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Atmospheric blocking represents an important aspect of the mid-latitude weather variability, but the different processes contributing to its formation and maintenance are not yet fully understood. This study investigates the role that diabatic processes, in particular the release of latent heating in strongly ascending airstreams, play in the dynamics and spatio-temporal variability of blocking in a detailed 38-year global climatological analysis. The results show that the formation and (re-)intensification of blocking are often preceded by latent heating connected to upstream baroclinic developments. While the importance of latent heating varies considerably between individual blocking events and different regions, in particular between ocean and continents, latent heating is generally most important during onset and in more intense and larger blocks. The episodic nature of latent heating during the blocking life cycle, associated with a series of transient cyclones approaching the blocking, can contribute to both the high- (fast onset and fluctuation in intensity and size) and low-frequency (maintenance and quasi-stationarity during maturation phase) properties of blocking anticyclones and provide the required flow amplification in addition to dry-dynamical interaction between synoptic eddies and blocking. This amplification results from a combination of the direct injection of anticyclonic air into the upper-troposphere within cross-isentropic ascending airstreams, setting up large-scale anticyclonic PV anomalies, and the advection of PV by the enhanced divergent outflow at the tropopause (indirect effect). This divergent outflow on the western flank of the blocking anticyclone interacts with the upper-level PV gradient and leads to a westward amplification of the ridge, diminishing the tendency for dissipation and the eastward advection by the background flow, thus contributing to blocking stationarity. Taking into account such diabatic mechanisms in blocking dynamics will be important to improve predictions of blocking and assess future changes in the extratropical large-scale circulation.

Weather extremes are often associated with atmospheric blocking, but how the underlying physical processes leading to blocking respond to climate change is not yet fully understood. Here we track blocks as upper-level negative potential vorticity (PV) anomalies and apply a Lagrangian analysis to 100 years of present-day (∼2000) and future (∼2100, under the RCP8.5 scenario) climate simulations restarted from the Community Earth System Model–Large Ensemble Project runs (CESM-LENS) to identify different physical processes and quantify how their relative importance changes in a warmer and more humid climate. The trajectories reveal two contrasting airstreams that both contribute to the formation and maintenance of blocking: latent heating in strongly ascending airstreams (moist processes) and quasi-adiabatic flow near the tropopause with weak radiative cooling (dry processes). Both are reproduced remarkably well when compared against ERA-Interim reanalysis, and their relative importance varies regionally and seasonally. The response of blocks to climate change is complex and differs regionally, with a general increase in the importance of moist processes due to stronger latent heating (+1 K in the median over the Northern Hemisphere) and a larger fraction (+15%) of strongly heated warm conveyor belt air masses, most pronounced over the storm tracks. Future blocks become larger (+7%) and their negative PV anomaly slightly intensifies (+0.8%). Using a Theil–Sen regression model, we propose that the increase in size and intensity is related to the increase in latent heating, resulting in stronger cross-isentropic transport of air with low PV into the blocking anticyclones. Our findings provide evidence that moist processes become more important for the large-scale atmospheric circulation in the midlatitudes, with the potential for larger and more intense blocks.

Recent years have seen severe wildfires in the Northern Hemisphere. This study statistically links atmospheric blocks to extreme fire weather (FDP99 ${\\text{FD}}_{\\mathit{P99}}$) and observed fires (OF) across seasons from 1979 to 2020. Based on co‐location and odds ratio statistics, we find that a substantial part of FDP99 ${\\text{FD}}_{\\mathit{P99}}$ co‐occurs with blocks. In areas where blocks occur regularly, blocks increase the odds of FDP99 ${\\text{FD}}_{\\mathit{P99}}$ by a factor of 4–5, with up to a 30‐fold increase locally. The link between blocks and FDP99 ${\\text{FD}}_{\\mathit{P99}}$ is stronger at latitudes north of 50° ^{\\circ}$N, but exhibits regional and seasonal variations. We also find a significant link between blocks and OF in the Arctic regions during summer. This study reveals new links between atmospheric blocks and wildfire danger.

An unseasonal dust storm hit large parts of Central Asia on 4–5 November 2021, setting records for the column aerosol burden and fine particulate concentration in Tashkent, Uzbekistan. The dust event originated from an agropastoral region in southern Kazakhstan, where the soil erodibility was enhanced by a prolonged agricultural drought resulting from La Niña-related precipitation deficit and persistent high atmospheric evaporative demand. The dust outbreak was triggered by sustained postfrontal northerly winds during an extreme cold air outbreak. The cold air and dust outbreaks were preceded by a chain of processes consisting of recurrent synoptic-scale transient Rossby wave packets over the North Pacific and North Atlantic, upper-level wave breaking and blocking over Greenland, followed by high-latitude blocking over Northern Europe and West Siberia, and the equatorward shift of a tropopause polar vortex and cold pool into southern Kazakhstan. Our study suggests that the historic dust storm in Uzbekistan was a compound weather event driven by cold extreme, high winds, and drought precondition.

