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Wildfires, and the sediment‐rich floods that commonly follow, increasingly threaten riverine ecosystems and water infrastructure. Suspended sediment exported throughout fire–flood sequences poses particular risks due to rapid transit times and direct impacts on water quality. However, opportunities to measure suspended‐sediment transport during and after post‐fire floods, and therefore to illuminate what controls the magnitude and timing of suspended‐sediment export from burned, flooded watersheds, are rare. A ~ 100‐year flood that occurred one year into a three‐year study monitoring suspended‐sediment response to wildfire in the Colorado Front Range provides a unique opportunity to (1) quantify how suspended‐sediment concentrations and loads change throughout a fire–flood sequence, and (2) infer what controls the timescale over which suspended‐sediment dynamics recover toward pre‐fire conditions. We find that suspended‐sediment concentrations (SSCs) during summer storms declined monotonically to background conditions over 3 years. Snowmelt SSCs peaked in the second year before declining to background levels. Sediment load calculations reveal that the flood exported ~35 years' worth of suspended sediment and triggered ~1.5 years of elevated SSCs and sediment loads. SSCs and sediment loads indicate a fairly short post‐fire recovery timescale of about 3 years. We suggest that the flood accelerated recovery by (1) exporting much of the available suspended sediment from this supply‐limited landscape and (2) facilitating the export of remaining sediment by making it more accessible to subsequent flows. Our results indicate that large post‐wildfire floods, though representing major geomorphic disturbances, may hasten post‐fire suspended‐sediment recovery to background conditions, at least in supply‐limited regions. [ABSTRACT FROM AUTHOR]

A comprehensive statistical study is conducted on O+ and H+ outflows obtained from the TEAMS/FAST data during the 23rd solar cycle (1996–2007). The study investigates interhemispheric asymmetry in ionospheric outflows during local summer, winter, and equinox seasons. Data are classified into two distinct periods: the pre‐storm and geomagnetic storm phases. Numerous statistical asymmetries are identified. The findings indicate that the dayside cusp consistently demonstrates more outflow rates of O+ and H+ in the northern hemisphere than southern hemisphere during geomagnetic storms in all seasons as well as during the pre‐storm period in the summer season with the exception of H+ during summer storms. Conversely, the nightside O+ and H+ outflow rates are higher in the southern hemisphere during pre‐storm and storm periods in the summer season. Additionally, the dawnside and duskside outflow rates of O+ and H+ are predominantly stronger in the southern hemisphere. Plain Language Summary: The Earth's hemispheres receive different solar extreme ultraviolet radiation levels in different local seasons. In addition, there is a displacement between Earth's magnetic and geographic poles. Both mentioned factors cause interhemispheric asymmetries in ionospheric parameters. For the first time, this study investigates asymmetry in O+ and H+ ionospheric outflows between the northern and southern hemispheres by focusing on similar local seasons with comparable solar radiation levels. Data from the FAST/Time‐of‐flight Energy Angle Mass Spectrograph (TEAMS) instrument (1996–2007) are used for storms and pre‐storms. Hemispherical ionospheric outflows are categorized into summer, winter, and equinox and are spatially averaged in the polar regions. Findings reveal asymmetric ion outflows between hemispheres. The dayside cusp outflows are higher in the northern hemisphere than in the southern hemisphere during geomagnetic storms in all seasons except for H+ in summer. Conversely, nightside O+ and H+ outflows are more in the southern hemisphere than in the northern hemisphere during pre‐storm and storm periods in summer. Additionally, in dawnside and duskside, O+ and H+ outflows are predominantly stronger in the southern hemisphere than in the northern hemisphere. Key Points: 11‐year statistics find the northern and southern hemispheres exhibit asymmetric ion outflow even during similar local seasonsDuring storms, the cusp dayside exhibits higher O+ and H+ outflow rates in the northern hemisphere compared to the southern hemisphereThe dawnside and duskside O+ and H+ outflow rates are stronger in the southern hemisphere than in the northern hemisphere [ABSTRACT FROM AUTHOR]

Petrels that breed in burrows and return to their colonies after dark are among the most poorly studied seabirds. Brown Skuas Stercorarius antarcticus (family Stercorariidae) are major predators of burrowing petrels at many seabird breeding islands in the Southern Ocean, so monitoring the diet of skuas can provide insights into petrel population trends. Regurgitated pellets and other prey remains indicate that petrels comprise 94% (monthly range 91–97%) of all prey items in the pellets and other prey remains on Inaccessible Island, Tristan da Cunha. Other seabirds (0.7%), land birds (1.0%), subantarctic fur seals Arctocephalus tropicalis (0.5%) and marine animals (3.5%) make up the remainder of the Brown Skua diet. At least 12 species of petrels are eaten, including two species that are not known to breed on Inaccessible Island, but five taxa comprised over 98% of all petrels eaten: Fregetta storm petrels (44%), White-faced Storm Petrels Pelagodroma marina (23%), Broad-billed Prions Pachyptila vittata (21%), Great Shearwaters Ardenna gravis (6%) and Common Diving Petrels Pelecanoides urinatrix (5%). Pellets containing 2 or 3 avian prey items (15% of pellets) were more likely to contain conspecifics than heterospecifics, indicating either local differences in prey distribution or individual dietary specialisation. The prey composition changed seasonally linked to the phenology of the prey species, with White-faced Storm Petrels more common in the skua diet in spring, and Fregetta storm petrels in summer. Fur seals and Great Shearwaters have become more important in the skua diet, reflecting known or suspected increases in the populations of these species on the island, whereas the populations of Common Diving Petrels and Subantarctic Shearwaters Puffinus elegans may have decreased. Modal tarsal length of Fregetta storm petrels changed from 37 mm in 1987/89 to 39 mm in 2009, suggesting a possible increase of F. tropica relative to F. grallaria in the skua diet. However, overall there has been little change in the diet of Brown Skuas on this island over the last four decades. [ABSTRACT FROM AUTHOR]

