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MOS

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MOS

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  1. MOS • What does acronym stand for ? • MODEL OUTPUT STATISTICS • What is the difference between the NGM and NGM MOS ?

  2. NGM MOS • BUF EC NGM MOS GUIDANCE 9/26/01 1200 UTC • DAY /SEPT 26 /SEPT 27 /SEPT 28 / • HOUR 18 21 00 03 06 09 12 15 18 21 00 03 06 09 12 15 18 21 00 • MN/MX 44 54 45 59 • TEMP 51 52 49 48 47 46 46 51 52 51 49 48 48 48 48 53 57 56 53 • DEWPT 40 41 42 43 43 43 44 44 44 45 45 44 44 44 44 44 43 43 44 • CLDS OV OV OV OV OV OV OV OV OV OV OV OV OV OV OV OV OV BK SC • WDIR 22 23 25 24 26 28 25 27 27 26 25 28 30 33 36 02 36 35 30 • WSPD 16 13 09 07 07 07 07 08 09 10 09 08 05 05 06 06 07 08 07 • POP06 70 61 61 72 60 55 47 23 24 • POP12 82 79 64 35 • QPF 1/ 1/ 1/1 2/ 1/2 1/ 1/1 0/ 0/0 • TSV06 10/ 0 7/ 0 9/ 0 3/ 1 26/ 0 21/ 0 10/ 0 10/ 0 9/ 0 • TSV12 14/ 0 9/ 1 33/ 0 16/ 0 • PTYPE R R R R R R R R R R R R R R R • POZP 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 • POSN 0 0 0 1 5 9 2 2 4 1 0 5 0 0 0 • SNOW 0/ 0/ 0/0 0/ 0/0 0/ 0/0 0/ 0/0 • CIG 4 4 4 4 5 4 3 4 4 4 5 5 5 • VIS 5 5 5 5 4 4 4 5 4 5 4 5 5 • OBVIS N N N N N F F N N N F N N

  3. NGM MODEL • Station: BUF Lat: 42.93 Lon: -78.73 Elev: 217 Closest grid pt: 13.5 km. • Initialization Time: 01-09-26 1200 UTC • PARAMETER/TIME 000 006 012 018 024 030 036 042 048 • ----------------------- ------ ------ ------ ------ ------ ------ ------ ------ • DAY / HOUR 26/12 26/18 27/00 27/06 27/12 27/18 28/00 28/06 28/12 • ----------------------- ------ ------ ------ ------ ------ ------ ------ ------ • TEMPS • 1000 MB (C) 7 12 13 11 9 12 14 15 13 • 950 MB (C) 4 9 10 8 6 9 11 12 10 • 900 MB (C) 1 4 6 4 3 4 6 7 7 • 850 MB (C) -2 0 1 0 -1 1 2 3 3 • 800 MB (C) -9 -10 -9 -10 -11 -12 -10 -8 -6 • 1000-500 THCK 5405 5418 5419 5404 5381 5386 5411 5439 5459 • MOISTURE • 1000 MB DP(C)/RH 6/93 4/59 5/57 6/75 9/95 7/73 7/63 7/60 8/68 • 850 MB DP(C)/RH -3/92 -1/91 0/91 0/97 -1/97 0/97 1/93 1/89 2/91 • 700 MB DP(C)/RH-10/93 -10/98 -10/97 -11/95 -12/90 -12/97 -11/94 -10/82 -9/78 • 500 MB DP(C)/RH-22/76 -25/64 -28/60 -24/77 -24/92 -24/99 -25/94 -24/86 -26/61 • PRCPABLE WTR (I 0.64 0.59 0.64 0.64 0.61 0.64 0.68 0.68 0.69 • CONV PRECIP (IN 0.02 0.07 0.01 0.00 0.00 0.01 0.00 0.00 • TOTAL PRECIP (I 0.02 0.07 0.01 0.00 0.00 0.01 0.00 0.00 • WIND DD/FFF (Kts) • 1000 MB 21/014 21/009 26/011 30/009 30/009 28/007 30/008 36/011 01/016 • 850 MB 23/025 23/021 25/017 28/011 30/011 31/013 32/011 36/014 01/017 • 700 MB 23/036 24/029 25/028 26/022 29/013 34/017 35/020 01/024 02/026 • 500 MB 22/049 23/045 25/039 25/034 27/021 33/016 00/027 02/038 03/044 • 250 MB 22/050 23/054 23/048 24/044 25/027 29/011 00/026 02/039 03/050

  4. MOS • NGM = Dynamical Model • Seven fundamental equations ! • NGM MOS = Statistical Model • No seven fundamental equations ! • Equations are statistical, not dynamical !

