A Cold Bias in the MRF

The current operational MRF has been observed to have a cold bias in the Northern Hemisphere mid-latitudes the last few months. Before the introduction of prognostic cloud liquid water in August 2001, the MRF had a warm bias over the Northern Hemisphere mid-latitude continents in summer. This page documents the cold bias of the MRF and examines its development for two periods, one with a ridge over the east coast of the United States (Nov. 26-Dec.16, 2001) and one with a more characteristic trough over the east coast (Dec. 24, 2001-Jan. 8, 2002).

December Drifts

This section examines the evolution of error in forecasts originating in December 2001. Forecasts every 24 hours from the 000 UT analyses for December to the 360-hr forecasts originating in December are examined. The verifying analyses for each forecast length are subtracted to determine the error drift.

Temperature

Area-averaged drifts

Global mean

30-60N

30-60N land

Longitude-forecast length cross-sections

40N

850 hPa

900 hPa

925 hPa

Latitude-forecast length cross-sections

0-90N

115E

110W

80W

Pressure-forecast length cross-sections

40N

115E

110W

80W

850 hPa surface contour

Height

Area-averaged drifts

Global mean

30-60N

30-60N land

Longitude-forecast length cross-sections

40N, 500 hPa

Latitude-forecast length cross-sections

0-90N

120E

135W

75W

Pressure-forecast length cross-sections

40N

120E

135W

75W

Longitude-time diagrams

40N, 0-360

500 hPa Heights

Analyses (zonal mean out)	Forecasts (zonal mean out)	Errors (zonal mean in)
		6-hr forecasts
For 1-dy forecasts		1-dy forecasts
For 2-dy forecasts		2-dy forecasts
For 3-dy forecasts	3-dy forecasts	3-dy forecasts
For 4-dy forecasts		4-dy forecasts
For 5-dy forecasts	5-dy forecasts	5-dy forecasts
For 7-dy forecasts	7-dy forecasts	7-dy forecasts
For 8-dy forecasts		8-dy forecasts
For 10-dy forecasts	10-dy forecasts	10-dy forecasts
For 15-dy forecasts	15-dy forecasts	15-dy forecasts

925 hPa Temperatures

Analyses (zonal mean out)	Forecasts (zonal mean out)	Errors (zonal mean in)
		6-hr forecasts
For 1-dy forecasts		1-dy forecasts
For 2-dy forecasts		2-dy forecasts
For 3-dy forecasts	3-dy forecasts	3-dy forecasts
For 4-dy forecasts		4-dy forecasts
For 5-dy forecasts	5-dy forecasts	5-dy forecasts
For 7-dy forecasts	7-dy forecasts	7-dy forecasts
For 8-dy forecasts		8-dy forecasts
For 10-dy forecasts	10-dy forecasts	10-dy forecasts
For 15-dy forecasts	15-dy forecasts	15-dy forecasts

40N, 180-360

500 hPa Heights

Analyses (zonal mean out)	Forecasts (zonal mean out)	Errors (zonal mean in)
		1-dy forecasts
		3-dy forecasts
For 5-dy forecasts	5-dy forecasts	5-dy forecasts
For 10-dy forecasts	10-dy forecasts	10-dy forecasts
For 15-dy forecasts	15-dy forecasts	15-dy forecasts

925 hPa Temperatures

Analyses (zonal mean out)	Forecasts (zonal mean out)	Errors (zonal mean in)
For 5-dy forecasts	5-dy forecasts	5-dy forecasts

Nov. 26-Dec. 16, 2001

500hPa Height

Climatology for December

Time-means (zonal mean out)	Forecast error (zonal mean in)	Fcst. diff. (zonal mean in)
Analyses	6 hour-anl
1 day forecasts	1 day-anl
2 day forecasts	2 day-anl	2 day-1 day
3 day forecasts	3 day-anl	3 day-2 day
4 day forecasts	4 day-anl	4 day-3 day
5 day forecasts	5 day-anl	5 day-4 day
7 day forecasts	7 day-anl	7 day-5 day
8 day forecasts	8 day-anl	8 day-7 day
10 day forecasts	10 day-anl	10 day-8 day
15 day forecasts	15 day-anl	15 day-10 day

925hPa Temperature

Climatology for December

Time-means (zonal mean out)	Forecast error (zonal mean in)	Fcst. diff. (zonal mean in)
Analyses	6 hour-anl
	1 day-anl
	2 day-anl	2 day-1 day
	3 day-anl	3 day-2 day
	4 day-anl	4 day-3 day
5 day forecasts	5 day-anl	5 day-4 day
	7 day-anl	7 day-5 day
	8 day-anl	8 day-7 day
10 day forecasts	10 day-anl	10 day-8 day
15 day forecasts	15 day-anl	15 day-10 day

Surface Fluxes

Precipitation

0-6 hour	Day 3–day 1
0-24 hour	Day 5–day 1
48-72 hour	Day 5–day 3
96-120 hour	Day 10–day 1
216-240 hour	Day 15–day 1
336-360 hour	Day 15–day 10

Sensible heat

0-6 hour
0-24 hour	Day 3–day 1
48-72 hour	Day 5–day 1
96-120 hour	Day 10–day 1
216-240 hour	Day 15–day 1
336-360 hour	Day 15–day 10

Latent heat

0-6 hour
0-24 hour	Day 3–day 1
48-72 hour	Day 5–day 1
96-120 hour	Day 10–day 1
216-240 hour	Day 15–day 1
336-360 hour	Day 15–day 10

Net short wave

0-6 hour
0-24 hour	Day 3–day 1
48-72 hour	Day 5–day 1
96-120 hour	Day 10–day 1
216-240 hour	Day 15–day 1
336-360 hour	Day 15–day 10

Net long wave

0-6 hour
0-24 hour	Day 3–day 1
48-72 hour	Day 5–day 1
96-120 hour	Day 10–day 1
216-240 hour	Day 15–day 1
336-360 hour	Day 15–day 10

Net heat flux

0-6 hour
0-24 hour	Day 3–day 1
48-72 hour	Day 5–day 1
96-120 hour	Day 10–day 1
216-240 hour	Day 15–day 1
336-360 hour	Day 15–day 10

Dec.24, 2001-Jan. 8, 2002

500hPa Height

Climatology for December

Time-means (zonal mean out)	Forecast error (zonal mean in)	Fcst. diff. (zonal mean in)
Analyses	6 hour-anl
	1 day-anl
	2 day-anl	2 day-1 day
3 day forecasts	3 day-anl	3 day-2 day
	4 day-anl	4 day-3 day
5 day forecasts	5 day-anl	5 day-4 day
7 day forecasts	7 day-anl	7 day-5 day
	8 day-anl
10 day forecasts	10 day-anl	10 day-7 day
15 day forecasts	15 day-anl	15 day-10 day

925hPa Temperature

Climatology for December

Time-means (zonal mean out)	Forecast error (zonal mean in)	Fcst. diff. (zonal mean in)
Analyses	6 hour-anl
	1 day-anl
	2 day-anl	2 day-1 day
3 day forecasts	3 day-anl	3 day-2 day
	4 day-anl	4 day-3 day
5 day forecasts	5 day-anl	5 day-4 day
7 day forecasts	7 day-anl	7 day-5 day
	8 day-anl
10 day forecasts	10 day-anl	10 day-7 day
15 day forecasts	15 day-anl	15 day-10 day