Starting from August 6th in 2019, Sentinel-5P TROPOMI along-track high spatial resolution (~5.5km at nadir) has been implemented.For data before August 6th of 2019, please check S5P_L2__AER_LH_1 data collection.The Copernicus Sentinel-5 Precursor (Sentinel-5P or S5P) satellite mission is one of the European Space Agency's (ESA) new mission family - Sentinels, and it is a joint initiative between the Kingdom of the Netherlands and the ESA. The sole payload on Sentinel-5P is the TROPOspheric Monitoring Instrument (TROPOMI), which is a nadir-viewing 108 degree Field-of-View push-broom grating hyperspectral spectrometer, covering the wavelength of ultraviolet-visible (UV-VIS, 270nm to 495nm), near infrared (NIR, 675nm to 775nm), and shortwave infrared (SWIR, 2305nm-2385nm). Sentinel-5P is the first of the Atmospheric Composition Sentinels and is expected to provide measurements of ozone, NO2, SO2, CH4, CO, formaldehyde, aerosols and cloud at high spatial, temporal and spectral resolutions.Copernicus Sentinel-5P TROPOMI aerosol layer height algorithm applies a forward model, which includes DISAMAR (Determining Instrument Specifications and Analyzing Methods for Atmospheric Retrieval, a Layer-Based Orders of Scattering algorithm) to calculate monochromatic reflectance, and also employs a neural network scheme for speedy processor performance. Data retrieval uses the Optimal Estimation Method (OEM) for spectral fitting with various aerosol layer pressures and aerosol optical thicknesses in the Oxygen-A band (758 -770nm). The aerosol baseline model assumes a single uniformly distributed aerosol layer with a fixed pressure thickness and a constant aerosol volume extinction coefficient and single scattering albedo. The aerosol parameterization is particularly suitable for elevated non-scattering aerosols such as volcanic ash, desert dust and biomass burning plume. The product main outputs include the mid-pressure and mid-altitude of aerosol layers, aerosol optical thickness at 760nm, error estimates, and other relevant diagnostics.Starting from orbit #12432 on March 7th of 2020, the S-NPP auxiliary cloud data source used in the aerosol layer height product data processing has been transitioned from the VIIRS Cloud Mask (VCM) into the Enterprise Cloud Mask (ECM).