Analyzing ozone variations and uncertainties at high latitudes during Sudden Stratospheric Warming events using MERRA-2

Stratospheric circulation is a critical part of the Arctic ozone cycle. Sudden stratospheric warming events (SSWs) manifest the strongest alteration of stratospheric dynamics. Changes in planetary wave propagation vigorously influence zonal mean zonal wind, temperature, and tracer concentrations in the stratosphere over the high latitudes. In this study, we examine six major SSWs from 2004 to 2020 using the Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2). Using the unique density of observations around the Greenland sector at high latitudes, we perform comprehensive comparisons of high latitude observations with the MERRA-2 ozone dataset during the six major SSWs. Our results show that MERRA-2 captures the high variability of mid stratospheric ozone fluctuations during SSWs over high latitudes. However, larger uncertainties are observed in the lower stratosphere and troposphere. The zonally averaged stratospheric ozone shows a dramatic increase of 9–29 % in total column ozone (TCO) near the time of each SSW, which lasts up to two months. The SSWs exhibit a more significant impact on ozone over high northern latitudes when the polar vortex is mostly elongated as seen in 2009 and 2018 compared to the events in which the polar vortex is displaced towards Europe. The regional impact of SSWs over Greenland has a similar structure as the zonal average, however, exhibits more intense ozone anomalies which is reflected by 15–37 % increase in TCO. The influence of SSW on mid stratospheric ozone levels persists longer than their impact on temperature. This paper is focused on the increased (suppressed) wave activity before (after) the SSWs and their impact on ozone variability at high latitudes. This includes an investigation of the different terms of tracer continuity using MERRA-2 parameters, which emphasizes the key role of vertical advection on mid-stratospheric ozone during the SSWs.

The problem of diagnosing jet waveguidability in the presence of large-amplitude eddies

The waveguidability of an upper tropospheric zonal jet quantifies its propensity to duct Rossby waves in the zonal direction. This property has played a central role in previous attempts to explain large wave amplitudes and the subsequent occurrence of extreme weather. In these studies, waveguidability was diagnosed with the help of ray tracing arguments using the zonal average of the observed flow as the relevant background state. Here, it is argued that this method is problematic both conceptually and mathematically. The issue is investigated in the framework of the non-divergent barotropic model. This model allows the straightforward computation of an alternative “zonalized” background state, which is obtained through conservative symmetrization of potential vorticity contours and which is argued to be superior to the zonal average. Using an idealized prototypical flow configuration with large-amplitude eddies, it is shown that the two different choices for the background state yield very different results; in particular, the zonal-mean background state diagnoses a zonal waveguide, while the zonalized background state does not. This result suggests that the existence of a waveguide in the zonal mean background state is a consequence of, rather than a precondition for large wave amplitudes, and it would mean that the direction of causality is opposite to the usual argument. The analysis is applied to two heatwave episodes from summer 2003 and 2010, yielding essentially the same result. It is concluded that previous arguments about the role of waveguidability for extreme weather need to be carefully re-evaluated to prevent misinterpretation in the future.

A Comparison of Global Surface Air Temperature Over the Oceans Between CMIP5 Models and NCEP Reanalysis

By utilizing eight CMIP5 model outputs in historical experiment that simulated daily mean sea surface temperature (SST) and NCEP reanalysis data over 12 ocean basins around the world from 1960 to 2005, this paper evaluates the performance of CMIP5 models based on the detrended fluctuation analysis (DFA) method. The results of National Centers for Environmental Prediction (NCEP) data showed that the SST in most ocean basins of the world had long-range correlation (LRC) characteristics. The DFA values of the SST over ocean basins are large in the tropics and small in high latitudes. In spring and autumn, the zonal average DFA of SST are basically distributed symmetrically in the Northern and Southern Hemispheres. In summer, the zonal average values of DFA in the Northern Hemisphere are larger than those in the southern hemisphere, and vice versa in winter. The performance of HadGEM2-AO, CNRM-CM5, and IPSL-CM5A-MR are all relative well among the eight models in simulating SST over most regions of the global ocean.

Global Patterns of Hottest, Coldest and Extreme Diurnal Variability on Earth

Most previous studies of extreme temperatures have primarily focused on atmospheric temperatures. Using 18 years of the latest version of the Moderate Resolution Imaging Spectroradiometer (MODIS) land surface temperature (LST) data, we globally investigate the spatial patterns of hot and cold extremes as well as diurnal temperature range (DTR). We show that the world’s highest LST of 80.8 °C, observed in the Lut Desert in Iran and the Sonoran Desert in Mexico, is over ten degrees above the previous global record of 70.7 °C observed in 2005. The coldest place on Earth is Antarctica with the record low temperature of -110.9 °C. The world’s maximum DTR of 81.8 °C is observed in a desert environment in China. We see strong latitudinal patterns in hot and cold extremes as well as DTR. Biomes worldwide are faced with different levels of temperature extremes and DTR: we observe the highest zonal average maximum LST of 61.1 ± 5.3 °C in the deserts and xeric shrublands; the lowest zonal average minimum LST of -66.6 ± 14.8 °C in the Tundra; and the highest zonal average maximum DTR of 43.5 ± 9.9 °C in the montane grasslands and shrublands. This global exploration of extreme LST and DTR across different biomes sheds light on the type of extremes different ecosystems are faced with.

