bluuebunny/crossref_metadata_2025_split huggingface dataset:
Observational Analysis of Cloud and Precipitation in Midlatitude Cyclones: Northern versus Southern Hemisphere Warm Fronts
Authors: Naud Catherine M. , Posselt Derek J. , van den Heever Susan C. 
Published: February 2012

Abstract
Extratropical cyclones are responsible for most of the precipitation and wind damage in the midlatitudes during the cold season, but there are still uncertainties on how they will change in a warming climate. A ubiquitous problem among general circulation models (GCMs) is a lack of cloudiness over the southern oceans that may be in part caused by a lack of clouds in cyclones. This study analyzes CloudSat, Cloud–Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO), and Advanced Microwave Scanning Radiometer for Earth Observing System (AMSR-E) observations for three austral and boreal cold seasons, and composites cloud frequency of occurrence and precipitation at the warm fronts for Northern and Southern Hemisphere oceanic cyclones. The authors find that cloud frequency of occurrence and precipitation rate are similar in the early stage of the cyclone life cycle in both the Northern and Southern Hemispheres. As cyclones evolve and reach their mature stage, cloudiness and precipitation at the warm front increase in the Northern Hemisphere but decrease in the Southern Hemisphere. This is partly caused by lower amounts of precipitable water being available to Southern Hemisphere cyclones, and smaller increases in wind speed as the cyclones evolve. Southern Hemisphere cloud occurrence at the warm front is found to be more sensitive to the amount of moisture in the warm sector than to wind speeds. This suggests that cloudiness in Southern Hemisphere storms may be more susceptible to changes in atmospheric water vapor content, and thus to changes in surface temperature than their Northern Hemisphere counterparts. These differences between Northern and Southern Hemisphere cyclones are statistically robust, indicating A-Train-based analyses as useful tools for the evaluation of GCMs in the next Intergovernmental Panel on Climate Change (IPCC) report.
A Decadal Prediction Case Study: Late Twentieth-Century North Atlantic Ocean Heat Content
Authors: Yeager Stephen , Karspeck Alicia , Danabasoglu Gokhan , Tribbia Joe , Teng Haiyan 
Published: February 2012

Abstract
An ensemble of initialized decadal prediction (DP) experiments using the Community Climate System Model, version 4 (CCSM4) shows considerable skill at forecasting changes in North Atlantic upper-ocean heat content and surface temperature up to a decade in advance. Coupled model ensembles were integrated forward from each of 10 different start dates spanning from 1961 to 2006 with ocean and sea ice initial conditions obtained from a forced historical experiment, a Coordinated Ocean-Ice Reference Experiment with Interannual forcing (CORE-IA), which exhibits good correspondence with late twentieth-century ocean observations from the North Atlantic subpolar gyre (SPG) region. North Atlantic heat content anomalies from the DP ensemble correlate highly with those from the CORE-IA simulation after correcting for a drift bias. In particular, the observed large, rapid rise in SPG heat content in the mid-1990s is successfully predicted in the ensemble initialized in January of 1991. A budget of SPG heat content from the CORE-IA experiment sheds light on the origins of the 1990s regime shift, and it demonstrates the extent to which low-frequency changes in ocean heat advection related to the Atlantic meridional overturning circulation dominate temperature tendencies in this region. Similar budgets from the DP ensembles reveal varying degrees of predictive skill in the individual heat budget terms, with large advective heat flux anomalies from the south exhibiting the highest correlation with CORE-IA. The skill of the DP in this region is thus tied to correct initialization of ocean circulation anomalies, while external forcing is found to contribute negligibly (and for incorrect reasons) to predictive skill in this region over this time period.
Using Relative Humidity as a State Variable in Climate Feedback Analysis
Authors: Held Isaac M. , Shell Karen M. 
Published: February 2012

