Northern Hemisphere Winter Research Articles

Wave energy potential analysis in the Kenitra-Atlantic coastal area (Morocco): First results

Waves generated by winds can transport a large amount of energy across the oceans with little loss. This paper explores the satellite-based data to assess the wave energy potential of Kenitra-Atlantic coastal area (Morocco), with an overall purpose of supporting the plans for developing and using wave energy, and provide guidance about the appropriate applications of wave energy of the Kenitra coastal area. Kenitra is important harbour and industrial city in Morocco. Various indexes, including the temporal distributions of wave parameters and wave energy fluxes, the occurrence of the effective significant wave height and wave energy flux, the variability and frequency of the wave status, were calculated from satellite measured weekly wave data, covering about 3 years (June 2019-November 2022) period. Results indicated that the area is characterized by moderate energy compared to South Africa, the most energetic site in the continent, with average wave significant wave of 1.6 ± 0.7, average wave period of 8.4 ± 2.4 s, average wave energy flux of 11.7 ± 14.0 kW m−1 and with the rate of variability of 28–45%. High energy above the threshold (> 10 kW m−1) for viable electricity production, applying turbines directly powered by waves, occurs only during the northern hemisphere winter (December–March). Hence, for off shore Kenitra, the study recommends other applications for wave energy other than electricity production through wave powered turbines, such as, reverse osmosis membrane-based electricity production technology, desalination, irrigation and water pumping for marine culture, mini-hydro and recreational. Subsequently, future studies may focus on the socio-economic viability of these wave energy applications and on developing other low energy demanding applications.

Sub‐Auroral Ion Drifts (SAID) Developed Over the Northern Winter Hemisphere at Dawn During 2016–2017

AbstractWe investigated the rare events of sunward (westward) sub‐auroral ion drifts (SAID) development in the dawn magnetic local time (MLT) sector by utilizing horizontal ion velocity measurements collected by the Defense Meteorological Satellite Program F16 spacecraft. We surveyed the 2‐year time period of 2016–2017 and found only 15 SAID detections made in the 3–6 MLT sector over the northern winter hemisphere: seven in 2016 and eight in 2017. Results show that the dawnside SAID developed poleward of the ring‐current‐related plasma density trough, called ring ionospheric trough (RIT). With a few inner‐magnetosphere observations, we demonstrated that the favorable conditions were created by (a) the proton/ring current injections occurring across the newly‐formed dawnside plasmapause where (b) the ring current ions became unstable. As a result of (a), the outward SAID electric (E) field developed via short‐circuiting, mapped down to the ionosphere as a poleward E field and drove the sunward (westward) SAID flow in the dawn MLT sector. As a result of (b), a localized heat source developed near the newly‐formed dawnside plasmapause in the hot zone and the resultant downward heat flux led to stable auroral red (SAR) arc development when the electron temperature was sufficiently high. Then, the dawnside SAID flow developed parallel with the RIT and SAR arc.

The precipitation distribution set by eddy fluxes: the case of boreal winter

The latitudinal precipitation distribution shows a secondary peak in midlatitudes and a minimum in the subtropics. This minimum is widely attributed to the descending branch of the Eulerian Hadley cell. This study however shows that the precipitation distribution aligns more closely with the transformed Eulerian mean (TEM) vertical motion. In Northern Hemisphere winter, maximum TEM descent (ascent) and precipitation minimum (maximum) are collocated at ~20°N (~40°N). The subtropical descent is mostly driven by the meridional flux of zonal momentum by large-scale eddies, while the midlatitude ascent is driven by the meridional flux of heat by the eddies. When the poleward eddy momentum flux is sufficiently strong, however, the secondary precipitation peak shifts to 60°N corresponding to the location of the TEM ascent driven by the eddy momentum flux. Moisture supply for the precipitation is aided by evaporation which is enhanced where the TEM descending branch brings down dry air from the upper troposphere/lower stratosphere. This picture is reminiscent of dry air intrusions in synoptic meteorology, suggesting that the descending branch may embody a zonal mean expression of dry air intrusions. Moist air rises following the TEM ascending branch, suggesting that the ascending branch may be interpreted as a zonal mean expression of warm conveyor belts. This study thus offers a large-scale dynamics perspective of the synoptic description of precipitation systems. The findings here also suggest that future changes in the eddy momentum flux, which is poorly understood, could play a pivotal role in determining the future precipitation distribution.