[...]this arrangement may soon prove to be untenable as shipping traffic in the region rapidly increases. \"as maritime activity rapidly increases, finding a solution will be more urgent than ever before\" Canada has long claimed the Northwest Passage as internal territorial waters, on the basis of a long history of native Inuit use of the waters, as well as legal arguments stemming from decades-old cases settled by the the International Court of Justice. [...]the inevitable rise in shipping will lead to other concerns – such as how to ensure adequate search and rescue (SAR) capabilities in the event of emergencies. According to a 2011 Arctic Council agreement, the U.S. is responsible for search and rescue in a wide swath of ocean stretching from Alaska to the North Pole and the Kamchatka Peninsula, an area that does not overlap with Canada’s territorial claim.

Carbon pricing efforts at the national level, including Bill Clinton’s BTU (British Thermal Unit) energy tax and the Waxman-Markey cap-and-trade bill in 2009, have been unsuccessful. To give a sense of what $100/ton looks like, California’s current cap-and-trade system results in a carbon price of around $15/ton, which translates to about 13 cents/gallon more in gasoline prices for consumers, and a 19 percent increase in natural gas prices. According to a 2017 MIT study, a plan similar to Baker-Shultz with a modest tax starting at $40 per ton rising at 4 percent per year would generate almost $200 billion dollars in revenue by 2020, growing to $450 billion by 2050. [...]far from being some sort of capitulation to fossil fuel interests or “incrementalist” climate skeptics, a carbon tax would in fact play a very practical role in a progressive climate plan, by being a potentially massive source of revenue generation and vehicle for targeting investment towards vulnerable areas or populations.

According to the IPCC, as much as 37 percent of global greenhouse gas emissions come from agriculture and food production. A number of companies, ranging from food retailers such as Carrefour and Tesco to other companies not usually associated with the food industry such as global shipping company Maersk, are viewing solving the problem of food waste not just as an opportunity to increase business sustainability but also as an opportunity to increase profit. While extra refrigeration is obviously energy-intensive, even short periods of exposure to room temperatures or above can greatly reduce food’s shelf life and increase spoilage.

Even though district standards are lower than those of the citywide programs, many underperforming schools do not have enough students meeting the standard to fill a single G&T class. [...]standards would have to be adjusted to specific schools to ensure that a program could be started. [...]most G&T expansion should be focused on district programs in areas that currently are far away from citywide programs or that have few existing district programs. [...]schools began to focus more on remedial education, getting as many students as possible up to a minimum standard. Many Asian cultures place a high value on education, and many low-income families see it as a path to success. Because academic achievement does not necessarily correlate with aggregate economic status among NYC’s Asian-American population, attempts to rebalance the racial/ethnic makeup of schools via policies that focus solely on income often miss the mark.

[...]the report could contribute to the emergence of xenophobic or racist attitudes towards Chinese in academia; secondly, it helps support some assumptions that the purpose and mission of U.S. academic institutions in a globalized academic environment is to feed the U.S. military-industrial complex. [...]the report reveals further evidence of the United States’ hypocrisy related to economic and intellectual espionage. Earlier examples include CIA monitoring of Japanese auto executives during trade talks in 1995 as part of the ECHELON surveillance program, or NSA eavesdropping on negotiations between Airbus and Saudi Arabian airline executives, which were leveraged into providing business openings for U.S. aircraft companies. [...]FBI expectations that U.S. institutions should operate under the assumption that “the Chinese government takes advantage of every opportunity — from academic collaboration to economic espionage — to develop and maintain a strategic economic edge” have the potential to create an atmosphere where fear and suspicion between colleagues and classmates undermine important collaborative research.

When extreme weather events affect large areas, their regional to sub-continental spatial scale is important for their impacts. We propose a novel machine learning (ML) framework that integrates spatial extreme-value theory to model weather extremes and to quantify probabilities associated with the occurrence, intensity, and spatial extent of these events. Our approach employs new loss functions adapted to extreme values, enabling our model to prioritize the tail rather than the bulk of the data distribution. Applied to a case study of Western European summertime heat extremes, we use daily 500-hPa geopotential height fields and local soil moisture as predictors to capture the complex interplay between local and remote physical processes. Our generative model reveals that different facets of heat extremes are influenced by individual circulation features, such as the relative position of upper-level ridges and troughs that are part of a large-scale wave pattern. This enriches our process understanding from a data-driven perspective. Our approach can extrapolate beyond the range of the data to make risk-related probabilistic statements. It applies more generally to other weather extremes and offers an alternative to traditional physical and ML-based techniques that focus less on the extremal aspects of weather data.