Abstract
An approach to climate change feedback analysis is described in which tropospheric relative humidity replaces specific humidity as the state variable that, along with the temperature structure, surface albedos, and clouds, controls the magnitude of the response of global mean surface temperature to a radiative forcing. Despite being simply a regrouping of terms in the feedback analysis, this alternative perspective has the benefit of removing most of the pervasive cancellation between water and lapse-rate feedbacks seen in models. As a consequence, the individual feedbacks have less scatter than in the traditional formulation. The role of cloud feedbacks in controlling climate sensitivity is also reflected more clearly in the new formulation.
The Subpolar Front of the Japan/East Sea. Part III: Competing Roles of Frontal Dynamics and Atmospheric Forcing in Driving Ageostrophic Vertical Circulation and Subduction
Authors: Yoshikawa Yutaka , Lee Craig M. , Thomas Leif N. 
Published: February 2012

ABSTRACT
The effects of wind stress and surface cooling on ageostrophic vertical circulation and subduction at the subpolar front of the Japan/East Sea are investigated using a nonhydrostatic numerical model. In experiments forced by wind and/or cooling, ageostrophic vertical circulation is enhanced relative to the unforced case. Both surface cooling and wind stress intensify the circulation by enhancing frontogenesis associated with frontal meandering. Winds further strengthen vertical motions by generating internal gravity waves. Downfront winds (i.e., oriented along the frontal jet) transport surface water from the denser to lighter side of the front, causing it to migrate toward the region of higher stratification and enhancing the vertical mixing at the front. This induces outcropping of isopycnals from the middle of the pycnocline along which surface water is subducted. Hence downfront winds enhance subduction down to the middle of the pycnocline, but not beneath. On the other hand, cooling uplifts isopycnals from greater depths to the surface so that it allows for the subduction of fluid to greater depths. In contrast to the vertical circulation, frontal subduction is more intensified by surface cooling than wind stress, because part of wind-forced circulation (e.g., internal gravity wave) does not contribute to subduction. Ageostrophic vertical circulation and frontal subduction are most intense when both wind stress and surface cooling are at play.
The World Ocean Thermohaline Circulation*
Authors: Döös Kristofer , Nilsson Johan , Nycander Jonas , Brodeau Laurent , Ballarotta Maxime 
Published: February 2012

Abstract
A new global streamfunction is presented and denoted the thermohaline streamfunction. This is defined as the volume transport in terms of temperature and salinity (hence no spatial variables). The streamfunction is used to analyze and quantify the entire World Ocean conversion rate between cold/warm and fresh/saline waters. It captures two main cells of the global thermohaline circulation, one corresponding to the conveyor belt and one corresponding to the shallow tropical circulation. The definition of a thermohaline streamfunction also enables a new method of estimating the turnover time as well as the heat and freshwater transports of the conveyor belt. The overturning time of the conveyor belt is estimated to be between 1000 and 2000 yr, depending on the choice of stream layer. The heat and freshwater transports of these two large thermohaline cells have been calculated by integrating the thermohaline streamfunction over the salinity or temperature, yielding a maximum heat transport of the conveyor belt of 1.2 PW over the 34.2-PSU salinity surface and a freshwater transport of 0.8 Sv (1 Sv ≡ 106 m3 s−1) over the 9°C isotherm. This is a measure of the net interocean exchange of heat between the Atlantic and Indo-Pacific due to the thermohaline circulation.
Radiative Impact on Tropopause Polar Vortices over the Arctic
Authors: Cavallo Steven M. , Hakim Gregory J. 
Published: February 2012

