Special issues are a collection of timely, high-quality invited articles on a particular topic which are published together in a single issue of the journal. We began to organize special issues from 2016 and now we are delighted to present several special issues for 2017 and 2018, with more planned.
Advances in Meteorological Research and Operation Since the Founding of The People’s Republic of China
Since 2014, the Climate Science for Service Partnership China (CSSP China), as a flagship project of the Newton Fund (channeled through the UK-China Research and Innovation Partnership in China), has built a strong foundation for climate science and climate services to support economic development and social welfare in China and the UK by close collaborative work among research experts and user representatives from the China Meteorological Administration’s National Climate Center (CMA NCC) and the Institute of Atmospheric Physics (IAP) of the Chinese Academy of Sciences, the Met Office, and other key UK and Chinese universities, institutes and companies. This special issue will illustrate the rapidly developing capability to develop and deliver climate services in China through progress in science and technology raised by CSSP China.
Research in atmospheric sciences needs high-quality, high-resolution, long-time-series global and regional meteorological data. Unfortunately, neither observational data nor model output alone can satisfy such a requirement. As a promising solution, reanalysis of past observations with a consistent, state-of-the-art numerical model and data assimilation system aims at producing a high-quality climate data, which consists of numerous meteorological variables in a physically consistent and spatiotemporally regular manner. Atmospheric reanalysis products have been widely used in research related to the mechanisms of the earth's climate system, the study of predictability, climate monitoring, and climate change study. China Meteorological Administration (CMA) has started the ReAnalysis project (CRA) of CRA-40 since early 2014, aiming at producing its first-generation 40-yr (1979–2018) global atmosphere and land reanalysis data. In early 2018, a 10-yr (2007–2016) interim product (CRA-Interim) was generated with a 34-km horizontal resolution. More recently, CRA-40 is in production.
Special Issue on Advanced Applications of Meteorological Satellite Observations in Ecological Remote SensingIn past decades, the satellite observations have been widely used for environmental monitoring. In 2018, CMA national ecological remote sensing annual report first time claims that the national vegetation coverage increases 3.7%/year during 2000 to 2017. Meanwhile, the aerosol optical depth and other pollutants declines by 19.3% with respect to the mean of 16 years from 2003 to 2018. On 2/16/2019, NASA also reported the world is getting greener and thanks the tree planning and agriculture in China and India. In the past, there is skepticism that earth greening from satellite observations may be either a result of degradation of satellite instrument performance or stitching of satellite data from a series of instruments. This special issue will present the state-of-the art remote sensing algorithms and satellite products used for the national ecological monitoring. The scientists who are contributing to this special issue are the lead experts in satellite instrument calibration, algorithm developments and product applications.
Land Data Assimilation Systems (LDASs) have gone through almost two decades of research and development where numerous exciting and inspiring progresses have been witnessed. Since the initiation of the North American and Global LDAS (NLDAS and GLDAS) by scientists from the NASA, NOAA, Princeton University, University of Washington, as well as other universities in the beginning of 2000, various national and regional LDASs have been developed in Europe, South America, Canada, and China. These systems have also been extended from offline (uncoupled), semi-coupled, to fully coupled. With satellite products becoming widely and continuously available, LDASs have been largely improved with benefits of data assimilation. At the same time, as more and more in situ and satellite observations become available, the scientific understating of land surface processes and land surface models (LSM) have been greatly improved by addition of more realistic physical processes, optimized model parameters, new soil and vegetation datasets, and upgraded model structures. Improvements in LSM and assimilation of satellite data improved the quality and reliability of LDAS products such that they can be used to provide optimal initial conditions for coupled weather and climate modeling and to support drought monitoring, agricultural crop planning, and water resources management. Many LDAS systems have been operationally implemented at various national service centers to produce timely products to users. Two examples are the NLDAS at NCEP/NOAA and the China Meteorological Administration (CMA) LDAS system (CLDAS for short) at the National Meteorological Information Center (NMIC)/CMA.
Climate system models (CSMs) are essential tools for understanding the mechanisms of climate variability, and predicting and projecting future climate. Due to the complex topography and land-sea distribution, East Asia exhibits distinct climate characteristics, raising a great challenge to the present-day climate models. Most of the climate models still suffer from significant biases in simulating the climate of East Asia, which limits the utilization of these models in understanding the mechanisms of East Asian climate variability as well as in predicting its future changes. In recent years, to meet the demand for climate simulation and prediction in the East Asian region, the Chinese Academy of Meteorological Sciences (CAMS) has been devoted to developing a CSM. By surveying the performance of current CSMs, the CAMS-CSM was established, based on a number of state-of-the-art component models. Some unique features have been incorporated into the CAMS-CSM, such as the treatment of the East Asian topography, the water vapor transport scheme, and the cloud-radiation scheme. The CAMS-CSM has been officially planned to take part in the Coupled Model Intercomparison Project Phase 6 (CMIP6).
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 observatio-nal 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 Afri-can, 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.
Aerosols can affect the earth's atmospheric radiation budget, directly through absorbing and scattering shortwave and longwave radiation, and/or indirectly by altering cloud microphysical properties as cloud condensation nuclei and/or ice nuclei, eventually resulting in changes in the hydrological cycle and climate. Featuring a variety of complicated processes over a cascade of scales from local to global, the aerosol-cloud-radiation interactions are one of the greatest sources of uncertainty in projections of future climate change, and are therefore quite a challenge to be quantified through either observations or modeling. The descriptions of cloud microphysics, aerosol-cloud interaction, and associated radiative processes need to be improved, and the mechanisms of aerosol- and cloud-mediated climatic impacts and the ways to observe and quantify these effects need to be investigated.