Decadal trend of synoptic temperature variability over the Northern Hemisphere in winter

Synoptic temperature variability gives rise to cold waves and extreme cold events in winter. Based on four reanalysis datasets, this study investigates the decadal trend of synoptic temperature variability in boreal winter during the period from 1980 to 2019, with particular focus on the sharp drops in synoptic-scale temperature, which are associated with cold waves. The result shows that the synoptic-scale standard deviation of temperature decreases significantly with a trend of − 0.15 K/decade (− 0.09 to − 0.21 K/decade among reanalysis datasets) over continental regions in mid-high latitudes. Correspondingly, the rapid cooling events (RCEs), defined based on the day-to-day temperature decrease exceeding 6 K, also show a general decreasing trend in terms of their frequency and intensity. The strongest decrease occurs over eastern North America (ENA) and western Eurasia (WE). The weakening of the RCEs is closely connected to the decreased trend of eddy kinetic energy (EKE), suggesting that the weakened transient eddy activities may have mitigated the synoptic-scale temperature variability and the associated RCEs over mid-high latitudes. This study highlights that the decreased synoptic temperature variability leads to fewer and weaker RCEs on the synoptic scale over mid-high latitudes in winter though the mean state of winter temperature continues to warm.

Constraining the Varied Response of Northern Hemisphere Winter Circulation Waviness to Climate Change

AbstractWhile a large latitudinal displacement of the westerly jet brings about disproportionate socioeconomic impacts over Northern Hemisphere midlatitude continents, it is not well understood as to whether the winter circulation will become wavier or less in response to climate change. Here, using observations and large ensembles of climate models, we show that changes in atmospheric waviness can be estimated from the optimal structures of the westerly jet for wavier circulation, which are obtained from an advection‐diffusion model. Thus, the changes in westerly jet structure in climate models under climate change provide a physical constraint on changes in atmospheric waviness, indicating that the North Atlantic wave activity will experience a robust decline in a warmer climate, while future North Pacific wave activity is obscured by model uncertainty rather than internal variability. These findings highlight the changes to jet stream structure as a constraint for regional circulation waviness in a changing climate.

The Role of Coupled North Pacific Atmosphere–Ocean Interactions in Impacts of Tibetan Plateau Snow Anomalies on the Northern Hemisphere Winter Atmospheric Circulation

Abstract Previous studies indicate observed influences of autumn and winter Tibetan Plateau (TP) snow-cover anomalies on the winter Pacific–North American (PNA) teleconnection. This study simulates atmospheric and oceanic responses to persistent autumn–winter TP snow forcing using an atmospheric general circulation model (AGCM) and a coupled atmospheric-oceanic general circulation model (AOGCM), and quantifies the role of atmosphere–ocean interactions over North Pacific in TP snow effects. The AOGCM experiment induces a stronger and more realistic remote PNA response to heavy TP snow anomalies, and also a significant winter horseshoe-like North Pacific sea surface temperature (SST) pattern resulting from an anomalous equivalent barotropic cyclone, or a strengthened Aleutian low, with associated cyclonic wind stress anomalies. The horseshoe-like SST anomaly pattern is used as boundary forcing (without prescribed heavy TP snow) in another AOGCM experiment, which simulates an enhanced winter Aleutian low and a PNA-like response similar to the original AOGCM responses, indicating that that the direct Pacific–North American atmospheric response to persistent TP snow forcing in the AGCM is amplified in the AOGCM by the North Pacific midlatitude atmosphere–ocean interactions. This suggests that the mechanisms of the winter PNA responses to TP snow forcing involve dynamical atmospheric processes such as horizontal propagation of Rossby wave energy and transient eddy feedbacks, and also North Pacific atmosphere–ocean interactions, which provide a positive feedback on the development of the remote PNA teleconnection. Significance Statement The Tibetan Plateau has a 2.5 million km2 area and a 4000 m average elevation, and is often called “the third pole” because of its polar-like climate in midlatitude Eurasia. A heavy Tibetan Plateau snow cover increases the albedo effect and causes tropospheric cold temperature and low height changes that can be carried or advected to the North Pacific by the prevailing westerlies. The purpose of this study is to better understand how Tibetan Plateau snow anomalies influence the North Pacific and the remote atmospheric circulation through numerical simulations. Our results find that those North Pacific responses amply the direct atmospheric response to Tibetan Plateau snow-cover anomalies. This greatly improves our understanding of physical mechanisms of Tibetan Plateau snow impacts.

