bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Impact of Air–Sea Interactions on the Predictability of the Tropical Intraseasonal Oscillation
Authors: Pegion Kathy , Kirtman Ben P. 
Published: May 2008

Abstract
This study investigates whether air–sea interactions contribute to differences in the predictability of the boreal winter tropical intraseasonal oscillation (TISO) using the NCEP operational climate model. A series of coupled and uncoupled, “perfect” model predictability experiments are performed for 10 strong model intraseasonal events. The uncoupled experiments are forced by prescribed SST containing different types of variability. These experiments are specifically designed to be directly comparable to actual forecasts. Predictability estimates are calculated using three metrics, including one that does not require the use of time filtering. The estimates are compared between these experiments to determine the impact of coupled air–sea interactions on the predictability of the tropical intraseasonal oscillation and the sensitivity of the potential predictability estimates to the different SST forcings.
Results from all three metrics are surprisingly similar. They indicate that predictability estimates are longest for precipitation and outgoing longwave radiation (OLR) when the ensemble mean from the coupled model is used. Most importantly, the experiments that contain intraseasonally varying SST consistently predict the control events better than those that do not for precipitation, OLR, 200-hPa zonal wind, and 850-hPa zonal wind after the first 10 days. The uncoupled model is able to predict the TISO with similar skill to that of the coupled model, provided that an SST forecast that includes these intraseasonal variations is used to force the model. This indicates that the intraseasonally varying SSTs are a key factor for increased predictability and presumably better prediction of the TISO.
The Life Cycle of the South American Monsoon System
Authors: Raia Adma , Cavalcanti Iracema Fonsecade Albuquerque 
Published: May 2008

Abstract
The South American monsoon system (SAMS) life cycle plays an important role in the distribution and duration of the rainy season mainly over southwestern Amazonia, and the central west and southeast Brazil regions, affecting the economy through impacts on the agriculture and hydrology sectors. In this study a new criterion is applied to identify the monsoon onset and demise that was not used before in the SAMS region. This criterion is based on the atmospheric humidity flux over an area recognized as the monsoon core because of zonal wind reversal and changes in humidity from the transition seasons to summer and winter. Areas in Brazil that have a monsoon regime are identified, and several features associated with the life cycle are discussed. The climatological onset and demise are identified as the end of October and the end of March, respectively, and an interannual variability is found in the times of onset/demise. The main observed features in the two phases are discussed, such as the role of the South Atlantic subtropical high displacement, the northwestern moisture flux east of Andes and from the Atlantic Ocean, the zonal wind intensity and direction over central South America, the vertical motion over the continent, and the expansion/reduction of the Bolivian high circulation with associated high-level divergence. The frontal systems contribute to the pressure decrease, wind direction changes, and soil moisture increase previous to the onset. Low-frequency troughs with intraseasonal variability establish conditions favorable to the monsoon onset, and low-frequency ridges are related to late onset.
Interannual-to-Decadal Variability in the Oyashio and Its Influence on Temperature in the Subarctic Frontal Zone: An Eddy-Resolving OGCM Simulation
Authors: Nonaka Masami , Nakamura Hisashi , Tanimoto Youichi , Kagimoto Takashi , Sasaki Hideharu 
Published: May 2008

Abstract
Output of an eddy-resolving OGCM simulation is used to investigate mechanisms for interannual-to-decadal variability in the Oyashio and its influence on the subarctic frontal zone in the western North Pacific. Lag correlation analysis reveals that positive anomalies both in basin-scale wind stress curl and in local Ekman pumping can intensify the southward Oyashio almost simultaneously via barotropic and baroclinic Rossby wave propagations, respectively. The Oyashio strength can also be influenced by anomalous Ekman pumping that is exerted in the western portion of the basin through the baroclinic wave propagation with the lag of 3 yr, which appears to arise from a periodicity in the wind field. The intensification of the Oyashio is accompanied by negative anomalies both in the sea surface temperature and height off of Hokkaido Island of Japan and is followed by their eastward development along the southern branch of the Oyashio Extension and associated subarctic frontal zone in association with a southward displacement of their axes. These changes are associated with cool sea surface temperature anomalies and low potential vorticity anomalies at the thermocline level in the frontal zone. The surface cooling, thus induced in the frontal zone by those oceanic processes, accompanies anomalous downward surface heat fluxes, indicative of ocean-to-atmosphere feedback forcing associated with the Oyashio variations.
The Droplike Nature of Rain and Its Invariant Statistical Properties
Authors: Ignaccolo Massimiliano , De Michele Carlo , Bianco Simone 
Published: May 2008

