Tropical Storm 30Y_03


ARCHER-V2 Auto-positioning Information
Advanced Dvorak Technique (ADT)
Version 9.0
 

                                         -------FORECAST-----   ----ARCHER---- 50% cert  95% cert Eyewall   Conf Alpha  Eye
     Date/Time(UTC)     Source   Sensor    Lat     Lon   Vmax      Lat     Lon   radius    radius  radius  Score Score  Prob    .
   20200611 13:40:00  HIMAWARI   NearIR   14.95 -121.10  30.0    14.77 -121.59     0.23      0.66   0.05    0.87  7.17 100.0 GIF
   20200611 14:10:00  HIMAWARI   NearIR   14.95 -121.01  30.0    15.28 -121.50     0.60      1.70   0.10    0.36  2.80 100.0 GIF
   20200611 14:30:00  HIMAWARI   NearIR   14.96 -120.95  30.0    15.14 -121.24     0.13      0.36   0.05    1.58 13.34 100.0 GIF
   20200611 15:10:00  HIMAWARI   NearIR   15.00 -120.85  30.0    15.47 -121.42     2.21      6.24   0.05    0.13  0.76  62.1 GIF
   20200611 15:40:00  HIMAWARI   NearIR   15.04 -120.79  30.0    15.24 -121.41     0.19      0.54   0.05    1.05  8.73 100.0 GIF
   20200611 16:10:00  HIMAWARI   NearIR   15.08 -120.73  30.0    15.23 -121.12     0.24      0.67   0.05    0.86  7.07 100.0 GIF
   20200611 16:40:00  HIMAWARI   NearIR   15.14 -120.67  30.0    15.14 -120.60     0.25      0.69   0.05    0.83  6.84 100.0 GIF
   20200611 17:10:00  HIMAWARI   NearIR   15.19 -120.63  30.0    15.39 -120.78     0.20      0.55   0.05    1.03  8.57 100.0 GIF
   20200611 17:40:00  HIMAWARI   NearIR   15.26 -120.58  30.0    15.23 -120.63     0.40      1.14   0.05    0.52  4.18  99.6 GIF
   20200611 18:10:00  HIMAWARI   NearIR   15.32 -120.54  30.0    15.55 -120.92     2.02      5.70   0.05    0.14  0.83  49.3 GIF
   20200611 18:40:00  HIMAWARI   NearIR   15.39 -120.49  30.0    14.52 -119.38     1.18      3.34   0.35    0.21  1.42  49.9 GIF
   20200611 19:10:00  HIMAWARI   NearIR   15.46 -120.45  30.0    14.03 -119.99     1.09      3.07   0.10    0.22  1.55  61.7 GIF
   20200611 19:40:00  HIMAWARI       IR   15.77 -120.04  30.0    14.12 -119.99     0.39      1.10   0.05    0.64  4.30  96.8 GIF
   20200611 20:10:00  HIMAWARI   NearIR   15.83 -119.96  30.0    14.61 -119.49     0.60      1.68   0.20    0.37  2.82  73.3 GIF
   20200611 20:40:00    SSMI15 85-92GHz   15.85 -119.93  30.0   -80.23   41.95     0.36      1.00    N/A    0.64  4.71   0.0 GIF
   20200611 21:10:00    SSMI15 85-92GHz   15.85 -119.93  30.0   -80.23   41.95     0.36      1.00    N/A    0.64  4.65   0.0 GIF
   20200611 21:40:00    SSMI15 85-92GHz   15.85 -119.93  30.0   -80.23   41.95     0.36      1.00    N/A    0.64  4.56   0.0 GIF
   20200611 22:10:00  HIMAWARI   NearIR   16.00 -119.64  30.0    14.55 -119.30     0.30      0.84   0.10    0.69  5.62  84.6 GIF
   20200611 22:40:00    SSMI15 85-92GHz   15.85 -119.93  30.0   -80.23   41.95     0.36      1.00    N/A    0.64  4.36   0.0 GIF
   20200611 23:10:00    SSMI15 85-92GHz   15.85 -119.93  30.0   -80.23   41.95     0.36      1.00    N/A    0.64  4.24   0.0 GIF
   20200611 23:40:00    SSMI15 85-92GHz   15.85 -119.93  30.0   -80.23   41.95     0.36      1.00    N/A    0.64  4.12   0.0 GIF
