnings. We investigate weather warnings in Sweden from 2011 to 2020 regarding their distributions and frequencies in time (at daily level) and space (at warning district level) from both an individual and compound perspective. We illustrate the methodology and results by focusing on compound flood-related risk, generated by combinations of heavy rainfall, high streamflow and high sea level, and contextualize with two actual compound flood events in Sweden. We find compound fluvial and coastal flood risk primarily along the southwest coast during the winter half year as well as compound fluvio-pluvial flood risk during the summer half year. The results show that severe weather warnings can be used to assess the frequency and compounding nature of natural hazards, as well as to identify actual cases for further investigation, and we encourage similar investigations elsewhere.
Journal Article
From manager's emotional intelligence to objective store performance: Through store cohesiveness and sales-directed employee behavior
The relationships among manager’s emotional intelligence, store cohesiveness, sales-directed employee behavior, and objective store performance were investigated. Non-managerial sales employees of a large retail electronics chain in South Korea (N = 1611) rated the emotional intelligence of their own store managers as well as the group cohesiveness within their stores. Store managers (N = 253) separately rated the sales-directed behavior of their employees. Objective sales data were collected one month later for each store. No direct relationship between manager emotional intelligence and objective store performance was found. Instead, the results supported the hypothesized four-variable, three-path mediation model: store manager’s emotional intelligence was related to store cohesiveness, which in turn was related to the sales-directed behavior of the frontline employees, which ultimately predicted the objective performance of the stores. Manager emotional intelligence and store cohesiveness are seen as intangible organizing resources or socio-psychological capital for non-managerial store employees. Implications for future research and more effective management of retail firms are discussed.
Journal Article
Proportions of convective and stratiform precipitation revealed in water isotope ratios
Tropical and midlatitude precipitation is fundamentally of two types, spatially limited and high-intensity convective or widespread and lower-intensity stratiform, owing to differences in vertical air motions and microphysical processes governing rain formation. These processes are difficult to observe or model and precipitation partitioning into rain types is critical for understanding how the water cycle responds to changes in climate. Here, we combine two independent data sets—convective and stratiform precipitation fractions, derived from the Tropical Rainfall Measuring Mission satellite or synoptic cloud observations, and stable isotope and tritium compositions of surface precipitation, derived from a global network—to show that isotope ratios reflect rain type proportions and are negatively correlated with stratiform fractions. Condensation and riming associated with boundary layer moisture produces higher isotope ratios in convective rain, along with higher tritium when riming in deep convection occurs with entrained air at higher altitudes. On the basis of our data, stable isotope ratios can be used to monitor changes in the character of precipitation in response to periodic variability or changes in climate. Our results also provide observational constraints for an improved simulation of convection in climate models and a better understanding of isotope variations in proxy archives, such as speleothems and tropical ice.
Distinguishing convective and stratiform rainfall is key to understanding how the water cycle responds to climate change. An analysis of satellite and surface data shows that rain isotope ratios reflect the proportions of these types of rain.
Journal Article
The greenhouse gas offset potential from seagrass restoration
Awarding CO
2
offset credits may incentivize seagrass restoration projects and help reverse greenhouse gas (GHG) emissions from global seagrass loss. However, no study has quantified net GHG removal from the atmosphere from a seagrass restoration project, which would require coupled C
org
stock and GHG flux enhancement measurements, or determined whether the creditable offset benefit can finance the restoration. We measured all of the necessary GHG accounting parameters in the 7-km
2
Zostera marina
(eelgrass) meadow in Virginia, U.S.A., part of the largest, most cost-effective meadow restoration to date, to provide the first seagrass offset finance test-of-concept. Restoring seagrass removed 9,600 tCO
2
from the atmosphere over 15 years but also enhanced both CH
4
and N
2
O production, releasing 950 tCO
2
e. Despite tripling the N
2
O flux to 0.06 g m
−2
yr
−1
and increasing CH
4
8-fold to 0.8 g m
−2
yr
−1
, the meadow now offsets 0.42 tCO
2
e ha
−1
yr
−1
, which is roughly equivalent to the seagrass sequestration rate for GHG inventory accounting but lower than the rates for temperate and tropical forests. The financial benefit for this highly successful project, $87 K at $10 MtCO
2
e
−1
, defrays ~10% of the restoration cost. Managers should also consider seagrass co-benefits, which provide additional incentives for seagrass restoration.