Diagnosing jet waveguidability in the presence of large-amplitude eddies

<p>The waveguidability of an upper tropospheric zonal jet quantifies its propensity to duct Rossby waves in the zonal direction. This property has played a central role in previous attempts to explain large wave amplitudes and the subsequent occurrence of extreme weather. In these studies, waveguidability was diagnosed with the help of the refractive index using the zonal average of the observed flow as the relevant background state. Here, it is argued that this method is problematic both conceptually and mathematically.</p><p>The issue is investigated in the framework of the non-divergent barotropic model. This model allows the straightforward computation of an alternative "zonalized" background state, which is obtained through conservative symmetrisation of potential vorticity contours and which is argued to be superior to the zonal average. Using an idealized prototypical flow configuration with large-amplitude eddies, it is shown that the two different choices for the background state yield very different results; in particular, the zonal-mean background state diagnoses a zonal waveguide, while the zonalized background state does not. This result suggests that the existence of a waveguide in the zonal mean background state is a consequence of, rather than a precondition for large wave amplitudes, and it would mean that the direction of causality is opposite to the usual argument.</p><p>The analysis is applied to two heatwave episodes from summer 2003 and 2010, yielding essentially the same result. It is concluded that previous arguments about the role of waveguidability for extreme weather need to be carefully re-evaluated to prevent misinterpretation in the future.</p>

Agrarian potential of personal subsidiary plots

The article discusses the methodology for assessing the personal subsidiary plots production potential. Comparison of the private household plots efficiency is an important problem that requires early solution. It is the most promising direction for optimizing state support and stimulating production. The study purpose is to determine the territories of the Samara region that most effectively use the personal subsidiary plots resources for the agricultural production. The production potential value was the highest in the private household plots of the Samara region southern zone. On average, 1122.2 thousand rubles per hectare fall to personal subsidiary farms in one district of this zone. The production potential value is 36% lower in the Central (719.4 thousand rubles/ha) and by 56% - in the Northern zone (493.0 thousand rubles/ha). The households of the Central natural-economic Zone most effectively use the production potential. The zonal average utilization rate value is 1.14. The available resources are used in the best way by the personal subsidiary plots of the Bezenchuksky district (Kp = 1.67), the worst - by the Sergievsky district (0.62). The considered methodology allows solving important problems - to assess the possibilities and the production real state in the private household plots sector.

Warmer–wetter climate drives shift in δD–δ18O composition of precipitation across the Queen Elizabeth Islands, Arctic Canada

We examine how recent increases in air temperature and precipitation, together with reductions in sea ice extent, may have affected the regional δD–δ18O composition of precipitation. In spring 2014, 80 snow samples were collected from six glaciers and ice caps across the Queen Elizabeth Islands, and in 2009 and 2014, two shallow ice cores were collected from Agassiz Ice Cap and White Glacier, respectively. The snow samples showed average δ18O values from 2013 to 2014 to be approximately 2‰–3‰ higher than those recorded in 1973–1974 in nearby locations, with the ice cores showing similar trends in δ18O values. A zonal average water isotope model was used to help understand the causes of the increased δ18O values, using inputs calibrated for observed changes in temperature, vapour flux, and sea ice extent. Model results indicate that atmospheric temperature changes account for <1‰ of the observed change in δ18O values, and that changes in local water input and precipitation driven by changes in sea ice extent only have an effect in coastal regions. Enhanced meridional vapour flux to the Queen Elizabeth Islands is, therefore, also required to explain the observed increases in δ18O values, with fluxes ∼7% higher today than in the 1970s, consistent with the change in precipitation.

