The excitation of the Madden-Julian Oscillation in atmospheric adjustment to equatorial heating

We study the adjustment of the tropical atmosphere to localized surface heating using a Lagrangian atmospheric model (LAM) that simulates a realistic Madden-Julian Oscillation (MJO) – the dominant, eastward-propagating mode of tropical intraseasonal variability modulating atmospheric convection. Idealized warm sea surface temperature (SST) anomalies of different aspect ratios and magnitudes are imposed in the equatorial Indian Ocean during MJO-neutral conditions and then maintained for 15 days. Throughout these experiments, we observe a robust generation of an MJO event, evident in precipitation, velocity, temperature and moisture fields, which becomes a key element of atmospheric adjustment along with the expected Kelvin and Rossby waves. The MJO circulation pattern gradually builds up during the first week, and then starts to propagate eastward at a speed of 5-7m/s. The upper-level quadrupole circulation characteristic of the MJO becomes evident around day 14, with two anticyclonic gyres generated by the Gill-type response to convective heating and two cyclonic gyres forced by the excited Kelvin waves and extratropical Rossby wave trains. A moisture budget analysis shows that the eastward propagation of the MJO is controlled largely by the anomalous advection of moisture and by the residual between anomalous moisture accumulation due to converging winds and precipitation. The initial MJO event is followed by successive secondary events, maintaining the MJO for several more cycles. Thus, this study highlights the fundamental role that the MJO can play in the adjustment of the moist equatorial atmosphere to localized surface heating.

Analysis of the Dominant Spatial Patterns of Summer Precipitation and Circulation Characteristics in Northwest China

<p>In recent years, the summer rainfall shows an increasing trend in Northwest China. Based on the NCEP/NCAR reanalysis data, the RESST data from NOAA and the precipitation data from 351 meteorological observation stations in Northwest China from 1981-2018, the dominant modes of summer precipitation anomalies, the corresponded circulation characteristic and the main influence systems were analyzed by diagnostic methods. There were three dominant EOF modes about summer rainfall, the first one showed the same anomaly in whole region, the second showed a inverse pattern between the east and west, and the third showed the opposite anomaly between the south and north. The variance contribution of the first mode accounted for 20% and the first mode was represented as the primary mode in the subsequent analysis. The high impact region of circulation which affected the precipitation in Northwest China was the middle and high latitudes area of Eurasia and the subtropical area: for the first mode’s positive phase, the 500hPa height field showed a "+ - +" distribution in the middle latitude of Eurasia, while on the 200hPa wind field, there was an anticyclone near the Ural and a cyclone near Lake Baikal, it also has an anticyclone on the Chinese mainland, this configuration will facilitates the strengthening of westerly jets. The tropical Pacific and the North Atlantic are the main external forcing signals of the circulation pattern: SST characteristics showed that the negative phase of the North Atlantic SST Tripole in spring, from winter of the previous year to summer of the current year, SST of the equatorial Middle East Pacific developed from warm to cold. The distribution of 500 hPa height field corresponding to the main mode of summer precipitation in Northwest China is similar to that of EU remote correlation type. An index(I<sub>Hgt</sub>) was defined to reflect circulation patterns in mid-latitude and subtropical regions, when the index is positive/negative, most of the precipitation in northwest China is more/less. After 2000, the correlation between the two increased significantly. Given the performance of the I<sub>Hgt</sub> index in describing the summer precipitation, it could be used as a good indicator in the monitoring and prediction of the summer precipitation in Northwest China.</p>

Analysis on thermal and hydraulic performance of a T-shaped vapor chamber designed for motorcycle led lights

Experiment and numerical analyses were conducted to study the thermal performance and circulation characteristic of the working fluid of a T-shaped vapor chamber special designed for the motorcycle LED light. The influences of heat loads and cooling magnitude were experimentally investigated. Results show that both the heat loads and cooling conditions have strong influences on the thermal performance of the vapor chamber, and the thermal resistance in the extended section occupies over 75.8% of the overall thermal resistance of the vapor chamber. Simulation results indicate that large pressure drop occurs along the extended section of the vapor chamber, and causes large temperature difference along the extended section.

