The broad climatological features associated with the Asian monsoon circulation, including its mean state and intraseasonal and interannual variability over the Indian subcontinent, as simulated in ...the CCSR/NIES coupled A–O GCM in its control experiment are presented in this paper. The model reproduces the seasonal cycle as well as basic observed patterns of key climatic parameters, in spite of some limitations in simulation of the monsoon rainfall. While the seasonality in rainfall over the region is well simulated and the simulated area-averaged monsoon rainfall is only marginally higher than the observed rainfall, the peak rainfall is simulated to be about two-thirds of the observed precipitation intensity over central India. The transient experiments performed with the model following the four SRES 'Marker' emission scenarios, which include revised trends for all the principal anthropogenic forcing agents for the future, suggest an annual mean area-averaged surface warming over the Indian subcontinent to range between 3.5 and 5.5°C over the region during 2080s. During winter, India may experience between 5 and 25% decline in rainfall. The decline in wintertime-rainfall over India is likely to be significant and may lead to droughts during the dry summer months. Only a 10 to 15% increase is projected in area-averaged summer monsoon rainfall over the Indian subcontinent. The date of onset of summer monsoon over India could become more variable in future.
In climate change projections, inter-model differences in cloud feedback have been identified as the largest source of uncertainty. The source terms of the cloud condensate tendency equation (CCTD) ...are expected to be useful diagnostics to better understand the different cloud responses to a CO2 increase in GCMs. To demonstrate the idea, analysis of the CCTD response to CO2 doubling is presented using two versions of a climate model with different climate sensitivities of 6.2°C ('HS'version) and 4.1°C ('LS'version). The model's response to CO2 doubling is characterized with a marked difference in the cloud feedback between the two versions, which is consistent with the cloud response in the southern middle latitudes: cloud decreases in the HS version and increases in the LS version. Analysis of the source terms reveals that the difference in cloud response is attributable to the ice sedimentation process. The results also suggest the importance of the vertical cloud ice profile which controls the ice sedimentation response to a CO2 increase, indicating the potential for providing constraints on the aspect of cloud feedback.
Simulated daily discharge derived from a relatively high-resolution (approximately 1.1-degree) general circulation model was used to investigate future projections of extremes in river discharge ...under global warming. The frequency of floods was projected to increase over many regions, except those including North America and central to western Eurasia. The drought frequency was projected to increase globally, while regions such as northern high latitudes, eastern Australia, and eastern Eurasia showed a decrease or no significant changes. Changes in flood and drought are not explained simply by changes in annual precipitation, heavy precipitation, or differences between precipitation and evapotranspiration. Several regions were projected to have increases in both flood frequency and drought frequency. Such regions show a decrease in the number of precipitation days, but an increase in days with heavy rain. Several regions show shifts in the flood season from springtime snowmelt to the summer period of heavy precipitation.
In this study we present a simple scheme for the diagnosis of the strength of climate feedback. The scheme is based on straightforward calculations using the conventional output of a general ...circulation model (GCM), and evaluates the major radiative feedbacks concerning the surface, clear‐sky atmosphere, and clouds. We place an emphasis on evaluating shortwave (SW) feedbacks. Assumptions involved in extracting the SW surface feedback are validated by accurate calculations and considered to be acceptable. The performance of our scheme is demonstrated via a doubled CO2 experiment. Compared to conventional methods, we can evaluate SW feedbacks more accurately while the evaluation of LW feedbacks is essentially similar between the two methods. The ready application of our scheme to the output of various GCMs should be of great use for multi‐model ensemble analyses, which contribute to reducing the uncertainty in future climate projections.
Acral melanocytic nevi have parallel patterns on dermoscopy; however, it is not understood why pigment distributions exhibit such patterns.
To clarify the reason why melanin distributions in acral ...melanocytic nevi exhibit a parallel pattern on dermoscopy.
A serial sectioning perpendicular to the skin markings was performed, and each section was stained with modified Fontana-Masson staining to pick out melanin granules. These sections were then reconstructed to three-dimensional images by an image processing software, and these three-dimensional images were analyzed.
