Conference Agenda

Using satellite observations of trace gases and aerosols, this project will study the air pollution in the most populous regions in China: the North China Plain (NCP) and along the Yangtze River. With a total population of about 700 million, these regions are amongst the most densely populated regions in the world. Human activities, traffic, transportation and heavy industry in these areas result in high anthropogenic emissions with a variety of adverse effects. Monitoring and analysis of air quality is essential to evaluate different factors (emissions and emission reduction policy, meteorological factors, atmospheric chemistry and physics) contributing to the pollutant concentrations. Coordinated pollution control is currently a big challenge in China. In recent years, the Wuhan urban area has become the most polluted area after Beijing-Tianjin-Hebei (BTH) and the Yangtze River Delta (YRD). Accurate short-term forecasting and sub-seasonal predicting of air quality is an important basis for formulating effective management and control strategies. Thus, we will focus on the important components of air quality (AQ): nitrogen oxides (NO_x), sulphur dioxide (SO₂), ammonia (NH₃), carbon monoxide (CO), ozone (O₃), volatile organic compounds (VOCs) and aerosols.
This project aims at the use of satellite data to improve our knowledge of AQ and processes influencing AQ. The effects of emission reduction to improve AQ and competing meteorological processes will be evaluated using satellite remote sensing (continuing the work started in the EMPAC project of DRAGON5). An important issue is the development of an improved understanding of the relationship between satellite-retrieved column densities of aerosols and trace gases and the concentrations near the surface. To achieve this, satellite observations (TROPOMI, IASI, CrIS, Mopitt, GIIRS, GEMS, EMI, FY-4C) will be used together with ground-based observations and modelling. The Chinese and European partners will cooperate in four complementary work packages addressing different aspects relevant to AQ.

The Earth Cloud, Aerosol and Radiation Explorer (EarthCARE) will be launched in May 2024, and it will provide global profiles of clouds, aerosols and precipitation along with co-located radiative flux measurements. The EarthCARE satellite includes four scientific instruments: an atmospheric lidar, a Doppler cloud radar, a multispectral imager and a broadband radiometer. With the combination of active and passive instruments, the vertical structure and horizontal distribution of cloud and aerosol fields, together with shortwave and longwave outgoing radiation will be measured simultaneously. The EarthCARE products will be used to evaluate cloud and aerosol in weather forecasting and climate models and to improve our understanding of cloud and aerosol radiative impact and feedback mechanisms (Wehr et al., 2023).

The representations of clouds, aerosols, and cloud–aerosol–radiation impacts have large uncertainties in the assessment of climate change. Aerosols scatter and absorb solar and terrestrial radiation, thereby changing the planetary albedo. Aerosols also act as cloud condensation nuclei (CCN) or ice nuclei particles (INP). The aerosol–radiation and aerosol–cloud interactions will trigger fast adjustments to the profiles of temperature, moisture, and cloud water content. The objective of this project is to understand the role of aerosol cloud interaction at selected regions using satellite data. In order to understand these complex process we need EarthCARE (profile) products and cloud and aerosol products from geostationary satellites (MSG or MTG, FY-4) because of the temporal resolution of geostationary satellites. TROPOMI data will be used to select absorbing aerosol cases. The analysis will focus on urban aerosols, biomass burning aerosols, and desert dusts. For cloud scenes we will separate ice and water clouds.

The project will be supported by ESA EarthCARE projects (for example DISC). Currently we are involved in the ESA EarthCARE CARDINAL project and airsense project. In IAP the project will be supported by NSFC project and part of the Second Comprehensive Scientific Expedition of the Tibetan Plateau.

Global observations of atmospheric wind profiles and aerosol profiles are significant for NWP, radiative forcing and air quality. Spaceborne Doppler Wind Lidars (DWLs) and High Spectral Resolution Lidars (HSRLs) are capable of measuring global wind and aerosol profiles. Before the operational application of spaceborne lidar systems, dedicated and strict calibrations and validations (CAL/VAL) activities have to be conducted. This project will focus on the CAL/VAL and data assessment of three spaceborne lidar missions, which are ALADIN onboard Aeolus, ATLID (Atmospheric Lidar) onboard EarthCARE (Earth Cloud, Aerosol and Radiation Explorer), both initiated by the European Space Agency (ESA), and ACDL (Aerosol and Carbon Detection Lidar) onboard DQ (Daqi)-1, developed by Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences.