Tumor Lysis Syndrome

Tumor lysis syndrome (TLS) is an acute, life-threatening disease among adults and children that is associated with the initiation of cytoreductive therapy in the treatment of malignancy. A pattern of metabolic derangements occurs as a result of a massive release of intracellular contents into the systemic circulation. Characteristic findings include hyperuricemia, hyperphosphatemia, hyperkalemia, hypocalcemia, and uremia, all of which can lead to cardiac arrhythmia, seizures, renal failure, and sudden death. The incidence of TLS appears to be increasing because of a rapidly growing armamentarium of highly effective biologic and targeted therapies. Risk assessment and prevention are at the forefront of management and rely on clinician awareness, prophylactic measures, and vigilant laboratory monitoring. Established TLS requires early, aggressive intervention with intravenous hydration, electrolyte management, and the use of hypouricemic agents. This review highlights the central role of diagnostic laboratory criteria for TLS, and summarizes the clinical findings, pathophysiology, and evidence-based guidelines for the prevention and management of TLS.

Multiscale Hydro-Meteorological Factors Variations and Its Links to Large-Scale Atmospheric Circulation Systems in the Source Region of Yangtze River

Studying hydro-meteorological factors variations and its links to large-scale atmospheric circulation systems can facilitate the understanding of the hydrological processes and sustainable water resources management in the source region of the Yangtze River (SRYR). Currently, researches mostly focused on the temporal and spatial variation characteristics in hydro-meteorological factors; however, researches on the hydro-meteorological variations and its links to large-scale atmospheric circulation systems in the SRYR are scarce. Based on long-term hydro-meteorological and reanalysis data, this research investigated multiscale variations of hydro-meteorological factors and its links to large-scale atmospheric circulation characteristic indices during 1957~2012 in the SRYR. The results showed that the amounts of streamflows and precipitation in the SRYR declined during the 1990s. Since the 2000s, the amounts of streamflows and precipitation had increased significantly climate in the SRYR. The change trends of precipitation and streamflows in the SRYR are synergetic at annual and seasonal scales, and have three significant periods, namely 3~5 years, 15–20 years and 30–40 years. The South Asia monsoon (SAM) plays a relatively more important role in the hydro-meteorological factors changes in the SRYR. The relative contributions of SAM to streamflows and precipitation changes were 83.6% and 78%, respectively. During the driest (wettest) year, the SAM is relatively weak (strong), and brings less (more) southwest airflow into the SRYR, less (more) precipitation and streamflows will be generated in the SRYR.

The Natural Circulation Characteristic Analysis of AP1000 IRWST

The natural convection passive residual heat removal system is an essential system of AP1000 nuclear power plants, which works in the non-LOCA accident. It can discharge the waste heat in the reactor core timely, and prevent the reactor accident. The In-Containment Refueling Water Storage Tank (IRWST) is one of the most important equipments of passive residual heat removal system, which supplies the hot trap to the system. The purpose of the paper is to research the natural circulation characteristic of fluid in IRWST. In this paper, FLUENT hydrodynamics analysis software was used to simulate the flow and heat-transfer characteristics of natural convection. Temperature field and flow field in different time or locations were compared to analyze the course of natural circulation. The error was evaluated by comparing the average temperature on the outlet of heat exchanger and the design temperature. The result showed that FLUENT could simulate the flow and heat-transfer characteristics of natural convection, and the error of the simulation was acceptable. In conclusion, natural convection heat exchanger of the study can discharge the waste heat in the reactor core timely. Due to the complex structure of the heat exchanger and the IRWST, the “heat-transfer dead zones” and “flow dead zones” are generated in local parts. The presence of dead zones affects the formation of natural convection. With the development of natural circulation, the temperature field and flow field in the IRWST keep stable and the temperate rise rate become slowly.

Investigation on the Wall Circulation Characteristic of Boiler under Solar-Coal Complementary Electric Generation Condition

Utilizing multi energy sources synthetically is one of the trends of energy utilization. China has splendid solar energy resource, however, the majority of the electricity production still comes from coal-fired power plants. It is of great necessity to investigate the solar-coal complementary electric generation technology. A 300MW unit thermal-circulation boiler has been studied; calculations about the wall circulation characteristics have been made under 40 conditions. The influence of solar-energy utilization on wall circulation has been analyzed. Calculation and analysis indicated the following: the utilization of solar energy has prominent influences on the steaming point and the under-heating condition of the drum water; the solar energy could be used at high load or low load with the high pressure heaters bypassed conditions, but should not used at 60%-70% load.