  5. MOS • Why even have MOS ? • Predicts parameters that dynamical models don’t • Visibility • Cloud ceilings • Predicts some parameters better than models (averaged over all cases) • Surface temperature • Surface wind • Surface dewpoint

  6. MOS • How does MOS make its predictions? • Uses technique of association • Objectively relates (associates) model output to observed weather using statistical technique of linear regression

  7. MOS • Two steps to MOS ………. • Equation Development • Equation Application

  8. MOS • Equation Development ->> • PREDICTOR • Variable that is doing the PREDICTING • PREDICTAND • Variable that is getting PREDICTED • Linear Regression • Relates PREDICTOR to PREDICTAND

  9. MOS: Equation Development Y1 = mx1 + b1

  10. MOS: Temperature • Predictors • Model low level temps (i.e. 850mb) • Model relative humidity • Accounts for clouds • Model wind direction /speed • Climatology • Previous days min (max) • Single site development

  11. MOS: Precipitation • Predictors • Model mean relative humidity (i.e. 1000-500mb layer average) • Precipitation output of model • Model vertical velocity (i.e. 700, 500, 850mb) • Model low level wind direction (i.e. 10m) • Regional development

  12. MOS: Wind • Predictors • Low level wind direction/speed output of model (i.e. 10m, 850mb wind) • Single site development

  13. MOS Characteristics • Requires large sample size • Several years of model output • Increases statistical significance

  14. MOS • Partially removes systematic model errors (i.e. biases) • If model has a cool bias at 850mb, MOS will account for/remove model bias • Works best when models are not tweaked (i.e. no change to physics)

  15. MOS: Equation Application

  16. NGM MODEL • Station: BUF Lat: 42.93 Lon: -78.73 Elev: 217 Closest grid pt: 13.5 km. • Initialization Time: 01-09-26 1200 UTC • PARAMETER/TIME 000 006 012 018 024 030 036 042 048 • ----------------------- ------ ------ ------ ------ ------ ------ ------ ------ • DAY / HOUR 26/12 26/18 27/00 27/06 27/12 27/18 28/00 28/06 28/12 • ----------------------- ------ ------ ------ ------ ------ ------ ------ ------ • TEMPS • 1000 MB (C) 7 12 13 11 9 12 14 15 13 • 950 MB (C) 4 9 10 8 6 9 11 12 10 • 900 MB (C) 1 4 6 4 3 4 6 7 7 • 850 MB (C) -2 0 1 0 -1 1 2 3 3 • 800 MB (C) -9 -10 -9 -10 -11 -12 -10 -8 -6 • 1000-500 THCK 5405 5418 5419 5404 5381 5386 5411 5439 5459 • MOISTURE • 1000 MB DP(C)/RH 6/93 4/59 5/57 6/75 9/95 7/73 7/63 7/60 8/68 • 850 MB DP(C)/RH -3/92 -1/91 0/91 0/97 -1/97 0/97 1/93 1/89 2/91 • 700 MB DP(C)/RH-10/93 -10/98 -10/97 -11/95 -12/90 -12/97 -11/94 -10/82 -9/78 • 500 MB DP(C)/RH-22/76 -25/64 -28/60 -24/77 -24/92 -24/99 -25/94 -24/86 -26/61 • PRCPABLE WTR (I 0.64 0.59 0.64 0.64 0.61 0.64 0.68 0.68 0.69 • CONV PRECIP (IN 0.02 0.07 0.01 0.00 0.00 0.01 0.00 0.00 • TOTAL PRECIP (I 0.02 0.07 0.01 0.00 0.00 0.01 0.00 0.00 • WIND DD/FFF (Kts) • 1000 MB 21/014 21/009 26/011 30/009 30/009 28/007 30/008 36/011 01/016 • 850 MB 23/025 23/021 25/017 28/011 30/011 31/013 32/011 36/014 01/017 • 700 MB 23/036 24/029 25/028 26/022 29/013 34/017 35/020 01/024 02/026 • 500 MB 22/049 23/045 25/039 25/034 27/021 33/016 00/027 02/038 03/044 • 250 MB 22/050 23/054 23/048 24/044 25/027 29/011 00/026 02/039 03/050

  17. NGM MOS • BUF EC NGM MOS GUIDANCE 9/26/01 1200 UTC • DAY /SEPT 26 /SEPT 27 /SEPT 28 / • HOUR 18 21 00 03 06 09 12 15 18 21 00 03 06 09 12 15 18 21 00 • MN/MX 44 54 45 59 • TEMP 51 52 49 48 47 46 46 51 52 51 49 48 48 48 48 53 57 56 53 • DEWPT 40 41 42 43 43 43 44 44 44 45 45 44 44 44 44 44 43 43 44 • CLDS OV OV OV OV OV OV OV OV OV OV OV OV OV OV OV OV OV BK SC • WDIR 22 23 25 24 26 28 25 27 27 26 25 28 30 33 36 02 36 35 30 • WSPD 16 13 09 07 07 07 07 08 09 10 09 08 05 05 06 06 07 08 07 • POP06 70 61 61 72 60 55 47 23 24 • POP12 82 79 64 35 • QPF 1/ 1/ 1/1 2/ 1/2 1/ 1/1 0/ 0/0 • TSV06 10/ 0 7/ 0 9/ 0 3/ 1 26/ 0 21/ 0 10/ 0 10/ 0 9/ 0 • TSV12 14/ 0 9/ 1 33/ 0 16/ 0 • PTYPE R R R R R R R R R R R R R R R • POZP 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 • POSN 0 0 0 1 5 9 2 2 4 1 0 5 0 0 0 • SNOW 0/ 0/ 0/0 0/ 0/0 0/ 0/0 0/ 0/0 • CIG 4 4 4 4 5 4 3 4 4 4 5 5 5 • VIS 5 5 5 5 4 4 4 5 4 5 4 5 5 • OBVIS N N N N N F F N N N F N N

  18. MOS ERRORS: Who’s at fault? • Model’s fault • Garbage In = Garbage Out • MOS’s fault • Imperfect statistical relationships (i.e. lines of best fit are not line of prefect fit!)