   20200612 00:10:00    SSMI15 85-92GHz   15.85 -119.93  30.0   -80.23   41.95     0.36      1.00    N/A    0.64  4.00   0.0 GIF
   20200612 00:40:00    SSMI15 85-92GHz   15.85 -119.93  30.0   -80.23   41.95     0.36      1.00    N/A    0.64  3.88   0.0 GIF
   20200612 01:10:00    SSMI15 85-92GHz   15.85 -119.93  30.0   -80.23   41.95     0.36      1.00    N/A    0.64  3.76   0.0 GIF
   20200612 01:40:00    SSMI15 85-92GHz   15.85 -119.93  30.0   -80.23   41.95     0.36      1.00    N/A    0.64  3.64   0.0 GIF
   20200612 02:10:00  HIMAWARI      Vis   16.20 -118.99  30.0    15.85 -118.91     0.45      1.27   0.05    0.32  3.73  61.0 GIF
   20200612 02:30:00  HIMAWARI      Vis   16.21 -118.94  30.0    15.84 -118.91     0.35      0.98   0.05    0.39  4.86  64.9 GIF
   20200612 03:10:00    SSMI15 85-92GHz   15.85 -119.93  30.0   -80.23   41.95     0.36      1.00    N/A    0.64  3.30   0.0 GIF
   20200612 03:40:00    SSMI15 85-92GHz   15.85 -119.93  30.0   -80.23   41.95     0.36      1.00    N/A    0.64  3.19   0.0 GIF
   20200612 04:10:00    SSMI15 85-92GHz   15.85 -119.93  30.0   -80.23   41.95     0.36      1.00    N/A    0.64  3.09   0.0 GIF
   20200612 04:40:00  HIMAWARI   NearIR   16.39 -118.55  30.0    15.64 -118.19     0.56      1.59   0.05    0.39  2.99  49.5 GIF
   20200612 05:10:00    SSMI15 85-92GHz   15.85 -119.93  30.0   -80.23   41.95     0.36      1.00    N/A    0.64  2.89   0.0 GIF
   20200612 05:40:00  HIMAWARI      Vis   16.51 -118.36  30.0    16.11 -118.31     0.47      1.33   0.10    0.30  3.56  70.1 GIF
   20200612 06:10:00  HIMAWARI      Vis   16.57 -118.27  30.0    16.17 -118.14     0.45      1.27   0.15    0.32  3.75  62.2 GIF
   20200612 06:40:00  HIMAWARI      Vis   16.64 -118.18  30.0    16.21 -118.02     0.60      1.70   0.05    0.25  2.78  55.9 GIF
   20200612 07:10:00    SSMI15 85-92GHz   15.85 -119.93  30.0   -80.23   41.95     0.36      1.00    N/A    0.64  2.54   0.0 GIF
   20200612 07:40:00  HIMAWARI      Vis   16.56 -117.13  30.0    16.29 -117.10     0.45      1.27   0.15    0.32  3.73  56.1 GIF
   20200612 08:10:00    SSMI15 85-92GHz   15.85 -119.93  30.0   -80.23   41.95     0.36      1.00    N/A    0.64  2.38   0.0 GIF
   20200612 08:40:00  HIMAWARI       IR   16.70 -116.95  30.0    15.72 -117.47     0.62      1.76   0.15    0.48  2.69  61.4 GIF
   20200612 09:10:00    SSMI15 85-92GHz   15.85 -119.93  30.0   -80.23   41.95     0.36      1.00    N/A    0.64  2.24   0.0 GIF
   20200612 09:40:00    SSMI18 85-92GHz   16.76 -116.87  30.0   -80.33   50.90     0.36      1.01    N/A    0.63  4.66   0.0 GIF
   20200612 10:10:00    SSMI18 85-92GHz   16.76 -116.87  30.0   -80.33   50.90     0.36      1.01    N/A    0.63  4.59   0.0 GIF
   20200612 10:40:00    SSMI16 85-92GHz   16.85 -116.74  30.0   -80.10   44.93     0.26      0.72    N/A    1.20  6.49   0.0 GIF
   20200612 11:10:00    SSMI16 85-92GHz   16.85 -116.74  30.0   -80.10   44.93     0.26      0.72    N/A    1.20  6.35   0.0 GIF
   20200612 11:40:00    SSMI16 85-92GHz   16.85 -116.74  30.0   -80.10   44.93     0.26      0.72    N/A    1.20  6.18   0.0 GIF