Abstract
This study looks for statistically invariant properties of the sequences of inter-drop time intervals and drop diameters. The authors provide evidence that these invariant properties have the following characteristics: 1) large inter-drop time intervals (≳10 s) separate drops of small diameter (≲0.6 mm); 2) the rainfall phenomenon has two phases: a quiescent phase, whose contribution to the total cumulated flux is virtually null, and an active, nonquiescent, phase that is responsible for the bulk of the precipitated volume; 3) the probability density function of inter-drop time intervals has a power-law-scaling regime in the range of ∼1 min and ∼3 h); and 4) once the moving average and moving standard deviation are removed from the sequence of drop diameters, an invariant shape emerges for the probability density function of drop diameters during active phases.
Variability and Predictability of Central Asia River Flows: Antecedent Winter Precipitation and Large-Scale Teleconnections
Authors: Barlow Mathew A. , Tippett Michael K. 
Published: May 2008

Abstract
Warm season river flows in central Asia, which play an important role in local water resources and agriculture, are shown to be closely related to the regional-scale climate variability of the preceding cold season. The peak river flows occur in the warm season (April–August) and are highly correlated with the regional patterns of precipitation, moisture transport, and jet-level winds of the preceding cold season (November–March), demonstrating the importance of regional-scale variability in determining the snowpack that eventually drives the rivers. This regional variability is, in turn, strongly linked to large-scale climate variability and tropical sea surface temperatures (SSTs), with the circulation anomalies influencing precipitation through changes in moisture transport. The leading pattern of regional climate variability, as resolved in the operationally updated NCEP–NCAR reanalysis, can be used to make a skillful seasonal forecast for individual river flow stations. This ability to make predictions based on regional-scale climate data is of particular use in this data-sparse area of the world.
The river flow is considered in terms of 24 stations in Uzbekistan and Tajikistan available for 1950–85, with two additional stations available for 1958–2003. These stations encompass the headwaters of the Amu Darya and Syr Darya, two of the main rivers of central Asia and the primary feeders of the catastrophically shrinking Aral Sea. Canonical correlation analysis (CCA) is used to forecast April–August flows based on the period 1950–85; cross-validated correlations exceed 0.5 for 10 of the stations, with a maximum of 0.71. Skill remains high even after 1985 for two stations withheld from the CCA: the correlation for 1986–2002 for the Syr Darya at Chinaz is 0.71, and the correlation for the Amu Darya at Kerki is 0.77. The forecast is also correlated to the normalized difference vegetation index (NDVI); maximum values exceed 0.8 at 8-km resolution, confirming the strong connection between hydrology and growing season vegetation in the region and further validating the forecast methodology.
A New Approach to Stochastically Generating Six-Monthly Rainfall Sequences Based on Empirical Mode Decomposition
Authors: McMahon Thomas A. , Kiem Anthony S. , Peel Murray C. , Jordan Phillip W. , Pegram Geoffrey G. S. 
Published: May 2008

