Western Pacific oceanic heat content: a better predictor of La Niña than of El Niño

The western equatorial Pacific oceanic heat content (Warm Water Volume in the west or WWVW) is the best El Niño–Southern Oscillation (ENSO) predictorbeyond1‐year lead. Using observations and selected Coupled Model Intercomparison Project Phase 5 (CMIP5) simulations, we show that a discharged WWVW in boreal fall is a better predictor of La Niña than a recharged WWVW for El Niño13 months later, both in terms of occurrence and amplitude. These results are robust when considering the heat content across the entire equatorial Pacific (WWV) at shorter lead‐times, including all CMIP5 models or excluding Niño‐Niña and Niña‐Niño phase transitions. Suggested mechanisms for this asymmetry include 1) the negatively skewed WWVW distribution with stronger discharges related to stronger wind stress anomalies during El Niño and 2) the stronger positive Bjerknes feedback loop during El Niño. The possible role of stronger subseasonal wind variations during El Niño is also discussed

Current status of a helicopter transportation system on remote islands for patients undergoing mechanical thrombectomy

Background: Mechanical thrombectomy (MT) is standard treatment for acute ischemic stroke (AIS) with large-vessel occlusion within 6 h of symptom onset to treatment initiation (OTP). Recent trials have extended the therapeutic time window for MT to within 24 h. However, MT treatment remains low in remote areas. Nagasaki Prefecture, Japan has many inhabited islands with no neurointerventionalists. Our hospital on the mainland is a regional hub for eight island hospitals. We evaluated clinical outcomes of MT for patients with AIS on these islands versus on the mainland. Methods: During 2014–2019, we reviewed consecutive patients with AIS who received MT at our hospital. Patients comprised the Islands group and Mainland group. Patient characteristics and clinical outcomes were compared between groups. Results: We included 91 patients (Islands group: 15 patients, Mainland group: 76 patients). Seven patients (46.7%) in the Islands group versus 43 (56.6%) in the Mainland group achieved favorable outcomes. Successful recanalization was obtained in 11 patients (73.3%) on the islands and 67 (88.2%) on the mainland. The median OTP time in the Islands was 365 min. In both the Islands and Mainland groups, the OTP time and successful recanalization were associated with functional outcome. The modified Rankin Scale (mRS) score at 90 days ≤2 was obtained in two patients and mRS = 3 in four patients among eight patients with OTP time >6 h. Conclusions: Few patients with AIS on remote islands have received MT. Although patients who underwent MT on the islands had longer OTP, the clinical outcomes were acceptable. OTP time on remote islands must be shortened, as this is related to functional outcome. In some cases with successful recanalization, a favorable outcome can still be obtained even after 6 h. Even if OTP exceeds 6 h, it is desirable to appropriately select patients and actively perform MT

The whole blood transcriptional regulation landscape in 465 COVID-19 infected samples from Japan COVID-19 Task Force

「コロナ制圧タスクフォース」COVID-19患者由来の血液細胞における遺伝子発現の網羅的解析 --重症度に応じた遺伝子発現の変化には、ヒトゲノム配列の個人差が影響する--. 京都大学プレスリリース. 2022-08-23.Coronavirus disease 2019 (COVID-19) is a recently-emerged infectious disease that has caused millions of deaths, where comprehensive understanding of disease mechanisms is still unestablished. In particular, studies of gene expression dynamics and regulation landscape in COVID-19 infected individuals are limited. Here, we report on a thorough analysis of whole blood RNA-seq data from 465 genotyped samples from the Japan COVID-19 Task Force, including 359 severe and 106 non-severe COVID-19 cases. We discover 1169 putative causal expression quantitative trait loci (eQTLs) including 34 possible colocalizations with biobank fine-mapping results of hematopoietic traits in a Japanese population, 1549 putative causal splice QTLs (sQTLs; e.g. two independent sQTLs at TOR1AIP1), as well as biologically interpretable trans-eQTL examples (e.g., REST and STING1), all fine-mapped at single variant resolution. We perform differential gene expression analysis to elucidate 198 genes with increased expression in severe COVID-19 cases and enriched for innate immune-related functions. Finally, we evaluate the limited but non-zero effect of COVID-19 phenotype on eQTL discovery, and highlight the presence of COVID-19 severity-interaction eQTLs (ieQTLs; e.g., CLEC4C and MYBL2). Our study provides a comprehensive catalog of whole blood regulatory variants in Japanese, as well as a reference for transcriptional landscapes in response to COVID-19 infection