   20200612 12:10:00    SSMI16 85-92GHz   16.85 -116.74  30.0   -80.10   44.93     0.26      0.72    N/A    1.20  5.99   0.0 GIF
   20200612 12:40:00    SSMI16 85-92GHz   16.85 -116.74  30.0   -80.10   44.93     0.26      0.72    N/A    1.20  5.79   0.0 GIF
   20200612 13:10:00  HIMAWARI   NearIR   17.08 -116.45  30.0    15.81 -116.98     0.28      0.78   0.05    0.74  6.07 100.0 GIF
   20200612 13:40:00    SSMI16 85-92GHz   16.85 -116.74  30.0   -80.10   44.93     0.26      0.72    N/A    1.20  5.38   0.0 GIF
   20200612 14:10:00  HIMAWARI       IR   16.69 -116.79  35.0    16.72 -116.55     0.11      0.31   0.05    1.75 15.23 100.0 GIF
   20200612 14:30:00  HIMAWARI       IR   16.73 -116.74  35.0    16.53 -116.34     0.28      0.78   0.05    0.82  6.09 100.0 GIF
   20200612 15:10:00    SSMI16 85-92GHz   16.85 -116.74  30.0   -80.10   44.93     0.26      0.72    N/A    1.20  4.77   0.0 GIF
   20200612 15:40:00    SSMI16 85-92GHz   16.85 -116.74  30.0   -80.10   44.93     0.26      0.72    N/A    1.20  4.57   0.0 GIF
   20200612 16:10:00    SSMI16 85-92GHz   16.85 -116.74  30.0   -80.10   44.93     0.26      0.72    N/A    1.20  4.39   0.0 GIF
   20200612 16:40:00  HIMAWARI   NearIR   17.04 -116.41  35.0    16.64 -116.30     0.25      0.72   0.05    0.81  6.62 100.0 GIF
   20200612 17:10:00    SSMI16 85-92GHz   16.85 -116.74  30.0   -80.10   44.93     0.26      0.72    N/A    1.20  4.04   0.0 GIF
   20200612 17:40:00    SSMI16 85-92GHz   16.85 -116.74  30.0   -80.10   44.93     0.26      0.72    N/A    1.20  3.88   0.0 GIF
   20200612 18:10:00    SSMI16 85-92GHz   16.85 -116.74  30.0   -80.10   44.93     0.26      0.72    N/A    1.20  3.72   0.0 GIF
   20200612 18:40:00    SSMI16 85-92GHz   16.85 -116.74  30.0   -80.10   44.93     0.26      0.72    N/A    1.20  3.57   0.0 GIF
   20200612 19:10:00    SSMI16 85-92GHz   16.85 -116.74  30.0   -80.10   44.93     0.26      0.72    N/A    1.20  3.43   0.0 GIF
   20200612 19:40:00    SSMI16 85-92GHz   16.85 -116.74  30.0   -80.10   44.93     0.26      0.72    N/A    1.20  3.30   0.0 GIF
   20200612 20:10:00    SSMI16 85-92GHz   16.85 -116.74  30.0   -80.10   44.93     0.26      0.72    N/A    1.20  3.18   0.0 GIF
   20200612 20:40:00    SSMI16 85-92GHz   16.85 -116.74  30.0   -80.10   44.93     0.26      0.72    N/A    1.20  3.06   0.0 GIF
   20200612 21:10:00  HIMAWARI       IR   17.20 -115.73  35.0    15.83 -115.68     0.51      1.44   0.05    0.54  3.29  90.8 GIF
   20200612 21:40:00     AMSR2 85-92GHz   17.10 -116.19  35.0   -80.27   52.21     0.52      1.47    N/A    0.18  2.90   0.0 GIF
   20200612 22:10:00    SSMI16 85-92GHz   17.26 -115.64  35.0   -80.24   52.73     0.24      0.68    N/A    1.32  6.90   0.0 GIF
   20200612 22:40:00    SSMI18 85-92GHz   17.35 -115.53  35.0   -80.25   52.68     0.20      0.58    N/A    1.70  8.18   0.0 GIF
   20200612 23:10:00    SSMI18 85-92GHz   17.35 -115.53  35.0   -80.25   52.68     0.20      0.58    N/A    1.70  8.02   0.0 GIF
