molts: Model Output Location Time Series

General Data Description

The Model Output Location Time Series (MOLTS) data are provided by the National Centers for Environmental Prediction (NCEP). Currently there are over 500 MOLTS stations across the United States (including Alaska and Hawaii) and southern Canada. The locations of the MOLTS stations are based on requests from the scientific community.

The measurements provided here are products of NCEP's mesoscale numerical weather prediction (NWP) model known as the Early Eta Model and its associated 4-D data assimilation system, known as the EDAS (for Eta Data Assimilation System). The name "Eta" derives from the model's vertical coordinate known as the "eta" or "step-mountain" coordinate. Whereas the Eta forecast model generates forecast fields out to 36 hours from initial states at 00Z and 12Z, the EDAS generates eight 3-hourly initial states or analyses during each 24-hour period, utilizing a vast set of observed data.

These data are the hourly output at the selected locations that contain values for various surface parameters and "sounding" output at model levels.

There are two possible classes assigned to each station, Class 0 (basic) and Class 1 (enhanced). The classes differ in the number of surface parameters and sounding parameters reported. After November 1999 only Class 1 data are provided but with many more stations than previously.

Measurement Description

MOLTS Measurements

Temporal Coverage

Data Stream NameStart Date End Date
nsamoltsedassfcclass0X1.a1 and nsamoltsedassndclass0X1.a1 06/01/1997 09/27/1999
sgpmoltsedassfcclass0X1.a1 and sgpmoltsedassndclass0X1.a1 06/01/1997 09/27/1999
nsamoltsedassfcclass1X1.a1 and nsamoltsedassndclass1X1.a1** 06/01/1997 present
pyemoltsedassfcclass1X1.a1 and pyemoltsedassndclass1X1.a1 03/01/2005 present
sgpmoltsedassfcclass1X1.a1 and sgpmoltsedassndclass1X1.a1 ** 06/01/1997 present
** There is a gap from 9/28/1999 - 2/29/2000.

Data are available at the ARM Archive approximately 4 days after they are generated.

Area Covered

SGP Lat = 31.941 : 41.00; Lon = -103.541 : -91.585
NSA Lat > 60.0; Lon = -140 : -175
PYE Lat =34.3 : 42.539; Lon = -127.607 : -120.862

Data Stream Inputs

*nacmoltsedasclass0X1.00 (ends September 27, 1999)
*nac=North American Continent

Notification Form Link

molts data streams


Alice Cialella
Brookhaven National Laboratory

Shaocheng Xie
Lawrence Livermore National Laboratory

Processing History

Beginning on January 1, 2005 the measurement named time_offsets was changed to time_offset in

Data User Notes

See the following Data Quality Reports at the DQR Browse Web Page

D020131.7 SGP/NSA/MOLTS/X1- value incorrect

D001031.1 SGP/NSA/MOLTS- gap in data

D000627.3 NSA/MOLTS- Misnamed units

D000627.2 SGP /MOLTS - Misnamed units

D000531.7 SGP/NSA/MOLTS - Misnamed measurement - short name

D041112.2, D041112.5, D041112.7, D041112.8 and P040012.1 - all document the error in the measurement name time_offsets (changed to time_offset)


MOLTSModel Output Location Time Series
NACNorth American Continent
NCEPNational Centers for Environmental Prediction
NSANorth Slope of Alaska
NWPNumerical Weather Prediction
PYEPoint Reyes
SGPSouthern Great Plains

Citable References

Rogers, E., D. G. Deaven and G. J. DiMego, 1995. The Regional Analysis System for the Operational "Early" Eta Model: Original 80-km Configuration and Recent Changes, Weather and Forecasting, 10:810-825

Yarosh, Ropelewski, Mitchell, 1996. Comparisons of humidity observations and Eta model analyses and forecasts for water balance studies. Journal of Geophysical Research, 101(18):23,289-23,298.