Melanin columns in the cornified layer were mainly seen in the dermoscopic images of acral melanocytic nevi. In the parallel-furrow pattern melanin columns were arranged vertically, and in the fibrillar pattern they were arranged in a slanting fashion.
Melanin columns in the cornified layer, not melanin in the basal layer, mainly contribute to the dermoscopic pattern of acral melanocytic nevi.
The Model for Interdisciplinary Research on Climate (MIROC), an atmosphere‐ocean coupled general circulation model (AOGCM), has two versions with different resolutions, high (Hi‐Res) and medium ...(Mid‐Res). While their equilibrium climate sensitivities (ECS) to CO2 increases are similar, the transient climate response (TCR) of the Hi‐Res version is larger than that of the Mid‐Res version. The former shows the highest transient response among the Intergovernmental Panel on Climate Change (IPCC) fourth assessment report (AR4) climate models. Our climate feedback analysis indicates that the higher TCR of the Hi‐Res version mainly comes from its larger ice‐albedo feedback (SFC‐SW) and lower ocean heat uptake (OHU). Since the Hi‐Res version shows better agreement with observation than the Mid‐Res version concerning the factors that affect the SFC‐SW and OHU, the TCR of the Hi‐Res version is not considered to be unrealistic compared to that of the Mid‐Res version. On the other hand, the two versions have similar SFC‐SW values and negligible OHU in ECS experiments performed by the atmosphere‐slab ocean coupled general circulation model (ASGCM). In the ASGCM, the difference in SFC‐SW between the two versions was likely suppressed due to artificial fluxes applied to the ocean and sea‐ice system.
DECADAL CLIMATE PREDICTION Meehl, Gerald A.; Goddard, Lisa; Boer, George ...
Bulletin of the American Meteorological Society,
02/2014, Letnik:
95, Številka:
2
Journal Article
Recenzirano
Odprti dostop
This paper provides an update on research in the relatively new and fast-moving field of decadal climate prediction, and addresses the use of decadal climate predictions not only for potential users ...of such information but also for improving our understanding of processes in the climate system. External forcing influences the predictions throughout, but their contributions to predictive skill become dominant after most of the improved skill from initialization with observations vanishes after about 6–9 years. Recent multimodel results suggest that there is relatively more decadal predictive skill in the North Atlantic, western Pacific, and Indian Oceans than in other regions of the world oceans. Aspects of decadal variability of SSTs, like the mid-1970s shift in the Pacific, the mid-1990s shift in the northern North Atlantic and western Pacific, and the early-2000s hiatus, are better represented in initialized hindcasts compared to uninitialized simulations. There is evidence of higher skill in initialized multimodel ensemble decadal hindcasts than in single model results, with multimodel initialized predictions for near-term climate showing somewhat less global warming than uninitialized simulations. Some decadal hindcasts have shown statistically reliable predictions of surface temperature over various land and ocean regions for lead times of up to 6–9 years, but this needs to be investigated in a wider set of models. As in the early days of El Niño–Southern Oscillation (ENSO) prediction, improvements to models will reduce the need for bias adjustment, and increase the reliability, and thus usefulness, of decadal climate predictions in the future.
Toll-like receptor 4 (TLR4) mediates lipopolysaccharide (LPS) signaling in a variety of cell types. MD-2 is associated with the extracellular domain of TLR4 and augments TLR4-dependent LPS responses ...in vitro. We show here that MD-2(-/-) mice do not respond to LPS, do survive endotoxic shock but are susceptible to Salmonella typhimurium infection. We found that in MD-2(-/-) embryonic fibroblasts, TLR4 was not able to reach the plasma membrane and predominantly resided in the Golgi apparatus, whereas TLR4 was distributed at the leading edge surface of cells in wild-type embryonic fibroblasts. Thus, MD-2 is essential for correct intracellular distribution and LPS-recognition of TLR4.
PDF
