Using model projections to study the emergence of observable climate signals presumes omniscient knowledge about the climate system. In reality, observational knowledge suffers from data quality and ...availability issues, for instance data gaps, changes in instrumentation, issues due to gridding and retrieval algorithms. Overlooking such deficiencies leads to misrepresentations of the time of emergence (ToE). We introduce a new definition of ToE that accounts for observational limitations, and show that significant corrections to the ToE may be necessary to achieve the same statistical confidence as would be afforded by omniscient knowledge. We also show how our method can inform future observational needs and observing systems design.
Plain Language Summary
Long‐term planning for climate change adaptation requires accurate forecasts of climate impacts. Such forecasts are produced using computer models, which provide omniscient knowledge of the climate states they simulate. However, real‐world knowledge is based on incomplete and sometimes flawed observational data. Ignoring these flaws yields a distorted view of the timing of observable climate impacts. We propose a method to address this issue by accounting for observational limitations such as data gaps, changes in measuring equipment, data post‐processing, etc. We also show how to use the method to plan future data collection.
Key Points
The degree of confidence placed in observed climate trends is misrepresented when overlooking observational limitations
We provide a nonparametric method to account for such limitations
The method can also inform the design of future observing platforms
Tropical cyclones (TCs) are associated with tropopause‐level cooling above tropospheric warming. We collect temperature retrievals from 2007 to 2014 near worldwide hurricane‐strength TCs using three ...remote sensing platforms: the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC), the Advanced Microwave Sounding Unit‐A (AMSU‐A), and geostationary infrared (IR) imagery. These retrievals are composited about the lifetime maximum intensity (LMI) to examine the evolution of the fine‐scale temperature structure within TCs. The convective structure evolves highly asymmetrically about LMI, while intensity evolution shows a much weaker degree of asymmetry. Relative to the far‐field structure, tropopause‐level cooling occurs before a tropospheric warm core is established. We speculate that the associated convective destabilization exerts a positive feedback on TC development by increasing the depth of existing convection. Tropopause‐level cold anomalies move away from the storm after LMI, potentially increasing the near‐surface horizontal pressure gradient toward the storm center and increasing the maximum winds.
Key Points
Tropopause‐level cooling occurs in tropical cyclones starting several days prior to maximum intensity
Tropopause‐level cooling has a similar magnitude as the warm core
Tropopause‐level cooling may affect tropical cyclone potential intensity
A ubiquitous cold signal near the tropopause, here called “tropopause layer cooling” (TLC), has been documented in deep convective regions such as tropical cyclones (TCs). Temperature retrievals from ...the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) reveal cooling of order 0.1–1 K day−1 on spatial scales of order 1000 km above TCs. Data from the Cloud Profiling Radar (onboard CloudSat) and from the Cloud–Aerosol Lidar with Orthogonal Polarization onboard the Cloud–Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) are used to analyze cloud distributions associated with TCs. Evidence is found that convective clouds within TCs reach the upper part of the tropical tropopause layer (TTL) more frequently than do convective clouds outside TCs, raising the possibility that convective clouds within TCs and associated cirrus clouds modulate TLC. The contribution of clouds to radiative heating rates is then quantified using the CloudSat and CALIPSO datasets: in the lower TTL (below the tropopause), clouds produce longwave cooling of order 0.1–1 K day−1 inside the TC main convective region, and longwave warming of order 0.01–0.1 K day−1 outside; in the upper TTL (near and above the tropopause), clouds produce longwave cooling of the same order as TLC inside the TC main convective region, and one order of magnitude smaller outside. Considering that clouds also produce shortwave warming, cloud radiative effects are suggested to explain only modest amounts of TLC while other processes must provide the remaining cooling.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A constellation of microwave sounders named the EUMETSAT Polar System–Sterna (EPS–Sterna) is under study at the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT), ...with the aim of complementing the backbone orbits of the global observing system in low Earth orbit. The satellites of this constellation would be similar to the Arctic Weather Satellite (AWS), which is being developed by the European Space Agency (ESA). The microwave sounder on board AWS is equipped with temperature sounding channels around the 50‐GHz oxygen absorption band, water‐vapour sounding channels around the 183‐ and 325‐GHz absorption bands, and also window channels at 89 and 165 GHz. An observing‐system simulation experiment (OSSE) has been conducted at the Centre National de Recherches Météorologiques (CNRM) to evaluate the impact of this constellation on numerical weather prediction (NWP) at the global scale with the Action de Recherche Petite Echelle Grande Echelle (ARPEGE) model. Two periods ranging from August–October 2021 and December 2021–February 2022 have been chosen to compute the nature run and to run 4D‐Var data assimilation experiments. As validation of the OSSE framework, the impact of a Metop‐B denial experiment in the OSSE is compared with the impact of a Metop‐B denial with real observations. This comparison shows that the Metop‐B denial impacts are very similar in the OSSE and with real observations, with the OSSE slightly overestimating the impact. Then, the impacts of various scenarios for the EPS–Sterna constellation are assessed by computing forecast errors, fractions skill scores, and moist global energy norms, and comparing these with the results of a baseline experiment without the EPS–Sterna constellation. Significant and positive improvements of the forecasts are found up to 96 h, for every variable tested, with an impact increasing with the number of satellites.