Distinct impacts of two types of El Niño events on northern winter high-latitude temperatures simulated by CMIP6 climate models

The interannual variability of the Northern Hemisphere winter climate is strongly linked to the El Niño-southern oscillation (ENSO). While North Pacific and North America often exhibit a robust response to ENSO, so-called the Pacific–North America pattern, the Arctic and Eurasian climate responses to ENSO remain elusive. This study examines 40 different climate models from the coupled model intercomparison project phase 6 (CMIP6) to find the distinct Arctic and Eurasian temperature response to two types of El Niño events. Specifically, Central Pacific El Niño events are accompanied by significant pan-Arctic warming, whereas Eastern Pacific (EP) El Niño events are accompanied by cooling over the Barents-Kara Seas and Eurasian continent. During the EP El Niño events, pan-Arctic sea-level pressure (SLP) effectively strengthens, leading to weaker westerlies and surface air cooling over the northern Eurasian continent. These distinct Arctic and Eurasian winter temperature responses to two types of El Niño do not appear clearly in reanalysis data, spanning 1979–2021, probably because of the small sample size of El Niño events since the satellite era.

Preparing for the Next Influenza Season: Monitoring the Emergence and Spread of Antiviral Resistance.

The relaxation of pandemic restrictions in 2022 has led to a reemergence of respiratory virus circulation worldwide and anticipation of substantial influenza waves for the 2022/2023 Northern Hemisphere winter. Therefore, the antiviral susceptibility profiles of human influenza viruses circulating in Germany were characterized. Between October 2019 (week 40/2019) and March 2022 (week 12/2022), nasal swabs from untreated patients with acute respiratory symptoms were collected in the national German influenza surveillance system. A total of 598 influenza viruses were isolated and analyzed for susceptibility to oseltamivir, zanamivir and peramivir, using a neuraminidase (NA) inhibition assay. In addition, next-generation sequencing was applied to assess molecular markers of resistance to NA, cap-dependent endonuclease (PA) and M2 ion channel inhibitors (NAI, PAI, M2I) in 367 primary clinical samples. Furthermore, a genotyping assay based on RT-PCR and pyrosequencing to rapidly assess the molecular resistance marker PA-I38X in PA genes was designed and established. While NAI resistance in the strict sense, defined by a ≥ 10-fold (influenza A) or ≥5-fold (influenza B) increase of NAI IC50, was not detected, a subtype A(H1N1)pdm09 isolate displayed 2.3- to 7.5-fold IC50 increase for all three NAI. This isolate carried the NA-S247N substitution, which is known to enhance NAI resistance induced by NA-H275Y. All sequenced influenza A viruses carried the M2-S31N substitution, which confers resistance to M2I. Of note, one A(H3N2) virus displayed the PA-I38M substitution, which is associated with reduced susceptibility to the PAI baloxavir marboxil. Pyrosequencing analysis confirmed these findings in the original clinical specimen and in cultured virus isolate, suggesting sufficient replicative fitness of this virus mutant. Over the last three influenza seasons, the vast majority of influenza viruses in this national-level sentinel were susceptible to NAIs and PAIs. These findings support the use of antivirals in the upcoming influenza season.