Aeolus was the first satellite mission to acquire profiles of Earth’s wind on a global scale. It was launched on 22 August 2018 and finished its nominal lifetime on 30 April 2023 before an assisted re-entry on 28 July 2023. The Aeolus satellite’s only payload is a direct detection DWL ALADIN. During its lifetime, it has measured the global wind profiles and aerosol profiles simultaneously and continuously for more than 4 years. The reprocessing of the Aeolus data products to improve data quality will continue in the next 5 years during phase F.

The launch of ESA’s EarthCARE satellite is scheduled for May 2024. The spacecraft will carry four instruments: the Cloud Profiling Radar (CPR) with Doppler capability, the Atmospheric Lidar (ATLID) with HSRL capability, the Multi-Spectral Imager (MSI), and the Broad-Band Radiometer (BBR). The satellite measurements will be used to retrieve global profiles of cloud, aerosol, and precipitation properties along with Top-Of-Atmosphere (TOA) Long- and Short-wave fluxes. The HSRL payload ATLID will provide vertical profiles of aerosols and thin clouds. It will operate at a wavelength of 355 nm and have a high-spectral resolution receiver and depolarization channel.

The Chinese atmospheric environment monitoring satellite DQ-1 has been successfully launched on 16 April 2022. As an integrated detection scientific research satellite, it will serve as an important part of Chinese atmospheric environment monitoring system. The DQ-1 equips five sensors including an Aerosol and Carbon Detection Lidar (ACDL), a Particulate Observing Scanning Polarimeter (POSP), a Directional Polarization Camera (DPC), an Environmental trace gas Monitoring Instrument (EMI) and a Wide Swath Imaging system (WSI). As the primary payload among them, ACDL is a HSRL with two-wavelength polarization detection, that can be utilized to derive the aerosol optical properties. The aerosol and cloud optical properties products of the ACDL include total depolarization ratio, backscatter coefficient, extinction coefficient, lidar ratio and color ratio. At present, DQ-1 is still in the commission phase and the products of ACDL are under calibration and validation (CAL/VAL).

To guarantee the data quality and refine the retrieval algorithms, an assessment of Aeolus’ reprocessed data needs to be conduct, whereas CAL/VAL campaigns for ATLID and ACDL products needs to be implemented.

In this project, we will use ground-based, airborne and shipborne lidar measurements to calibrate and validate the simultaneous observations from ALADIN, ACDL and ATLID. Besides, we will finish perform an assessment of their products via direct intercomparisons. The main instrumentation will be involved in this project include: Spaceborne lidar ALADIN on board Aeolus satellite, spaceborne lidar ATLID on board EarthCARE satellite, EARLINET within ACTRIS, PollyNet within EARLINET/ACTRIS, mobile ACTRIS aerosol and cloud remote sensing platforms of TROPOS (OCEANET, LACROS), and eVe reference lidar system of ESA from European side; Spaceborne lidar ACDL on board DQ-1 satellite, Coherent Doppler Lidars (CDLs) net (including more than 200 CDLs) over China, Direct detection Doppler Lidar (HSRL), polarization and Raman lidar Water vapor, Cloud and Aerosol Lidar (WACAL), Direct Spectrum Measurement Lidar (DSML) from Chinese side.

The expected results will include the assessment report (seasonal and annual) for the Aeolus reprocessed data and the validation results of the ACDL and ATLID by comparing with the airborne, shipborne and ground-based lidars.

In this project, we plan to provide validations of the magnetic field and plasma measurements from multiple low Earth orbiting satellites, including the ESA’s Swarm constellation, the China Seismo-Electromagnetic Satellite (CSES), as well as the Macau Science Satellite (MSS-1). All three missions are equipped with high-resolution magnetometers. Swarm and CSES are equipped with Langmuir probes. These similar in situ measurements provide a good opportunity for cross-validation between them and will improve data quality of the three missions. In addition, we plan to involve the earlier missions, like GOCE, CHAMP, GRACE/GRACE-FO and CryoSat missions. We plan to develop a set of well-calibrated indices for the magnetospheric and ionospheric currents. Empirical models for representing the climatologic and near-real-time magnetic/plasma environment of Earth are also planned to be developed. We plan to make studies in space science that profit from the co-analyzation of multiple missions.