**  Thu Jul 27 11:50:59 2017   Andy Jacobson <andy.jacobson@noaa.gov> **

  CT-NRT.v2017 runs from 2015-12-Dec (near the end of CT2016) until
  2017-29-Apr.

  This release represents a significant change to the CarbonTracker
  methodology, implemented to simulate the 2015-2016 El Nino.  This is
  the first major El Nino to have occurred since the beginning of the
  CarbonTracker project, and some modifications were needed to the
  assimilation scheme.  Those two changes were:

  (1) Increase the assimilation window length from 5 weeks to 12
  weeks.  This means that the last week for which the fluxes were
  optimized using a full 12 weeks of data starts on 2017-Feb-04.
  Results are presented for the following 3 months, but each
  subsequent week has one week less of optimization.  That means
  fluxes in the week starting 2017-Feb-11 have seen only 11 weeks of
  optimization; those in 2017-Feb-18 have seen 10 weeks, etc.

  (2) Inflate prior covariance for land regions by a factor of 4 (in
  variance space; factor of 2 in std. dev. space).

  These changes are experimental, and we'd appreciate any feedback or
  information from your analysis to see how we're doing.  If there are
  no problems detected with this assimilation scheme, we may implement
  these changes for CT2017.
  
**  Thu Jul 27 12:04:01 2017   Andy Jacobson <andy.jacobson@noaa.gov> **

  We use the following CO2 observations in the assimilation:

    Prior to 2016-Jan-01, we use observations prepped for CT2016

    From 2016-Jan-01 on, we use observations prepped
    obspack_co2_1_NRT_v3.3_2017-04-19.