Explore the vast range of titles available.

Salinity distribution in a large tidal estuary is subject to estuarine adjustment under the influences of multiple physical drivers such as freshwater pulses and sea level rise, and is crucial to upstream water quality, aquaculture, and ecosystem functions of the estuary. To better understand the estuarine salinity response to climate change, the unstructured-grid Finite Volume Community Ocean Model was implemented to simulate the salt intrusion in the Delaware Bay Estuary. The model was first validated by multiple observational data sets and subsequently applied in an idealized setting to examine the response of salt front to freshwater pulses in high flow conditions, followed by a long-term drought condition supported by a multi-decadal streamflow drought analysis in the estuary. The model results showed that after the freshwater pulses the salt front location moved further upstream with sea level rise. Under the simulated long-term drought condition, the adjustment timescale of salt intrusion varies nonlinearly with sea level rise. With a significant increase in sea level rise, the adjustment timescale starts to decrease. This shift suggests a transition into a different regime where the estuary becomes more stratified, as indicated by an increasing bulk Simpson number with rising sea levels.

Salinity distribution in a large tidal estuary is subject to estuarine adjustment under the influences of multiple physical drivers such as freshwater pulses and sea level rise, and is crucial to upstream water quality, aquaculture, and ecosystem functions of the estuary. To better understand the estuarine salinity response to climate change, the unstructured-grid Finite Volume Community Ocean Model was implemented to simulate the salt intrusion in the Delaware Bay Estuary. The model was first validated by multiple observational data sets and subsequently applied in an idealized setting to examine the response of salt front to freshwater pulses in high flow conditions, followed by a long-term drought condition supported by a multi-decadal streamflow drought analysis in the estuary. The model results showed that after the freshwater pulses the salt front location moved further upstream with sea level rise. Under the simulated long-term drought condition, the adjustment timescale of salt intrusion varies nonlinearly with sea level rise. With a significant increase in sea level rise, the adjustment timescale starts to decrease. This shift suggests a transition into a different regime where the estuary becomes more stratified, as indicated by an increasing bulk Simpson number with rising sea levels.

Salinity distribution in a large tidal estuary is subject to estuarine adjustment under the influences of multiple physical drivers such as freshwater pulses and sea level rise, and is crucial to upstream water quality, aquaculture, and ecosystem functions of the estuary. To better understand the estuarine salinity response to climate change, the unstructured-grid Finite Volume Community Ocean Model was implemented to simulate the salt intrusion in the Delaware Bay Estuary. The model was first validated by multiple observational data sets and subsequently applied in an idealized setting to examine the response of salt front to freshwater pulses in high flow conditions, followed by a long-term drought condition supported by a multi-decadal streamflow drought analysis in the estuary. The model results showed that after the freshwater pulses the salt front location moved further upstream with sea level rise. Under the simulated long-term drought condition, the adjustment timescale of salt intrusion varies nonlinearly with sea level rise. With a significant increase in sea level rise, the adjustment timescale starts to decrease. This shift suggests a transition into a different regime where the estuary becomes more stratified, as indicated by an increasing bulk Simpson number with rising sea levels.

The time needed by deep convection to bring the atmosphere back to equilibrium is called convective adjustment timescale or simply adjustment timescale, typically denoted by τ$\\tau $ . In the Community Atmospheric Model|Community Atmosphere Model (CAM), τ$\\tau $is the convective available potential energy (CAPE) relaxation timescale and is 1 hr, worldwide. Observational evidence suggests that τ$\\tau $is generally longer than 1 hr. Further, continental and oceanic convection are different in terms of the vigor of updrafts and can have different longevities. So using τ=1$\\tau =1$hour worldwide in CAM has two potential caveats. A longer τ$\\tau $improves the simulation of the mean climate. However, it does not address the land‐ocean heterogeneity of atmospheric deep convection. We investigate the prescription of two different CAPE relaxation timescales for land (τL=1${\\tau }_{L}=1$  hr) and ocean (τO=1${\\tau }_{O}=1$to 4 hr). It is arguably an extremely crude parameterization of boundary layer control on atmospheric convection. We contrast a suite of 5‐year‐long simulations with two different τ$\\tau $for land and ocean to having one τ$\\tau $globally. The choice of longer τ$\\tau $over ocean is guided by previous studies and inspired by observational pieces of evidence. Nonetheless, to complement our variable τO${\\tau }_{O}$experiments, we perform a simulation with τO=1${\\tau }_{O}=1$  hr and τL=4${\\tau }_{L}=4$  hrs. Most importantly, our key findings are immune to the exact values of prescribed τL${\\tau }_{L}$and τO${\\tau }_{O}$ . The CAM model, with two τ$\\tau $values τO>τL$\\left({\\tau }_{O} > {\\tau }_{L}\\right)$ , improves convective‐stratiform rainfall partitioning and the Madden–Julian oscillation propagation characteristics. Plain Language Summary A thermodynamically unstable atmosphere releases its energy by creating clouds. Deep clouds take time to decay and bring the atmosphere back to equilibrium. The decay time of deep clouds is called convective adjustment timescale or simply adjustment timescale, typically denoted by τ in climate model formulations. In the Community Atmospheric Model it is defined as the convective available potential energy consumption time scale and set to 1 hr globally. Since convection behaves differently over land and sea using different values of τ for continents and oceans could better represent their distinct convection behaviors. Our climate simulations using CAM showed that setting τ over the oceans to 4 hr and τ over continents to 1 hr improved the accuracy of the simulations, particularly for the Madden‐Julian Oscillation. It suggests that using two different τ values for continent and ocean is recommended. Key Points Two distinct values of convective available potential energy relaxation timescale, τ$\\tau $ , over land and ocean in the convective parameterization scheme are prescribed The mean climate stays qualitatively the same, except for a moister and colder near‐surface atmosphere for longer τ$\\tau $over the oceans A primary gain of using two different τ$\\tau $for land and ocean is improved simulation of the Madden–Julian oscillation propagation features