Abstract
Tropopause polar vortices (TPVs) are commonly observed, coherent circulation features of the Arctic with typical radii as large as approximately 800 km. Intensification of cyclonic TPVs has been shown to be dominated by infrared radiation. Here the hypothesis is tested that while radiation alone may not be essential for TPV genesis, radiation has a substantial impact on the long-term population characteristics of cyclonic TPVs.
A numerical model is used to derive two 10-yr climatologies of TPVs for both winter and summer: a control climatology with radiative forcing and an experimental climatology with radiative forcing withheld. Results from the control climatology are first compared to those from the NCEP–NCAR reanalysis project (NNRP), which indicates sensitivity to both horizontal grid resolution and the use of polar filtering in the NNRP. Smaller horizontal grid resolution of 60 km in the current study yields sample-mean cyclonic TPV radii that are smaller by a factor of ~2 compared to NNRP, and vortex track densities in the vicinity of the North Pole are considerably larger compared to NNRP. The experimental climatologies show that winter (summer) vortex maximum amplitude is reduced by 22.3% (38.0%), with a net tendency to weaken without radiation. Moreover, while the number and lifetime of cyclonic TPVs change little in winter without radiation, the number decreases 12% and the mean lifetime decreases 19% during summer without radiation. These results suggest that dynamical processes are primarily responsible for the genesis of the vortices, and that radiation controls their maximum intensity and duration during summer, when the destructive effect of ambient shear is weaker.
Application of a Lightning Data Assimilation Technique in the WRF-ARW Model at Cloud-Resolving Scales for the Tornado Outbreak of 24 May 2011
Authors: Fierro Alexandre O. , Mansell Edward R. , Ziegler Conrad L. , MacGorman Donald R. 
Published: February 2012

Abstract
This study presents the assimilation of total lightning data to help initiate convection at cloud-resolving scales within a numerical weather prediction model. The test case is the 24 May 2011 Oklahoma tornado outbreak, which was characterized by an exceptional synoptic/mesoscale setup for the development of long-lived supercells with large destructive tornadoes. In an attempt to reproduce the observed storms at a predetermined analysis time, total lightning data were assimilated into the Weather Research and Forecasting Model (WRF) and analyzed via a suite of simple numerical experiments. Lightning data assimilation forced deep, moist precipitating convection to occur in the model at roughly the locations and intensities of the observed storms as depicted by observations from the National Severe Storms Laboratory’s three-dimensional National Mosaic and Multisensor Quantitative Precipitation Estimation (QPE)—i.e., NMQ—radar reflectivity mosaic product. The nudging function for the total lightning data locally increases the water vapor mixing ratio (and hence relative humidity) via a simple smooth continuous function using gridded pseudo-Geostationary Lightning Mapper (GLM) resolution (9 km) flash rate and simulated graupel mixing ratio as input variables. The assimilation of the total lightning data for only a few hours prior to the analysis time significantly improved the representation of the convection at analysis time and at the 1-h forecast within the convective permitting and convective resolving grids (i.e., 3 and 1 km, respectively). The results also highlighted possible forecast errors resulting from errors in the initial mesoscale thermodynamic variable fields. Although this case was primarily an analysis rather than a forecast, this simple and computationally inexpensive assimilation technique showed promising results and could be useful when applied to events characterized by moderate to intense lightning activity.
Intercomparison of Global Model Precipitation Forecast Skill in 2010/11 Using the SEEPS Score
Authors: Haiden Thomas , Rodwell Mark J. , Richardson David S. , Okagaki Akira , Robinson Tom , Hewson Tim 
Published: February 2012

AbstractPrecipitation forecasts from five global numerical weather prediction (NWP) models are verified against rain gauge observations using the new stable equitable error in probability space (SEEPS) score. It is based on a 3 × 3 contingency table and measures the ability of a forecast to discriminate between “dry,” “light precipitation,” and “heavy precipitation.” In SEEPS, the threshold defining the boundary between the light and heavy categories varies systematically with precipitation climate. Results obtained for SEEPS are compared to those of more well-known scores, and are broken down with regard to individual contributions from the contingency table. It is found that differences in skill between the models are consistent for different scores, but are small compared to seasonal and geographical variations, which themselves can be largely ascribed to the varying prevalence of deep convection. Differences between the tropics and extratropics are quite pronounced. SEEPS scores at forecast day 1 in the tropics are similar to those at day 6 in the extratropics. It is found that the model ranking is robust with respect to choices in the score computation. The issue of observation representativeness is addressed using a “quasi-perfect model” approach. Results suggest that just under one-half of the current forecast error at day 1 in the extratropics can be attributed to the fact that gridbox values are verified against point observations.
A Statistical Downscaling Model for Forecasting Summer Rainfall in China from DEMETER Hindcast Datasets
Authors: Chen Huopo , Sun Jianqi , Wang Huijun 
Published: February 2012

