Mixed layer temperature response to the southern annular mode: Mechanisms and model representation

Previous studies have shown that simulated sea surface temperature (SST) responses to the southern annular mode (SAM) in phase 3 of the Coupled Model Intercomparison Project (CMIP3) climate models compare poorly to the observed response. The reasons behind these model inaccuracies are explored. The ocean mixed layer heat budget is examined in four of the CMIP3 models and by using observations- reanalyses. The SST response to the SAM is predominantly driven by sensible and latent heat flux and Ekman heat transport anomalies. The radiative heat fluxes play a lesser but nonnegligible role. Errors in the simulated SST responses are traced back to deficiencies in the atmospheric response to the SAM. The models exaggerate the surface wind response to the SAM leading to large unrealistic Ekman transport anomalies. During the positive phase of the SAM, this results in excessive simulated cooling in the 40°-65°S latitudes. Problems with the simulated wind stress responses, which relate partly to errors in the simulated winds themselves and partly to the transfer coefficients used in the models, are a key cause of the errors in the SST response. In the central Pacific sector (90°-150°W), errors arise because the simulated SAM is too zonally symmetric. Substantial errors in the net shortwave radiation are also found, resulting from a poor repre- sentation of the changes in cloud cover associated with the SAM. The problems in the simulated SST re- sponses shown by this study are comparable to deficiencies previously identified in the CMIP3 multimodel mean. Therefore, it is likely that the deficiencies identified here are common to other climate models

Attribution of observed changes in stratospheric ozone and temperature

Three recently-completed sets of simulations of multiple chemistry-climate models with greenhouse gases only, with all anthropogenic forcings, and with anthropogenic and natural forcings, allow the causes of observed stratospheric changes to be quantitatively assessed using detection and attribution techniques. The total column ozone response to halogenated ozone depleting substances and to natural forcings is detectable in observations, but the total column ozone response to greenhouse gas changes is not separately detectable. In the middle and upper stratosphere, simulated and observed SBUV/SAGE ozone changes are broadly consistent, and separate anthropogenic and natural responses are detectable in observations. The influence of ozone depleting substances and natural forcings can also be detected separately in observed lower stratospheric temperature, and the magnitudes of the simulated and observed responses to these forcings and to greenhouse gas changes are found to be consistent. In the mid and upper stratosphere the simulated natural and combined anthropogenic responses are detectable and consistent with observations, but the influences of greenhouse gases and ozone-depleting substances could not be separately detected in our analysis

Revisiting the Mystery of Recent Stratospheric Temperature Trends

Simulated stratospheric temperatures over the period 1979–2016 in models from the Chemistry-Climate Model Initiative are compared with recently updated and extended satellite data sets. The multimodel mean global temperature trends over 1979–2005 are -0.88 ± 0.23, -0.70 ± 0.16, and -0.50 ± 0.12 K/decade for the Stratospheric Sounding Unit (SSU) channels 3 (~40–50 km), 2 (~35–45 km), and 1 (~25–35 km), respectively (with 95% confidence intervals). These are within the uncertainty bounds of the observed temperature trends from two reprocessed SSU data sets. In the lower stratosphere, the multimodel mean trend in global temperature for the Microwave Sounding Unit channel 4 (~13–22 km) is -0.25 ± 0.12 K/decade over 1979–2005, consistent with observed estimates from three versions of this satellite record. The models and an extended satellite data set comprised of SSU with the Advanced Microwave Sounding Unit-A show weaker global stratospheric cooling over 1998–2016 compared to the period of intensive ozone depletion (1979–1997). This is due to the reduction in ozone-induced cooling from the slowdown of ozone trends and the onset of ozone recovery since the late 1990s. In summary, the results show much better consistency between simulated and satellite-observed stratospheric temperature trends than was reported by Thompson et al. (2012, https://doi.org/10.1038/nature11579) for the previous versions of the SSU record and chemistry-climate models. The improved agreement mainly comes from updates to the satellite records; the range of stratospheric temperature trends over 1979–2005 simulated in Chemistry-Climate Model Initiative models is comparable to the previous generation of chemistry-climate models

Effects of different logging practices on soil density and root mass

Any movements of forest machines under the forest canopy are harmful for the stand. Their tracks and wheels damage the soil surface: strip off the litter, disturb the sequence of horizons, alter soil hydro-physical properties. These impacts affect the root content of soils. Especially sensitive in this sense is the spruce, whose roots are mostly concentrated in the topsoil which is disturbed by vehicles. To address the problem of stand damage, it is essential to wisely choose the logging technology and machinery. The widely used practices in Karelia are tree-length skidding by crawler tractors, as well as cut-to-length harvesting. The study aimed to assess the effect of various partial cut practices on soil density and the mass of spruce roots up to 3 mm thick in the middle taiga of Karelia. Soil density was studied in skid trails and in the interior of forest blocks not accessed by machines; root masses were compared. The method of soil monoliths sampled from skid trails and blocks throughout the logging area was used. Cutting to length by machines (harvester + forwarder) was found to cause the heaviest topsoil compaction, as compared to mechanized cut-to-length harvesting (chain-saw + forwarder) or tree-length skidding. Root mass in the trail and inside the block, where machines did not reach, remained different for 12 subsequent years whichever practice was used. The difference was the greatest in the first several years after logging. Soil density in the trail recovered at a faster rate than the root mass