Seasonal quiet-day morphology of VLF signal strength at Ibadan

Very Low Frequency (VLF) signal amplitude is enhanced during solar flare events. Hence, it can be used as remote sensing for tracking solar flares and studying the lower ionosphere. However, the enhancement is not directly proportional to the magnitude of a solar flare hindering the effectiveness of the VLF signal as a remote sensor for tracking solar flare. Preliminary analysis shows that the level of enhancement recorded for a particular solar flare occurrence depends on the background fluctuations. Thus, this study aims to explore the background fluctuations of the VLF signal using quiet-day data and investigate the impact of background fluctuations on solar flare detectability using the VLF signal. The VLF data used for this study were collected using a VLF receiver installed at KolaDaisi University, Ibadan (KDU-I). The VLF data were from three stations; GBZ (Freq.: 19.8 kHz, Lat.: 21.82°, Long.: 114.17°), NWC (Freq.: 19.58 kHz, Lat.: 54.91°, Long.: 003.28°) and VTX4 (Freq.: 19.2, kHz Lat.: 08.38°, Long.: 077.75°) recorded between 2019 and 2022 at Ibadan (Lat.: 7.6248°, Long.: 3.9131°). The results revealed that the time series has a cyclic pattern that corresponds to each global season classification in the northern hemisphere (Summer, autumn, winter and spring) with an upward trend from wet to dry season. This observation shows that similar geophysical parameters that drive meteorology also have an impact on the background fluctuations of VLF amplitude. It was also observed that the sensitivity of VLF amplitude in sensing solar flare depends on the background fluctuation. It is recommended that the effect of meteorology and background fluctuation be considered when modelling VLF amplitude as a remote sensor for tracking solar flares.

Compensation between Resolved Wave Forcing and Parameterized Orographic Gravity Wave Drag in the Northern Hemisphere Winter Stratosphere Revealed in NCEP CFS Reanalysis Data

Abstract Compensation between the resolved wave (RW) forcing and the parameterized orographic gravity wave drag (OGWD) accompanying barotropic/baroclinic (BT/BC) instability in the realistic atmosphere is investigated using Climate Forecast System Reanalysis data in the Northern Hemisphere winter stratosphere. When sufficiently narrow and/or strong negative OGWD drives instability, RWs are generated in situ, providing positive Eliassen–Palm flux divergence that compensates for the parameterized OGWD enhancement; this is consistent with the findings of previous studies based on the idealized general circulation models. However, dependence of the compensation rate on RW forcing differs from the nearly complete compensation in the previous studies, implying that an additional mechanism operates for the compensation: the refractive-index modification by BT/BC instability. The negative meridional gradient of the quasigeostrophic potential vorticity leads to the negative refractive index squared for RWs with phase speeds less than the zonal-mean zonal wind. This prevents RWs from entering the destabilized areas, resulting in the divergence of Eliassen–Palm fluxes that cancels out the parameterized OGWD perturbation. Although both mechanisms act simultaneously, the refractive-index modification plays an important role in the compensation processes in the stratosphere where RWs are dominated by the planetary-scale waves.

Mid-Holocene reinforcement of North Atlantic atmospheric circulation variability from a western Baltic lake sediment record

Abstract. Knowledge about the timing, amplitude and spatial gradients of Holocene environmental variability in the circum-Baltic region is key to understanding its responses to ongoing climate change. Based on a multi-dating and proxy approach, we reconstruct changes in productivity using total organic carbon (TOC) contents in sediments of Lake Kälksjön (KKJ) from west–central Sweden spanning the last 9612 (+255/-114) years. An exception is the period from 1878 CE until today, in which sedimentation was dominated by anthropogenic lake level lowering and land use. In-lake productivity was higher during periods of warmer winters with shortened ice cover and prolonged growing seasons. A multi-millennial increase in productivity throughout the last ∼ 9600 years is associated with progressively warmer winters in northwestern Europe, likely triggered by the coinciding increase in Northern Hemisphere winter insolation. Decadal to centennial periods of higher productivity in KKJ tend to correspond to warmer winters during a more positive North Atlantic Oscillation (NAO) polarity, as reconstructed for the last 8000 years. In consequence, we assume our decadal to centennial productivity record from KKJ sediments for the complete ∼ 9600 years to provide a qualitative record of NAO polarity. A shift towards higher productivity variability at ∼ 5450 cal a BP is hypothesized to reflect a reinforcement of NAO-like atmospheric circulation variability, possibly driven by more vigorous changes in North Atlantic deep-water formation.

