wp_no=4002
wp_name=Validation of GOME-2 NO2 column products
list_of_product_IDs=O3M-02,O3M-07,O3M-36,O3M-37,O3M-50,O3M-51,O3M-52,O3M-53 
wp_start=02/2017
wp_end=12/2021
wp_responsible=BIRA
no_of_participants=3
BIRA 1.5 2 2.5 0 0 0 10000
RMI 1 1 1 0.5 0.5 0.25 11000
AUTH 1 1 1 0 0 0 5000

wp_objectives:
The objective of this WP is the validation of the O3M SAF NO2 total and tropospheric column products.

wp_methodology:
Validation (VAL) consist in a full investigation of the geophysical coherence of the data and of its quality. Validation exercises are required to assess new products or in case of major algorithmic revision. They make full use of all existing correlative data and lead to the production of a comprehensive validation report. This is based on an end-to-end approach, consisting in independent verification and validations of intermediate steps of the level-1-to-2 retrieval chain. This approach uses a set of correlative observations performed by complementary ground-based instruments, measurements from other satellites, and modelling support. 

VAL tasks: 
- (BIRA) Analyse consistency between total and tropospheric NO2 columns from GOME-2/Metop-A/B/C
- (BIRA) Collect, process and evaluate data records of stratospheric NO2 columns from NDACC UV-Vis DOAS stations
- (BIRA) Collect, process and evaluate data records of tropospheric NO2 columns from independent satellite sensors 
- (BIRA) Collect, process and evaluate tropospheric NO2 column and profile data from BIRA MAXDOAS instruments at O.H.P. (France, 44N), Xianghe (China, 40N), Uccle (Belgium, 50.8N), Bujumbura (Burundi, 3S) and Reunion Island (22S)
- (BIRA) Collect and use NO2 total column data from selected DirectSun instruments from the Pandora network
- (AUTH) Collect, process and evaluate NO2 column data from ground-based MaxDOAS instruments at Thessaloniki (Greece) and Guangzhu (China)
- (RMI) Collect, process and evaluate data records of NO2 surface concentration provided by pollution-monitoring networks in the framework of the EMEP programme
- (RMI) By means of a chemical transport model and surface network measurements, build a reference dataset on tropospheric NO2 data. The modelling domain will be three-folded: 2 coarse resolution domains for Asia (as a function of the observational network) and the current European domain, while for Belgium, a high-resolution (7 km) model domain including the BENELUX can be provided. 
- (RMI, BIRA) By means of modelling results and surface network data, perform a study of the horizontal representativeness of the validation sites for tropospheric NO2

wp_datasources:
- GOME-2/Metop-A/B/C NO2 column data 
- Tropospheric and stratospheric NO2 data measured at O.H.P., Xianghe, Uccle, Bujumbura and Reunion Island
- Total and tropospheric NO2 data measured at Thessaloniki (Greece) and Guangzhu (China) by ground-based MaxDOAS UV-visible spectrometers
- NO2 stratospheric column data from the NDACC UV-Visible network (a suitable subset of the 30 NDACC stations distributed from pole to pole)
- NO2 total column data from the PANDORA network (hosted at NASA)
- NO2 total and stratospheric columns from other satellite sensors
- NO2 surface observations from air pollution-monitoring networks in Europe
- Modelled NO2 data from the CHIMERE model
- Auxiliary/meteorological data

wp_deliverables:
- GOME-2/Metop-C NO2 validation report 

End