AbstractThis paper introduces a new approach to stochastically generating rainfall sequences that can take into account natural climate phenomena, such as the El Niño–Southern Oscillation and the interdecadal Pacific oscillation. The approach is also amenable to modeling projected affects of anthropogenic climate change. The method uses a relatively new technique, empirical mode decomposition (EMD), to decompose a historical rainfall series into several independent time series that have different average periods and amplitudes. These time series are then recombined to form an intradecadal time series and an interdecadal time series. After separate stochastic generation of these two series, because they are independent, they can be recombined by summation to form a replicate equivalent to the historical data. The approach was applied to generate 6-monthly rainfall totals for six rainfall stations located near Canberra, Australia. The cross correlations were preserved by carrying out the stochastic analysis using the Matalas multisite model. The results were compared with those obtained using a traditional autoregressive lag-one [AR(1)], and it was found that the new EMD stochastic model performed satisfactorily. The new approach is able to realistically reproduce multiyear–multidecadal dry and wet epochs that are characteristic of Australia’s climate and are not satisfactorily modeled using traditional stochastic rainfall generation methods. The method has two advantages over the traditional AR(1) approach, namely, that it can simulate nonstationarity characteristics in the historical time series, and it is easy to alter the decomposed time series components to examine the impact of anthropogenic climate change.
Observed and Simulated Soil Moisture Variability over the Lower Mississippi Delta Region
Authors: Mostovoy Georgy V. , Anantharaj Valentine G. 
Published: May 2008

Abstract
To better understand error and spatial variability sources of soil moisture simulated with land surface models, observed and simulated values of soil moisture (using offline simulations with the Noah land surface model with four soil layers and approximately 1-km horizontal grid spacing) were compared. This comparison between observed and modeled daily values of soil moisture was performed over the Lower Mississippi Delta region during summer–fall months 2004–06. The Noah simulations covered the 2.5° × 2.5° latitude–longitude domain and were forced by the North American Land Data Assimilation System (NLDAS) atmospheric forcing fields. Hourly soil moisture measurements and other data, including local meteorological and soil physical properties data from 12 Soil Climate Analysis Network (SCAN) sites, were used. The results show that both the observed and simulated level of soil moisture depend critically on the specified–sampled soil texture. Soil types with a relatively high observed clay content (more than 50% of weight) retain more water as a result of low water diffusivity than silty–sandy soils with 20% or less clay, provided that other conditions are the same. This fact is in agreement with previous studies and implies a strong soil texture control (through related hydraulic parameters) on the accuracy of simulated soil moisture. Sensitivity tests using the Noah model were performed to assess the effect of using the hydraulic parameters related to the site-specific soil texture on soil moisture quality. Indeed, at some SCAN sites, the errors (root-mean-square difference and bias) were reduced. Simulated soil moisture showed at least a 50% reduction when the site-specific soil texture was used in Noah simulations compared to those derived from the State Soil Geographic (STATSGO) data. The most significant improvement of simulated soil moisture was observed within the top 0–10 cm layer where an original positive bias (an excessive wetness) was almost eliminated. Meanwhile, excessive dryness (negative soil moisture bias), which was dominant within the second and third model layers, was also reduced. These improvements are expected to be valid at sites/regions with low (&lt;0.3) vegetation fraction.
Implications of Regime Transitions for Mountain-Wave-Breaking Predictability
Authors: Doyle James D. , Reynolds Carolyn A. 
Published: May 2008

Abstract
A suite of high-resolution two-dimensional ensemble simulations are used to investigate the predictability of mountain waves, wave breaking, and downslope windstorms. For relatively low hills and mountains, perturbation growth is weak and ensemble spread is small. Gravity waves and wave breaking associated with higher mountains exhibit rapid perturbation growth and large ensemble variance. Near the regime boundary between mountain waves and wave breaking, a bimodal response is apparent with large ensemble variance. Several ensemble members exhibit a trapped wave response and others reveal a hydraulic jump and large-amplitude breaking in the stratosphere. The bimodality of the wave response brings into question the appropriateness of commonly used ensemble statistics, such as the ensemble mean, in these situations. Small uncertainties in the initial state within observational error limits result in significant ensemble spread in the strength of the downslope wind speed, wave breaking, and wave momentum flux. These results indicate that the theoretical transition across the regime boundary for gravity wave breaking can be interpreted as a finite-width or blurred transition zone from a practical predictability standpoint.
A Reduced Radiation Grid for the ECMWF Integrated Forecasting System
Authors: Morcrette Jean-Jacques , Mozdzynski George , Leutbecher Martin 
Published: May 2008