Abstract
A new statistical downscaling (SD) scheme is proposed to predict summertime multisite rainfall measurements in China. The potential predictors are multiple large-scale variables from operational dynamical model output. A key step in this SD scheme is finding optimal predictors that have the closest and most stable relationship with rainfall at a given station. By doing so, the most robust signals from the large-scale circulation can be statistically projected onto local rainfall, which can significantly improve forecast skill in predicting the summer rainfall at the stations. This downscaling prediction is performed separately for each simulation with a leave-one-out cross-validation approach and an independent sample validation framework. The prediction skill scores exhibited at temporal correlation, anomaly correlation coefficient, and root-mean-square error consistently demonstrate that dynamical model prediction skill is significantly improved under the SD scheme, especially in the multimodel ensemble strategy. Therefore, this SD scheme has the potential to improve the operational skill when forecasting rainfall based on the coupled models.
Risk stratification–directed donor lymphocyte infusion could reduce relapse of standard-risk acute leukemia patients after allogeneic hematopoietic stem cell transplantation
Authors: Yan Chen-Hua , Liu Dai-Hong , Liu Kai-Yan , Xu Lan-Ping , Liu Yan-Rong , Chen Huan , Han Wei , Wang Yu , Qin Ya-Zhen , Huang Xiao-Jun 
Published: February 2012

Abstract
We studied the impact of risk stratification–directed interventions for minimal residual disease (MRD) on relapse and disease-free survival (DFS) prospectively in 814 subjects with standard-risk acute leukemia receiving allotransplantation in first or second complete remission. A total of 709 subjects were MRD− after transplantation (Group A); 105 subjects were MRD+, 49 received low-dose IL-2 (Group B), and 56 received modified donor lymphocyte infusion (DLI) with or without low-dose IL-2 (Group C). Posttransplantation immune suppression for GVHD was also modified based on MRD state. The cumulative risk of relapse was significantly less and DFS was significantly better in subjects in Group C than in subjects in Group B (P = .001 and P = .002, respectively), but was not different from subjects in Group A (P = .269 and P = .688, respectively). Multivariate analyses confirmed that MRD state and modified DLI were significantly correlated with relapse (P = .000, odds ratio [OR] = 0.255 and P = .000, OR = 0.269) and DFS (P = .001, OR = 0.511 and P = .006, OR = 0.436, respectively). These data suggest that risk stratification–directed interventions with modified DLI in patients with standard-risk acute leukemia who are MRD+ after transplantation may improve transplantation outcomes.
The cold-induced basic helix-loop-helix transcription factor gene MdCIbHLH1encodes an ICE-like protein in apple
Authors: Feng Xiao-Ming , Zhao Qiang , Zhao Ling-Ling , Qiao Yu , Xie Xing-Bin , Li Hui-Feng , Yao Yu-Xin , You Chun-Xiang , Hao Yu-Jin 
Published: February 2012

Abstract

Background
Plant growth is greatly affected by low temperatures, and the expression of a number of genes is induced by cold stress. Although many genes in the cold signaling pathway have been identified in Arabidopsis, little is known about the transcription factors involved in the cold stress response in apple.