   20200612 23:40:00    SSMI18 85-92GHz   17.35 -115.53  35.0   -80.25   52.68     0.20      0.58    N/A    1.70  7.79   0.0 GIF
   20200613 00:10:00    SSMI18 85-92GHz   17.35 -115.53  35.0   -80.25   52.68     0.20      0.58    N/A    1.70  7.52   0.0 GIF
   20200613 00:40:00    SSMI18 85-92GHz   17.35 -115.53  35.0   -80.25   52.68     0.20      0.58    N/A    1.70  7.23   0.0 GIF
   20200613 01:10:00    SSMI18 85-92GHz   17.35 -115.53  35.0   -80.25   52.68     0.20      0.58    N/A    1.70  6.93   0.0 GIF
   20200613 01:40:00  HIMAWARI      Vis   18.54 -114.97  40.0    18.24 -115.05     0.24      0.67   0.20    0.54  7.04  63.1 GIF
   20200613 02:10:00    SSMI18 85-92GHz   17.35 -115.53  35.0   -80.25   52.68     0.20      0.58    N/A    1.70  6.33   0.0 GIF
   20200613 02:30:00    SSMI18 85-92GHz   17.35 -115.53  35.0   -80.25   52.68     0.20      0.58    N/A    1.70  6.13   0.0 GIF
   20200613 03:10:00  HIMAWARI      Vis   18.78 -114.72  40.0    18.51 -114.88     0.20      0.56   0.35    0.65  8.49  69.7 GIF
   20200613 03:40:00    SSMI18 85-92GHz   17.35 -115.53  35.0   -80.25   52.68     0.20      0.58    N/A    1.70  5.49   0.0 GIF
   20200613 04:10:00    SSMI18 85-92GHz   17.35 -115.53  35.0   -80.25   52.68     0.20      0.58    N/A    1.70  5.23   0.0 GIF
   20200613 04:40:00  HIMAWARI       IR   19.01 -114.47  40.0    18.58 -115.79     0.24      0.68   0.05    0.91  6.94  98.9 GIF
   20200613 05:10:00  HIMAWARI   NearIR   19.08 -114.39  40.0    18.68 -115.45     0.34      0.96   0.35    0.61  4.94  68.9 GIF
   20200613 05:40:00    SSMI18 85-92GHz   17.35 -115.53  35.0   -80.25   52.68     0.20      0.58    N/A    1.70  4.53   0.0 GIF
   20200613 06:10:00    SSMI18 85-92GHz   17.35 -115.53  35.0   -80.25   52.68     0.20      0.58    N/A    1.70  4.33   0.0 GIF
   20200613 06:40:00  HIMAWARI      Vis   19.55 -114.96  40.0    19.45 -115.36     0.25      0.71   0.40    0.52  6.69  75.7 GIF
   20200613 07:10:00  HIMAWARI      Vis   19.68 -114.91  40.0    19.58 -115.47     0.29      0.81   0.05    0.46  5.83  71.3 GIF
   20200613 07:40:00  HIMAWARI      Vis   19.79 -114.85  40.0    19.89 -115.52     0.28      0.79   0.05    0.47  5.97  87.9 GIF
   20200613 08:10:00    SSMI18 85-92GHz   17.35 -115.53  35.0   -80.25   52.68     0.20      0.58    N/A    1.70  3.62   0.0 GIF
   20200613 08:40:00    SSMI18 85-92GHz   17.35 -115.53  35.0   -80.25   52.68     0.20      0.58    N/A    1.70  3.47   0.0 GIF
   20200613 09:10:00    SSMI18 85-92GHz   17.35 -115.53  35.0   -80.25   52.68     0.20      0.58    N/A    1.70  3.32   0.0 GIF
   20200613 09:40:00    SSMI18 85-92GHz   17.35 -115.53  35.0   -80.25   52.68     0.20      0.58    N/A    1.70  3.19   0.0 GIF
   20200613 10:10:00    SSMI18 85-92GHz   17.35 -115.53  35.0   -80.25   52.68     0.20      0.58    N/A    1.70  3.06   0.0 GIF
   20200613 10:40:00    SSMI18 85-92GHz   17.35 -115.53  35.0   -80.25   52.68     0.20      0.58    N/A    1.70  2.94   0.0 GIF
   20200613 11:10:00    SSMI18 85-92GHz   20.18 -114.28  40.0   -80.22   53.52     0.37      1.05    N/A    0.57  4.48   0.0 GIF
