@phdthesis{74561,
  author = {R. Gelaro and R. Langland and R. Todling},
  title = {Recent developments in the use and understanding of adjoint-derived estimates of observation impact},
  year = {2009},
  journal = {ECMWF Workshop on Diagnostics of data assimilation system performance, 15 - 17 June 2009},
  pages = {97-106},
  month = {2009},
  publisher = {ECMWF},
  address = {Shinfield Park, Reading},
  language = {eng},
}