The observing‐system simulation experiments conducted in this study demonstrate the significant and positive impacts of the EPS–Sterna constellation on numerical weather prediction, for every variable tested, up to +96 h, with an impact increasing with the number of satellites. As a point of comparison, the impacts of EPS–Sterna are scaled with the impact of a single Metop satellite, demonstrating an impact of about 1.7 Metop‐B in the Southern Hemisphere and 0.7 Metop‐B in the Northern Hemisphere for the six‐satellite EPS–Sterna scenario.
Remote sensing data from GPS radio occultation reveal temperatures lower than climatological average over a layer several kilometers deep near the tropopause above tropical cyclones (TCs). This ...signal, here referred to as tropopause layer cooling (TLC), occurs primarily during TC intensification and on spatial scales of the order of 1000 km. TLC has been hypothesized to be the result of: 1) Adiabatic expansion in cloud tops that overshoot the local level of neutral buoyancy. 2) Long wave radiative effects near the cloud top. 3) Adiabatic expansion in the TC secondary circulation. The relative role of these mechanism has not been quantified yet, perhaps pertaining to the large uncertainties and relative lack of vertical resolution of observational data sets and numerical modeling studies near the tropopause. Given the complex relationships between the thermal structure of the upper troposphere and the TC secondary circulation, determining which mechanisms are at play is paramount. TLC is also expected to destabilize the upper troposphere to convection and allow clouds to reach higher altitudes, likely leading to subtle but consequential changes in the secondary circulation and associated latent heating vertical distribution. Low temperatures near the tropopause can lead to in situ formation of cirrus clouds, which impact the radiative budget in the tropical tropopause layer. Lastly, low temperatures above convective systems have been linked to dehydration of the stratosphere, prompting the question of the role of TCs on the climate. Mechanism 1 is discussed in light of existing literature and suggested to be of marginal importance. Mechanisms 2 and 3 are examined using a combination of observational and theoretical analysis, and numerical modeling. Radiative heating rates calculated using cloud properties retrieved by the A-train suggest that mechanism 2 may explain up to half of TLC in the inner core, but only marginal amounts of TLC at larger radii. While reanalysis data sets suggest that mechanism 3 may explain TLC, numerical simulations of TCs with higher resolution suggest that mechanism 3 does not act in a way consistent with the secondary circulation as is typically pictured, and may need to be revisited. Other mechanisms involving processes which violate gradient wind balance near the tropopause need to be formulated. Finally, feedbacks between TLC, cloud structure, and TC dynamics are examined using parcel theory and idealized simulations. Parcel theory predicts that the TC thermal structure exerts a positive feedback on cloud top height during intensification, especially when convective entrainment is taken into account. While idealized simulations capture this general behavior, they exhibit other complex, transient behaviors which indicate breaking points in the interaction between clouds and their thermal environment.
The Convective Transport of Active Species in the Tropics (CONTRAST) experiment was an aircraft‐based field campaign conducted from Guam (14°N, 145°E) during January–February 2014. Aircraft ...measurements included over 80 vertical profiles from the boundary layer to the upper troposphere (~15 km). A large fraction of these profiles revealed layered structures with very low water vapor (relative humidity <20%) and enhanced ozone, primarily in the lower‐middle troposphere (~3–9 km). Comparing CONTRAST water vapor measurements with co‐located profiles from National Centers for Environmental Prediction Global Forecast System (GFS) analyses, we find good agreement for dry layers, including profile‐by‐profile comparisons and statistical behavior. We then utilize GFS data to evaluate the frequency of occurrence and 3‐D structure of dry layers for the CONTRAST period to provide perspective to the campaign measurements and evaluate the global climatological behavior based on a longer record. GFS data show that dry layers occur ~50–80% of the time in the subtropical troposphere, maximizing on the equatorward side of the subtropical jets in the winter hemisphere. Subtropical dry layers occur most frequently over isentropic levels ~320–340 K, which extend into the extratropical upper troposphere‐lower stratosphere (UTLS). Similar statistical behavior of dry, ozone‐rich layers is found in long‐term balloon measurements from Reunion Island (21°S, 56°E). The climatologically frequent occurrence of dry, ozone‐rich layers, plus their vertical and spatial structures linked to the subtropical jets, all suggest that dry layers are linked to quasi‐isentropic transport from the extratropical UTLS and suggest a ubiquitous UTLS influence on the subtropical middle troposphere.
Key Points
Airborne observed dry layers in the tropical troposphere are well represented in GFS analyses
GFS global climatology shows strong connection between dry layers and subtropical jet
Ubiquitous dry, ozone‐rich air is a signature of extratropical UTLS influence in subtropics
Gastric cancer (GC) with peritoneal metastases (PMs) is a poor prognostic evolution. Cytoreductive surgery (CRS) yields promising results, but the impact of hyperthermic intraperitoneal chemotherapy ...(HIPEC) remains controversial. Here we aimed to compare outcomes between CRS-HIPEC versus CRS alone (CRSa) among patients with PMs from GC.
