Close

Service Interruption

CLPX-Model: Local Analysis and Prediction System: 4-D Atmospheric Analyses

Summary

The Local Analysis and Prediction System (LAPS), run by the NOAA's Forecast Systems Laboratory (FSL), combines numerous observed meteorological data sets into a collection of atmospheric analyses. LAPS analyses data include hourly three-dimensional and surface distributions of temperature, surface u and v winds, vertical velocity, dew-point temperature, relative humidity, specific humidity, pressure, MSL pressure, cloud type, mean cloud drop diameter, cloud base, cloud top, fractional cloud cover, cloud liquid water, cloud ice, surface precipitation type, rain concentration, snow concentration, soil moisture, snow accumulation, snow water equivalent, and snowmelt over the Cold Land Processes Experiment (CLPX) study areas in Colorado and Wyoming, USA (approximately 36.1°N through 45.8°N latitude, and 113.8°W through 97.2°W longitude). The CLPX LAPS analyses archive spans the period 1 September 2001 through 31 August 2003. Data are separated into a 2-D surface field group and a 3-D upper air group. Data are available at an hourly resolution on a 10-km horizontal grid (125 x 105), with the 3-D upper air group comprising 21 vertical levels. All data files are delivered in netCDF format.

The NASA Cold Land Processes Experiment (CLPX) is a multi-sensor, multi-scale experiment that focuses on extending a local-scale understanding of water fluxes, storage, and transformations to regional and global scales. Within a framework of nested study areas in the central Rocky Mountains of the western United States, ranging from 1-ha to 160,000 km2, intensive ground, airborne, and spaceborne observations are collected. Data collection focuses on two seasons: mid-winter, when conditions are generally frozen and dry, and early spring, a transitional period when both frozen and thawed, dry and wet conditions are widespread.

Citing These Data

Liston, G.E. 2004. CLPX-Model: Local Analysis and Prediction System: 4-D Atmospheric Analyses. Boulder, CO: National Snow and Ice Data Center. Digital Media.

Overview Table

Category Description
Data format NetCDF (network Common Data Form)
Spatial coverage

CLPX Large Regional Study Area (LRSA) in Colorado and southern Wyoming, USA.
(Upper Left: 42°N, 108.5°W; Lower Right: 38.5°N, 104°W )

Temporal coverage and resolution 1 September 2001 through 31 August 2003. Data were collected hourly.
File size 148.3 GB for the entire three-year data set.
Procedures for obtaining data Data are available via FTP

Table of Contents

1. Contacts
2. Detailed Data Description
3. Data Access
4. Data Acquisition
5. References and Related Publications
6. Document Information

1. Contacts

Investigator(s) Name and Title

Glen E. Liston
Atmospheric Sciences
S205 ATMOS. SCIENCE ANNEX
Colorado State University
Fort Collins, CO 80523

Technical Contact

NSIDC User Services
National Snow and Ice Data Center
CIRES, 449 UCB
University of Colorado
Boulder, CO 80309-0449  USA
phone: +1 303.492.6199
fax: +1 303.492.2468
form: Contact NSIDC User Services
e-mail: nsidc@nsidc.org

2. Detailed Data Description

LAPS makes use of a wide range of observational data sets as part of its analyses, including: 1) surface observations at specific sites every 5 minutes, 2) hourly surface aviation observations, 3) Doppler radar volume scans every 6 minutes, 4) wind and temperature Radio Acoustic Sounding System (RASS) profiles from the NOAA Demonstration Profiler Network every 60 minutes, 5) GOES [Geostationary Operational Environmental Satellites] visible data every 30 minutes, 6) multi-spectral image and sounding radiance data every 90 minutes, and 7) automated aircraft observations.

Iinformation on the LAPS system can be found at the Local Analysis and Prediction Branch (NOAA/FSL) web site, and in a detailed LAPS Readme document. A general introduction to LAPS can also be found at http://laps.fsl.noaa.gov/birk/LAPS_FACTS.htm.