The lateral migration of a river meander is driven by erosion on the outer bank and deposition on the inner bank, both of which are affected by shear stress (and therefore channel slope) through complex morphodynamic feedbacks. To test the sensitivity of lateral migration to channel slope, we quantify slope change induced by glacial isostatic adjustment along the Red River (North Dakota, USA and Manitoba, Canada) and two of its tributaries over the past 8.5 ka. We demonstrate a statistically significant, positive relationship between normalized cutoff count, which we interpret as a proxy for channel lateral migration rate, and slope change. We interpret this relationship as the signature of slope change modulating the magnitude of shear stress on riverbanks, suggesting that slope changes that occur over thousands of years are recorded in river floodplain morphology. Plain Language Summary Rivers move through the landscape by eroding river bank material on their outer bank and depositing sediment on their inner bank, a process that forms meander bends. Understanding what factors drive river meandering is important for interpreting how rivers interact with landscapes. One factor that could impact river meandering is river slope. To understand the impact of slope on river meandering we quantify how slope has changed along the Red River (North Dakota, USA and Manitoba, Canada) over the past 8.5 Kyr. Over this time, vertical land movement substantially reduced the slope of the river, through the ongoing solid Earth response to the retreat of massive North American ice sheets in a process known as glacial isostatic adjustment (GIA). We find that change in slope, induced by GIA, positively correlates with river migration rate along the Red River, suggesting that slope plays an important role in determining the pace of river meandering. Key Points Glacial isostatic adjustment (GIA) is the primary control on slope change for the Red River (ND, USA and MB, Canada) since it began to flow 8.5 ka Slope change caused by GIA significantly correlates with river cutoff frequency, a proxy for lateral migration rate We infer that slope change modulates the magnitude of shear stress on the riverbank, driving changes in lateral migration rate

A novel, inverse-pendulum wave energy converter (NIPWEC) is a device that can achieve natural period control via a mass-position-adjusting mechanism and a moveable internal mass. Although the energy capture capacity of a NIPWEC has already been proven, it is still meaningful to research how to effectively control the NIPWEC in real time for maximum wave energy absorption in irregular waves. This paper proposes a multi-timescale lookup table based maximum power point tracking (MLTB MPPT) strategy for the NIPWEC. The MLTB MPPT strategy was implemented to achieve a theoretical “optimal phase” and “optimal amplitude” by adjusting both the position of the internal mass and linear power take-off (PTO) damping. It consists of two core parts, i.e., internal mass position adjustment based on a 1D resonance position table and PTO damping tuning based on a 2D optimal PTO damping table. Furthermore, power assessments and sensitivity study were conducted for eight irregular-wave sea states with diverse wave spectra. The results show that energy period resonance and the lookup table based PTO damping tuning have the highest possibility of obtaining the maximum mean time-averaged absorbed power. Additionally, both of them are robust to parameter variations. In the next step, the tracking performance of the MLTB MPPT strategy in terms of changing sea states will be studied in-depth.

Bias in regional climate model (RCM) data makes bias correction (BC) a necessary pre-processing step in climate change impact studies. Among a variety of different BC methods, quantile mapping (QM) is a popular and powerful BC method. Studies have shown that QM may be vulnerable to reductions in calibration sample size. The question is whether this also affects the climate change signal (CCS) of the RCM data. We applied four different QM methods without subsampling and with three different subsampling timescales to an ensemble of seven climate projections. BC generally improved the RCM data relative to observations. However, the CCS was significantly modified by the BC for certain combinations of QM method and subsampling timescale. In conclusion, QM improves the RCM data that are fundamental for climate change impact studies, but the optimal subsampling timescale strongly depends on the chosen QM method.