Table 1.
Abbreviations for various observation types.
Fig. 1.
The average forecast sensitivity to the background error covariance parameter (grey bar, J kg−1 d−1), the average forecast sensitivity to the observation covariance parameters (grey bar, J kg−1 d−1), and the associated 99% confidence interval (black line) in August 2012.
Table 2.
The error covariance adjustment parameters corresponding to the background error covariance (B) and the observation error variances of ATOVS, AIRS, IASI, Geo_AMV, ASCAT, SSMI/S, GPSRO, aircraft temperature (AIRCRAFT_t), aircraft wind (AIRCRAFT_uv), SONDE temperature (SONDE_t), SONDE wind (SONDE_uv), SONDE specific humidity (SONDE_q), surface temperature (SURFACE_t), surface wind (SURFACE_uv), surface pressure (SURFACE_p), and surface specific humidity (SURFACE_q) for July and August 2012. Rejection occurs when the specific forecast sensitivity to the error covariance data is greater than three times of standard deviation from the time-averaged values.
Table 3.
The observation error variances (K) of AMSU-A, AMUS-B, and HIRS, used operationally in the KMA UM 4DVAR system and those deflated. Channels 1, 2, 3, and 15 of AMSU-A, channels 1 and 2 of AMSU-B, and channels 1, 2, 3, 8, 9, 10, 13, 14, 16, 17, 18, 19, and 20 of HIRS are not used for the DA.
Fig. 2.
The for various observation types and variables for July and August 2012, corresponding to 10% (black circle), 30% (red circle), 50% (blue circle), 70% (green circle), and 90% (purple circle) inflation of .
Fig. 3.
Time series of the nonlinear FER (black solid line, J kg−1), the approximated FER in the observation space (observation impact; red solid line, J kg−1), the approximated FER in the parametric space (error covariance impact; blue dashed line, J kg−1) in (a) July and August 2012 and (b) the nonlinear FER (black solid line, J kg−1), the observation impact (red solid line, J kg−1) in August 2012, the error covariance impact (blue dashed line, J kg−1) by the – sensitivity and – sensitivity of August 2012 and the error covariance adjustment parameters in Table 2. The green shading with black solid line (J kg−1) in (b) denotes the difference between error covariance impact of ADJ_COV and error covariance impact of CTL in August 2012.
Fig. 4.
Schematic of the control experiment (CTL: black line) and the experiment with the adjusted observation error variance (ADJ_COV: grey line).
Fig. 5.
The ratio between the time-integrated O-A of ADJ_COV and CTL in the observation space for August 2012, stratified by each observation type and variable.
Fig. 6.
The ratio between the time-integrated O-F of ADJ_COV and CTL in the observation space for August 2012, stratified by each observation type and variable.
Fig. 7.
Time series of the ratio between the average O-Fs of ADJ_COV and CTL in the observation space for August 2012. The O-Fs of ADJ_COV and CTL are averaged for all observation types.
Fig. 8.
Vertical profile of the root mean square (RMS) of the average O-F of ADJ_COV (grey dashed) and CTL (black solid) in the observation space. The RMS error is calculated based on global SONDE (TEMP, PILOT, and PRFL) observations in August 2012.
Fig. 9.
The RMS of the average O-F of ADJ_COV (grey bar), CTL (black bar), and the reduction rate (dark grey with dashed line) in the observation space. The RMS of the average O-F is calculated based on (a) Metop-A AMSU-A and (b) NOAA19 AMSU-A channels globally in August 2012.
Fig. 10.
(a) The RMS of the average O-F of ADJ_COV (red bar) and CTL (blue bar) and (b) reduction rate (dark grey bar) in the observation space. The RMS of the average O-F is calculated based on global MetOp-A IASI channels in August 2012. The wavelength range, which corresponds to the channel number, is represented by a dashed line.