Effects of Arctic sea-ice concentration on turbulent surface fluxes in four atmospheric reanalyses

Peer reviewe

Impact of stratospheric variability on tropospheric climate change

An improved stratospheric representation has been included in simulations with the Hadley Centre HadGEM1 coupled ocean atmosphere model with natural and anthropogenic forcings for the period 1979–2003. An improved stratospheric ozone dataset is employed that includes natural variations in ozone as well as the usual anthropogenic trends. In addition, in a second set of simulations the quasi biennial oscillation (QBO) of stratospheric equatorial zonal wind is also imposed using a relaxation towards ERA-40 zonal wind values. The resulting impact on tropospheric variability and trends is described. We show that the modelled cooling rate at the tropopause is enhanced by the improved ozone dataset and this improvement is even more marked when the QBO is also included. The same applies to warming trends in the upper tropical troposphere which are slightly reduced. Our stratospheric improvements produce a significant increase of internal variability but no change in the positive trend of annual mean global mean near-surface temperature. Warming rates are increased significantly over a large portion of the Arctic Ocean. The improved stratospheric representation, especially the QBO relaxation, causes a substantial reduction in near-surface temperature and precipitation response to the El Chichón eruption, especially in the tropical region. The winter increase in the phase of the northern annular mode observed in the aftermath of the two major recent volcanic eruptions is partly captured, especially after the El Chichón eruption. The positive trend in the southern annular mode (SAM) is increased and becomes statistically significant which demonstrates that the observed increase in the SAM is largely subject to internal variability in the stratosphere. The possible inclusion in simulations for future assessments of full ozone chemistry and a gravity wave scheme to internally generate a QBO is discussed

Mesosphere-to-stratosphere descent of odd nitrogen in February–March 2009 after sudden stratospheric warming

Rajčica je zeljasta jednogodišnja biljka. Sastoji se od 93 do 95 % vode, 5 do 7 % suhe tvari, organskih kiselina (limunske i jabučne), šećera (glukoze, fruktoze i saharoze), tvari netopljivih u alkoholu (proteini, celuloza, pektin, polisaharidi), karotenoida i lipida. Cilj ovog rada bio je testiranje učinkovitosti primjene mikrokapsula na bazi alginata sa simultano inkapsuliranim ionima bakra (Cu2+) ili kalcija (Ca2+) i spora gljive Trichoderma viride, na prinos i kvalitetu rajčice uzgojene u tlu u zaštićenom negrijanom plasteniku. Tijekom višekratne berbe utvrđen je broj tržnih i netržnih plodova, masa tržnih i netržnih plodova, prinos i kvalitativna svojstva. Kemijskom analizom utvrđen je udio karotenoida, ukupnih polifenola te antioksidacijska aktivnost plodova. Rezultati su pokazali pozitivan utjecaj mikrokapsula na rajčicu. Izdvojiti posebno neki tretman kod rajčice je teško jer uz genetiku svake sorte rajčice, svaki tretman je pokazao svoj rezultat. Tretman mikrokapsula s Cu2+ je u prosjeku davao najbolje rezultate u smislu morfoloških karakteristika. Tretmani mikrokapsula s kalcijevim ionima imali su pozitivan utjecaj na sadržaj likopena.Tomato is a herbaceous one-year plant. It consists of 93-95% water, 5-7% dry matter, organic acids (lemon and apple), sugars (glucose, fructose and sucrose), alcohol-insoluble substances (proteins, cellulose, pectin, polysaccharides), carotenoids and lipids. The aim of this paper was to test the efficacy of microcapsules based on biopolymer alginate with simultaneously encapsulated copper (Cu2 +) or calcium (Ca2 +) and Trichoderma viride fungus spores on the yield and quality of tomatoes grown in soil in protected nonheated greenhouses. During the multiple harvests, the number of marketable and non-marketable fruits, the mass of marketable and non-marketable fruits, yield and qualitative properties was established. Chemical analysis showed the proportion of carotenoids, total polyphenols, and antioxidant activity of fruits. The results showed a positive influence on the tomatoes treated with microcapsules. To distinguish a particular tomato treatment is difficult because, with the genetics of each tomato variety, each treatment showed relatively different results. Treatment with microcapsules with Cu2 + gave the best results in terms of morphological characteristics. Microcapsules loaded with Ca2+ had a positive effect on lycopene content