West African Sahel extreme rainfall events cause flooding and property damage, and some areas are more prone to their occurrence. One favorable region is southwestern Mali. NASA IMERG precipitation and ERA5 reanalysis data are used to examine the most extreme boreal summer rainfall events from 2000 – 2019 over southwestern Mali to understand why they form, and to explain why this region has frequent activity. Events are sorted into 4 types based on the timing of the peak rainfall (before or after 00Z) and the associated mid-tropospheric circulation pattern (coastal low or ridge). The coastal low types are associated not with an increase of the low-level inflow of moisture into southwestern Mali, but a weakening of the mid-level westward transport of moisture out of the region. The timing and longevity of the event depends on whether there is a second low to the east in the southern storm track. The coastal ridge types are associated with a build-up of warm, dry air over the western Sahara that leads to a stronger temperature inversion cap over southwestern Mali, allowing instability to build beneath the cap. How fast the cap dissipates and whether there is synoptic activity to the east in the southern or northern storm track determines when convective activity occurs. Thus, southwestern Mali is exposed to coastal lows and ridges in addition to the Saharan heat low and the summer southern storm track for African easterly wave disturbances. The confluence of these factors makes southwestern Mali a region conducive for convective rainfall activity. [ABSTRACT FROM AUTHOR]

Convective storms represent a dangerous atmospheric phenomenon, particularly for the heavy and concentrated precipitation they can trigger. Given their high velocity and variability, their prediction is challenging, though it is crucial to issue reliable alarms. The paper presents a neural network approach to forecast the convective cell trajectory and intensity, using, as an example, a region in northern Italy that is frequently hit by convective storms in spring and summer. The predictor input is constituted by radar-derived information about the center of gravity of the cell, its reflectivity (a proxy for the intensity of the precipitation), and the area affected by the storm. The essential characteristic of the proposed approach is that the neural network directly forecasts the evolution of the convective cell position and of the other features for the following hour at a 5-min temporal resolution without a relevant loss of accuracy in comparison to predictors trained for each specific variable at a particular time step. Besides its accuracy ( R 2 of the position is about 0.80 one hour in advance), this machine learning approach has clear advantages over the classical numerical weather predictors since it runs at orders of magnitude more rapidly, thus allowing for the implementation of a real-time early-warning system. [ABSTRACT FROM AUTHOR]

Anthropogenic warming can alter large-scale circulation patterns in the atmosphere, which could have serious consequences for regional climate impacts and extreme weather. Observed thermodynamic changes in boreal extratropics have been attributed to human emissions with high confidence, but most circulation changes have not. In particular, not only that in the previous suite of climate models most models do not capture the recent boreal summer storm tracks weakening, but also a quantification of the role of human emissions in the recent storm tracks weakening has not been conducted to date. Here we use the latest suite of climate models, which are found to adequately capture the recent storm tracks weakening, and show that this weakening is attributable to anthropogenic emissions. Human emissions have resulted in more-rapid warming of the high latitudes, and the associated reduction in poleward temperature gradient has weakened the storms. The physical consistency between models and reanalyses increases our confidence in the projected weakening, which presents regional risks including hot-dry extremes in summer. [ABSTRACT FROM AUTHOR]

Copyright of Gozdarski Vestnik is the property of Federation of Forestry Associations of Slovenia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Hydrology and meteorological data from relatively undisturbed watersheds aid in identifying effects on ecosystem services, tracking hydroclimatic trends, and reducing model uncertainties. Sustainable forest, water, and infrastructure management depends on assessing the impacts of extreme events and land use change on flooding, droughts, and biogeochemical processes. For example, global climate models predict more frequent high-intensity storms and longer dry periods for the southeastern USA. We summarized 17 years (2005–2021) of hydrometeorological data recorded in the 52 km2, third-order Turkey Creek watershed at the Santee Experimental Forest (SEF), Southeastern Coastal Plain, USA. This is a non-tidal headwater system of the Charleston Harbor estuary. The study period included a wide range of weather conditions; annual precipitation (P) and potential evapotranspiration (PET) ranged from 994 mm and 1212 mm in 2007 to 2243 mm and 1063 in 2015, respectively. The annual runoff coefficient (ROC) varied from 0.09 in 2007 (with water table (WT) as deep as 2.4 m below surface) to 0.52 in 2015 (with frequently ponded WT conditions), with an average of 0.22. Although the average P (1470 mm) was 11% higher than the historic 1964–1976 average (1320 mm), no significant (α= 0.05) trend was found in the annual P (p = 0.11), ROC (p = 0.17) or runoff (p = 0.27). Runoff occurred on 76.4% of all days in the study period, exceeding 20 mm/day for 1.25% of all days, mostly due to intense storms in the summer and lower ET demand in the winter. No-flow conditions were common during most of the summer growing season. WT recharge occurred during water-surplus conditions, and storm-event base flow contributed 23–47% of the total runoff as estimated using a hydrograph separation method. Storm-event peak discharge in the Turkey Creek was dominated by shallow subsurface runoff and was correlated with 48 h precipitation totals. Estimated precipitation intensity–duration–frequency and flood frequency relationships were found to be larger than those found by NOAA for the 1893–2002 period (for durations ≥ 3 h), and by USGS regional frequencies (for ≥10-year return intervals), respectively, for the same location. We recommend an integrated analysis of these data together with available water quality data to (1) assess the impacts of rising tides on the hydroperiod and biogeochemical processes in riparian forests of the estuary headwaters, (2) validate rainfall–runoff models including watershed scale models to assess land use and climate change on hydrology and water quality, and (3) inform watershed restoration goals, strategies, and infrastructure design in coastal watersheds. [ABSTRACT FROM AUTHOR]