Format

LAPS data files are in netCDF format. NetCDF is a general format structure. For more information on the netCDF file format, please see the NetCDF Resources at NSIDC Web site. The detailed format of each data file is self-describing (via 'ncdump'), and is mirrored in a separate static file called the CDL.

LAPS data include the following variables:

Table 1. Hourly LAPS Output Variables

File Extension

LAPS Variable

CDF Variable

Number of Levels

Field (units)

surface: LSX

U

u

1

u Component of Surface Wind (m/s) (grid north)

V

v

1

v Component of Surface Wind (m/s) (grid north)

P

p

1

1500 m Pressure (Pa)

T

t

1

Surface Temp (K)

TD

td

1

Surface Dewpoint Temp (K)

VV

vv

1

Vertical Velocity (m/s)

RH

rh

1

Relative Humidity (%)

MSL

msl

1

MSL Pressure (Pa)

TAD

tad

1

Temperature Advection (K/s)

TH

th

1

Potential Temperature (K)

THE

the

1

Equivalent Potential Temperature (K)

PS

ps

1

Surface Pressure (Pa)

VOR

vor

1

Vorticity (/s)

MR

mr

1

Mixing Ratio (g/kg)

MRC

mrc

1

Moisture Convergence (g/kg/s)

DIV

div

1

Divergence (/s)

THA

tha

1

Potential Temperature Advection (kg/s)

MRA

mra

1

Moisture Advection (g/kg/s)

SPD

spd

1

Surface Wind Speed (m/s)

CSS

cssi

1

Colorado Severe Storm Index (none)

VIS

vis

1

Surface Visibility (m)

FWX

fwx

1

Fire Danger (none)

HI

hi

1

Heat Index (none)

TGD

tgd

1

Ground Temperature (K)

temp: LT1

HT

ht

21

Height (m)

T3

t3

21

Temperature (K)

accum: L1S

S01

s01

1

60 Minute Snow Accumulation (m)

STO

sto

1

Storm-Total Snow Accumulation (m)

R01

r01

1

60 Minute Liq Precip Accum (m)

RTO

rto

1

Storm-Total Liquid Precipitation Accumulation (m)

humid: LQ3

SH

sh

21

Specific Humidity (kg/kg)

humid: LH3

RH3

rh3

21

Relative Humidity (%)

RHL

rhl

21

Relative Humidity with resp to Liquid (%)

humid: LH4

TPW

tpw

1

Integrated Total Precipitable Water Vapor (m)

wind: LW3

U3

u3

21

u Component of Wind (m/s)

V3

v3

21

v Component of Wind (m/s)

OM

om

21

Wind Omega (Pa/s)

wind: LWM

SU

u

1

u Component of Surface wind (m/s)

SV

v

1

v Component of Surface wind (m/s)

cloud: LC3

LC3

lc3

42

Fractional Cloud Cover (levels 1-42) (0-1)

cloud: LCB

LCB

lcb

1

Cloud Base (m)

LCT

lct

1

Cloud Top (m)

CCE

cce

1

Cloud Ceiling (m)

cloud: LCV

LCV

cco

1

Cloud Cover (0-1)

CSC

csc

1

Cloud Analysis Implied Snow Cover (0-1)

CWT

cwt

1

Clear Sky Water Temperature (K)

S8A

s8a

1

IR Channel 4 (11.2µ) b-temp:averaged (K)

S3A

s3a

1

IR Channel 2 (3.9µ) b-temp:averaged (K)

ALB

alb

1

LAPS Derived Albedo (0-1)

soil: LM1

LSM

lsm

3

Soil Moisture (m/m)

soil: LM2

CIV

civ

1

Cumulative Infiltration Volume (m)

DWF

dwf

1

Depth To Wetting Front (m)

WX

wx

1

Wet/Dry Grid Point (none)

EVP

evp

1

Evaporation Data (m/s)

SC

sc

1

Snow Covered (0-1)

SM

sm

1

Snow Melt (m3/m3)

MWF

mwf

1

Wetting Front Soil Moisture Content (m3/m3)

 

File and Directory Structure

Processed LAPS files are available in compressed (tarred and zipped) files, such as laps-3d.20030610.tar.gz and laps-2d.20011214.tar.gz.

