Research Project Entitled "The Dynamics and Physical Processes in The Weather and Climate System" --Part Ⅰ: A Brief Introduction

In the beginning of the 21st century, the Tenth Five-Year Priority Research Projects of the Earth Sciences of the National Natural Science Foundation of China (NSFC) were initiated. After nearly a two-year long process to prepare, the first version of six Priority Research Projects of Earth Sciences was published in October 2001 by NSFC, viz., Local Response to Global Changes, Life Process and Environment,Dynamics and Physical Processes in the Weather and Climate System, Continental Dynamics, Regional Sustainable Development, Solar-Terrestrial Environment and Space Weather. The process involved more than 200 renowned Chinese scientists and many departments and agencies in China. The six Priority Research Projects guide the research effort of the earth sciences for the NSFC from year 2001 to 2005.This paper provides a brief introduction to the Third Priority Research Project of the Department of Earth Sciences of NSFC-Dynamics and Physical Processes in the Weather and Climate System (DPWOS).     

The Surface Friction and the Flow over Mountain

The flow over mountain is quite complicated. There are a lot of papers on this problem and a lot of progresses have been made. However, in the most of these papers, just the dynamics contributions of mountain have been analysed; the effect of the friction is often neglected. Since the frictional effect is always associated with flow, especially when it flows over the mountain. The study shows that the friction is small in the magnitude but it is not a negligible effect because it changes the features of the flow. In the case of super-or sub-critical flow, there are two extremes: one maximum, one minimum of the fluid surface on the lee-side of the mountain, while in the inviscid fluid, there is just one extreme. The frictional effect should neither be too strong nor too weak to make the situation happened according to the investigation of this paper.     

The no‐slip constraint and ocean models

Abstract

The conclusion that there is no vorticity and no vorticity transport in a boundary current, assuming no slip at the boundary, is shown to be robust to the level (L₁/L₂)², where L₁ is a characteristic width and L₂ a characteristic length of the boundary current. Vorticity transport into the interior from the boundary is shown to be related to the stress gradient at the boundary, which is in turn equal to the pressure gradient along the boundary. On western boundaries the flow is down the pressure gradient, a circumstance that usually leads to thin boundary layers. It is shown that in the inner, fractional, boundary layer both the stress and the energy dissipation depend on the thickness of the inner layer and become small when it is thin.     

The Modified Envelope Orography and the Air Flow over and around Mountains

By use of the two-layer adiabatic globe spectral model and the zonally averaged climatic data of winter season as initial values, 10-day integrations are carried out based on three kinds of model topography (i.e., (1) the averaged topography; (2) the envelope topography; (3) the modified envelope topography). The results show that the orography of the Northern Hemisphere plays an important role in the simulation of large-scale weather patterns in winter season. The simulation based on the envelope topography developed by Wallace et al. has some improvements in the Rocky Mountains area. But this scheme causes very serious horizontal expansion around the Tibetan Plateau (hereafter referred to as the TV). A modified envelope topography scheme has been worked out that increases the slope of the TP by decreasing the horizontal expansion while keeping the maximum altitude. The results show some improvements of the scheme around the TP. By analysis of the mechanical effects of the large-scale orography on the     

The Tibetan Plateau Surface–Atmosphere Coupling System and Its Weather and Climate Effects: The Third Tibetan Plateau Atmospheric Science Experiment

