SURFACE OBSERVATIONS FROM THE NEW ZEALAND FLEET

MONITORING OF DATA QUALITY BY THE UK MET OFFICE

Monitoring statistics are presented in the accompanying tables for pressure, temperature, wind speed, wind direction, relative humidity and sea surface temperature observations from each ship in the New Zealand fleet.

The tables have 5 columns:

Column 1 gives the ship identifier.

Column 2 gives the total number of observations received at Exeter over the GTS in the month. Only those observations received in time for use in the numerical models have been included, and the relevant cut-off times are 0715, 1315, 1915 and

0115 UTC for the observation times 0000, 0600, 1200 and 1800 UTC respectively. Identical reports having exactly the same position, time and observed value have only been counted once.

Column 3 gives the percentage of observations with gross error over the period. These are observations which differ from the background value by an amount which is far in excess of the likely background error (pressure 15 hPa, temperature 15 deg C, wind speed 25ms, wind direction 150 deg, relative humidity 50 %, sea surface temperature 10 deg C). The statistics for bias and standard deviation are calculated excluding these observations.

Column 4 gives the average observation bias over the month relative to reference values provided by the UK numerical forecasting system (these are short-term forecasts or background fields). The background values have been interpolated to the observation position and are valid for the relevant main synoptic hour (0000, 0600, 1200 or 1800 UTC). Corrections have been made for known biases in the background fields, and the resulting estimates of the observation bias are thought to be accurate to about 0.5 hPa/ms where there is a sufficiently large number of observations from the ship.

Column 5 gives SD or Normalised SD.

"Normalised SD" is a measure of the standard deviation of the differences of observations from the background values relative to all other marine surface observations in the region; a value of 1.0 means that the standard deviation is the same as the average for all other ships and buoys in the region, while a value of 2.0 means that it is twice as large, and so on. A value of 1.5 or less might be regarded as acceptable where there is a sufficiently large number of observations from the ship.

Mr Mike Harrison

Observations Data Monitoring Group

NWP Division

Met Office

Fitzroy Road

Exeter

Devon

United Kingdom

EX1 3PB

UK MET. OFFICE MONITORING STATISTICS

(FEBRUARY 2006)

PRESSURE (hPa)

WMO ID. TOTAL % GROSS ERROR BIAS NORMALISED SD

A8AL3 75 0 0.0 0.6

A8ES9 59 0 -0.3 0.6

IBVL 20 0 2.0 0.5

IBWK 20 0 -0.4 1.9

OVYB2 29 0 -0.5 1.1

OVZB2 52 0 -0.2 1.2

OWVI2 25 0 1.0 1.1

OYVQ2 41 0 -0.4 0.7

OZWN2 76 0 0.6 0.7

OZWP2 46 0 0.3 1.0

P3KT8 19 0 0.4 0.4

VRAE2 29 0 -0.4 0.8

VRAE3 11 0 -0.4 0.8

VRAE4 15 0 -0.2 1.1

VRWW8 29 0 -0.5 1.3

V2BE4 18 0 0.3 0.8

V2EU 50 0 -1.2 1.4

V7EL4 8 0 -0.6 1.0

YJYY2 32 3 0.5 1.7

ZCBX4 33 0 0.0 0.6

ZMFR 88 0 -0.1 1.4

ZMIO 14 0 0.1 0.6

ZMKA 22 0 0.1 0.4

ZMSO 17 0 0.6 2.4

ZM2619 15 0 0.4 3.0

3EAT6 14 0 -0.5 0.7

3FRR5 45 0 0.0 2.1

TEMPERATURE (deg C)

WMO ID. TOTAL % GROSS ERROR BIAS SD

A8AL3 75 0 0.3 1.1

A8ES9 59 0 0.2 1.0

IBVL 20 0 2.0 1.7

IBWK 20 0 0.9 1.1

OVYB2 29 0 0.1 1.1

OVZB2 52 0 0.7 1.3

OWVI2 25 0 0.6 1.3

OYVQ2 41 0 0.4 1.1

OZWN2 76 0 0.5 1.3

OZWP2 46 0 0.2 1.7

P3KT8 19 0 0.3 1.0

VRAE2 29 0 0.6 0.9

VRAE3 11 0 1.0 2.2

VRAE4 15 0 0.7 0.9

VRWW8 29 0 1.2 1.4

V2BE4 18 0 1.2 1.4

V2EU 50 0 0.5 1.3

V7EL4 9 0 -0.3 0.9

YJYY2 32 0 -0.1 1.2

ZCBX4 33 0 0.6 1.5

ZMFR 88 1 -0.1 1.1

ZMIO 14 0 0.3 1.3

ZMKA 22 0 0.0 1.2

ZMSO 17 0 -0.9 3.6

ZM2619 15 0 1.7 1.1

3EAT6 14 0 1.1 1.4

3FRR5 45 0 0.2 1.0

WIND SPEED (m s-1)