Arctic cyclone activity is an important component of the local climate, and the frequent occurrence of extreme summer storms has raised widespread scientific interest. In this paper, we investigated the distinctive structural characteristics of intense summer Arctic cyclones by utilizing ERA‐Interim reanalysis data and employing a deep learning algorithm for cyclone detection. We found that the northern edge of Eurasia (i.e., the marginal ice zone (MIZ)) and the Alpha Ridge of Arctic Ocean (AR, i.e. central Arctic) are the two most active regions for intense Arctic cyclone activities in summer (from June to September). However, the surface conditions and coupling frequency between surface cyclone and tropopause polar vortices (TPVs) are distinct over these two regions. By further analysis of 100 intense cyclone activities in these two areas, respectively, we found that cyclones in MIZ are often smaller in size but higher in intensity at their maximum intensity, and their life cycles are generally shorter. MIZ cyclones are typically accompanied by a large Eady growth rate and frontal structure in the lower troposphere and their intensification primarily attributed to the thermal‐baroclinic process. In contrast, cyclones in AR are more frequently associated with higher potential vorticity (PV) values and pronounced PV downward intrusion from the stratosphere, as well as notable "upper warm‐lower cold" structures. The downward intrusion of TPVs and stratosphere vortices contribute to a decrease in the upper and column air mass deficit, leading to the intensification of surface Arctic cyclones in these regions. Plain Language Summary: In this study, we researched intense summer storms in the Arctic. We found that there are two main areas where these storms occur: the marginal ice zone (MIZ) near Eurasia and the Alpha Ridge (AR) in the central Arctic. However, storms in these two areas have different characteristics. In the MIZ, the storms are smaller but stronger, and they do not last as long. They are mainly driven by instability in the lower troposphere. On the other hand, the storms in AR respond more to the downward intrusion of potential vorticity from the stratosphere. These storms have a unique structure where the upper air is warmer than their surroundings, and the lower air is colder than their surroundings, especially in AR. This structure makes them more intense and longer‐lasting. Exploring these differences helps us understand how Arctic storms work, and how they might be affected by climate change. Key Points: Both the marginal ice zone (MIZ) and Alpha Ridge exhibit active summer Arctic cyclone activities, especially for intense stormsIn the MIZ, baroclinic instability plays a more prominent role in the intensification and maintenance of cyclonesCyclones in Alpha Ridge are more commonly accompanied by potential vorticity downward intrusion, and "upper warm‐lower cold" structures [ABSTRACT FROM AUTHOR]

We report on the mountain top observation of three terrestrial gamma‐ray flashes (TGFs) that occurred during the summer storm season of 2021. To our knowledge, these are the first TGFs observed in a mountaintop environment and the first published European TGFs observed from the ground. A gamma‐ray sensitive detector was located at the base of the Säntis Tower in Switzerland and observed three unique TGF events with coincident radio sferic data characteristic of TGFs seen from space. We will show an example of a "slow pulse" radio signature (Cummer et al., 2011, https://doi.org/10.1029/2011GL048099; Lu et al., 2011, https://doi.org/10.1029/2010JA016141; Pu et al., 2019, https://doi.org/10.1029/2019GL082743; Pu et al., 2020, https://doi.org/10.1029/2020GL089427), a −EIP (Lyu et al., 2016, https://doi.org/10.1002/2016GL070154; Lyu et al., 2021, https://doi.org/10.1029/2021GL093627; Wada et al., 2020, https://doi.org/10.1029/2019JD031730), and a double peak TGF associated with an extraordinarily powerful and complicated positive‐polarity sferic, where each TGF peak is possibly preceded by a short burst of stepped leader emission. Plain Language Summary: We present the first report of mountain top observations of terrestrial gamma‐ray flashes (TGFs) that occurred during the summer storm season of 2021. A gamma‐ray sensitive detector was placed at the base of the Säntis Tower in Switzerland and detected three distinct TGF events. Each event is associated with a coincident lightning flash. We analyze the radio emission of the associated lightning flash and make comparisons with previously published associations between TGFs and certain radio sferics. Additionally, one of the observed TGFs is likely a two‐pulse event where each gamma‐ray peak may be preceded in time by a brief burst of X‐ray stepped leader emission. Key Points: First terrestrial gamma ray flashe (TGF) observations from a mountaintopFirst ground observation of a TGF associated with a "slow pulse" radio sfericPossible stepped leader X‐rays preceding a double pulsed TGF [ABSTRACT FROM AUTHOR]

In this study, new and traditional organic wastes (green waste compost, farmyard manure (FYM), anaerobic digestate or straw) were ploughed into an arable field experiment at a range of rates (1-3 t C ha-1) and under spring and winter cropping rotations for 5 years. The stability of the soil surface structure (<5 cm) was assessed in Years 3, 4 and 5 to guide the use of organic wastes in arable field management. Aggregate stability was determined by immersing each soil sample in water (fast-wetting test, relevance to summer storms) and measuring the size distribution of the aggregates (mean weight diameter, MWD). The MWD value was compared with the different classes of aggregate stability (very stable, stable, medium, unstable or very unstable) to classify each result. All the arable field samples were classified as unstable, and there were no significant differences (p > .05) in MWD after any treatment. Potentially, this approach is too imprecise to detect differences, so porescale analyses using CT scanning were used. There were no significant differences in porosity or pore shape (features associated with microbial activity) between the control and organic waste treatments. The results contradicted published data from the Broadbalk experiment (established in 1843), which was the basis for this study, so its soils were studied to understand this discrepancy. Broadbalk soils were classified as unstable, including soils treated with annual FYM applications. Instead, we found a significant relationship between MWD and clay content and previous interpretations had not taken this variable (23%-39% clay content) texture into consideration. In conclusion, to achieve a stable soil surface structure, a 150% improvement in aggregate stability would be needed here and ploughing in organic wastes was not a successful management approach on these arable field experiments. [ABSTRACT FROM AUTHOR]