Stratospheric PULSE–continental cold air outbreak coupling relationships: Interannual and interdecadal changes

Stratospheric processes and their role in weather and climate have attracted increasing interests. The correspondence between the occurrence of pulse-like, stronger stratospheric poleward warm airmass transport (PULSE) events and the continental-scale cold air outbreak (CAO) events in northern hemispheric winter is found to be unstable from year to year. This increases the difficulties in utilizing the more predictable stratospheric variability in the sub-seasonal forecasts of CAOs, which can cause cold hazards. Using the ERA5 reanalysis data covering 37 winters (November–March) in the period 1979–2015, this study categorizes the CAO events over mid-latitudes of Eurasia (CAO_EA) and those over North America (CAO_NA) into two groups: those coupled with and those decoupled with the PULSE events. The coupled CAOs are further categorized into events that are, respectively, lead-coupled and lag-coupled with PULSEs. The intensity and affected area of extremely cold temperatures tend to be larger during CAOs that are coupled with PULSEs, particularly during the CAO_NA events that are lag-coupled with PULSEs and the CAO_EA events that are lead-coupled with PULSEs. Remarkable interannual and interdecadal variations are observed in the percentage of CAOs that are coupled with PULSEs for each winter, which is an important reference for determining the window of opportunity for skillful sub-seasonal forecasts of CAO by using the stratospheric signals. At both interdecadal and interannual timescales, a warm phase of the El Niño–Southern Oscillation (ENSO) in winter is favorable for the higher lag-coupling rate of CAO_NA and the lead-coupling rate of CAO_EA, and vice versa. The ENSO signals related to the interdecadal changes of the CAO coupling rate in winter can be traced back to the previous winter, while an ENSO phase transition from the previous winter to the current winter is closely related to the interannual changes of the CAO coupling rate.

WINTER ATMOSPHERIC BLOCKINGS IN THE NORTHERN HEMISPHERE UNDER CLIMATE CHANGES IN RECENT DECADES (1980–2018)

The analysis of winter atmospheric blockings in the Northern Hemisphere (NH) under climate changes in 1980–2018 was carried out. The results of the analysis indicate a significant increase in the total duration of winter atmospheric blockings τ in the NH in recent decades. The noted trend was revealed against the background of a rapid increase in the NH surface air temperature T in winter seasons. The parameter of sensitivity of the atmospheric blockings duration to changes in the NH surface air temperature in winter seasons for the period 1980–2018 was estimated. The statistically significant estimate obtained means an increase in τ by more than one and a half times with an increase in the mean winter surface air temperature of the NH by 1K. A more significant relationship with T was obtained for values of τ above the average value of τc for the period 1980–2018, while at τ τc, the relationship was found to be statistically insignificant. The noted features are associated with differences in different phases of the key modes of climatic variability. In particular, the mean value of the surface air temperature of the NH in winter in the positive phase of the Atlantic Multidecadal Oscillation (AMO) within the analyzed period of 1980–2018 significantly exceeded the corresponding mean value of T in the negative phase of AMO. At the same time, it was found that the mean value of the winter blockings duration in the NH in the positive AMO phase is one and a half times longer than in the negative AMO phase. For winter seasons, the estimates of the relationship between τ and the intensity of the Arctic anticyclonic center of action depending on the AMO phase were obtained.

Impact of COVID-19 on the Spatio-temporal Distribution of CO2 Emission

CO2 is the determining factor of global warming, affecting the intensity and rate of global warming. Although the outbreak of COVID-19 deeply affected the emission of global carbon, the impact on the temporal variation and spatial distribution of CO2 emission rate (ECO2 ) is not yet conclusive. This study systematically analyzed the spatial-temporal distribution of EC02 from 2019 to 2021 based on one latest near real-time CO2 dataset named GRACED. Studies show that COVID-19 has no significant impact on the spatial distribution of CO2 in the world, but significantly reduce the values. From the perspective of the seasonal cycle, the outbreak of COVID-19 caused a shift in the minimum ECO2 in 2020 from the Northern Hemisphere summer (JJA) to the Northern Hemisphere winter (MAM), reflecting the impact of the COVID-19 outbreak on global ECO2. As for the temporal variation, the impact of the COVID-19 outbreak on the monthly cycle mainly occurred in 2020, especially from March to June of that year. By 2021, the global mean values of E-C02 had largely recovered to 2019 levels as the impact of COVID-19 faded.

