Hurricane Research Articles

The role of diabatic heating/cooling in outer rainbands in the secondary eyewall formation and evolution in a numerically simulated tropical cyclone

In this study, the role of diabatic heating/cooling in outer rainbands (ORBs) in the formation and evolution of the secondary eyewall of a numerically simulated tropical cyclone (TC) is investigated. This is done through a series of sensitivity experiments under idealized conditions using a high-resolution cloud-resolving atmospheric model. The results show that artificially increasing diabatic heating in rainbands enhances convective activities in ORBs and leads to an earlier secondary eyewall formation (SEF), and later the faster weakening and earlier dissipation of the primary eyewall. Reducing diabatic heating in ORBs weakens the rainbands and delays the SEF but prolongs the duration of the double eyewall structure if the SEF occurs. Reducing diabatic cooling in ORBs enhances convective activity in rainbands but has little effect on convection in the primary eyewall prior to the SEF. However, it results in a widened eyewall structure and a stronger TC after the eyewall replacement. Increasing diabatic cooling in ORBs largely suppresses convection in rainbands and prohibits the SEF. These results demonstrate that diabatic heating/cooling in ORBs plays important roles in the SEF and evolution. Since diabatic heating/cooling in rainbands is sensitive to the near-core environmental relative humidity, our results demonstrate the critical importance of large-scale environmental moist condition to the formation and evolution of secondary eyewall in TCs. In addition, it is also found that when the area-averaged diabatic heating rate in ORBs becomes similar in magnitude to that in the primary eyewall, the secondary eyewall forms. Plain language summaryPrevious studies have demonstrated the importance of diabatic heating/cooling in outer rainbands to the structure and intensity changes of tropical cyclones (TCs) with a single eyewall. It is unclear whether and how diabatic heating/cooling in outer rainbands may affect the formation and evolution of the secondary eyewall in TCs. These issues have been addressed based on a series of sensitivity experiments under idealized conditions using a high-resolution atmospheric model. Results show that diabatic heating in outer rainbands is favorable for the secondary eyewall formation (SEF). Increasing diabatic heating in outer eyewall can lead to faster weakening and thus earlier dissipation of the primary eyewall. Diabatic cooling in outer rainbands suppresses convection in outer rainbands and prohibits the SEF. Since diabatic heating/cooling in outer rainbands is sensitive to the near-core environmental relative humidity, our results demonstrate the importance of the large-scale environmental moist condition to the SEF of TCs. We also found that when the area-averaged diabatic heating rate in outer rainbands becomes similar in magnitude to that in the primary eyewall, the secondary eyewall would form, which can be considered as a measure of the SEF in TCs. Key points1.Increasing diabatic heating in outer rainbands leads to earlier SEF, and faster weakening and earlier dissipation of the primary eyewall.2.Increasing diabatic cooling in outer rainbands suppresses convective activity in outer rainbands and is unfavorable for the SEF.3.When the area-averaged diabatic heating rate in outer rainbands and the eyewall become similar in magnitude, the secondary eyewall forms.

Characterizing interactive compound flood drivers in the Pearl River Estuary: A case study of Typhoon Hato (2017)

Tropical cyclone (TC) induced compound floods involve dynamic interactions among astronomical tides, storm surges, precipitation, and associated river pulses. This study employs a one-way coupled WRF, Delft3D, and HEC-RAS model to investigate the impacts of oceanic, pluvial, and fluvial processes on compound flood dynamics during Typhoon Hato (2017) in the Pearl River Estuary (PRE), South China. Total water levels driven by different combinations of flood drivers are modeled and analyzed. Relative contributions of each type of flood driver are quantified and used to categorize flood zones. This study highlights the persistent impacts of storm surges and their nonlinear interactions with other flood drivers. They can modify both the timing and magnitude of maximum water levels, thereby distorting tidal signals and contributing to post-TC landfall water level peaks. Along coastal regions, water levels exhibit three successive peaks, predominantly driven by storm surge, rainfall, and the combined actions of both factors, respectively. In upstream regions and coastal areas sheltered from islands, a singular water level peak arises exclusively from rainfall-runoff processes. Moreover, nonlinear interactions between surge and rainfall-runoff have non-negligible impacts on the relative contribution of individual flood drivers, which underscores the necessity of considering both rainfall and storm surge in modeling compound flood water levels. During the flooding period, peak storm surge and the following peak rainfall resulted in a time-varying distribution of flood zones. Alternating feedback between compounded and ocean-dominant areas manifests in the midsections of the upper PRE. Maximum flooding depth, extent, and duration are mainly influenced by rainfall. Storm surges play a secondary role, causing intense but short-lived flooding in coastal regions. These findings aid in understanding the generation mechanism of compound floods and provide references for hazard mitigation strategies.