An operational hail suppression program has been based in Romania since 2005. The program is designed to reduce hail damage in the most vulnerable agricultural areas (protected areas) of the country. An exploratory analysis of volume-scan, S-band and C-band radars data, using a storm cell tracking software, was conducted to calculate six radar-derived parameters associated with hail from 51 seeded storms during the summers of 2017 to 2022. All selected hailstorms had a lifetime of more than one hour, which was divided into three stages: before seeding, during seeding, and after seeding. The statistical t-test was used to test the null hypothesis of no seeding effect. Comparing values before seeding and during seeding, the data support claims that seeding causes an increase in most of the analysed parameters. These can indicate the stimulation of the development of seeded clouds, due to the so-called dynamic effect. After seeding, a decrease in the values of all the parameters analysed was observed (with decreases in average values ranging between 10% to 15%). Furthermore, a spatial analysis of hail kinetic energy shows that areas with values over 300 J/m2 are lower in the protected areas compared to the neighbouring ones where the clouds have not been seeded. [ABSTRACT FROM AUTHOR]

Stable water isotopes are naturally occurring conservative tracers that can 'fingerprint' water sources and track ecohydrological fluxes across the critical zone (CZ). Parsimonious, tracer‐aided models allow effective quantification of the ecohydrological partitioning of rainfall into different water fluxes. We incorporated stable water isotopes into a one‐dimensional, tracer‐aided model (EcoIsoPlot) to follow the pathway of precipitation through the CZ at a lowland catchment—the long‐term experimental Demnitzer Millcreek Catchment (DMC), Germany—with contrasting vegetation covers (forest, agroforestry, grassland and arable). Precipitation (amount and δ2H), potential evapotranspiration (PET), leaf area index (LAI), air temperature and relative humidity were used as input data for modelling the growing season of 2021. The year had relatively average overall wetness, but a dry, cold spring with snowfall, and an exceptionally large summer storm event (~60 mm precipitation). Multi‐criteria calibration of the model was conducted using depth‐specific soil moisture and soil water δ2H measurements as targets. The novel incorporation of isotopes into model calibration constrained process representation of the estimated water balance with reasonable simulations and uncertainty bounds for water partitioning. Throughout the soil profile, soil moisture dynamics and stable water isotope variations were captured reasonably well. Green water fluxes (evapotranspiration) were highest at the forest site and blue water fluxes (groundwater recharge) highest at the grassland. Comparing simulations with estimated potential evapotranspiration (ET) and measured groundwater table fluctuations added further confidence to the modelling result. Overall, these may suggest a slight underestimation of ET and slight overestimation of recharge, though the results are similar to previous findings. Our study demonstrated the potential of stable water isotope data to enhance relatively simple, transferrable approaches to ecohydrological modelling of water fluxes in the CZ and to help improve model consistency. Such low‐parameterised tracer‐aided models have major potential for evidence‐based applications to aid management and help stakeholder communication. [ABSTRACT FROM AUTHOR]

In recent decades, the Arctic minimum sea ice extent has transitioned from a predominantly thick multiyear ice cover to a thinner seasonal ice cover. We partition the total (observed) Arctic summer area loss into thermodynamic and dynamic (convergence, ridging, and export) sea ice area loss during the satellite era from 1979 to 2021 using a Lagrangian sea ice tracking model driven by satellite-derived sea ice velocities. Results show that the thermodynamic signal dominates the total summer ice area loss and the dynamic signal remains small (∼20%) even in 2007 when dynamic loss was largest. Sea ice loss by compaction (within pack ice convergence) dominates the dynamic area loss, even in years when the export is largest. Results from a simple (Ekman) free-drift sea ice model, supported by results from the Lagrangian model, suggest that nonlinear effects between dynamic and thermodynamic area loss can be important for large negative anomalies in sea ice extent, in accord with previous modeling studies. A detailed analysis of two all-time record minimum years (2007 and 2012)—one with a semipermanent high in the southern Beaufort Sea and the other with a short-lived but extreme storm in the Pacific sector of the Arctic in late summer—shows that compaction by Ekman convergence together with large thermodynamic melt in the marginal ice zone dominated the sea ice area loss in 2007 whereas, in 2012, it was dominated by Ekman divergence amplified by sea–ice albedo feedback—together with an early melt onset. We argue that Ekman divergence from more intense summer storms when the sun is high above the horizon is a more likely mechanism for a "first-time" ice-free Arctic. [ABSTRACT FROM AUTHOR]

Short‐term increases in stream temperature in response to storm events have frequently been observed in urban areas, highlighting the need for improved understanding of the factors influencing urban stream temperature. Urban land cover complexity and infrastructure designed for rapid water routing to the sewer system create a direct link between storm events and water release processes, influencing urban stream temperature responses. This study aims to identify predictors of diverse stream temperature response patterns to summer storms. We analysed 403 storm events from six urban and semi‐urban catchments along the US East Coast using dynamic time warping to identify archetype patterns of stream temperature responses. We further disentangled observed stream temperature increase patterns to reveal the drivers associated with 'heat pulses', which are characterized by a rapid but high‐magnitude temperature increase followed by a sharp temperature drop at the start of the hydrograph increase. Our results show that stream temperature patterns were event‐specific and linked to pre‐event conditions and rainfall–runoff characteristics, with the shape of the hydrograph and rainfall–runoff response identified as the most important determinators of the observed temperature response patterns. Ponded surface waters and storm drains, as well as cooler water from the shallow subsurface, were identified as potential sources contributing to temperature patterns. These findings have important implications for understanding urban hydrology and the contributions of different source zones in urban catchments. Specifically, our results suggest that stream temperature may serve as a cost‐effective tracer providing information about urban water sources and pathways, thus aiding in the understanding of complex urban hydrology. [ABSTRACT FROM AUTHOR]