Abstract
A specific interface between the radiation transfer calculations and the rest of the ECMWF model was introduced in 2003, potentially providing substantial economy in computer time by reducing the spatial resolution at which radiation transfer is evaluated, without incurring some of the deficiencies produced by the sampling strategy previously used in the ECMWF model. The introduction of a new more-computer-intensive radiation package (McRad) in June 2007 has led to a differentiated use of this interface depending on the applications. The history of the interface, how it is used, and its impact when using the new radiation scheme are discussed here. For a given model resolution, the impact of a lower-resolution radiation grid on the model behavior is studied here, in the context of 10-day forecasts at high resolution (TL799L91), of medium-resolution forecasts (TL399L62) used in the Ensemble Prediction System (EPS), and of low-resolution simulations (TL159L91) as used for model development and seasonal forecasts with an interactive ocean. Results for the high-resolution forecasts are compared in terms of objective scores and of the quality of “surface” parameters (total cloud cover, 2-m temperature and specific humidity, and 10-m wind) usually verified in a meteorological context. For the medium-resolution forecasts, the impact of the radiation grid is studied in terms of the potential increase in the efficiency of the EPS system without deteriorating the probabilistic skill. The impact of changes in the radiation grid resolution on the low-resolution versions of model is discussed in terms of cloud–radiation interactions and ocean surface temperature. For these operational applications, a radiation grid with a coarsening factor even as large as 2.5 for TL799L91 and TL159L91 and 4.2 for the EPS TL399L62 is shown to give results free of any systematic differences linked to the spatial interpolation and to the coarser resolution of both the inputs to and the outputs from the radiation transfer schemes.
The cytoplasmic tail of CD45 is released from activated phagocytes and can act as an inhibitory messenger for T cells
Authors: Kirchberger Stefanie , Majdic Otto , Blüml Stefan , Schrauf Catharina , Leitner Judith , Gerner Christopher , Paster Wolfgang , Gundacker Nina , Sibilia Maria , Stöckl Johannes 
Published: May 2008

AbstractCD45 is the prototypic transmembrane protein tyrosine phosphatase (PTP), which is expressed on all nucleated hematopoietic cells and plays a central role in the integration of environmental signals into immune cell responses. Here we report an alternative function for the intracellular domain of CD45. We dis-covered that CD45 is sequentially cleaved by serine/metalloproteinases and γ-secretases during activation of human monocytes and granulocytes by fungal stimuli or phorbol 12-myristate 13-acetate but not by other microbial stimuli. Proteolytic processing of CD45 occurred upon activation of monocytes or granulocytes but not of T cells, B cells, or dendritic cells and resulted in a 95-kDa fragment of the cytoplasmic tail of CD45 (ct-CD45). ct-CD45 was released from monocytes and granulocytes upon activation-induced cell death. Binding studies with ct-CD45 revealed a counter-receptor on preactivated T cells. Moreover, T-cell proliferation induced by dendritic cells or CD3 antibodies was inhibited in the presence of ct-CD45. Taken together, the results of our study demonstrate that fragments of the intracellular domain of CD45 from human phagocytes can function as intercellular regulators of T-cell activation.
A selective sphingosine kinase 1 inhibitor integrates multiple molecular therapeutic targets in human leukemia
Authors: Paugh Steven W. , Paugh Barbara S. , Rahmani Mohamed , Kapitonov Dmitri , Almenara Jorge A. , Kordula Tomasz , Milstien Sheldon , Adams Jeffrey K. , Zipkin Robert E. , Grant Steven , Spiegel Sarah 
Published: May 2008