Turbidity estimation from an acoustic backscatter signal in a tropical coral reef system.

This study investigated the estimation of Nephelometric Turbidity Units (NTU) from backscatter signals in a tropical coral reef system using a 1200-kHz towed Acoustic Doppler Current Profiler (ADCP). In order to perform the estimation, simultaneous acoustic backscatter and turbidity data were collected near the surface (above the pycnocline). Simultaneously, water samples at the same depths were analyzed to determine sediment composition. The results showed that a second-degree polynomial model provided the best correlation (r=0.69) between backscatter signals and turbidity measurements, highlighting the nonlinear relationship between acoustic signals and turbidity values obtained from optical devices. The reef's bathymetry significantly influenced the seawater turbidity, revealing the importance of physical configuration and hydrodynamic conditions in sediment distribution. From the sediment composition, it was determined that 89% of the total suspended solids are terrigenous sediments. This integrated methodological approach provides a detailed understanding of sediment dynamics, essential for the conservation and sustainable management of coral reefs around the word in a noninvasive way.

Morphodynamics drive the transport and accumulation of anthropogenic microparticles in tropical coastal depositional systems in southeastern Brazil.

A significant limitation in current coastal pollution research is that microplastics (<5 mm) comprise only a fraction of all anthropogenic microparticles (AMP, <5 mm) scale residues. Comprehensive AMP assessments, including those comprising semisynthetic, and modified natural compositions, are lacking. For instance, the accumulation of AMP in different coastal morphological features within a depositional system remains poorly known, fueling long-lasting debates about the distribution process of microparticles. Using a multi-proxy approach, we address mutual interactions between distinct surface morphologies (tidal flats, beaches, and foredunes) and transport and deposition dynamics of AMP. This issue was addressed by analyzing sediment and water samples collected at a marine protected area in the south coastal of São Paulo (Brazil). Here, we showed that AMP abundance in the tidal mudflat (18,500-20,500 particles/kg) was four times higher than in beach sands (4700-5900 particles/kg), while the lowest abundance was observed in foredune sands (4350 particles/kg). This can be attributed to the low-energy hydrodynamics of tidal flats associated with the cohesive behavior of muddy sediments, which consequently favor trapping and act as the main sink for AMP. Further, coastal processes (waves and currents) drive AMP onshore through sediment transport from the surfzone to the beach, from where the AMP becomes available for onshore eolian transport. Higher AMP abundance (85 particles/L) was observed in the marine water samples compared to the estuarine water samples (35 particles/L). Fibers <1 mm appeared as the predominant AMP in the sediment (99-100 %) and water (80-95 %) samples, primarily consisting of modified cellulose (73 %), dye signature only (16 %), and microplastics (11 %). Consequently, we argue that to fully comprehend the spatial distribution of AMP in coastal sediments and waters, it is crucial to analyze these microparticles from an integrated perspective, primarily considering the hydro-wind dynamics of different coastal morpho-sedimentary compartments combined with sediment grain size.