Determining the mechanisms of runoff generation is essential to land and water resource conservation, but lateral flow processes in high‐relief mountain areas remain unclear due to the difficulty to observe and measure these processes. This study demonstrates that lateral flow in bedrock dominates both high and low flows in a catchment underlain with permeable sedimentary bedrock in the high‐relief Chichibu Mountains. Through measurement of precipitation, discharge, soil, and stream temperatures and tracers (SiO2 and δ18O) in the first‐order stream Bakemonozawa (0.51 km2) and comparison of its water balance with the nested Kawamata catchment (93.58 km2) i, we showed that 831–1012 mm/year or 47%–53% of annual precipitation leaked from Bakemonozawa. The streamflow was discharged from an average depth of 2.3 m or deeper, which were deeper than the measured deepest soil near the gauge. Furthermore, stream temperature decreased significantly during a large summer storm, demonstrating that the relative contribution of the deep bedrock flowpath increased. Large isotopic variation in precipitation was dampened in the stream, suggesting that most baseflow and some higher flows arose from groundwater storage with a constant isotopic ratio due to dispersion and mixing. The discharge–SiO2 relationship suggested at least two groundwater sources, namely, shallow and deep bedrock groundwater, with different runoff responses. Discharge increased dramatically when the catchment became wet, coinciding with the deep bedrock groundwater contribution. Further research is needed to clarify the hydrological characteristics of bedrock. [ABSTRACT FROM AUTHOR]

The scarcity of high‐resolution palaeoclimate records from the interior of West Asia has limited our understanding of the mechanisms of past climate change and their potential impacts on early human societies of the Eastern Fertile Crescent. Here, we present a multiproxy sedimentological, geochemical and palynological record from the Hashilan Wetland in the central Zagros Mountains, spanning the time interval from 22 to 2.2 kcal bp. Our results indicate a cold, dry climate for the last deglaciation (22 to 10 kcal bp) with amplified aridity during the Last Glacial Maximum, Heinrich Stadial 1, the Younger Dryas and the 8.2 and 3.2 ka events. The Early Holocene (11.6 to 7.8 kcal bp) is characterised by prolonged dry summers, frequent spring/summer dust storms and restricted oak woodlands that gradually expanded as summers shortened toward the second half of the Holocene (<6 kcal bp). We show an out‐of‐phase Holocene moisture variation between the interior of West Asia and the Indian Summer Monsoon domain and conclude that summer insolation‐driven latitudinal shifts of the Hadley cell played a key role in seasonality changes in the interior of West Asia by modulating the strength and pathway of the subtropical high‐pressure cells. Finally, we explore possible impacts of these changes on regional prehistoric human communities. [ABSTRACT FROM AUTHOR]

The study analyses a winter thunderstorm that passed over the Milesovka meteorological observatory on 4 February 2022, between 2300 and 2330 UTC. Lightning was recorded directly over the observatory by both the observer and the EUCLID lightning network at 2320 UTC. To analyse the state of the atmosphere at the time when the lightning occurred, we used data from the X-band Doppler polarimetric radar and the Ka-band Doppler polarimetric vertical profiler, both located at the observatory. We also applied data from the Meteosat Second Generation satellite, and data from standard meteorological instruments located at the observatory. In addition, we run our cloud electrification model to simulate cloud electrification of the winter thunderstorm to find out whether the model develops conditions suitable for the occurrence of lightning and if so, under what circumstances. Our results show that the lightning appeared at the very end of the storm passage defined by high radar reflectivity. At the same time, it is clear from the radar observations that before lightning occurred, the cloud contained hydrometeors (graupel, cloud or rain water, and ice or snow) which are commonly associated with charge separation by collisions. Our analysis of the radar data also suggests that in at least several parts of the cloud the electric field was strong. Although the cloud top height was very low compared to summer storms, the model results indicate conditions suitable for lightning occurrence. However, uncertainty remains on how to properly formulate the initial conditions for model simulations for this type of storm which was shallow and occurs rarely in winter. [ABSTRACT FROM AUTHOR]

We applied the Kentucky Mesonet (mesoscale network) system for a statewide spatial and seasonal analysis of key erosive storm characteristics (total storm precipitation, duration, maximum intensity and erosivity). Storm intensity and erosivity Maximum 5-min intensities were generally greater during the summer, corresponding to the more active convective season with shorter storm durations typically associated with more intense rainfall output (Figure 6). For example, two storms of different durations generating the same rainfall amount may still produce similar total storm erosivity measures if the longer storm experienced a shorter period of intense rainfall within the overall storm rainfall distribution, compared to a shorter storm with an even distribution of rainfall. [Extracted from the article]

Copyright of Arid Zone Research / Ganhanqu Yanjiu is the property of Arid Zone Research Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A poem "Poetry and Medicine: Through the Holland Tunnel" by Rainer Maria Rilke. First line: She drove the Oldsmobile Ninety-Eight, Last line: just like that— in the blink of an eye.

