The focus of the SAG TAD (formerly named SAG on Precipitation Chemistry) was recently expanded to include dry and total deposition to reflect current scientific knowledge that total (wet plus dry) atmospheric deposition characterizes the exchange process between the atmosphere and the underlying surface, while precipitation chemistry and wet deposition capture only part of this exchange. The goal of the SAG TAD is to provide a more comprehensive understanding and quantification of total atmospheric deposition, which is of critical importance for satisfying the needs of the GAW Programme.