Study of tropical cyclone wave characteristics based on a hybrid track clustering method

Study of tropical cyclone wave characteristics based on a hybrid track clustering method

Possible Causes for the Unprecedented Low/High Tropical Cyclone Activities in the Northern Pacific/Atlantic in 2023 El Niño

AbstractThis study reported the unprecedented tropical cyclone (TC) activity in the western North Pacific (WNP) and North Atlantic (NA) during the developing year of the 2023/2024 El Niño. The possible causes behind these unusual features were addressed. In contrast to previous El Niño events, an unusual low/high TC genesis number in the WNP/NA was identified during the typhoon season (June–November) in 2023. Meanwhile, the mean TC genesis location in the WNP exhibited a La Niña‐like northwestward shift, rarely observed in an El Niño developing year. An observational diagnosis on TC‐genesis‐related large‐scale dynamics and thermodynamics revealed that the lower/higher TC numbers in the WNP/NA were primarily attributed to an anticyclonic/cyclonic anomaly linked to trans‐basin sea surface temperature anomalies in the tropics and extratropics. Additionally, weaker intraseasonal oscillation activity compared to previous El Niños also partially contributed to fewer TCs in the WNP.

Tropical Cyclone Rainfall Structure and Its Long-Term Trend over the Western North Pacific

Abstract The tropical cyclone (TC) rainfall structure over the western North Pacific is categorized into four typical types. Clusters I and IV are featured by the southward-shifted and northward-shifted rainfall centers, respectively. Meanwhile, clusters II and III are characterized by the weak and strong maximum rainfall rates near the TC center, respectively. Apart from rainfall, clusters I–IV show diverse features in locations, intensities, and lifetime stages. Both clusters I and III appear over the low-latitude regions. However, TCs in cluster III have the strongest intensity and are in the mature stage of their lifetime, while TCs in cluster I are relatively weaker and in earlier stages. On the contrary, cluster IV has the highest mean latitude positions and strong intensity, mainly in their later lifetime period. Cluster II shows the weakest TC intensity and mainly locates in the subtropics. Diverse TC locations lead to different effects of large-scale circulation on TC rainfall patterns in clusters I–IV. For clusters I and III, abundant moisture provided by the southwest monsoon causes heavy rainfall. In contrast, cluster IV is mainly affected by midlatitude westerly troughs, which is responsible for the northward-shifted rainfall center. Cluster II shows the weakest TC intensity, resulting in a small rainfall rate. Further analysis shows that the changes in the relative frequency contributed 36% of the decreasing trend of basin-mean inner-core rainfall during 1998–2019, and the shift of rainfall pattern from cluster III to cluster I due to the enhanced monsoon plays a central role.

Tropical Cyclone Wind Shear-Relative Asymmetry in Reanalyses

Abstract While tropical cyclones (TCs) are axisymmetric vortices to the first order, they often exhibit noteworthy structural asymmetries. These often result from environmental vertical wind shear, which tilts the vortex and induces a wavenumber 1 pattern in the circulation and precipitation fields. Reanalyses and climate models have improved in representing the TC structure and climatology, but their relatively coarse resolution and dependence on parameterized physics cast doubt on their ability to capture the asymmetric TC structure. We perform the most comprehensive process-oriented assessment of TC asymmetry to date in reanalyses. Specifically, we analyze the composite shear-relative TC structure in ERA5 and Climate Forecast System Reanalysis (CFSR), which vary in their resolutions, physical parameterization suites, and data assimilation techniques. These structures are compared with aircraft reconnaissance radar observations. In agreement with the observations, the strongest tangential winds are usually found left-of-shear, while inner core rainfall, ascent, vortex tilt, and low-level inflow are favored directly downshear or in the downshear-left quadrant. Outer rainband convection generally peaks in the downshear-right quadrant. Thermodynamic asymmetries are also apparent, with anomalous low-level moisture right-of-shear, midlevel warmth in the upshear-right quadrant (uptilt), and cloud properties suggestive of a realistic precipitation life cycle from growth to fallout. We also decompose rainfall contributions from the convective parameterization and large-scale cloud schemes and highlight the roles of vorticity advection, buoyancy advection, and diabatic processes in driving asymmetric vertical motions in the inner core and outer rainband regions. Our results suggest that process-level studies of TC asymmetry and TC–wind shear interaction under future warming are viable using climate models. Significance Statement Asymmetries are common in tropical cyclones (TCs), influencing their intensity, track, and hazards. Vertical wind shear often plays a leading-order role in causing these asymmetries. It is uncertain how well asymmetric structures and processes are captured in reanalyses and global climate models (GCMs) with grid spacings of 0.25° and coarser. In this study, we first evaluate TC asymmetry in reanalyses, which have the benefit of being forced by observations. This helps to assess whether the resolutions associated with GCMs sufficiently capture asymmetric structures and processes and motivates upcoming work with free-running GCMs to study how TC asymmetry may change in a warming climate.