File Size

The size of the entire data set is 148.3 GB. Daily 2-D files are approximately 38 MB each, and daily 3-D files are approximately 170 MB each.

Spatial Coverage and Resolution

LAPS data covers the CLPX Large Regional Study Area, shown in the following map. LAPS covers a 10-km horizontal grid.

Temporal Coverage and Resolution

LAPS data were produced hourly from 1 September 2001 through 31 August 2003.

Parameter or Variable

LAPS parameters are meteorological parameters, as shown in Table 1.

3. Data Access

Data Access

Data are available by FTP.

Software and Tools

Information about installing and using the LAPS program can be found at the Local Analysis and Prediction Branch (NOAA/FSL) web site.

The NetCDF package required for LAPS is available at 'http://www.unidata.ucar.edu/packages/netcdf/. Version netcdf 3.3.1 or higher is required. For a list of tools for reading/viewing netCDF files, please see the NetCDF Resources at NSIDC: Software and Tools Web page.

Related Data Collections

All CLPX Data Sets

5. References and Related Publications

Albers, S. C., 1995: The LAPS wind analysis. Wea. Forecasting, 10,342-52.

Albers S. C., J. A. McGinley, D. L. Birkenheuer, and J. R. Smart, 1996: The Local Analysis and Prediction System (LAPS): Analyses of clouds, precipitation, and temperature. Wea. Forecasting, 11, 273-287.

Birkenheuer, D., 1999: The effect of using digital satellite imagery in the LAPS moisture analysis. Wea. Forecasting, 14, 782-788.

McGinley, J. A., S. C. Albers, and P. A. Stamus, 1991: Validation of a composite convective index as defined by a real-time local analysis system. Wea. Forecasting, 6, 337-356.

LAPS Publications by Year:

2004 - http://laps.fsl.noaa.gov/cgi/LAPB.pubs_04.cgi

2003 - http://laps.fsl.noaa.gov/cgi/LAPB.pubs_03.cgi

2002 - http://laps.fsl.noaa.gov/cgi/LAPB.pubs_02.cgi

2001 - http://laps.fsl.noaa.gov/cgi/LAPB.pubs_01.cgi

2000 - http://laps.fsl.noaa.gov/cgi/LAPB.pubs_00.cgi

1999 - http://laps.fsl.noaa.gov/cgi/LAPB.pubs_99.cgi

1998 - http://laps.fsl.noaa.gov/cgi/LAPB.pubs_98.cgi

1997 - http://laps.fsl.noaa.gov/cgi/LAPB.pubs_97.cgi

1996 - http://laps.fsl.noaa.gov/cgi/LAPB.pubs_96.cgi

1995 - http://laps.fsl.noaa.gov/cgi/LAPB.pubs_95.cgi

1994 - http://laps.fsl.noaa.gov/cgi/LAPB.pubs_94.cgi

1993 - http://laps.fsl.noaa.gov/cgi/LAPB.pubs_93.cgi

1992 - http://laps.fsl.noaa.gov/cgi/LAPB.pubs_92.cgi

Selected LAPB Publications by Topic:

http://laps.fsl.noaa.gov/cgi/LAPB.pubs_topical.cgi

6. Document Information

List of Acronyms

CLPX = NASA Cold Land Processes Experiment
FSL - Forecast Systems Laboratory
GOES – Geostationary Operational Environmental Satellites
ISA = Intensive Study Area
LRSA = Large Regional Study Area
NCAR = National Center for Atmospheric Research
NCEP - National Center for Environmental Prediction
NESDIS - National Environmental Satellite, Data and Information Service
NOAA - National Oceanic and Atmosphere Administration
NWS = National Weather Service

Document Creation Date

1 December 2004

Find Data

Stay Current

Learn About Snow and Ice