Journal Article
Multi-loop atomic Sagnac interferometry
The sensitivity of light and matter-wave interferometers to rotations is based on the Sagnac effect and increases with the area enclosed by the interferometer. In the case of light, the latter can be enlarged by forming multiple fibre loops, whereas the equivalent for matter-wave interferometers remains an experimental challenge. We present a concept for a multi-loop atom interferometer with a scalable area formed by light pulses. Our method will offer sensitivities as high as
2
×
10
-
11
rad/s at 1 s in combination with the respective long-term stability as required for Earth rotation monitoring.
Journal Article
Dynamics of benthic metabolism, O₂, and pCO₂ in a temperate seagrass meadow
Seagrass meadows play an important role in “blue carbon” sequestration and storage, but their dynamic metabolism is not fully understood. In a dense Zostera marina meadow, we measured benthic O₂ fluxes by aquatic eddy covariance, water column concentrations of O₂, and partial pressures of CO₂ (pCO₂) over 21 full days during peak growing season in April and June. Seagrass metabolism, derived from the O₂ flux, varied markedly between the 2 months as biomass accumulated and water temperature increased from 16°C to 28°C, triggering a twofold increase in respiration and a trophic shift of the seagrass meadow from being a carbon sink to a carbon source. Seagrass metabolism was the major driver of diurnal fluctuations in water column O₂ concentration and pCO₂, ranging from 173 to 377 μmol L−1 and 193 to 859 ppmv, respectively. This 4.5-fold variation in pCO₂ was observed despite buffering by the carbonate system. Hysteresis in diurnal water column pCO₂ vs. O₂ concentration was attributed to storage of O₂ and CO₂ in seagrass tissue, air–water exchange of O₂ and CO₂, and CO₂ storage in surface sediment. There was a ~ 1:1 mol-to-mol stoichiometric relationship between diurnal fluctuations in concentrations of O₂ and dissolved inorganic carbon. Our measurements showed no stimulation of photosynthesis at high CO₂ and low O₂ concentrations, even though CO₂ reached levels used in IPCC ocean acidification scenarios. This field study does not support the notion that seagrass meadows may be “winners” in future oceans with elevated CO₂ concentrations and more frequent temperature extremes.
Journal Article
Technical note: Measurements and data analysis of sediment–water oxygen flux using a new dual-optode eddy covariance instrument
Sediment–water oxygen fluxes are widely used as a proxy for organic carbon production and mineralization at the seafloor. In situ fluxes can be measured non-invasively with the aquatic eddy covariance technique, but a critical requirement is that the sensors of the instrument are able to correctly capture the high-frequency variations in dissolved oxygen concentration and vertical velocity. Even small changes in sensor characteristics during deployment as caused, e.g. by biofouling can result in erroneous flux data. Here we present a dual-optode eddy covariance instrument (2OEC) with two fast oxygen fibre sensors and document how erroneous flux interpretations and data loss can effectively be reduced by this hardware and a new data analysis approach. With deployments over a carbonate sandy sediment in the Florida Keys and comparison with parallel benthic advection chamber incubations, we demonstrate the improved data quality and data reliability facilitated by the instrument and associated data processing. Short-term changes in flux that are dubious in measurements with single oxygen sensor instruments can be confirmed or rejected with the 2OEC and in our deployments provided new insights into the temporal dynamics of benthic oxygen flux in permeable carbonate sands. Under steady conditions, representative benthic flux data can be generated with the 2OEC within a couple of hours, making this technique suitable for mapping sediment–water, intra-water column, or atmosphere–water fluxes.
Journal Article
Variation in seagrass meadow respiration measured by aquatic eddy covariance
Accurate daily metabolic estimates of respiration, gross primary production, and net ecosystem metabolism are necessary to assess ecosystem health and blue carbon contributions of vegetated coastal ecosystems. Using our database of 2115 hourly benthic oxygen (O2) fluxes measured by aquatic eddy covariance, we examine how respiration for a Zostera marina seagrass meadow varies through night and day, and how this affects commonly performed metabolic estimates. Respiration decreased linearly by 29% through the night and a corresponding linear increase in daytime respiration coupled with production described by a standard photosynthesis–irradiance curve accurately predicted measured daytime O2 fluxes. Many studies have questioned the widely used assumption in metabolic estimates that nighttime and daytime respiration are constant and equal. However, if respiration can be approximated as we found here by linear relationships, standard means for calculating daily metabolic numbers remain valid if estimates are based on full 24‐h records of flux data.
Journal Article