NOAA Office of Satellite and Product Operations

NUCAPS Sounding Products

NOTICE:
All the trace gases products derived from the Infrared Atmospheric Sounding Interferometer (IASI) and the NOAA Unique Combined Atmospheric Processing System (NUCAPS) are not validated yet by the science community and users should use them with precaution and at their own risks. These products will be updated soon after a through science validation.

The NOAA Unique Combined Atmospheric Processing System(NUCAPS) was developed to generate (1) spectrally and spatially thinned radiances, (2) retrieved products such as profiles of temperature, moisture, trace gases and cloud-cleared radiances, and (3) global validation products such as radiosonde matchups and gridded radiances and profiles. The thinned radiance products are produced in BUFR format using the NetCDF4 Reformatting Toolkit (N4RT) and are tailored to specifically Numerical Weather Prediction (NWP) centers. The NUCAPS Environmental Data Records (EDR) products are archived in Comprehensive Large Array-Data Stewardship System (CLASS) for non-real time users and can be acquired from www.nsof.class.noaa.gov.

These products are derived from the Cross-track Infrared Sounder (CrIS) and Advanced Technology Microwave Sounder (ATMS) currently onboard the Suomi National Polar-orbiting Partnership (SNPP) satellite and later will be available from the Joint Polar Satellite System (JPSS-1 and JPSS-2).

In order to obtain the near real time NUCAPS data a user needs to fill out the Data Access Request Form located at www.ospo.noaa.gov/Organization/About/access.html and submit it to the Sounding Product Area Lead (awdhesh.sharma@noaa.gov) with a copy to nesdis.data.access@noaa.gov. The thinned radiance products will not be archived at the CLASS and are available only for real time users.

NUCAPS/SNPP Global Granules Composite Images

The NUCAPS global granules composite images are produced for the last seven days at the 15 fixed air pressure levels or layers. They are produced by using the NUCAPS retrievals which are derived based on a fixed air pressure variable grid: temperature is derived at the fixed pressure levels (1014 mb, 853 mb, 707 mb, 497 mb, 407 mb, 300 mb, 260 mb, 201 mb, 151 mb, 103 mb, 71.5 mb, 51.1 mb, 29.1 mb, 9.5 mb, 1.0 mb), and mixing ratio variables are derived at the layer pressure using the effective air pressure variable (1000 mb, 840 mb, 695 mb, 487 mb, 399 mb, 293 mb, 254 mb, 196 mb, 147 mb, 99.5 mb, 68.8 mb, 49.3 mb, 27.6 mb, 8.82 mb, .838 mb). Each product is computed separately for each granule, and then the global image is generated by combining the data from individual granules based on the granule geographical location. For each image the granules from the preceding 12 hours of observation are used; each image combines the granules of data measured at both ascending and descending nodes.

NUCAPS/SNPP Global Gridded Products

SNPP Global Gridded 0.5 deg lat x 2 deg lon Images
NUCAPS EDR Global Gridded products include the Temperature (deg K), Water Vapor Mixing Ratio (g/Kg), Liquid Water Mixing Ratio (g/Kg), Ozone Mixing Ratio (ppb), Methane Mixing Ratio (ppb), Carbon Dioxide dry mixing ratio (ppm), Carbon Monoxide Mixing Ratio (ppb), Sulfur Dioxide mixing ratio (ppb), Nitric Acid Mixing Ratio (ppb), and Nitrous Oxide Mixing Ratio (ppb). The retrievals are derived based on a fixed air pressure variable grid: temperature is derived at the fixed pressure level (1014 mb, 853 mb, 707 mb, 497 mb, 407 mb, 300 mb, 260 mb, 201 mb, 151 mb, 103 mb, 71.5 mb, 51.1 mb, 29.1 mb, 9.5 mb, 1.0 mb) and mixing ratio variables are derived at the layer pressure using the effective air pressure variable (1000 mb, 840 mb, 695 mb, 487 mb, 399 mb, 293 mb, 254 mb, 196 mb, 147 mb, 99.5 mb, 68.8 mb, 49.3 mb, 27.6 mb, 8.82 mb, .838 mb).

NUCAPS/SNPP Retrieval Statistics

The NUCAPS retrieval statistics are generated for Temperature (Tp) over two layers: average over mid-troposphere (520-790 mb) and average over full troposphere (200-1100 mb); and Water Vapor Mixing Ratio (WVMR) statistics are generated over full troposphere. The NUCAPS retrieval estimates are compared with GFS estimates to compute bias and rms error over these layers and are plotted for each granule on the 24-hour scale for the day.

To generate the temperature bias and rms error over a large ensemble of K granules one needs to take the bias for a single granule, bias(k), weighted by the number of accepted cases, Nacc(k) such as:

bias = sum {Nacc(k)*bias(k)} / sum{Nacc(k)}, where sum is for k = 1, K
rms = sqrt [ {(sumNacc(k)*rms(k)^2) } / sum {Nacc(k)} ], where sum is for k = 1, K

To generate the WVMR bias and rms error over a large ensemble of K granules the following formulas are used:

bias = sum{qmean(k)*bias(k)} / sum{qmean(k)}, where sum is for k=1, K
rms = sqrt [ {sum (qmean(k)*rms(k)^2)} / sum{qmean(k)} ], where sum is for k = 1, K

NUCAPS Soundings Products Links

NUCAPS / SNPP Global Gridded 0.5 deg lat x 2 deg lon Images

NUCAPS / SNPP Granule Composite Images

NUCAPS / SNPP Retrieval Statistics

NUCAPS / SNPP Outgoing Longwave Radiation