Non‐perennial headwaters experience extremes in flow conditions that likely influence carbon fate. As surface waters contract through dry periods, reconnect during storms, and re‐expand or dry again, there is a great deal of variability in carbon emissions and export. We measured discharge, dissolved oxygen, carbon dioxide (CO2), and dissolved organic carbon (DOC) continuously in a persistent pool at the base of a non‐perennial, forested headwater stream in the southeastern United States to characterize how flow changes affect carbon emissions and export as the stream expands and shrinks. We also compared carbon concentrations and export during different stream flow categories before and after fall wet‐up. CO2 concentrations were high when discharge was lowest (median = 10.2 mg L−1) and low during high flows (3.2 mg L−1) and storms (1.1 mg L−1). High CO2 concentrations led to high emissions on a per area basis during low flow times, but whole‐channel stream CO2 emissions were limited by the small surface area of the stream during periods of surface water disconnection. DOC concentration varied by season (range = 0.1–16.2 mg L−1) with large pulses during smaller summer storms. We found that CO2 and DOC concentrations differed among binned stages of stream flow. As non‐perennial streams become more prevalent across the southeastern United States due to shifts in climate, the relationships between flow and carbon movement into and out of stream networks will become increasingly critical to understanding stream carbon biogeochemistry. Plain Language Summary: Non‐perennial streams lack continuously flowing surface water. We studied the movement of carbon through a forested non‐perennial headwater stream in the mountains of the southeastern United States. The stream channel was nearly empty at certain times in summer and early fall, when surface water was reduced to small pools, but storms could briefly cause the stream to flow again. These cycles of drying and rewetting influence concentrations of carbon dioxide gas and organic carbon dissolved in the stream water. As the stream dried up, oxygen decreased and carbon dioxide increased. When a storm occurred, much of the carbon dioxide in the stream was emitted into the atmosphere as water turbulence increased. Dissolved organic carbon was almost always very low, but storms sent large amounts of carbon downstream very quickly. Categorizing different levels of stream flow also helped explain how carbon cycles through a non‐perennial stream because distinct low flow phases varied in carbon concentration and transfer to downstream ecosystems. Non‐perennial streams are predicted to become more common as climate change affects precipitation patterns, so tracking how carbon moves into and out of streams that dry up and rewet will improve our understanding of freshwater contributions to the global carbon cycle. Key Points: Surface water disconnection led to high CO2 concentrations and emissionsDissolved organic carbon was low, except when storm pulses first reconnected surface water fragments with C sources within and beyond the stream channelInterim flows generated distinct C dynamics; focusing on only flowing or fragmented states likely misses key biogeochemical transitions [ABSTRACT FROM AUTHOR]

Copyright of Studia Universitatis Babes-Bolyai, Philologia is the property of Babes-Bolyai University, Cluj-Napoca, Romania and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

We studied the responses of the ionosphere over the southern and northern African sector. A RINEX formatted TEC data obtained from the global positioning system (GPS) was used to study the impact of geomagnetic storms of 23rd June and 20th December on a South African station, SUTM (33.97°N, 6.84°W) and a Moroccan station, RABT (32.41°S, 38.75°E). The storms which occurred in summer and winter (solstice months) were quantified using the Dst data from World Data Center, Kyoto, Japan. The results showed obvious hemispheric and seasonal influences on ionospheric responses to the geomagnetic storms. The substorm-time responses of the ionosphere were always positive across the stations and seasons. This is a result of increased particle and energy depositions occasioned by the proton density (PD). The rates of energy and particles intensifications during substorms were higher in the summer storm event than in winter for both stations. In other words, there was no hemispheric asymmetry observed. In addition to the storm onset time, its peak time and hemispheric location are crucial in storm-time ionospheric responses. Local timing of the orientations of the prompt penetration and disturbance dynamo electric fields during northward interplanetary magnetic fields determined the nature of ionospheric responses in the day and night sides. These results contribute to our understanding of the dynamics and complexities of the ionosphere over African mid latitude ionosphere. [ABSTRACT FROM AUTHOR]

The Predicted Particle Properties (P3) bulk microphysics scheme has been recently modified to combine the two major innovations. The triple‐moment approach to represent ice, allowing for a freely evolving spectral dispersion of the size distribution, is combined with the predicted liquid fraction, which enables an explicit representation of mixed‐phase particles. The impacts of this combination are examined in the context of high‐resolution (1‐km horizontal grid spacing) simulations of an observed mid‐latitude squall line using the Global Environmental Multiscale atmospheric model. The simulation of mixed‐phase particles results in a faster squall line propagation speed and stronger cold pool due to greater cooling from the microphysical processes of sublimation, melting and evaporation. There is a reduction in the mass of ice reaching the surface resulting from a decrease in the mean size of melting ice particles aloft with the predicted liquid fraction. Compared to the original double‐moment configuration, triple‐moment P3 configuration results in larger mean ice sizes at the surface. The reflectivity structure is improved with the new version, now with a more pronounced bright band in the melting zone with the predicted liquid fraction. Plain Language Summary: This article describes two major upgrades to a cloud microphysics scheme, which is a component of an atmospheric model that simulates the effects of cloud and precipitation processes. The first change allows for a more flexible representation of ice particles sizes; the second enables the representation of mixed‐phase (ice plus water) particles. The impacts of these changes are examined in the context of numerical simulations of a real‐case summer convective storm (squall line) using a weather prediction model. The modified cloud scheme results in faster movement of the model storm due to changes to in‐cloud microphysical processes, which affect the local air movement. There is also a reduction of ice amounts reaching the surface due to a decrease in the mean ice particle size. The model radar reflectivity structure is notably improved, in particular in the region of melting ice. Key Points: Recent changes to the Predicted Particle Properties (P3) microphysics scheme combine triple‐moment ice with a predicted liquid fraction of mixed‐phase hydrometeorsFor a simulated squall line, the changes to P3 reduce the ice accumulation at the surface and increase the cold pool strength and speedThe simulated reflectivity structure, including the bright band, improves with the new configurations [ABSTRACT FROM AUTHOR]