Surveillance of Severe Acute Respiratory Infection and Influenza Vaccine Effectiveness among Hospitalized Italian Adults, 2021/22 Season

Following an extremely low incidence of influenza during the first waves of the ongoing COVID-19 pandemic, the 2021/22 Northern Hemisphere winter season saw a resurgence of influenza virus circulation. The aim of this study was to describe epidemiology of severe acute respiratory infections (SARIs) among Italian adults and estimate the 2021/22 season influenza vaccine effectiveness. For this purpose, a test-negative case-control study was conducted in a geographically representative sample of Italian hospitals. Of 753 SARI patients analyzed, 2.5% (N = 19) tested positive for influenza, most of which belonged to the A(H3N2) subtype. Phylogenetic analysis showed that these belonged to the subclade 3C.2a1b.2a.2, which was antigenically different from the 2021/22 A(H3N2) vaccine component. Most (89.5%) cases were registered among non-vaccinated individuals, suggesting a protective effect of influenza vaccination. Due to a limited number of cases, vaccine effectiveness estimated through the Firth's penalized logistic regression was highly imprecise, being 83.4% (95% CI: 25.8-97.4%) and 83.1% (95% CI: 22.2-97.3%) against any influenza type A and A(H3N2), respectively. Exclusion of SARS-CoV-2-positive controls from the model did not significantly change the base-case estimates. Within the study limitations, influenza vaccination appeared to be effective against laboratory-confirmed SARI.

Long-term mesospheric record of EPP-IE NO measured by Odin/SMR

Due to the long lifetime of nitric oxide (NO) in darkness conditions, during polar winter, the NO produced by energetic particle precipitation (EPP) in the mesosphere and lower thermosphere (MLT) can descend, via the middle atmospheric residual circulation, to the lower mesosphere and stratosphere, where it is involved in catalytic destruction of ozone (O3). This process is known as energetic particle precipitation indirect effect (EPP-IE). There are still significant uncertainties on the estimated amount of EPP-IE NO. To improve such estimations, we measure the total winter flux of EPP-IE NO descending through three isentropic levels in the mesosphere, that is 2600K, 3300K and 4000K, based on 15 years of NO nighttime observations from the Sub-Millimetre Radiometer (SMR) on board Odin satellite. At the moment, Odin/SMR is the only instrument ensuring a global coverage of mesospheric NO observations within a few days and this is the first time EPP-IE NO has been quantified using its NO data set. Moreover, such an estimate had never been calculated for the most recent winters which are included in this study. In our method we calculate the median nighttime NO inside the polar vortex during the month prior to the descent of NO-rich air; this value is assumed as a background, produced by N2O oxidation, to be subtracted from the daily median nighttime concentrations inside the vortex; the result of this subtraction is then multiplied by the area of the vortex and the descent rate to obtain the flux; finally these daily quantities and integrated to calculate the total NO flux for each winter. We thus calculated the total EPP-IE NO flux through the mentioned levels for Northern Hemisphere (NH) winters between 2006–07 and 2020–21 and for Southern Hemisphere (SH) winters between 2007 and 2012. The total winter EPP-IE NO fluxes presented in this study are consistent with the quantities presented in similar studies. NH winters 2008–09, 2012–13 and 2018–19 are the ones presenting the highest NO fluxes at all levels. They are winters characterised by sudden stratospheric warmings followed by elevated stratopause (SSW-ES) events. The measured fluxes vary between 490 and 1000 Mmol at 4000K, 310 and 720 Mmol at 3300K, 270 and 510 Mmol at 2600K. All other NH and SH winters are characterised by sensibly lower values than SSW-ES winters. The fluxes from these more dynamically quiet winters vary from winter to winter following a trend similar to the one of geomagnetic activity, as indicated by the variations in Ap index. These results indicate that the variability in the total EPP-IE NO fluxes is dominated by dynamics during the SSW-ES winters, whereas during the remaining winters it is geomagnetic activity that plays a major role.