DOCK2 is involved in the host genetics and biology of severe COVID-19

「コロナ制圧タスクフォース」COVID-19疾患感受性遺伝子DOCK2の重症化機序を解明 --アジア最大のバイオレポジトリーでCOVID-19の治療標的を発見--. 京都大学プレスリリース. 2022-08-10.Identifying the host genetic factors underlying severe COVID-19 is an emerging challenge. Here we conducted a genome-wide association study (GWAS) involving 2, 393 cases of COVID-19 in a cohort of Japanese individuals collected during the initial waves of the pandemic, with 3, 289 unaffected controls. We identified a variant on chromosome 5 at 5q35 (rs60200309-A), close to the dedicator of cytokinesis 2 gene (DOCK2), which was associated with severe COVID-19 in patients less than 65 years of age. This risk allele was prevalent in East Asian individuals but rare in Europeans, highlighting the value of genome-wide association studies in non-European populations. RNA-sequencing analysis of 473 bulk peripheral blood samples identified decreased expression of DOCK2 associated with the risk allele in these younger patients. DOCK2 expression was suppressed in patients with severe cases of COVID-19. Single-cell RNA-sequencing analysis (n = 61 individuals) identified cell-type-specific downregulation of DOCK2 and a COVID-19-specific decreasing effect of the risk allele on DOCK2 expression in non-classical monocytes. Immunohistochemistry of lung specimens from patients with severe COVID-19 pneumonia showed suppressed DOCK2 expression. Moreover, inhibition of DOCK2 function with CPYPP increased the severity of pneumonia in a Syrian hamster model of SARS-CoV-2 infection, characterized by weight loss, lung oedema, enhanced viral loads, impaired macrophage recruitment and dysregulated type I interferon responses. We conclude that DOCK2 has an important role in the host immune response to SARS-CoV-2 infection and the development of severe COVID-19, and could be further explored as a potential biomarker and/or therapeutic target

Le sous-courant équatorial et les échanges de masse et de chaleur associés dans le Pacifique tropical : variabilité, liens avec les événements El Niño-La Niña