The Tibetan Plateau(TP) is a key area affecting forecasts of weather and climate in China and occurrences of extreme weather and climate events over the world. The China Meteorological Administration, the National Natural Science Foundation of China, and the Chinese Academy of Sciences jointly initiated the Third Tibetan Plateau Atmospheric Science Experiment(TIPEX-Ⅲ) in 2013, with an 8–10-yr implementation plan. Since its preliminary field measurements conducted in 2013, routine automatic sounding systems have been deployed at Shiquanhe, Gaize, and Shenzha stations in western TP, where no routine sounding observations were available previously. The observational networks for soil temperature and soil moisture in the central and western TP have also been established. Meanwhile, the plateau-scale and regional-scale boundary layer observations, cloud–precipitation microphysical observations with multiple radars and aircraft campaigns, and tropospheric–stratospheric air composition observations at multiple sites, were performed. The results so far show that the turbulent heat exchange coefficient and sensible heat flux are remarkably lower than the earlier estimations at grassland, meadow, and bare soil surfaces of the central and western TP. Climatologically, cumulus clouds over the main body of the TP might develop locally instead of originating from the cumulus clouds that propagate northward from South Asia. The TIPEX-Ⅲ observations up to now also reveal diurnal variations, macro-and microphysical characteristics, and water-phase transition mechanisms, of cumulus clouds at Naqu station. Moreover, TIPEX-Ⅲ related studies have proposed a maintenance mechanism responsible for the Asian "atmospheric water tower" and demonstrated the effects of the TP heating anomalies on African, Asian, and North American climates. Additionally, numerical modeling studies show that the Γ distribution of raindrop size is more suitable for depicting the TP raindrop characteristics compared to the M–P distribution, the overestimation of sensible heat flux can be reduced via modifying the heat transfer parameterization over the TP, and considering climatic signals in some key areas of the TP can improve the skill for rainfall forecast in the central and eastern parts of China. Furthermore, the TIPEX-Ⅲ has been promoting the technology in processing surface observations, soundings, and radar observations, improving the quality of satellite retrieved soil moisture and atmospheric water vapor content products as well as high-resolution gauge–radar–satellite merged rainfall products, and facilitating the meteorological monitoring, forecasting, and data sharing operations.     

Research Project Entitled “The Dynamics and Physical Processes in The Weather and Climate System“ --Part Ⅰ: A Brief Introduction

1. Introduction Human activities including social and economic de-velopments, are closely related to the change of theweather and climate system. Since the beginning oftime, weather and climate, which are the general termsfor the entire range of phenom…     

The Record-breaking Mei-yu in 2020 and Associated Atmospheric Circulation and Tropical SST Anomalies※

The record-breaking mei-yu in the Yangtze-Huaihe River valley (YHRV) in 2020 was characterized by an early onset, a delayed retreat, a long duration, a wide meridional rainbelt, abundant precipitation, and frequent heavy rainstorm processes. It is noted that the East Asian monsoon circulation system presented a significant quasi-biweekly oscillation (QBWO) during the mei-yu season of 2020 that was associated with the onset and retreat of mei-yu, a northward shift and stagnation of the rainbelt, and the occurrence and persistence of heavy rainstorm processes. Correspondingly, during the mei-yu season, the monsoon circulation subsystems, including the western Pacific subtropical high (WPSH), the upper-level East Asian westerly jet, and the low-level southwesterly jet, experienced periodic oscillations linked with the QBWO. Most notably, the repeated establishment of a large southerly center, with relatively stable latitude, led to moisture convergence and ascent which was observed to develop repeatedly. This was accompanied by a long-term duration of the mei-yu rainfall in the YHRV and frequent occurrences of rainstorm processes. Moreover, two blocking highs were present in the middle to high latitudes over Eurasia, and a trough along the East Asian coast was also active, which allowed cold air intrusions to move southward through the northwestern and/or northeastern paths. The cold air frequently merged with the warm and moist air from the low latitudes resulting in low-level convergence over the YHRV. The persistent warming in the tropical Indian Ocean is found to be an important external contributor to an EAP/PJ-like teleconnection pattern over East Asia along with an intensified and southerly displaced WPSH, which was observed to be favorable for excessive rainfall over YHRV.     

The development of children’s environmental attitude and behavior

Environmental attitude and behavior are at the roots of a sustainable future, yet little is known about their developmental origins in early childhood. This longitudinal study is the first to examine how children’s environmental attitude and behavior develop throughout childhood (ages 7 to 18, N = 118). Environmental attitude and behavior form around the age of 7, increase until the age of 10, level off until the age of 14, and then decline again. Environmental behavior develops from childhood to early adolescence and starts consolidating from age 10 onwards, whereas environmental attitude remains in flux at least through early adulthood.     