Evaluation of Improved Tef [Eragrostisteff /Zucc./Trotter] Production Technologies in Central High Lands of Ethiopia

A study was carried out to evaluate the performance of improved varieties of tef and production technologies in the Becho district of Oromia, Central Ethiopia. Five improved tef varieties along with the local were selected and used as treatments (that is, Dega tef (T1), Guduru (T2), Kena (T3), Kora(T4), Quncho (T5) and Local (T6)) arranged in a Randomized Complete Block Design (RCBD) with six replications using six farmers’ fields. Yield and yield-related parameters were analyzed using SAS statistical software version 9.0. Economic analysis/profitability, preference/acceptability, gender and nutrition, and environmental suitability data recording were performed to compare treatment advantages and identify the best performing variety/ies. All the yield and yield-related components were significantly different between the varieties at 5 % probability level %) except for plant height in which there was no significant difference among varieties. Variety Dega tef gave the highest grain yield with average grain yield of 3610.6kg/ha followed by Quncho and Kora and also had about 40% yield advantage over the local variety with average grain yield of 2577.83kg/ha and had about 116.95%, 110.25% and 90.80 % yield advantage over the national, regional and zonal average yield of tef in 2016/2017 Meher season of CSA data respectively. Based on farmer’s preference analysis variety Dega tef had high acceptability (75%) followed by Quncho (73%) and Kora (70%). Guduru variety has the least in acceptability (21%). As a result of the economic analysis showed that Dega tef variety had the maximum net benefit (79,536.69birr/ha) followed by Quncho (67,106.97birr/ha) and Kora (63,746.96birr/ha). Variety Guduru had the least net benefit result of about 53,648.17birr/ha. Based on the rules of decision making and the integrated scoring set for technology validation, two of the three improved varieties meet the requirements to be recommended. Therefore, we recommend Dega tef, Quncho, and Kora varieties for Becho areas and other areas with similar agro-ecological conditions in the central highlands of Ethiopia.

Human-induced changes to the global ocean water masses and their time of emergence

&lt;p&gt;The World Ocean is rapidly changing, with global and regional modification of temperature and salinity evident at the surface and depth. These changes have widespread and irreversible impacts including sea-level rise, changes to the oxygen and carbon contents of the ocean interior, or changing habitats, diversity and resilience of ecosystems. While the most pronounced temperature and salinity changes are located in the upper few hundred metres, changes in water-masses at depth are already observed and will likely strengthen and persist in the future as water-masses form at the surface and propagate in the deep ocean along density surfaces, storing the anthropogenic signal away from the atmosphere for decades to millennia. Here, using 11 climate models, we define when anthropogenic temperature and salinity changes are expected to emerge from natural background variability in the ocean interior. On a basin-scale zonal average, the model simulations predict that in 2020, 20&amp;#8211;55% of the Atlantic, Pacific and Indian basins have an emergent anthropogenic signal; reaching 40&amp;#8211;65% in 2050, and 55&amp;#8211;80% in 2080. The well-ventilated Southern Ocean water-masses emerge very rapidly, as early as the 1980s-1990s, while the Northern Hemisphere emerges in the 2010s to 2030s. Additionally, dedicated idealized simulations of the IPSL coupled climate model are examined to study the role of each separate surface forcing on the time scales associated with the patterns of temperature and salinity change under a global warming scenario, and the influence of excess versus redistributed heat and salt. Our results highlight the importance of maintaining and augmenting an ocean observing system capable of detecting and monitoring anthropogenic changes.&amp;#160;&lt;/p&gt;

Evaluation of Improved Tef [Eragrostisteff /Zucc./Trotter] Production Technologies in Central High Lands of Ethiopia

A study was carried out to evaluate the performance of improved varieties of tef and production technologies in Becho district of Oromia, Centeral Ethiopia. Five improved tef varieties along with the local were selected and used as treatments (that is, Dega tef (T1), Guduru (T2), Kena (T3), Kora(T4),Quncho(T5) and Local (T6)) arranged in a Randomized Complete Block Design (RCBD) with six replications using six farmers’ fields. Yield and yield related parameters were analyzed using SAS statistical software version 9.0. Economic analysis/profitability, preference/acceptability, gender and nutrition and environmental suitability data recording were performed to compare treatments advantages and identify the best performing varietity/ies. All the yield and yield related components were significantly different between the varieties at 5 % probability level %) except for plant height in which there was no significant difference among varieties. Variety Dega tef gave the highest grain yield with average grain yield of 3610.6kg/ha followed by Quncho and Kora and also had about 40% yield advantage over the local variety with average grain yield of 2577.83kg/ha and had about 116.95%, 110.25% and 90.80 % yield advantage over the national, regional and zonal average yield of tef in 2016/2017 Meher season of CSA data respectively. Based on farmer’s preference analysis variety Dega tef had high acceptability (75%) followed by Quncho (73%) and Kora (70%). Guduru variety has the least in acceptability (21%). As the result from the economic analysis showed that Dega tef variety had the maximum net benefit (79,536.69birr/ha) followed by Quncho (67,106.97birr/ha) and Kora (63,746.96birr/ha). Variety Guduru had the least net benefit result of about 53,648.17birr/ha. Based on the rules of decision making and the integrated scoring set for technology validation, two of the three improved varieties meet the requirements to be recommended. Therefore, we recommend Dega tef, Quncho, and Kora varieties for Becho areas and other areas with similar agro-ecological conditions in the central highlands of Ethiopia.