Bioretention is widely used in urban sustainable stormwater management; however, limited numerical research has been conducted on its performance in cold regions, particularly for winter snowmelt, spring runoff and summer large storms (>50 mm) for urban flood mitigation. In this study, HYDRUS 1D was used to explore these knowledge gaps. The model was comprehensively calibrated and validated against 2‐year hydrologic and water quality data of four bioretention columns with different designs under lab‐simulated cold region conditions. The Morris method was used to measure the sensitivity and interaction of the calibrated hydraulic parameters. The model revealed that the effective hydraulic conductivity (KS) values of the soil media were similar for winter snowmelt and spring runoff when the soil temperature was around −0.5°C. Preferential flow is likely to occur in soil media during winter or spring in cold regions. The summer modelling showed that bioretention could substantially reduce peak flow, ponding depth and duration for large storm events (even for a 1:100 local storm with 83.4 mm in 4 h). The water quality modelling confirmed experimental results that the bioretention effectively removed phosphate and ammonium but had leaching issues for chloride and nitrate. Finally, optimization and recommendations for bioretention columns were provided. [ABSTRACT FROM AUTHOR]

Based on the standardized precipitation evaporation index and reanalysis data, this article reveals that the relationship between the North Pacific Oscillation (NPO) and the drought over southern China in summer shifts from an insignificant correlation to a significant negative correlation after 2000. During the significant period (2001–2018), the positive NPO phase corresponds to an anomalous anticyclonic circulation dominating the mid‐low latitude North Pacific, which suppresses the moisture transport into southern China. Meanwhile, the easterly anomalies south of the anomalous anticyclonic circulation prevailing in the equatorial Pacific are coupled with a cooling of sea surface temperature in the central tropical Pacific, which enhances the Walker circulation and further induces an anomalous meridional circulation with the descending anomalies over southern China. Such moisture and dynamical conditions favor the occurrence of drought in southern China. During the former period (1983–2000), however, the NPO‐related atmospheric circulations over the North Pacific shift northward. In this case, the NPO shows insignificant relations with the moisture and dynamical conditions over southern China, thereby diluting the linkage of the NPO to the drought in southern China. The interdecadal strengthening in the relationship between the NPO and above atmospheric conditions is attributed to the westward (southward) extension of the NPO northern (southern) center. The larger interannual variability of spring sea ice in the Bering Sea and the southward movement of summer storm track over the North Pacific are hypothesized to account for the expansion of the NPO structure. Plain Language Summary: Southern China is an economically developed region with a large population. In recent decades, droughts frequently occurred in this region and severely affected agriculture production, forest‐fire prevention, and human lives. Therefore, it is very necessary to understand the physical mechanisms underlying the variability of droughts in southern China. In this study, we addressed the relationship of summer drought in southern China with the North Pacific Oscillation (NPO), which is characterized by the north–south seesaw pattern in sea level pressure over the North Pacific. We revealed that their relationship exhibits an interdecadal change around 2000, from an insignificant correlation to a significant negative correlation. Such an interdecadal strengthening is due to the expansion of the NPO structure, which may result from the changes of the spring sea ice in the Bering Sea and the summer storm track over the North Pacific. These findings are expected to deepen our understanding for the variation of drought in southern China and are also important for disaster prevention and mitigation. Key Points: Relationship between the summer drought in southern China and the North Pacific Oscillation (NPO) has strengthened after 2000Such a strengthening is attributed to the westward (southward) extension of the NPO northern (southern) centerThe expansion of the NPO structure is related to changes of spring sea ice in the Bering Sea and summer storm track over the North Pacific [ABSTRACT FROM AUTHOR]

The poem "Haiku" by Rika Inami is presented. First Line: After a summer storm; Last Line: Maiden of Fall.

Copyright of Iraqi Journal of Physics is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Synoptic-scale cyclones in the Arctic are an important source of short-term sea ice variability during the melt season. This study examines whether recent changes to the Arctic environment have made Arctic cyclones during the summer months more destructive to sea ice on short time scales. We compare the 1–7-day changes in sea ice area and thickness following days in each month with and without cyclones from two decades: 1991–2000 and 2009–18. Only in August do cyclones locally accelerate seasonal sea ice loss on average, and the ability of August cyclones to accelerate ice loss has become more pronounced in the recent decade. The recent increase in ice loss following August cyclones is most evident in the Amerasian Arctic (140°E–120°W), where reanalyses indicate that the average upper-ocean temperature has increased by 0.2°–0.8°C and the average ice thickness has decreased by almost 1 m between the two decades. Such changes promote cyclone-induced ocean mixing and sea ice divergence that locally increase the likelihood for rapid ice loss near cyclones. In contrast, June cyclones in both decades locally slow down seasonal sea ice loss. Moreover, the 7-day sea ice loss in June has increased from the early to the recent decade by 67% more in the absence of cyclones than in the presence of cyclones. The largest increases in June ice loss occur in the Eurasian Arctic (0°–140°E), where substantial reductions in average surface albedo in the recent decade have allowed more of the abundant insolation in the absence of cyclones to be absorbed at the sea surface. Significance Statement: This study determines whether Arctic storms during summer have become more destructive to sea ice in recent years. In comparing storms from two periods (1991–2000 vs 2009–18), we find that only storms in August have become more destructive to sea ice in the recent period, because of warmer upper-ocean temperatures and thinner ice, which strong winds move around more easily. In June, clear-sky conditions have become more destructive to sea ice in recent years because declining ice cover has allowed more sunlight to be absorbed at the sea surface, favoring further ice melt. These results suggest that sunny conditions in June followed by stormy conditions in August could cause the first ice-free summer in the Arctic. [ABSTRACT FROM AUTHOR]