1331. Pneumococcal Colonization Among Children 5 years of Age and Younger During SARS-CoV-2 Pandemic

Abstract Background Children ≤5 years of age have the highest rates of pneumococcal colonization and play an important role in the spread of pneumococcus. Our objective was to determine whether the public health measures (physical distancing, masking, and shelter-in-place orders) implemented to slow the spread of SARS-CoV-2 pandemic had an impact on pneumococcal colonization rates among children aged ≤5 years with and without respiratory symptoms during the first year of SARS-CoV-2 pandemic (4/1/20 to 3/31/21). Methods This is a single center retrospective cohort study. The study period was divided in 3 four-month periods to represent the initial period of strict adherence to public health measures (period 1: Apr-Jul), relaxation of some of these measures (period 2: Aug-Nov) and Northern hemisphere winter season (period 3: Dec-Mar). We used salvaged mid-turbinate samples obtained as part of routine care from patients without respiratory symptoms but screened for SARS-CoV-2 prior to surgery or aerosol generating procedures (asymptomatic) or from patients with respiratory symptoms tested for SARS-CoV-2 and/or other respiratory viruses (symptomatic). Samples were evaluated for pneumococcal colonization by real-time PCR using CDC lytA primers. Sample size was calculated based on the assumption of lower colonization rates in period 1 and gradual increase (10-15%) in the following study periods. Results A total of 311 patients were included (185 asymptomatic and 126 symptomatic). Demographics, SARS-CoV-2 PCR and pneumococcal colonization results are shown in Table 1. Pneumococcal colonization rates for asymptomatic and symptomatic children were 14% and 22% (p=0.06), respectively. The odds of colonization of asymptomatic children were similar during period 2 (OR 0.96 [95%CI 0.34-2.67]) and period 3 (OR 0.53 [95%CI 0.17-1.62]), using period 1 as reference and after adjusting for age, sex, and SARS-COV-2 results. The odds of colonization of symptomatic children were also similar across the 3 study periods (period 2 OR 1.28 [95%CI 0.41-4.01] and period 3 OR 0.73 [95% CI 0.24-2.18]). Table 1.Characteristics of asymptomatic and symptomatic groups Conclusion Pneumococcal colonization rates were not significantly impacted by public health measures implemented during the first year of the SARS-CoV-2 pandemic and did not correlate with SARS-CoV-2 positivity. Disclosures Liset Olarte, MD, MSc, GSK: Grant/Research Support|Merck: Grant/Research Support|Pfizer: Grant/Research Support|Sanofi: Grant/Research Support Douglas S. Swanson, MD, Merck: Grant/Research Support|Pfizer: Grant/Research Support|Sanofi: Grant/Research Support Brian R. Lee, PhD, MPH, CDC: Grant/Research Support|Merck: Grant/Research Support Christopher J. Harrison, MD, Astellas: Grant/Research Support|GSK: Grant/Research Support|Merck: Grant/Research Support|Pediatric News: Honoraria|Pfizer: Grant/Research Support Rangaraj Selvarangan, BVSc, PhD, D(ABMM), FIDSA, F(AAM), BioFire: Grant/Research Support|Luminex: Grant/Research Support.

Long‐Term Trends of Northern Hemispheric Winter Cyclones in the Extended ERA5 Reanalysis

AbstractUnderstanding how historical extratropical cyclone tracks respond to global warming is crucial for predicting future storm activity. Thus, long reanalysis data sets are needed to investigate long‐term changes in storm features and their impacts. By using a systematic change‐point analysis, we provide evidence that the presatellite ERA5 data of the Backward Extension (covering 1950–1978) is highly compatible with the standard ERA5 (1979–2021) data set. The joint ERA5 data from 1950 to 2021 is consistent in all storm‐related quantities, consequently allowing long‐term studies. Our trend analysis suggests that the intensity of extratropical cyclones has increased significantly during 1950–2021. The number of North Pacific storms has increased, and while they have longer life cycles and travel larger distances, they grow more slowly. For 1979–2021, we find notable increases in wind gusts for North Atlantic storms and in precipitation extremes for North Pacific storms. Our results also indicate an increase in Northern Hemispheric storminess based on an index of an extreme percentile of the central geopotential. Finally, we show potential impact locations using the findings of our trend analysis.