From prospective databases, we identified 277 patients with PMs from GC who were treated with complete CRS with curative intent (no residual nodules > 2.5 mm) at 19 French centers from 1989 to 2014. Of these patients, 180 underwent CRS-HIPEC and 97 CRSa. Tumor burden was assessed using the peritoneal cancer index. A Cox proportional hazards regression model with inverse probability of treatment weighting (IPTW) based on propensity score was used to assess the effect of HIPEC and account for confounding factors.
After IPTW adjustment, the groups were similar, except that median peritoneal cancer index remained higher in the CRS-HIPEC group (6
2;
= .003). CRS-HIPEC improved overall survival (OS) in both crude and IPTW models. Upon IPTW analysis, in CRS-HIPEC and CRSa groups, median OS was 18.8 versus 12.1 months, 3- and 5-year OS rates were 26.21% and 19.87% versus 10.82% and 6.43% (adjusted hazard ratio, 0.60; 95% CI, 0.42 to 0.86;
= .005), and 3- and 5-year recurrence-free survival rates were 20.40% and 17.05% versus 5.87% and 3.76% (
= .001), respectively; the groups did not differ regarding 90-day mortality (7.4%
10.1%, respectively;
= .820) or major complication rate (53.7%
55.3%, respectively;
= .496).
Compared with CRSa, CRS-HIPEC improved OS and recurrence-free survival, without additional morbidity or mortality. When complete CRS is possible, CRS-HIPEC may be considered a valuable therapy for strictly selected patients with limited PMs from GC.
Natural selection is commonly seen not just as an explanation for adaptive evolution, but as the inevitable consequence of “heritable variation in fitness among individuals”. Although it remains ...embedded in biological concepts, such a formalisation makes it tempting to explore whether this precondition may be met not only in life as we know it, but also in other physical systems. This would imply that these systems are subject to natural selection and may perhaps be investigated in a biological framework, where properties are typically examined in light of their putative functions. Here we relate the major questions that were debated during a three-day workshop devoted to discussing whether natural selection may take place in non-living physical systems. We start this report with a brief overview of research fields dealing with “life-like” or “proto-biotic” systems, where mimicking evolution by natural selection in test tubes stands as a major objective. We contend the challenge may be as much conceptual as technical. Taking the problem from a physical angle, we then discuss the framework of dissipative structures. Although life is viewed in this context as a particular case within a larger ensemble of physical phenomena, this approach does not provide general principles from which natural selection can be derived. Turning back to evolutionary biology, we ask to what extent the most general formulations of the necessary conditions or signatures of natural selection may be applicable beyond biology. In our view, such a cross-disciplinary jump is impeded by reliance on individuality as a central yet implicit and loosely defined concept. Overall, these discussions thus lead us to conjecture that understanding, in physico-chemical terms, how individuality emerges and how it can be recognised, will be essential in the search for instances of evolution by natural selection outside of living systems.
Background
The purpose of this study was to assess the efficacy and tolerance of induction chemotherapy combining LV5FU2 with increased doses of irinotecan adapted to UGT1A1 genotyping and cetuximab ...in untreated potentially resectable liver metastases of colorectal cancer.
Methods
Twenty-six patients, PS 0-1, with class II hepatic metastases received chemotherapy combining irinotecan 260 mg/m
2
on day 1 for UGT1A1 6/6 and 6/7 genotypes and 220 mg/m
2
for UGT1A1 7/7 genotypes, with leucovorin on day 1, 5FU 400 mg/m
2
bolus on day 1 and continuous 5FU infusion for 46 h, and cetuximab on day 1 (day 1 = day 14). Primary prevention with lenograstim (day 5–9) was given to UGT1A1 6/7 and 7/7 genotypes. The primary endpoint was the response rate (RECIST1.1), and the secondary endpoints were tolerance (NCI-CTC criteria) and R0 resection rate.
Results
The average number of cycles per patient was 6 (±1.9). The UGT1A1 genotype was 6/6 in 34.6 %, 6/7 in 53.9 %, and 7/7 in 11.5 % of patients. At 6 cycles, 18 patients (69.2 %) presented a partial response, 5 patients (19.2 %) had stable disease, 2 patients (7.7 %) died independently of chemotherapy, and 1 patient (3.9 %) refused the treatment after 3 cycles. Four patients received 2 more cycles and the cumulative response rate at 8 cycles was 76.9 % (20/26). There was no progression. Among assessable patients (
n
= 23), the overall response rate was 82.6 % and 21 patients (80.7 %) had a metastasis resection. The most frequent grade 3–4 toxicities were neutropenia (31 %), diarrhea (20.8 %), and anorexia (16.4 %). There were no deaths due to toxicity.
Conclusions
High-dose FOLFIRI combined with cetuximab yielded high response rates and enabled complete resection of class II hepatic metastases in most patients. It seemed to be well-tolerated among healthy selected patients thanks to irinotecan dose adaptation according to UGT1A1 pharmacogenomics status. This intensified chemotherapy regimen needs to be confirmed in a randomized, phase III study.
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