AbstractThe potent bioactive sphingolipid mediator, sphingosine-1-phosphate (S1P), is produced by 2 sphingosine kinase isoenzymes, SphK1 and SphK2. Expression of SphK1 is up-regulated in cancers, including leukemia, and associated with cancer progression. A screen of sphingosine analogs identified (2R,3S,4E)-N-methyl-5-(4′-pentylphenyl)-2-aminopent-4-ene-1,3-diol, designated SK1-I (BML-258), as a potent, water-soluble, isoenzyme-specific inhibitor of SphK1. In contrast to pan-SphK inhibitors, SK1-I did not inhibit SphK2, PKC, or numerous other protein kinases. SK1-I decreased growth and survival of human leukemia U937 and Jurkat cells, and enhanced apoptosis and cleavage of Bcl-2. Lethality of SK1-I was reversed by caspase inhibitors and by expression of Bcl-2. SK1-I not only decreased S1P levels but concomitantly increased levels of its proapoptotic precursor ceramide. Conversely, S1P protected against SK1-I–induced apoptosis. SK1-I also induced multiple perturbations in activation of signaling and survival-related proteins, including diminished phosphorylation of ERK1/2 and Akt. Expression of constitutively active Akt protected against SK1-I–induced apoptosis. Notably, SK1-I potently induced apoptosis in leukemic blasts isolated from patients with acute myelogenous leukemia but was relatively sparing of normal peripheral blood mononuclear leukocytes. Moreover, SK1-I markedly reduced growth of AML xenograft tumors. Our results suggest that specific inhibitors of SphK1 warrant attention as potential additions to the therapeutic armamentarium in leukemia.
Susceptibility to nontuberculous mycobacterial lung disease: Table 1—
Authors: Sexton P. , Harrison A. C. 
Published: May 2008

The nontuberculous mycobacteria (NTM) exhibit heterogeneous pathogenicity in humans. Articles on known and potential human factors capable of producing susceptibility to NTM lung disease (NTMLD) were identified by a systematic search of the medical literature, and are reviewed in the present study.Patients with pre-existing structural lung disease are known to be at risk of NTMLD. Other susceptible groups have become recognised since the 1980s, in particular middle-aged nonsmokers without previous lung disease (a group including those with Lady Windermere syndrome) and patients with genetically determined defects of cell-mediated immunity, including abnormalities of the interleukin-12/interferon-γ axis, certain human leukocyte antigen alleles, cystic fibrosis transmembrane conductance regulator mutations, and polymorphisms of solute carrier 11A1 (or natural resistance-associated macrophage protein 1) and the vitamin D receptor.Information is also accruing about acquired systemic causes of susceptibility to NTMLD, including inhibitory antibodies directed against interferon-γ, post-menopausal waning of endogenous oestrogen levels, coeliac disease and exposure to use of dietary phyto-oestrogens. It is not known whether immunosuppressive factors, such as oral corticosteroid treatment, chronic renal failure, diabetes mellitus and other known risk factors for pulmonary tuberculosis, are also risk factors for the development of NTMLD. Caution is appropriate in managing such patients.
Evolution of the CDKN1C-KCNQ1 imprinted domain
Authors: Ager Eleanor I , Pask Andrew J , Gehring Helen M , Shaw Geoff , Renfree Marilyn B 
Published: May 2008

Abstract

Background
Genomic imprinting occurs in both marsupial and eutherian mammals. The CDKN1C and IGF2 genes are both imprinted and syntenic in the mouse and human, but in marsupials only IGF2 is imprinted. This study examines the evolution of features that, in eutherians, regulate CDKN1C imprinting.

Results
Despite the absence of imprinting, CDKN1C protein was present in the tammar wallaby placenta. Genomic analysis of the tammar region confirmed that CDKN1C is syntenic with IGF2. However, there are fewer LTR and DNA elements in the region and in intron 9 of KCNQ1. In addition there are fewer LINEs in the tammar compared with human and mouse. While the CpG island in intron 10 of KCNQ1 and promoter elements could not be detected, the antisense transcript KCNQ1OT1 that regulates CDKN1C imprinting in human and mouse is still expressed.

Conclusion
CDKN1C has a conserved function, likely antagonistic to IGF2, in the mammalian placenta that preceded its acquisition of imprinting. CDKN1C resides in synteny with IGF2, demonstrating that imprinting of the two genes did not occur concurrently to balance maternal and paternal influences on the growth of the placenta. The expression of KCNQ1OT1 in the absence of CDKN1C imprinting suggests that antisense transcription at this locus preceded imprinting of this domain. These findings demonstrate the stepwise accumulation of control mechanisms within imprinted domains and show that CDKN1C imprinting cannot be due to its synteny with IGF2 or with its placental expression in mammals.