WMO ID. TOTAL % GROSS ERROR BIAS NORMALISED SD

A8AL3 75 0 0.5 1.1

A8ES9 59 0 -0.3 0.7

IBVL 19 0 0.7 1.2

IBWK 20 0 -0.3 1.2

OVYB2 29 0 -0.8 0.7

OVZB2 51 0 0.8 0.7

OWVI2 25 0 0.7 0.9

OYVQ2 40 0 1.3 1.2

OZWN2 66 0 0.6 0.8

OZWP2 44 0 0.8 1.5

P3KT8 19 0 1.1 0.6

VRAE2 27 0 -0.8 0.8

VRAE3 11 0 -0.7 0.5

VRAE4 15 0 0.0 0.7

VRWW8 28 0 0.1 0.8

V2BE4 18 0 -3.2 0.9

V2EU 48 0 -1.3 1.1

V7EL4 9 0 -0.5 0.8

YJYY2 27 0 -1.2 1.0

ZCBX4 33 0 -1.6 0.6

ZMFR 88 0 -0.7 1.0

ZMIO 11 0 1.5 1.3

ZMKA 21 0 0.0 0.8

ZMSO 11 0 -1.3 0.9

ZM2619 15 0 -1.0 0.6

3EAT6 14 0 -0.5 0.6

3FRR5 45 0 -0.4 0.9

WIND DIRECTION (deg)

WMO ID. TOTAL % GROSS ERROR BIAS SD

A8AL3 54 0 -0.8 24.4

A8ES9 38 0 -0.6 9.6

IBVL 9 0 -10.1 42.5

IBWK 12 0 -6.1 10.3

OVYB2 17 0 2.3 27.7

OVZB2 20 0 5.3 12.5

OWVI2 15 0 11.0 15.8

OYVQ2 25 0 -6.5 22.8

OZWN2 40 0 -6.5 27.8

OZWP2 19 0 21.5 26.4

P3KT8 12 0 12.0 17.2

VRAE2 18 0 -10.4 21.4

VRAE3 5 0 -1.5 10.7

VRAE4 6 0 -12.3 14.2

VRWW8 14 0 10.3 22.4

V2EU 20 0 -0.8 16.8

V7EL4 6 0 12.0 12.2

YJYY2 7 0 -5.0 50.0

ZCBX4 13 0 7.4 22.5

ZMFR 59 0 2.9 18.2

ZMKA 12 0 6.5 19.0

ZM2619 8 0 16.6 25.7

3FRR5 27 0 -12.1 20.1

RELATIVE HUMIDITY (%)

WMO ID. TOTAL % GROSS ERROR BIAS SD

A8AL3 75 0 -3.2 6.3

A8ES9 59 0 1.1 5.4

IBVL 20 0 -5.5 9.3

IBWK 20 0 11.1 7.1

OVYB2 29 0 1.5 6.8

OVZB2 52 0 -1.8 6.7

OWVI2 25 0 -0.6 8.7

OYVQ2 41 0 -0.4 7.1

OZWN2 76 0 2.7 6.5

OZWP2 46 0 -1.2 8.8

P3KT8 19 0 0.4 7.0

VRAE2 29 0 0.0 6.0

VRAE3 11 0 -4.0 8.7

VRAE4 15 0 -0.8 5.7

VRWW8 29 0 -3.0 6.2

V2BE4 18 0 -4.2 6.6

V2EU 50 0 -0.4 6.8

V7EL4 8 0 -0.9 8.6

YJYY2 32 0 0.1 6.4

ZCBX4 33 0 -2.3 6.9

ZMFR 80 0 0.4 8.1

ZMIO 13 0 7.2 8.9

ZMKA 22 0 0.1 4.9

ZMSO 17 0 4.9 7.6

ZM2619 15 0 -4.7 8.0

3EAT6 14 0 -7.1 4.5

3FRR5 45 0 -0.2 5.9

SEA SURFACE TEMPERATURE (deg C)

WMO ID. TOTAL % GROSS ERROR BIAS NORMALISED SD

A8AL3 85 0 -0.2 1.0

A8ES9 43 0 0.1 1.3

IBWK 12 0 -1.6 1.2

OVYB2 28 0 1.0 0.5

OVZB2 52 0 0.8 0.3

OWVI2 25 0 1.2 0.4

OYVQ2 41 0 1.1 0.4

OZWN2 76 0 1.0 0.5

OZWP2 46 4 1.0 0.5

P3KT8 19 0 2.5 0.8

VRAE2 29 0 0.7 0.7

VRAE3 11 0 1.5 0.8

VRAE4 15 0 2.0 0.2

VRWW8 29 0 1.2 0.4

V2EU 50 0 0.5 0.6

V7EL4 10 0 0.3 0.6

YJYY2 32 0 -0.3 0.9

ZCBX4 33 0 0.2 0.6

ZMFR 87 5 -1.8 3.0

ZM2619 8 0 1.1 0.7

3EAT6 11 0 0.6 0.4

3FRR5 45 0 -1.2 1.1