1. NGAC verification NGAC verification is comparing NGAC forecast (current AOT only) with observations from ground-based and satellite measurements and with ICAP multi-model ensemble NGAC verification package includes: Daily verification AERONET ICAP-MME Monthly evaluation AERONET statistics Satellite

2. Daily verification: NGAC vs AERONET NGAC forecast is routinely compared with in- situ observations at AERONET sites  Data source AERONET: Level 1.5 total AOD @ multiple channels (http://aeronet.gsfc.nasa.gov/NCEP_U PLOAD/Table_yyyymmdd(http://aeronet.gsfc.nasa.gov/NCEP_U PLOAD/Table_yyyymmdd)  Data processing AOT550nm is calculated from AOT at 440nm and 675nm Bin 1-h time window centered at NGAC model synoptic output times of 0, 3, 6, 9, 12, 15, 18, and 21 UTC  NGAC dust AOD compared with total AERONET AOT Time series for the last 30 days ending yesterday are displayed For selected dust-prone site located in West Africa, North Africa and mid-East

3. Daily verification: NGAC vs ICAP-MME Compare NGAC aerosol optical thickness to ICAP-MME ensemble  Data source ICAP-MME: dust AOD, multi-model ensemble from ECMWF MACC, JMA MASINGAR, NASA GSFC/GMAO, FNMOC/NRL NAAPS, NOAA NGAC, Barcelona Supercomputing Centre NMMB/BSC-CTM and UK Met office unified model (http://www.usgodae.org/pub/outgoing /nrl/ICAP-MME/yyyy/yyyymm/(http://www.usgodae.org/pub/outgoing /nrl/ICAP-MME/yyyy/yyyymm/)  NGAC dust AOD compared with ICAP-MME AOT Spatial distribution every 12 hours for the 5 day forecast from yesterday are displayed Global and sub-tropical Atlantic

4. NGAC vs Satellite data Level 3 (gridded, monthly) MODIS total AOT retrievals at 550nm and 1 degree spatial resolution over Land and Ocean. MODIS Deep Blue product which observes AOT over bright surfaces. VIIRS total AOT retrieval at 0.25 degree OMI UV Index retrievals at 0.25 degree MISR total AOT retrieval at 0.5 degree

5. Monthly scale comparison between NGAC and satellites : August, 2014

6. Ongoing activity and future plan NGAC verification package is set up through collaboration between NCEP and SUNYA: Daily verification protocol is set up by SUNYA (Sheng-Po Chen and Sarah Lu) and is being ported to NCEP for operational NGAC verification ( Jun Wang) Satellite Verification is set up by NCEP (Partha Bhattacharjee) The verification website is under development and will go public in July 2015 Future plan Dust mask index from VIIRS at 0.25 degree Construct vertical structure from aerosol backscatter using CALIPSO Extend to include additional AERONET sites