Abstract 13270: Seasonal Variation in In-Hospital Outcomes of Takotsubo-Syndrome-Related Admissions: A National Inpatient Analysis, 2019

Background: Contemporary literature lacks data on the impact of climatic variations on the etiopathogenesis and outcomes of Takotsubo Syndrome (TTS)-related hospitalization in the U.S. Methods: Seasonal variation was identified based on meteorological classification of the northern hemisphere Spring, Summer, Fall and Winter using data from the National Inpatient Sample (2019) and odds of outcomes were assessed using multivariable regression models. Results: The TTS cohort (n=41830) in 2019 was mostly caucasian (80.6%), female (82.1%), and median age ≥65yrs (61.9%). Fall (25.9%) admissions were the highest, followed by summer (25%), spring (24.6%) and winter (24.5%). Despite a similar median length of stay (4-days; p<0.001), winter hospitalization expenditures (USD56763) were the highest and fall lowest (USD51649). Winter admissions had greater all-cause mortality (7.3%vs.6.7%) and dysrhythmias (29.8%vs.28.5%), including Atrial fibrillation (AF) (20.7%vs. 19.7%). Admissions in spring had a higher cardiac arrest (4.8%vs.4.1%) and Acute Venous Thromboembolism (VTE) (4.7%vs.3.5%) compared to overall TTS-related admissions. When adjusted for confounders, a higher risk of dysrhythmias was noted for [winter (OR:1.20; 95%CI:1.03-1.39), Spring (OR:1.15;95%CI:1.00-1.33) and Fall (OR:1.18;95%CI:1.03-1.36) vs. summer; p=0.063]. A higher risk was also noted for AF in winter (OR:1.22;95%CI:1.02-1.45), Spring (OR:1.20;95%CI:1.02-1.42) and Fall (OR:1.28;95%CI:1.08-1.51) when compared to summer; p=0.028]. Spring admissions had a greater risk of VTE than summer admissions [(OR:1.54;95%CI:1.09-2.16) vs. summer; p=0.067]. Other outcomes, such as all-cause mortality and cardiogenic shock, had an association after controlling for confounding variables. Conclusions: Compared to Summer, Winter hospitalizations increased the risk of dysrhythmia and AF, while Spring admissions revealed a higher risk of VTE.

A Statistical Study of Nighttime Ionospheric NmF2 Enhancement at Middle‐to‐High Latitudes in the Northern Hemisphere

AbstractThe electron density in the ionosphere usually continuously decreases during nighttime due to the vanishing of sunlit ionization. However, it sometimes increases unexpectedly, which has been called nighttime ionospheric enhancement. Previous researches studied this type of phenomenon mainly in the low‐to‐middle latitude regions. Here, we investigate the nighttime ionospheric NmF2 enhancement at middle‐to‐high latitudes in the northern hemisphere (NH) during solar cycles 23–24 by analyzing the ionosonde observations at Chilton (51.1°N, 359.4°E, geomagnetic 48.5°N), Juliusruh (54.6°N, 13.4°E, 51.7°N), Tromsø (69.9°N, 19.6°E, 66.9°N), and Qaanaaq (77.5°N, 290.8°E, 84.3°N), as well as comparing with the Empirical Canadian High Arctic Ionospheric Model (E‐CHAIM). The observations show that the nighttime NmF2 enhancement occurs mainly in the winter solstice months (November–February), and the occurrence rate and relative amplitude of the enhancement are inversely related to solar activity. The observed results are in good agreement with the results obtained from E‐CHAIM. Furthermore, the model shows the spatial distribution of the enhancement at the middle‐to‐high latitudes in NH in winter, most obvious in geomagnetic latitude between 50°N and 65°N, and have longitudinal minima centered at 30°W and maxima centered at 120°W and 75°E. From these results, this unique phenomenon at middle latitude is explained probably by the plasma flux from the higher altitudes (e.g., topside ionosphere and plasmasphere) diffusing downward into the ionospheric F2 layer. However, at polar regions, under the influence of the abundant high‐density structures such as polar cap patches, auroral blob, particle precipitation, etc., the F region plasma density enhancement becomes more complicated.