Composition du jury: Serge Chauzy (président du jury) Gilles Reverdin (rapporteur) Yves Tourre (rapporteur) Joël Picaut (directeur de these) Bruno Blanke (examinateur) Michael McPhaden (examinateur)The Equatorial UnderCurrent (EUC) is part of the shallow subtropical/tropical meridional overturning cells (STCs/TCs), and by feeding the equatorial upwelling it may have strong influences on the eastern equatorial sea surface temperature (SST) and thus on ENSO (El Niño-Southern Oscillation) and its long-term variations. The EUC and the meridional overturning cells are studied using both in situ data, analytical and numerical models. Trajectories of water masses are calculated in a realistic ocean general circulation model (OGCM, forced by winds from NCEP reanalyses over 1948-1999 or from ERS satellites over 1992-1999). Their analysis reveals complex and asymmetric recharges/discharges of the equatorial band associated with the 1997-1998 El Niño-La Niña events. This lagrangian analysis also shows how the outcrop of cold water appearing during the rapid transition to La Niña in may 1998 was fed by STCs and the EUC. Then it is shown that transport, transport-weighted temperature and depth, and kinetic energy of the EUC over the entire meridional section, can be estimated by using TAO/TRITON moored data of current and temperature right at the equator, with their gaps carefully filled. Continuous time series at 170°W, 140°W and 110°W are constructed and show strong variations on seasonal to interannual time scales over 1980-2002. Their physical analysis reveals that the interannual variations in mass transport are a linear and quasi-stationary response to zonal wind stretch integrated zonally over the west and central Pacific. EUC temperature, which is important for the estimation of EUC heat transport, varies linearly with the difference of thermocline and EUC depths. The OGCM, validated especially with the EUC time series, is used to study over 1951-1999 the equatorial circulation associated with the EUC: pycnocline convergence, equatorial upwelling and surface divergence at 5°N and 5°S. Their interannual and long-term variations are all nearly equal (EUC is thus a good indicator of STCs strength), with some lags due to wave propagation. Such variations are mostly explained by linear ocean adjustment to zonal wind stretch integrated zonally over the equatorial Pacific, in agreement with linear theories. A decrease of about 30% in transport is thus seen over the last fifty years in the EUC and meridional overturning circulation, due to the overestimated decrease in NCEP easterlies. Analysis of the lags with equatorial SST, particularly the 5 months lead of upwelling and divergence over SST, reveals interesting cause to effect relationships, confirmed by heat budgets. The difference in temperature between divergence and convergence has the same variations as equatorial SST. A long-term decrease in EUC transport-weighted temperature of about 1°C is also seen, due to a shallower thermocline. For the heat budget of the eastern equatorial Pacific, EUC mass transport variations appear dominant on interannual timescale, but EUC transport-weighted temperature variations become also important on decadal timescale. For the heat budget of the equatorial band, both mass transport and temperature variations of meridional overturning are important. The links with theories of El Niño and decadal variability are finally discussed.Le sous-courant équatorial (EUC), en alimentant l'upwelling équatorial, peut avoir une forte influence sur la température de surface (SST) du Pacifique équatorial Est et donc sur la variabilité associée à El Niño. L'EUC et les cellules de circulation méridienne (shallow subtropical/tropical overturning cells, STCs/TCs) l'alimentant sont étudiés en combinant données in situ et modélisation. Les trajectoires de masses d'eau sont calculées dans des simulations réalistes (le modèle OPA forcé par les vents des réanalyses NCEP sur 1948-1999 ou des satellites ERS sur 1992-1999). Leur analyse met en évidence des cheminements des masses d'eaux propres aux évènements El Niño-La Niña de 1997-1998, avec des recharges et décharges de la bande équatoriale complexes et asymétriques. Cette analyse montre aussi l'apport d'eaux froides par les STCs et l'EUC lors de la brusque transition vers La Niña en mai 1998. Les données de courant et de température des mouillages TAO/TRITON le long de l'équateur à 170°W, 140°W et 110°W sont méthodiquement bouchées sur 1980-2002. On montre que des séries continues du débit, de la température, de la profondeur et de l'énergie cinétique de l'EUC sur toute son extension méridienne peuvent alors être construites. Leur analyse révèle que la forte variabilité interannuelle du débit de l'EUC est une réponse linéaire et quasi-stationnaire à la tension de vent zonale équatoriale intégrée zonalement dans le Pacifique Ouest et central. La température de l'EUC, indispensable pour l'estimation du transport de chaleur, varie elle linéairement avec la différence des profondeurs de la thermocline et de l'EUC dans le Pacifique central. Le modèle numérique, validé entre autre à l'aide des séries de l'EUC, est utilisé pour étudier sur 1951-1999 la circulation équatoriale associée à l'EUC: la convergence dans la pycnocline, l'upwelling équatorial et la divergence en surface à 5°N et 5°S. Leurs variabilités en débit sont quasi-égales à celle de l'EUC, qui est donc un bon indicateur de la force des STCs. Ces variabilités sont principalement causées par la tension de vent zonale intégrée zonalement sur tout le bassin, en accord avec des théories linéaires. Des déphasages avec la SST équatoriale, notamment l'avance de 5 mois de l'upwelling et de la divergence sur la SST, révèlent des relations de cause à effet très intéressantes, confirmées par les bilans de chaleur. La différence de température entre la divergence et la convergence a des variations interannuelles et à plus long-terme égales à celles de la SST équatoriale. Les conséquences sur les bilans et échanges de masse et de chaleur dans la bande équatoriale sont ensuite quantifiées. La variabilité du transport de chaleur méridien associé à la convergence/divergence est due aussi bien aux variations de débit que de température de la convergence et de la divergence. Ainsi, pendant un événement El Niño, la baisse des débits aura tendance à réchauffer la bande équatoriale (recharge), alors que l'augmentation de la différence entre les températures de la divergence et de la convergence aura l'effet contraire (décharge). Pour le Pacifique Est, les variations interannuelles du débit dominent celles de la température de l'EUC pour le transport de chaleur de l'EUC. Les liens avec les théories d'El Niño et sa variabilité décennale sont discutés

Le sous-courant équatorial et les échanges de masse et de chaleur associés dans le Pacifique tropical (variabilité, liens avec les événements El Nino-La Nina)

TOULOUSE3-BU Sciences (315552104) / SudocTOULOUSE-Observ. Midi Pyréné (315552299) / SudocSudocFranceF