   20200613 11:40:00    SSMI18 85-92GHz   20.18 -114.28  40.0   -80.22   53.52     0.37      1.05    N/A    0.57  4.42   0.0 GIF
   20200613 12:10:00    SSMI18 85-92GHz   20.18 -114.28  40.0   -80.22   53.52     0.37      1.05    N/A    0.57  4.34   0.0 GIF
   20200613 12:40:00    SSMI18 85-92GHz   20.18 -114.28  40.0   -80.22   53.52     0.37      1.05    N/A    0.57  4.25   0.0 GIF
   20200613 13:10:00    SSMI18 85-92GHz   20.18 -114.28  40.0   -80.22   53.52     0.37      1.05    N/A    0.57  4.15   0.0 GIF
   20200613 13:40:00    SSMI18 85-92GHz   20.18 -114.28  40.0   -80.22   53.52     0.37      1.05    N/A    0.57  4.05   0.0 GIF
   20200613 14:10:00    SSMI18 85-92GHz   20.18 -114.28  40.0   -80.22   53.52     0.37      1.05    N/A    0.57  3.94   0.0 GIF
   20200613 14:30:00    SSMI18 85-92GHz   20.18 -114.28  40.0   -80.22   53.52     0.37      1.05    N/A    0.57  3.87   0.0 GIF
   20200613 15:10:00  HIMAWARI       IR   20.14 -113.74  35.0    19.89 -113.10     0.38      1.08   0.15    0.65  4.40  92.9 GIF
   20200613 15:40:00  HIMAWARI   NearIR   20.18 -113.66  35.0    20.00 -111.98     0.22      0.62   0.05    0.92  7.62 100.0 GIF
   20200613 16:10:00    SSMI18 85-92GHz   20.18 -114.28  40.0   -80.22   53.52     0.37      1.05    N/A    0.57  3.50   0.0 GIF
   20200613 16:40:00    SSMI18 85-92GHz   20.18 -114.28  40.0   -80.22   53.52     0.37      1.05    N/A    0.57  3.39   0.0 GIF
   20200613 17:10:00  HIMAWARI   NearIR   20.31 -113.40  35.0    20.19 -111.64     0.15      0.43   0.05    1.32 11.13 100.0 GIF
   20200613 17:40:00    SSMI18 85-92GHz   20.18 -114.28  40.0   -80.22   53.52     0.37      1.05    N/A    0.57  3.18   0.0 GIF
   20200613 18:10:00    SSMI18 85-92GHz   20.18 -114.28  40.0   -80.22   53.52     0.37      1.05    N/A    0.57  3.08   0.0 GIF
   20200613 18:40:00    SSMI18 85-92GHz   20.18 -114.28  40.0   -80.22   53.52     0.37      1.05    N/A    0.57  2.98   0.0 GIF
   20200613 19:10:00    SSMI18 85-92GHz   20.18 -114.28  40.0   -80.22   53.52     0.37      1.05    N/A    0.57  2.89   0.0 GIF
   20200613 19:40:00    SSMI18 85-92GHz   20.18 -114.28  40.0   -80.22   53.52     0.37      1.05    N/A    0.57  2.80   0.0 GIF
   20200613 20:10:00    SSMI18 85-92GHz   20.18 -114.28  40.0   -80.22   53.52     0.37      1.05    N/A    0.57  2.71   0.0 GIF
   20200613 20:40:00    SSMI18 85-92GHz   20.18 -114.28  40.0   -80.22   53.52     0.37      1.05    N/A    0.57  2.62   0.0 GIF
   20200613 21:10:00  HIMAWARI   NearIR   20.90 -112.64  35.0    21.27 -113.76     0.52      1.46   0.05    0.42  3.24  53.8 GIF
   20200613 21:40:00    SSMI16 85-92GHz   20.95 -112.58  35.0   -80.15   55.64     0.45      1.27    N/A    0.34  3.74   0.0 GIF
   20200613 22:10:00    SSMI16 85-92GHz   20.95 -112.58  35.0   -80.15   55.64     0.45      1.27    N/A    0.34  3.71   0.0 GIF
   20200613 22:40:00    SSMI18 85-92GHz   21.05 -112.47  35.0   -80.14   55.88     0.40      1.14    N/A    0.47  4.15   0.0 GIF
   20200613 23:10:00    SSMI18 85-92GHz   21.05 -112.47  35.0   -80.14   55.88     0.40      1.14    N/A    0.47  4.10   0.0 GIF