Stronger Westerly Wind Bursts in a Warming Climate: The Effects of the Pacific Warming Pattern, the Madden–Julian Oscillation, and Tropical Cyclones

Abstract Westerly wind bursts (WWBs) in the western–central equatorial Pacific are critical in El Niño–Southern Oscillation (ENSO) dynamics. Understanding how they may change with global warming has important implications for future projections of El Niño. In this study, we investigate how the enhanced eastern equatorial Pacific warming pattern, emerging in future climate projections, can influence WWB characteristics in an atmospheric general circulation model, CAM6. Changes in three main factors affecting WWBs—El Niño-conditions mean westerly wind stress anomalies, the Madden–Julian oscillation (MJO), and tropical cyclones (TCs)—are analyzed. We find that during El Niño onset (December–April), the WWB wind stress intensity remains largely unchanged but WWBs shift westward by about 20° of longitude. In contrast, during El Niño development (May–November), the WWB intensity increases by 41% or 79% in two warming scenarios considered [shared socioeconomic pathways (SSP5-8.5) and SSP2-4.5, respectively], which is mainly caused by a higher frequency of TC occurrence in the central tropical Pacific within 15°N/S. Further, we find that westerly wind speed anomalies associated with El Niño and the MJO also increase during El Niño development. However, as trade winds weaken in the central-eastern equatorial Pacific, the mean strength of the resulting westerly wind stress anomalies does not change much, and no significant eastward shift of WWBs is observed. Thus, our atmospheric model simulations suggest a strong TC-driven increase in WWB wind stress anomalies during El Niño development and hence a more important role of TCs in WWB generation, which in a coupled system could lead to stronger ENSO events, enhanced TC–ENSO coupling, and even greater intensification of WWBs.

Projected increase in the frequency of extremely active Atlantic hurricane seasons.

Future changes to the year-to-year swings between active and inactive North Atlantic tropical cyclone (TC) seasons have received little attention, yet may have great societal implications in areas prone to hurricane landfalls. This work investigates past and future changes in North Atlantic TC activity, focusing on interannual variability and evaluating the contributions from anthropogenic forcing. We show that interannual variability of Atlantic TC activity has already increased, evidenced by an increase in the occurrence of both extremely active and inactive TC seasons. TC-resolving general circulation models project a 36% increase in the variance of North Atlantic TC activity, measured by accumulated cyclone energy, by the middle of the 21st century. These changes are the result of increased variability in vertical wind shear and atmospheric stability, in response to enhanced Pacific-to-Atlantic interbasin sea surface temperature variations. Robust anthropogenic-forced intensification in the variability of Atlantic TC activity will continue in the future, with important implications for emergency planning and societal preparedness.

