Tropical and subtropical cloud transitions in weather and climate prediction models: The GCSS/WGNE pacific cross-section intercomparison (GPCI)

International audienceA model evaluation approach is proposed in which weather and climate prediction models are analyzed along a Pacific Ocean cross section, from the stratocumulus regions off the coast of California, across the shallow convection dominated trade winds, to the deep convection regions of the ITCZ-the Global Energy and Water Cycle Experiment Cloud System Study/Working Group on Numerical Experimentation (GCSS/WGNE) Pacific Cross-Section Intercomparison (GPCI). The main goal of GPCI is to evaluate and help understand and improve the representation of tropical and subtropical cloud processes in weather and climate prediction models. In this paper, a detailed analysis of cloud regime transitions along the cross section from the subtropics to the tropics for the season June-July-August of 1998 is presented. This GPCI study confirms many of the typical weather and climate prediction model problems in the representation of clouds: underestimation of clouds in the stratocumulus regime by most models with the corresponding consequences in terms of shortwave radiation biases; overestimation of clouds by the 40-yrECMWFRe-Analysis (ERA-40) in the deep tropics (in particular) with the corresponding impact in the outgoing longwave radiation; large spread between the different models in terms of cloud cover, liquid water path and shortwave radiation; significant differences between the models in terms of vertical cross sections of cloud properties (in particular), vertical velocity, and relative humidity. An alternative analysis of cloud cover mean statistics is proposed where sharp gradients in cloud cover along the GPCI transect are taken into account. This analysis shows that the negative cloud bias of some models and ERA-40 in the stratocumulus regions [as compared to the first International Satellite Cloud Climatology Project (ISCCP)] is associated not only with lower values of cloud cover in these regimes, but also with a stratocumulus-to-cumulus transition that occurs too early along the trade wind Lagrangian trajectory. Histograms of cloud cover along the cross section differ significantly between models. Some models exhibit a quasi-bimodal structure with cloud cover being either very large (close to 100%) or very small, while other models show a more continuous transition. The ISCCP observations suggest that reality is in-between these two extreme examples. These different patterns reflect the diverse nature of the cloud, boundary layer, and convection parameterizations in the participating weather and climate prediction models. © 2011 American Meteorological Society

Feeding stimulants for the colorado beetle

Potato leaf extract was fractionated and the fractions obtained were tested for their activity as feeding stimulants for Colorado beetle larvae. Also leaves and leaf extracts of different kinds of plants, as well as a number of known pure compounds and mixtures of them, were tested for this activity. It was concluded that the Colorado beetle does not require any «odd substance» to evoke feeding and that such a "token phagostimulant" is not even likely to be involved in the insects food preference. An experimental mixture of some "sapid nutrients" can be at least as active as a potato leaf extract

The improvement of the low-temperature behaviour of natural rubber vulcanizates by chemical modification with thiol acids

Applied Science

Recent development in insect pheromone research, in particular in the Netherlands

A review is given of recent pheromone work carried out in the Netherlands on Lepidoptera, cockroaches, pharaoh's ants and termites, special emphasis being given to isolation and identification aspects. The sex pheromones of three leaf roller moths (Tortricidae) have been isolated, identified and field tested, viz. those of Adoxophyes orana (cis-9-tetradecenyl acetate (tda) and cis-I1-tda in the ratio 9:1), Clepsis spectrana (cis-9-tda:cis-11-tda, 1:3) and Archipspodana (cis-11-tda:trans-l1-tda, about 1:1). For ?ponomeuta, data have been obtained indicating a correlation between taxonomic groups and pheromone structure. Two sex pheromones (periplanone A and B) of the American cockroach, Periplaneta americana, have been isolated and partially identified. Their elementary formulas, C. 15H. 20O. 2 and C. 15H. 20O. 3, respectively, suggest that they are sesquiterpenoids, spectral data of periplanone B indicating that it has the germacrane skeleton. The aggregation pheromone of the German cockroach, Blattella germanica appears to be a complex mixture in which certain free acids play an important role. Three heterocyclic compounds have been isolated from Pharaoh's ants, Monomorium pharaonis. Monomorine I, C. 13H. 25N, is the first indolizine derivative found in the animal kingdom. Monomorine II, C. 13H. 27N, and monomorine III, C. 15H. 29N, are pyrrolidine derivatives. The three compounds are constituents of the odour trail and are present in excretions collected from the insect's sting. These excretions have a function in trail-following as well as in defense. In choice tests monomorine I and III act as attractants. Cis-3, cis-6, trans-8-dodecatrienol, initially identified as a trail pheromone of the termite Reticulitermes virginicus, was found to be a trail pheromone also for Reticulitermes santonensis. Eight dodecatrienol isomers were tested for activity towards this termite. In their ability to evoke trail-following behaviour as well as their attractancy in choice tests, they resemble each other qualitatively, but quantitatively, they show considerable differences. From fungus-infected wood a compound was isolated which effectively induces trail-following behaviour, and moreover, is a potent attractant. Its elementary formula, C. 15H. 24O, and the presence of acorane among its hydrogenation products, show that it is a sesquiterpenoid. Two other potent attractants for R. santonensis were found in wood oils: tricycloekasantalal, C. 12H. 13O in East-Indian sandalwood oil and dihydroagarofuran, C. 15H. 20O in West-Indian sandalwood oil. © 1974 BRILL