   20200613 23:40:00    SSMI18 85-92GHz   21.05 -112.47  35.0   -80.14   55.88     0.40      1.14    N/A    0.47  4.03   0.0 GIF
   20200614 00:10:00    SSMI18 85-92GHz   21.05 -112.47  35.0   -80.14   55.88     0.40      1.14    N/A    0.47  3.95   0.0 GIF
   20200614 00:40:00    SSMI18 85-92GHz   21.05 -112.47  35.0   -80.14   55.88     0.40      1.14    N/A    0.47  3.87   0.0 GIF
   20200614 01:10:00    SSMI18 85-92GHz   21.05 -112.47  35.0   -80.14   55.88     0.40      1.14    N/A    0.47  3.78   0.0 GIF
   20200614 01:40:00  HIMAWARI      Vis   21.55 -111.94  35.0    21.55 -112.23     0.38      1.07   0.10    0.37  4.44  79.9 GIF
   20200614 02:10:00  HIMAWARI      Vis   21.62 -111.86  35.0    21.65 -112.07     0.34      0.95   0.05    0.40  4.98  90.6 GIF
   20200614 02:30:00    SSMI18 85-92GHz   21.05 -112.47  35.0   -80.14   55.88     0.40      1.14    N/A    0.47  3.52   0.0 GIF
   20200614 03:10:00    SSMI18 85-92GHz   21.05 -112.47  35.0   -80.14   55.88     0.40      1.14    N/A    0.47  3.39   0.0 GIF
   20200614 03:40:00  HIMAWARI      Vis   21.85 -111.62  35.0    22.30 -111.92     0.31      0.87   0.05    0.44  5.47 100.0 GIF
   20200614 04:10:00  HIMAWARI      Vis   21.93 -111.54  35.0    22.13 -111.70     0.41      1.17   0.05    0.34  4.07  86.9 GIF
   20200614 04:40:00  HIMAWARI      Vis   22.00 -111.46  35.0    22.40 -111.73     0.53      1.49   0.05    0.28  3.19  75.1 GIF
   20200614 05:10:00  HIMAWARI      Vis   22.08 -111.38  35.0    22.35 -111.44     0.35      1.00   0.45    0.38  4.73  78.8 GIF
   20200614 05:40:00  HIMAWARI      Vis   22.15 -111.30  35.0    22.40 -111.25     0.33      0.94   0.35    0.41  5.05  84.7 GIF
   20200614 06:10:00  HIMAWARI      Vis   22.22 -111.22  35.0    22.62 -111.30     0.29      0.83   0.30    0.45  5.74  96.9 GIF
 
 
Key:

  - Date/Time: UTC time. If this observation is used in the track it is marked with a "*". If it is used for its own 30-minute window, it is put in bold.

  - Source/sensor: Satellite source of the analyzed image.

  - Vmax: Maximum winds listed in the forecast center analysis/forecast, *not* ARCHER.

  - ARCHER lat/lon: Coordinates of the ARCHER algorithm, valid at the time of the observation. If no center fix could be found, then it is "***".

  - Geo ref lat/lon: Coordinates of the ARCHER algorithm, valid at the time of the *nearest geo image*.

  - 50% cert. rad.: Radius of the circle (in degrees) that defines the area in which the ARCHER center of rotation is 50% certain. The lower the number, the more certain the position.

  - 95% cert. rad.: Radius of the circle (in degrees) that defines the area in which the ARCHER center of rotation is 95% certain.

  - Eye diam (deg): ARCHER-resolved eye diameter (in degrees). Green: robust, yellow: less certain, red: not robust.

  - % cert. of eye: Percent certainty that an eye exists in this image, determined by ARCHER. Currently only available for IR and 85-92 GHz imagery.

 
Links to related versions:
  - Track Plot
  - Summary table
  - Intensity Estimation