Investigating Tropical Cyclone Warm Core and Boundary Layer Structures with Constellation Observing System for Meteorology, Ionosphere, and Climate 2 Radio Occultation Data

The Constellation Observing System for Meteorology, Ionosphere, and Climate 2 (COSMIC-2) collects data covering latitudes primarily between 40 degrees north and south, providing abundant data for tropical cyclone (TC) research. The radio occultation data provide valuable information on the boundary layer. However, quality control of the data within the boundary layer remains a challenging issue. The aim of this study is to obtain a more accurate COSMIC-2 radio occultation (RO) dataset through quality control (QC) and use this dataset to validate warm core structures and explore the planetary boundary layer (PBL) structures of TCs. In this study, COSMIC-2 data are used to analyze the distribution of the relative local spectral width (LSW) and the confidence parameter characterizing the random error of the bending angle. An LSW less than 20% is set as a data QC threshold, and the warm core and PBL composite structures of TCs at three intensities in the Northwest Pacific Ocean are investigated. We reproduce the warm core intensity and warm core height characteristics of TCs. In the radial direction of the typhoon eyewall, the impact height of the PBL increases from 3.45 km to 4 km, with the tropopause ranging from 160 hPa to 100 hPa. At the bottom of the troposphere, the variations in the positive and negative bias between the RO-detected and background field bending angles correspond well to the PBL heights, and the variations in the positive bias between the RO-detected and background field refractivity reach 14%. This research provides an effective QC method and reveals that the bending angle is sensitive to the PBL height.

The Impacts of Convectively Coupled Equatorial Waves on Extreme Rainfall in Northern Australia

Abstract Convectively coupled equatorial waves (CCEWs) with an off-equatorial convective center, such as equatorial Rossby (ER) waves, mixed Rossby–gravity (MRG) waves, and tropical depression (TD)-type waves, can be the potential sources of predictability for subseasonal to seasonal prediction over northern Australia. To establish the statistical relationship of the wave–rainfall interaction, we investigate the influences of CCEWs on rainfall means and extremes during the austral summer (December–February) and autumn (March–May) from 1981 to 2018. The results show that ER waves increase the average daily rainfall by up to 7 mm day−1 (4 mm day−1) during the austral summer (autumn) and increase the probability of extreme rainfall (above the 90th percentile) by around 1.5–2.4 times (summer) and 1.1–1.8 times (autumn) relative to climatology. MRG and TD-type waves are shown to have a smaller impact, increasing rainfall by around 1–4 mm day−1 (1–1.5 and 1–3 mm day−1) during the summer (autumn) and extreme probability by 1.4–1.6 times and 1.25–1.9 times (1.3–1.8 times and 1.27–1.7 times), respectively. The increase in rainfall can be attributed to the enhancement of moisture convergence during the time of the rainfall. Furthermore, moisture gain and enhancement of moisture advection were found ahead of the convective center. Additionally, we find that interactions between multiple waves can act to amplify or suppress the mean daily and probability of extreme rainfall. This research highlights the important role of CCEWs on northern Australian precipitation variability. Significance Statement This research is the first to delve into the significant role of convectively coupled equatorial waves (CCEWs) on subseasonal rainfall variability over northern Australia, particularly equatorial Rossby (ER) waves, mixed Rossby–gravity (MRG) waves, and tropical-depression-type (TD-type) waves. A robust statistical relationship is found between these waves and rainfall, suggesting these waves are major contributors to increased daily rainfall and extreme rainfall probabilities during austral summer and autumn. These findings emphasize the significance of CCEWs on northern Australian rainfall variability and highlight the potential of CCEWs for subseasonal to seasonal forecasts in Australia.

Impact of tropical cyclones and socioeconomic exposure on flood risk distribution in the Mekong Basin

Impact of tropical cyclones and socioeconomic exposure on flood risk distribution in the Mekong Basin

Factors Affecting the Weakening Rate of Landfalling Tropical Cyclones Over China

Factors Affecting the Weakening Rate of Landfalling Tropical Cyclones Over China

Enhanced Typhoon Center Localization Using Geostationary Satellite Imagery

AbstractAn accurate center localization in near real‐time is critical for tropical cyclone (TC) monitoring and forecasting. This study presents a robust algorithm for localizing typhoon centers using the Chinese geostationary (GEO) meteorological satellite. The results using the Advanced Geostationary Radiation Imager (AGRI) onboard Fengyun‐4A (FY‐4A) satellite data, achieving a mean absolute error (MAE) of 29.4 km across various typhoon intensities in the Western North Pacific, superior to other baseline methods. By harnessing the multi‐spectral imagery from the FY‐4A and incorporating an attention mechanism, it significantly boosts the deep learning convolutional neural network's ability to identify typhoon cloud features and their centers, even during their initial and weakest stages, which is laudable because these are the most difficult for center fixing even for human analysts. Remarkably, it requires just a single moment satellite imagery to locate the center of typhoon, enabling automated updates of the typhoon centers in near real‐time applications.