The Interannual Variability and Predictability in a Global Climate Model

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The Characteristics of Ground Flashes in Beijing and Lanzhou Regions

Over twenty thousand lightning location data obtained by using Lightning Location System(LLS) from Lanzhou and Beijing regions have been analysed to ascertain the characteristics of ground flashes in both regions. The strength of positive flashes is 5 times higher in Lanzhou than in Beijing. The strength of positive flashes is 3 times and 2.2 times as large as negative flashes in Beijing and in Lanzhou respectively. It has been found that the strength of positive and negative flashes is submitted to the normal distribution, and is independent of the characteristics of thunderstorm. So the lightning strength obtained by DF may be used to forecast the coming of thunderstorm. Although the stroke number in both regions decreases as exponent regulation, the maximum number of return stroke for one lightning in Beijing is more than that in Lanzhou. The peak flash rate occurs in late afternoon for both regions, but the maximum and minimum flash rate appeared an hour earlier in Beijing than in Lanzhou.The relati     

The Latent and Sensible Heat Fluxes over the Western Tropical Pacific and Its Relationship to ENSO

In this paper the Bulk Aerodynamic Formulas are used to compute the latent and sensible heat fluxes over the area 8°S-20°N, 130°-180°E for each month from January 1950 through December 1979 by using the data set of COADS supplied by N'OAA of USA. The annual and monthly geographical distributions and the seasonal cycle of heat fluxes are carried out and a seasonal change of heal tluxes for ENSO year is also obtained by compositing individual ENSO year including 1951, 1953, 1957, 1963, 1965, 1969, 1972 and 1976. It is found that outing ENSO epi sodes positive anomalies of heal fluxes appeared during the period of March to July and negative anomalies from August to March of the following year. The time series of sum of heat fluxes for March, April, May, June and July in each year from 1950 through 1979 had a significant link to the eastern tropical Pacific SST index (Wright, 1983). The correlation coefficient was 0.56. As it is found that in the latter half of each ENSO year (August-December) the frequ     

The trap of climate change-induced “natural” disasters and inequality

The purpose of the present paper is to disentangle the mechanisms that connect climate change-induced disasters, inequality and vulnerability by accounting for both directions of causality. We do so by means of a simultaneous equations approach on a panel of 149 countries from 1992 to 2018. The empirical analysis reveals that countries with higher levels of income inequality suffer greater damages when hit by a natural disaster. At the same time, inequality is found to increase the number of people affected by disasters. Our analysis discloses the existence of a vicious cycle that keeps some countries stuck in a disasters-inequality trap.     

The distinction between canopy and boundary‐layer urban heat islands

Air temperature measurements from car traverses in and near Vancouver, B.C. are used to test two urban heat island models: one an empirical model, the other a theoretical advective model. The empirical model describes the Vancouver observations well, whereas the advective one performs rather poorly. This discrepancy may be attributed to a failure to distinguish between meteorological conditions in the urban canopy, and those in the overlying urban boundary layer. This leads to a reassessment of the explanation of the relationship between city size (as measured by population) and the heat island intensity (as measured in the urban canopy).     

The delineation of rain areas from visible and IR satellite data for GATE and mid‐latitudes

Abstract

Two‐dimensional pattern matching has been used to delineate raining areas of clouds from GATE and Montreal GOES visible and IR satellite data, with radar as ground truth. For the cases examined, the cloud cover was of the order of 4 times larger than the rain area, requiring skill to separate out low‐thick or high‐thin non‐precipitating clouds from cumulus systems, which is difficult using a single threshold. The more flexible approach described here has allowed useful rain maps to be generated for all the types of weather systems examined. The optimum boundary separating raining from non‐raining areas is relatively insensitive to diurnal and day‐to‐day variations, but is different for the tropical Atlantic and for Montreal.     