Improving and Harmonizing El Niño Recharge Indices

El Niño Southern Oscillation (ENSO) is the leading mode of interannual climate variability, with large socioeconomical and environmental impacts. The main conceptual model for ENSO, the Recharge Oscillator (RO), considers two independent modes: the fast zonal tilt mode in phase with central-eastern Pacific Temperature (Te), and the slow recharge mode in phase quadrature. However, usual indices (western or equatorial sea level/thermocline depth h) do not orthogonally isolate the slow recharge mode, leaving it correlated with Te. Furthermore the optimal index is currently debated. Here, we develop an improved recharge index by objectively optimizing the RO equations fit to observations. (a) Te-variability is regressed out, to build hind statistically-independent from Te. Capturing the pure recharge, hind reconciles usual indices. (b) The optimum is equatorial plus southwestern Pacific hind_eq+sw (because of ENSO Ekman pumping meridional asymmetry). Using hind_eq+sw, the RO becomes more consistent with observations. hind_eq+sw is more relevant for ENSO operational diagnostics. Key Points To clarify the debate on the Recharge Oscillator index, we develop an objective approach optimizing equation fit to observations The recharge index must be based on the slow component of sea level/thermocline depth, taken independently from the fast zonal tilt mode: this reconciles usual metrics The optimal index is this independent component averaged in the equatorial and southwestern Pacific. It is better suited for operational diagnostics Plain Language Summary El Niño and La Niña events have important impacts globally. A key element for long-lead forecasts is the recharge state of the tropical Pacific Ocean, as captured in the Recharge Oscillator (RO) conceptual model. The RO considers two independent modes of oceanic variability, a fast adjustment process and a slow recharge/discharge process. However, usual recharge indices mix these two modes of variability, and can thus lead to ambiguous operational diagnostics of the actual oceanic recharge state. Here we develop a better recharge index, independent of the fast mode, which reconciles typical indices and allows us to go beyond the current geographical debate on the optimal metrics. We use an objective approach optimizing the RO resemblance to observations to find the optimal index: the independent sea level (or equivalently thermocline depth) averaged over the equatorial and southwestern tropical Pacific. We recommend this simple and unambiguous index for El Niño operational forecasts diagnostics

Tropical pathways, equatorial undercurrent variability and the 1998 La Niña

International audienc

Factors controlling the Indian summer monsoon onset in a coupled model

International audienceThe observed Indian Summer Monsoon (ISM) onset occurs around 30 May and 2 June, with a standard deviation of 8 to 9 days, according to the estimates. The relationship between interannual variability of the ISM onset and SSTs (Sea Surface Temperature) remains controversial. The role of Indian Ocean SSTs remain unclear, some studies have shown a driving role while other suggests a passive relation between Indian Ocean SSTs and ISM. The intrinsic impact of ENSO (El Nino-Southern Oscillation) is also difficult to estimate from observations alone. Finally, the predictability of the ISM onset remains drastically limited by the inability of both forced and coupled model to reproduce a realistic onset date. In order to measure objectively the ISM onset, different methods have been developed based on rainfall or dynamical indices (Ananthakrishnan and Soman, 1988 ; Wang and Ho 2002 ; Joseph et al. 2006). In the study we use the Tropospheric Temperature Gradient (TTG), which is the difference between the tropospheric temperature in a northern and a southern box in the Indian areas (Xavier et al. 2007). This index measures the dynamical strength of the monsoon and provides a stable and precise onset date consistent with rainfall estimates. In the SINTEX-F2 coupled model, the ISM onset measured with the TTG is delayed of approximately 10 days and is in advance of 6 days in the atmosphere-only (ECHAM) model. The 16 days lag between atmospheric-only and coupled runs suggests a crucial role of the coupling, especially SST biases on the delayed onset. With the help of several sensitivity experiments, this study tries to identify the keys regions influencing the ISM onset. Many studies have shown a strong impact of the Arabian Sea and Indian Ocean SST on the ISM onset. Nevertheless, the correction of the SSTs, based on AVHRR, in the tropical Indian Ocean only slightly corrects the delayed onset in the coupled model, which suggests an impact of SST in others regions on the ISM onset. During May and June, the main tropical SST biases in the coupled model are a strong warm bias in the Atlantic Ocean and a warm bias in the tropical Pacific Ocean, except along the equator around 140°W-100°W, where there is a cold tongue bias. The correction of the warm bias in the Atlantic Ocean slightly improves the onset date. Conversely, the correction of SST biases in the tropical and equatorial Pacific Oceans advances the onset date of 12 and 10 days, respectively, compared to the control coupled run. This result suggests that, at least in this model, the ISM onset is mainly control by the Pacific Ocean SSTs. Even if ENSO has an impact on the onset date it does not explain the delay, which is related to the biased SST mean state in the Pacific Ocean