Assessment of CCMP in Capturing High Winds with Respect to Individual Satellite Datasets

High-wind structures were identified in the Cross-Calibrated Multi-Platform (CCMP) ocean wind vector reanalysis for comparison with winds measured by satellite radiometers, scatterometers, and synthetic aperture radar (SAR) instruments from February to October 2023. The comparison aims to evaluate bias, uncertainty, and spatial correlations with the goal of enhancing the accuracy of ocean wind datasets during tropical cyclones (TCs). In 10° longitude × 10° latitude blocks, each containing a TC, Soil Moisture Active Passive (SMAP) and Advanced Microwave Scanning Radiometer 2 (AMSR2) winds are 6.5 and 4.8% higher than CCMP, while Advanced Scatterometer (ASCATB) is 0.8% lower. For extratropical cyclones, AMSR2 and SMAP also show stronger winds with a 5% difference, and ASCATB is about 0.3% weaker compared to CCMP. The comparison between SAR and CCMP for TC winds, sampled at the locations and time frames of SAR tiles, indicates that SAR winds around TCs are about 9% higher than CCMP winds. Using empirically defined TC structural indices, we find that the TCs observed by CCMP are shifted in locations and lack a compact core region. A Random Forest (RF) regressor was applied to TCs in CCMP with corresponding SAR observations, nearly correcting the full magnitude of low bias in CCMP statistically, with a 15 m/s correction in the core region. The hierarchy of importance among the predictors is as follows: CCMP wind speed (62%), distance of SAR pixels to the eye region (21%) and eye center (7%), and distance of CCMP pixels to the eye region (5%) and eye center (5%).

Augmented reality about Tropical Cyclones in the Dominican Republic: evaluation of learning and cognitive load

Abstract Introduction The Dominican Republic, due to its nature as a Small Island Developing State (SIDS), faces several challenges in the face of extreme weather phenomena such as hurricanes. Therefore, integrating technologies such as Augmented Reality (AR) in teaching these topics in class can influence student motivation and improve learning. Aim This article has three objectives: 1) to evaluate the learning results of the participating students using the pre-test and post-test methodology; 2) to find out the cognitive load it produces in the participating students and 3) to analyze the relationships between the different types of cognitive load. Methodology It has a quantitative approach, with a quasi-experimental design using the pre-test-post-test technique. It was carried out between May and July 2024 and consists of a non-probabilistic sample (N = 45). In addition, the student’s cognitive load was measured when interacting with the AR object, in its three types: internal, external, and relevant. Results When comparing the results of the pre-test and post-test, we obtained average values of 3.84 with a high level of variability and 4.75, with less dispersion in the answers. On the other hand, the cognitive load instrument shows high levels of internal consistency with 0.93 for the total instrument. The strongest correlation, 0.93, was obtained between external cognitive load and mental effort invested. Conclusions The hypothesis has been tested: participating students have better learning outcomes about hurricanes (tropical cyclones) after interacting with the learning object in AR format.