The Relation between Atmospheric Intraseasonal Oscillation and Summer Severe Flood and Drought in the Changjiang-Huaihe River Basin

The intraseasonal oscillation (ISO) is studied during the severe flood and drought years of the Changjiang-Huaihe River Basin with the NCEP/NCAR reanalysis data and the precipitation data in China. The results show that the upper-level (200 hPa) ISO pattern for severe flood (drought) is charac-terized by an anticyclonic (cyclonic) circulation over the southern Tibetan Plateau and a cyclonic (anti-cyclonic) circulation over the northern Tibetan Plateau. The lower-level (850 hPa) ISO pattern is char-acterized by an anticyclonic (cyclonic) circulation over the area south of the Changjiang River, the South China Sea, and the Western Pacific, and a cyclonic (anticyclonic) circulation from the area north of the Changjiang River to Japan. These low-level ISO circulation patterns are the first modes of the ISO wind field according to the vector EOF expansion with stronger amplitude of the EOF1 time coefficient in se-vere flood years than in severe drought years. The analyses also reveal that at 500 hPa and 200 hPa,the atmospheric ISO activity over the Changjiang-Huaihe River basin, North China, and the middle-high latitudes north of China is stronger for severe flood than for severe drought. The ISO meridional wind over the middle-high latitude regions can propagate southwards and meet with the northward propagating ISO meridional wind from lower latitude regions over the Changjiang-Huaihe River Basin during severe flood years, but not during severe drought years.     

The Tibetan Ozone Low and Its Long-Term Variation During 1979–2010

A Tibetan ozone low was found in the 1990s after the Antarctic ozone hole.Whether this ozone low has been recovering from the beginning of the 2000s following the global ozone recovery is an intriguing topic.With the most recent merged TOMS/SBUV(Total Ozone Mapping Spectrometer/Solar Backscatter Ultra Violet) ozone data,the Tibetan ozone low and its long-term variation during 1979-2010 are analyzed using a statistical regression model that includes the seasonal cycle,solar cycle,quasi-biennial oscillation(QBO),ENSO signal,and trends.The results show that the Tibetan ozone low maintains and may become more severe on average during 1979-2010,compared with its mean state in the periods before 2000,possibly caused by the stronger downward trend of total ozone concentration over the Tibet.Compared with the ozone variation over the non-Tibetan region along the same latitudes,the Tibetan ozone has a larger downward trend during 1979-2010,with a maximum value of-0.40±0.10 DU yr 1 in January,which suggests the strengthening of the Tibetan ozone low in contrast to the recovery of global ozone.Regression analyses show that the QBO signal plays an important role in determining the total ozone variation over the Tibet.In addition,the long-term ozone variation over the Tibetan region is largely affected by the thermal-dynamical proxies such as the lower stratospheric temperature,with its contribution reaching around 10% of the total ozone change,which is greatly different from that over the non-Tibetan region.     

The Structure and Rainfall Features of Tropical Cyclone Rammasun （2002）

Tropical Rainfall Measuring Mission (TRMM) data [TRMM Microwave Imager/Precipitation Radar/Visible and Infrared Scanner (TMI/PR/VIRS)] and a numerical model are used to investigate the structure and rainfall features of Tropical Cyclone (TC) Rammasun (2002). Based on the analysisof TRMM data, which are diagnosed together with NCEP/AVN [Aviation (global model)] analysis data,some typical features of TC structure and rainfall are preliminary discovered. Since the limitations of TRMM data are considered for their time resolution and coverage, the world observed by TRMM at several moments cannot be taken as the representation of the whole period of the TC lifecycle, therefore the picture should be reproduced by a numerical model of high quality. To better understand the structure and rainfall features of TC Rammasun, a numerical simulation is carried out with mesoscale model MM5 in which the validations have been made with the data of TRMM and NCEP/AVN analysis.     

The Effect of the Interaction among Multi-Scale Systems and the Asymmetric an

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