Overview

This document focuses on temperature data from NARR. NARR is a regional reanalysis covering the North America using a Northern Lambert Conformal Conic grid with an approximately 0.3 degrees (32 km) spatial resolution at the lowest latitude. Dataset was originally produced at NOAA's National Center for Atmospheric Prediction (NCEP), and detailed description is provided at https://psl.noaa.gov/data/gridded/data.narr.html#detail with online Analysis and Plotting Tools at https://psl.noaa.gov/cgi-bin/data/getpage.pl.

Provider's contact information

Physical Sciences Laboratory: Data Management

NOAA/ESRL/PSL

325 Broadway

Boulder, CO 80305-3328

psl.data@noaa.gov.

Licensing and citation

This work is licensed under a Creative Commons Attribution 4.0 International Licence.

There are no restrictions for the use of data.

If the data are taken from PSD, the providers ask that the data is acknowledged by including text such as NCEP Reanalysis data provided by the NOAA/OAR/ESRL PSD, Boulder, Colorado, USA, from their Web site at http://www.esrl.noaa.gov/psd/ in any documents or publications using these data.

If the data are taken from NCAR, the citation should include the following: National Centers for Environmental Prediction/National Weather Service/NOAA/U.S. Department of Commerce. 2005, updated monthly. NCEP North American Regional Reanalysis (NARR). Research Data Archive at the National Center for Atmospheric Research, Computational and Information Systems Laboratory. https://rda.ucar.edu/datasets/ds608.0/. Accessed dd mmm yyyy.

Variable name and units:

The variables are divided into three sections: Pressure level, Monolevel (surface and others) and Subsurface. 2 m temperature [K] and 2 m Dew Point Temperature data are available in the list of Monolevel variables and they are the output of the analysis and first guess forecast:

Table with snow variables available in NetCDF format at NOAA:

Values labelled 3 hourly values are output at that exact time (no averaging).

For a complete list of model output variables, see NCEP's variable list. Details for Monolevel variables are provided on https://psl.noaa.gov/data/gridded/data.narr.monolevel.html .

NARR is also offering a variable named Surface temperature. This variable is the "skin" temperature. Over water, it is the SST. Over land, it would be the "radiative" temperature of the surface. The skin temperature is generated from the land surface model. Note, the skin temperature is not the top layer soil temperature. During the day, the surface temperature is typically higher than the soil and 2 m air temperature.

Spatial coverage and resolution:

The data is available for all of North America at an approximate 0.3 degrees (32 km) spatial resolution at the lowest latitude, on a Northern Lambert Conformal Conic grid. Corners of this grid are 1.000001 N, 145.5 W; 0.897945 N, 68.32005 W; 46.3544 N, 2.569891 W; 46.63433 N, 148.6418 E. A page describing the coverage along with information on reading the projection is available.

Temporal coverage and resolution:

Data is available as 3h values, Daily and Monthly means, for the period 1979/01/01 to 2021/05/31.

Information about observations

The data that are assimilated in order to initialize the model are temperatures, winds, and moisture from radiosondes as well as pressure data from surface observations. Also included in this dataset are dropsondes, pibals, aircraft temperatures and winds, satellite radiance (a measure of heat) from polar (orbiting Earth) satellites, and cloud-drift winds from geostationary (fixed at one location viewing Earth) satellites. The sources of observations are summarized in the table below.

Previous tests on assimilation of 2 m land surface station air temperatures, in NARR proved to be harmful in the sense of making the first guess considerably worse, throughout the troposphere. Consequently, 2 m land surface station air temperatures are not assimilated by NARR.

The following figure presents the distributions of surface assimilated data for 1 January 1988.

Figure 1. Distribution of surface observations

Methodology

The NARR project is an extension of the NCEP Global Reanalysis which is run over the North American Region. The NARR model uses a high-resolution NCEP Eta Model (32 km/45 layer) together with the Regional Data Assimilation System (RDAS) using 3DVAR method, and it is one of the few reanalysis that assimilates precipitation along with other variables, also over Canada this feature is much reduced comparable to US. It is using the ETA / NOAH land surface model and it is assimilating snow depths from US Air Force daily snow depth analysis.

For more information, please refer to the publication in the references section below.

Information about the technical and scientific quality

The improvements in the model/assimilation have resulted in a dataset with substantial improvements in the accuracy of temperature, winds and precipitation compared to the NCEP-DOE Global Reanalysis 2 (the parent global reanalysis). Wind improvement is especially greatest in the upper troposphere in winter. The 10 m winds improved greatly in winter, a little bit in summer. Relative humidity also improved in both analysis and first guess forecast.

Precipitation over Canada: the number of gauge observations is insufficient to do better than the model is doing.

Tests on assimilation of 2 m land surface station air temperatures, in NARR proved to be harmful in the sense of making the first guess considerably worse, throughout the troposphere. Consequently, 2 m land surface station air temperatures are not assimilated by NARR.

Useful information can be found at NCEP's NARR FAQ page: http://www.emc.ncep.noaa.gov/mmb/rreanl/faq.html .

Data is updated on a monthly base.

Limitations and strengths for application in North Canada

A very small amount of surface data is assimilated over North Canada.

References to documents describing the methodology or/and the dataset

Mesinger, F., G. DiMego, E. Kalnay, K. Mitchell, and Coauthors, 2006: North American Regional Reanalysis. Bulletin of the American Meteorological Society, 87, 343–360, doi:10.1175/BAMS-87-3-343.

Link to download the data and format of data:

NARR is available through NOAA ftp page, UCAR and from NCDC page.

NOAA: ftp://ftp.cdc.noaa.gov/Datasets/NARR/ (NetCDF standard format; the data are divided by variable and year and month into separate files; Missing data is flagged with a value of 9.96921e+36f.)

NCDC: https://www.ncdc.noaa.gov/data-access/model-data/model-datasets/north-american-regional-reanalysis-narr (GRIB format)

UCAR: https://rda.ucar.edu/datasets/ds608.0/ (GRIB format)

Publications including dataset evaluation or comparison with other data in northern Canada.