Monitoring Heavy Rainfall Events in East Asia Using High‐Resolution Isotopic Observations

AbstractIt is important to understand the mechanisms of heavy rainfall events, as such information could improve forecasting of these events and help mitigate their adverse impacts on life and property. In this study, we analyzed hourly stable isotopic compositions in water vapor (δ18Ov and d‐excessv) during heavy rainfall events in the summer monsoon season (June to September) from 2013 to 2023 in Nanjing, eastern China. These data were extracted from the longest data set of high‐resolution and continuous in situ observations of water vapor isotopes globally. Based on these data, we identified four evolution patterns of δ18Ov during heavy rainfall events, corresponding to different weather systems: slow‐declining (tropical cyclone interacting with mid‐ and high‐latitude system), W‐shaped (tropical cyclone), U‐shaped (cold vortex system), and inclined L‐shaped (upper‐level trough system). The isotopic variations suggest that heavy rainfall events in eastern China were mainly sustained by moisture from adjacent oceans (including the South China Sea and the East China Sea) and terrestrial environment rather than from the distant Indian Ocean as previously suggested. In addition, for some heavy rainfall events with an intermittent period, the nearby oceanic moisture transport alters before and after the intermittent period due to an intensity change or overall transition of low‐level weather systems. This study serves as a benchmark for tracing heavy rainfall processes in East Asia using high‐resolution water vapor isotopes.

A-PoRM SIPLAS: Assessing The Post-Disaster Recovery Of Mangrove Forest In Siargao Island Protected Landscape And Seascape (SIPLAS) Area Using Sentinel-1 SAR Data

Abstract. Tropical cyclones and typhoons pose significant threats to coastal ecosystems, particularly mangrove forests. Assessing the extent of mangrove damage and monitoring recovery post-disaster is vital for effective conservation and management strategies. Space-based observations have become increasingly common in monitoring forest damage in tropical regions. However, the predominant methods for change detection rely on satellite optical imagery, which faces challenges in humid tropical zones. Technological advancements have led to the development of detection techniques utilizing synthetic aperture radar (SAR) to address cloud cover issues. The study specifically targets Siargao Island Protected Landscape and Seascape (SIPLAS), the largest contiguous forest in the Philippines, from destruction caused by Super typhoon Rai (Odette). The study utilized SAR time-series data, unsupervised log ratio change detection method and Cumulative Sum (CuSum) analysis via Google Earth Engine (GEE). Analysis of Sentinel-1 GRD images found VV polarization had the highest accuracy at 92% and an F-measure of 0.92. VH polarization had 87.5% accuracy and an F-measure of 0.87, while combining VV and VH and VV/VH achieved the same results of 80.5% overall accuracy with an F-measure of 0.82. With that, results indicated that 53% of mangroves in SIPLAS area were damaged, with 38.05% regenerating by 2022 and 56.75% by 2023, notably after September 16, 2022 detected from CuSum analysis using the VV polarization. These findings substantiate the robustness of the data and methodologies employed in monitoring mangrove resilience and supporting conservation initiatives within the SIPLAS area.

Spatial benefit assessment and marine climate response of coastal zone in Fujian Province under cross-system influence.

To gain a scientific understanding of the cross-system impact of coastal zones and promote the sustainable development and protection of coastal areas, we constructed a spatial benefit evaluation system that encompassed both terrestrial and marine systems, focusing on the ecological, economic, and social dimensions. We employed the entropy method, moving average method, and Mann-Kendall trend test to quantitatively characterize the spatial benefits of the coastal zone in Fujian Province, China, and the evolution of the marine climate from 2005 to 2020. Building on this, the grey relational analysis method was applied to investigate the correlation between spatial benefits and marine climate and to explore the trends and magnitude of the impact of marine climate on spatial benefits. During the study period, the spatial benefits of the coastal zone in Fujian Province exhibited a fluctuating pattern of an initial increase followed by a decrease, with spatial benefits varying among cities. The role of the economic system in enhancing spatial benefits was not considerable. Changes in the marine climate aligned with the global warming trend, with the most considerable changes observed in sea level and tropical cyclone frequency and intensity, which are sensitive to human activities. There was a high degree of correlation between coastal zone spatial benefits and marine climate, with seawater salinity being most closely related to spatial benefits, while tropical cyclones showed the weakest correlation. The results of this study support sustainable development efforts in coastal zones.