This collection contains Sentinel-5 Precursor Level-2 atmospheric measurements derived from the TROPOMI spectrometer. The products consist of the geolocated cloud fraction, cloud pressure and cloud albedo with a spatial resolution of 7 × 3.5 km observed at about 13:30 local solar time from spectra measured by TROPOMI. The main objective of the Copernicus Sentinel-5P mission is to perform atmospheric measurements with high spatio-temporal resolution, to be used for air quality, ozone and UV radiation, and climate monitoring and forecasting. Sensor: TROPOMI (TROPOspheric Monitoring Instrument) Revisit time and coverage: daily global coverage Launch date: 13 October 2017 Archiving start date: 10 July 2018 Mission Status: ongoing Terms and conditions for the use of Sentinel data: https://scihub.copernicus.eu/twiki/pub/SciHubWebPortal/TermsConditions/TC_Sentinel_Data_31072014.pdf Sentinel-5P Mission Overview: https://sentinel.esa.int/web/sentinel/missions/sentinel-5p Sentinel-5P TROPOMI Level-2 Products and Algorithms: https://sentinel.esa.int/web/sentinel/technical-guides/sentinel-5p/products-algorithms Sentinel-5P TROPOMI Level 2 Product User Manual Cloud Properties: https://sentinel.esa.int/documents/247904/2474726/Sentinel-5P-Level-2-Product-User-Manual-Cloud Suggested software for visualization: https://www.giss.nasa.gov/tools/panoply/ File format of measurement data: netCDF

GOME (Global Ozone Monitoring Experiment) stands for a family of satellite instruments named after the first GOME (https://wdc.dlr.de/sensors/gome/) instrument on ERS-2 launched in April 1995. Currently two GOME-2 instruments are operative on Metop-A and B (https://wdc.dlr.de/sensors/gome2/). The tropical tropospheric ozone is retrieved with convective cloud differential method (Valks et al., 2014 http://www.atmos-meas-tech.net/7/2513/2014/amt-7-2513-2014.html). The tropospheric column is retrieved by subtracting the stratospheric ozone column from the total column. The stratospheric ozone column is estimated as the column above high reaching convective clouds.

The Global Ozone Monitoring Experiment-2 (GOME-2) was launched on October 2006 on board EUMETSAT's Metereological Operational Satellite (MetOp-A). This instrument continues the long-term monitoring of atmospheric trace gas constituents started with GOME/ERS-2 and SCIAMACHY/Envisat. It can measure a range of atmospheric trace constituents, with the emphasis on global ozone distributions. Furthermore cloud properties and intensities of ultraviolet radiation are retrieved. These data are crucial for monitoring the atmospheric composition and the detection of pollutants. DLR generates operational GOME-2/MetOp level 2 products in the framework of EUMETSAT's Satellite Application Facility on Atmospheric Chemistry Monitoring (AC-SAF). GOME-2 near-real-time products are available already two hours after sensing. The operational ozone total column products are generated using the algorithm GDP (GOME Data Processor) version 4.x integrated into the UPAS (Universal Processor for UV/VIS Atmospheric Spectrometers) processor for generating level 2 trace gas and cloud products. The new improved DOAS-style (Differential Optical Absorption Spectroscopy) algorithm called GDOAS, was selected as the basis for GDP version 4.0 in the framework of an ESA ITT. GDP 4.x performs a DOAS fit for ozone slant column and effective temperature followed by an iterative AMF/VCD computation using a single wavelength. The main improvements compared to GDP 3.0 are: • Molecular Ring Correction parameterised [M. van Roozendael et al. (2006)] • On-the-fly RTM simulations using LIDORT v3.3 [R. Spurr (2003)] • Cloud Correction using OCRA and ROCINN v2.0 [D. Loyola et al. (2007)] • Intra-Cloud, Sunglint and Snow/Ice Correction [D. Loyola et al. (2011)] For more details please refer to https://atmos.eoc.dlr.de/app/missions/gome2

The Global Ozone Monitoring Experiment-2 (GOME-2) was launched on October 2006 on board EUMETSAT's Metereological Operational Satellite (MetOp-A). This instrument continues the long-term monitoring of atmospheric trace gas constituents started with GOME/ERS-2 and SCIAMACHY/Envisat. It can measure a range of atmospheric trace constituents, with the emphasis on global ozone distributions. Furthermore cloud properties and intensities of ultraviolet radiation are retrieved. These data are crucial for monitoring the atmospheric composition and the detection of pollutants. DLR generates operational GOME-2/MetOp level 2 products in the framework of EUMETSAT's Satellite Application Facility on Atmospheric Chemistry Monitoring (AC-SAF). GOME-2 near-real-time products are available already two hours after sensing. The operational BrO total column products are generated using the algorithm GDP (GOME Data Processor) version 4.x integrated into the UPAS (Universal Processor for UV/VIS Atmospheric Spectrometers) processor for generating level 2 trace gas and cloud products. Activities on further improvements of the BrO column algorithm are ongoing [Van Roozendael and Theys (2005), Theys et al. (2009b)] This work focuses on optimizing the accuracy of global total BrO columns, as well as polar tropospheric BrO columns. DOAS slant column fitting On the basis of noise driven considerations, the fitting window 336-351.5 nm was selected for the GOME-2. A BrO cross-section is included in the fit, as well as the cross-sections of the interfering trace gases: ozone, NO2, O2-O2. Two Ring reference spectrums are included as an additive fitting parameter. The detailed DOAS settings used for GOME-2 BrO slant columns retrieval are given in the [DLR/GOME-2/ATBD]. AMF and VCD determination The AMF is calculated with the LIDORT 3.3 model for the fitting window mid-point, since BrO is an optically thin absorber in this wavelength region. To incorporate the seasonal and latitudinal variation in stratospheric BrO in the AMF calculations, a stratospheric BrO profile climatology is used [Bruns et al. (2003)]. This climatology contains monthly mean BrO profiles as a function of latitude, based on the chemistry transport model SLIMCAT. For more details please refer to https://atmos.eoc.dlr.de/app/missions/gome2