The Lidar on the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) mission, makes robust measurements of dust and has generated a record that is significant both seasonally and interannually. We exploit this record to determine the properties of dust emanating from different source types during sand and dust storms (SDS). We use the relevant browsed images to describe the characteristics of the SDS layers qualitatively and the average properties quantitatively. In particular, we examine dust optical depths, dust layer frequencies, and layer heights during three sandstorms. The data are screened by using standard CALIPSO quality-assurance flags, cloud aerosol discrimination (CAD) scores, overlying features, and layer properties. To evaluate the effects of the SDS origin, phenomena such as morphology, vertical extent, and size of the dust layers, we compare probability distribution functions of the layer integrated volume depolarization ratios, geometric depths, and integrated attenuated color ratios as a function of source type. This study includes 17 individual dust storm cases observed near the city of Kuwait from three categories of sources: single source, combined sources, and unspecified sources. The strongest dust storms occurred in the summer months. The dust layers reached the highest altitudes for the combined cases. The layer top altitudes were approximately 3 km for the SDS from unspecified and single sources whereas the layer top altitudes averaged 4.1 km for the SDS from combined sources. Particles from single and combined sources recorded depolarization ratios of 0.22 and 0.23, respectively, whereas the depolarization ratios of SDS particles from unspecified sources were noticeably lower at 0.17. SDS from single sources resulted in the highest average AOD (0.66) whereas the SDS from combined sources and unspecified sources resulted in AODs of 0.41 and 0.28, respectively. Winter dust layers were disorganized, especially at night when the boundary layer was weak. The most well-organized layers close to the ground were observed in the daytime during the summer months. [ABSTRACT FROM AUTHOR]

This study investigates the organizational modes of convective storms and associated severe weather in spring and summer (March–August) of 2015–19 over southern China. These storms are classified into three major organizational structures (cellular, linear, and nonlinear), including 10 dominant morphologies. In general, cellular systems are most frequent, followed by linear systems. Convective storms are common in spring, increasing markedly from April to June, and peak in June. Convective storm cases are usually longer lived in spring, while shorter lived in summer. They also present pronounced diurnal variations, with a primary peak in the afternoon and several secondary peaks during the night to the morning. Approximately 79.7% of initial convection clearly exhibits a dominant eastward movement, with a faster moving speed in spring. Convective storms frequently evolve among organizational modes during their life spans. Linear systems produce the most severe weather observations, in which convective lines with trailing stratiform rain are most prolific. Bow echoes are most efficient in producing severe weather events among all systems, despite their rare occurrences. In spring, lines with parallel stratiform rain are abundant producers of severe wind events, ranking the second highest probability. In summer, embedded lines produce the second largest proportion of intense rainfall events, whereas lines with leading stratiform rain are most efficient in generating extremely intense rainfall and thus pose a distinct flooding threat. Broken lines produce the largest proportion of severe weather events among cellular storms. In contrast, nonlinear systems possess the weakest capability to produce severe weather events. Significance Statement: Under the influence of the East Asian summer monsoon, severe weather events produced by convective storms occur frequently in China, leading to serious natural disasters. Numerous studies have demonstrated that the morphologies of convective storms are helpful to improve our understanding and prediction of convective storms. However, fewer attempts have been made to examine the convective morphologies over southern China. We aim to reveal the general features of convective organizational modes (e.g., frequencies, durations, variations, etc.) and determine which particular types of severe weather are more or less likely to be associated with particular convective morphologies. These results are of benefit to local forecasters for better anticipating the storm types and issuing warnings for related hazardous weather. [ABSTRACT FROM AUTHOR]

At broad spatial scales, primary productivity in lakes is known to increase in concert with nutrients, and variables that may disrupt or modify the tight coupling of nutrients and algae are of increasing interest, particularly for those shifting with climate change. Storms may disrupt algae–nutrient relationships, but the expected effects differ between winter and summer seasons, particularly for seasonally ice‐covered lakes. In winter, storms can dramatically change the under‐ice light environment, creating light limitation that disrupts algae–nutrient relationships. Further, storms can bring both snow that blocks light and also wind that blows snow off of ice. In open water conditions, storms may promote turbulence and external nutrient loading. Here, we test the hypotheses that winter and summer storms differentially affect algae–nutrient relationships across 84 seasonally ice‐covered lakes included in the Ecology Under Lake Ice dataset. While nutrients explained most of the variation in chlorophyll across these lakes, we found that secondary drivers differed between seasons. Under‐ice chlorophyll was higher under a variety of precipitation and wind conditions that tend to promote snow‐free clear ice, highlighting the importance of light as a limiting factor for algal growth during winter. In summer, higher water temperatures and storms corresponded with higher chlorophyll. Our study suggests that examining ice‐covered lakes in a gradient from the perennial ice cover of the poles to the intermittent ice cover of lower latitudes would yield key information on the shifts in light and nutrient limitation that control algal biomass. [ABSTRACT FROM AUTHOR]

NASA's InSight lander monitored the Martian atmosphere while conducting its primarily geophysical investigation. Atmospheric imaging was used to study dust and ice at the site for over two Mars years in 2018–2022. An optical depth record, including dust and ice, was derived from systematic sky imaging in the mornings (for the first part of the mission) and evenings. Optical depths ranged from 0.5 to 1.9 but were typically under 1. Dust storms were seen at expected times in late northern autumn and early winter, including one shortly after landing, along with one late summer storm in January 2022. The optical depth record closely matched that of Curiosity, 600 km to the south, except for the expected additional water ice content during the aphelion cloud belt (ACB, spring to early summer). In addition to ice hazes, the ACB included discrete clouds, whose motion was tracked to show northeasterly to southeasterly daytime winds. While InSight recorded many meteorological vortices, no dust devils were seen, requiring that dust-devil occurrence was <10−3 times as common as during Spirit rover dust devil seasons. • We describe the derivation of InSight's record of optical depth from sky images. • InSight required new techniques compared to previous Martian optical depth records. • InSight had similar optical depths to nearby Curiosity, with more ice and clouds. • Cloud motion was characterized during the aphelion cloud belt season. • An extensive search revealed no dust devils despite the abundant vortices. [ABSTRACT FROM AUTHOR]