Results
Here, we show that the apple bHLH (basic helix-loop-helix) gene MdCIbHLH1 (Cold-Induced bHLH1), which encodes an ICE-like protein, was noticeably induced in response to cold stress. The MdCIbHLH1 protein specifically bound to the MYC recognition sequences in the AtCBF3 promoter, and MdCIbHLH1 overexpression enhanced cold tolerance in transgenic Arabidopsis. In addition, the MdCIbHLH1 protein bound to the promoters of MdCBF2 and favorably contributed to cold tolerance in transgenic apple plants by upregulating the expression of MdCBF2 through the CBF (C-repeat-binding factor) pathway. Our findings indicate that MdCIbHLH1 functions in stress tolerance in different species. For example, ectopic MdCIbHLH1 expression conferred enhanced chilling tolerance in transgenic tobacco. Finally, we observed that cold induces the degradation of the MdCIbHLH1 protein in apple and that this degradation was potentially mediated by ubiquitination and sumoylation.

Conclusions
Based on these findings, MdCIbHLH1 encodes a transcription factor that is important for the cold tolerance response in apple.
Effect of calcification on the mechanical stability of plaque based on a three-dimensional carotid bifurcation model
Authors: Wong Kelvin KL , Thavornpattanapong Pongpat , Cheung Sherman CP , Sun Zhonghua , Tu Jiyuan 
Published: February 2012

Abstract

Background
This study characterizes the distribution and components of plaque structure by presenting a three-dimensional blood-vessel modelling with the aim of determining mechanical properties due to the effect of lipid core and calcification within a plaque. Numerical simulation has been used to answer how cap thickness and calcium distribution in lipids influence the biomechanical stress on the plaque.

Method
Modelling atherosclerotic plaque based on structural analysis confirms the rationale for plaque mechanical examination and the feasibility of our simulation model. Meaningful validation of predictions from modelled atherosclerotic plaque model typically requires examination of bona fide atherosclerotic lesions. To analyze a more accurate plaque rupture, fluid-structure interaction is applied to three-dimensional blood-vessel carotid bifurcation modelling. A patient-specific pressure variation is applied onto the plaque to influence its vulnerability.

Results
Modelling of the human atherosclerotic artery with varying degrees of lipid core elasticity, fibrous cap thickness and calcification gap, which is defined as the distance between the fibrous cap and calcification agglomerate, form the basis of our rupture analysis. Finite element analysis shows that the calcification gap should be conservatively smaller than its threshold to maintain plaque stability. The results add new mechanistic insights and methodologically sound data to investigate plaque rupture mechanics.

Conclusion
Structural analysis using a three-dimensional calcified model represents a more realistic simulation of late-stage atherosclerotic plaque. We also demonstrate that increases of calcium content that is coupled with a decrease in lipid core volume can stabilize plaque structurally.
The associations between body and knee height measurements and knee joint structure in an asymptomatic cohort
Authors: Teichtahl Andrew J , Wluka Anita E , Strauss Boyd J , Wang Yuanyuan , Berry Patricia , Davies-Tuck Miranda , Cicuttini Flavia M 
Published: February 2012

Abstract

Background
It has been suggested that knee height is a determinant of knee joint load. Nonetheless, no study has directly examined the relationship between anthropometric measures of height and knee joint structures, such as cartilage.

Methods
89 asymptomatic community-based adults aged 25-62 with no diagnosed history of knee arthropathy were recruited. Anthropometric data (knee height and body height) were obtained by standard protocol, while tibial cartilage volume and defects, as well as bone area were determined from magnetic resonance imaging. Static knee alignment was measured from the joint radiograph.

Results
All anthropometric height measures were associated with increasing compartmental tibial bone area (p ≤ 0.05). Although knee height was associated with tibial cartilage volume (e.g. β = 27 mm3 95% CI 7- 48; p = 0.009 for the medial compartment), these relationship no longer remained significant when knee height as a percentage of body height was analysed. Knee height as a percentage of body height was associated with a reduced risk of medial tibial cartilage defects (odds ratio 0.6; 95% confidence interval 0.4 - 1.0; p = 0.05).

Conclusion
The association between increased anthropometric height measures and increased tibial bone area may reflect inherently larger bony structures. However the beneficial associations demonstrated with cartilage morphology suggest that an increased knee height may confer a beneficial biomechanical environment to the chondrocyte of asymptomatic adults.