The Global Ozone Monitoring Experiment-2 (GOME-2) was launched on September 2012 on board EUMETSAT's Metereological Operational Satellite (MetOp-B). This instrument continues the long-term monitoring of atmospheric trace gas constituents started with GOME/ERS-2 and SCIAMACHY/Envisat. It can measure a range of atmospheric trace constituents, with the emphasis on global ozone distributions. Furthermore cloud properties and intensities of ultraviolet radiation are retrieved. These data are crucial for monitoring the atmospheric composition and the detection of pollutants. DLR generates operational GOME-2/MetOp level 2 products in the framework of EUMETSAT's Satellite Application Facility on Atmospheric Chemistry Monitoring (AC-SAF). GOME-2 near-real-time products are available already two hours after sensing. For details see https://atmos.eoc.dlr.de/app/missions/gome2

Currently there are two Global Ozone Monitoring Experiment-2 (GOME-2) instrument operating in tanden on board EUMETSAT's Metereological Operational Satellites (MetOp-A and MetOp-B). GOME-2 can measure a range of atmospheric trace constituents, with the emphasis on global ozone distributions. Furthermore cloud properties and intensities of ultraviolet radiation are retrieved. These data are crucial for monitoring the atmospheric composition and the detection of pollutants. DLR generates operational GOME-2/MetOp level 2 products in the framework of EUMETSAT's Satellite Application Facility on Atmospheric Chemistry Monitoring (AC-SAF). GOME-2 near-real-time products are available already two hours after sensing. For more details please refer to https://atmos.eoc.dlr.de/app/missions/gome2

SWACI is a research project of DLR supported by the State Government of Mecklenburg-Vorpommern. Radio signals, transmitted by modern communication and navigation systems may be heavily disturbed by space weather hazards. Thus, severe temporal and spatial changes of the electron density in the ionosphere may significantly degrade the signal quality of various radio systems which even may lead to a complete loss of the signal. By providing specific space weather information, in particular now- and forecast of the ionospheric state, the accuracy and reliability of impacted communication and navigation systems shall be improved. The total electron content (TEC) is defined as the integral of the electron density along the ray path between satellite and receiver. Thus, TEC provides the number of electrons per square meter. The most frequently used unit is 1TECU = 1x1016 electrons / m2. TEC is derived from dual frequency code and carrier phase measurements provided by Global Navigation Satellite Systems (GNSS). SWACI uses GPS measurements from various European GNSS networks such as the International GNSS Service (IGS), European Reference Frame (EUREF), Norwegian Mapping Authority (NMA), and ascos distributed by the Federal Agency of Cartography and Geodesy (BKG) Frankfurt. The global TEC maps are mainly created by using data provided by the International GNSS Service Real-Time Pilot Project (IGS-RTPP). To generate TEC maps of vertical TEC, the slant measurements have to be transformed to the vertical. In a first approximation the ionospheric range error in GNSS is proportional to TEC. These TEC maps are used to derive latitudinal and zonal gradients, rate of change of TEC (5 min increments), 27 days medians, hourly forecasts of TEC, and corresponding error estimates. Spatial resolution (latitude x longitude): 2 °x 2° (Europe), 2.5° x 5° (globally)

SWACI is a research project of DLR supported by the State Government of Mecklenburg-Vorpommern. Radio signals, transmitted by modern communication and navigation systems may be heavily disturbed by space weather hazards. Thus, severe temporal and spatial changes of the electron density in the ionosphere may significantly degrade the signal quality of various radio systems which even may lead to a complete loss of the signal. By providing specific space weather information, in particular now- and forecast of the ionospheric state, the accuracy and reliability of impacted communication and navigation systems shall be improved. The total electron content (TEC) is defined as the integral of the electron density along the ray path between satellite and receiver. Thus, TEC provides the number of electrons per square meter. The most frequently used unit is 1TECU = 1x1016 electrons / m2. TEC is derived from dual frequency code and carrier phase measurements provided by Global Navigation Satellite Systems (GNSS). SWACI uses GPS measurements from various European GNSS networks such as the International GNSS Service (IGS), European Reference Frame (EUREF), Norwegian Mapping Authority (NMA), and ascos distributed by the Federal Agency of Cartography and Geodesy (BKG) Frankfurt. The global TEC maps are mainly created by using data provided by the International GNSS Service Real-Time Pilot Project (IGS-RTPP). To generate TEC maps of vertical TEC, the slant measurements have to be transformed to the vertical. In a first approximation the ionospheric range error in GNSS is proportional to TEC. These TEC maps are used to derive latitudinal and zonal gradients, rate of change of TEC (5 min increments), 27 days medians, hourly forecasts of TEC, and corresponding error estimates. Spatial resolution (latitude x longitude): 2 °x 2° (Europe), 2.5° x 5° (globally)