ATOVS Aerosol, Cloud and Radiation Products

The ATOVS system has been enhanced with new product algorithms for generating Cloud and Radiation type parameter suites. Like the sounding products, the Cloud and Radiation products are global, for both METOP-A and NOAA-19 and generated routinely in near-real time.

The two 4 quadrant images below shows a series of hurricanes and tropical storms (which formed off the west coast of Africa) moving west to northwest across the Atlantic Ocean. There are several other Cloud and Radiation products in two suites including TROPOPAUSE TEMPERATURE; TROPOPAUSE PRESSURE; OUTGOING LONGWAVE RADIATION (all_sky and clear_sky); 4 LAYER COOLING RATES (clear_sky). The Clear-Sky Radiation products utilize the Cloud products to determine Clear-Sky conditions.
To see all products from the previous day, click on either image.

Hurricane Earl, Eff. Cloud Amount, Cloud Top Pressure, HIRS Channel 8 and Cloud Product Error Quad.

EFFECTIVE CLOUD AMOUNT represents the physical cloud density and is the ratio of radiance difference fields.

CLOUD TOP PRESSURE is the pressure at the cloud top.

HIRS/4 channel #8 is the longwave CO2 infrared window channel (for reference).

CLOUD PRODUCT ERROR is the quantative product accuracy assessment. This parameter may be utilized for operational product monitoring or by the user community to down-select the data which meets their accuracy requirements.

 

The Cloud Product Error is calculated in a three step process:

  1. Cloud properties (such as  ECA, CTP and CTT)) are retrieved;
  2. The retrieved cloud properties (ECA and CTP) are used with other parameters to cloud clear the measured channel data; and
  3. The cloud cleared channel data is used (instead of the measured channel data) to re-retrieve the ECA which at this point is called the Cloud Product Error.



 
Hurricane Earl, Aerosol, Cloud QC Indicator, Cloud Top Temperature and Cloud Difference Flag Quad image.

AEROSOL is shown separately in this image but is generated as part of the global Effective Cloud Amount. Although Aerosol is present everywhere it cannot be distinguished separately in the presence of Water Vapor or Ice clouds.

  • GRAY represents areas that are either clear or have Water Vapor or Ice clouds.

Q/C Indicator is used to flag the processing path as follows:

  • GRAY, BRIGHT GREEN and LIGHT BLUE indicate clear areas
  • DARK BLUE indicates areas retrieved as Water Vapor or Ice clouds, with the original ECA function
  • DARK GREEN indicates areas retrieved as Aerosols, with the original ECA function
  • WHITE indicates areas where the ECA is small and the original function does not work reliably so an alternative ECA function was used for these thin Aerosols or Water Vapor / Ice clouds.

CLOUD TOP TEMPERATURE is shown with GRAY representing clear areas.

CLOUD DIFFERENCE FLAG is use for comparison of the Cloud products and the Sounding processing

  • CYAN indicates areas where the Sounding is retrieved as cloudy and the Cloud products are clear
  • DARK GREEN indicates areas where the Sounding is retrieved as cloudy as are the Cloud products
  • GRAY indicates areas where the Sounding is retrieved as clear as are the Cloud products
  • RED indicates areas where the Sounding is retrieved as clear and the Cloud products retrieved thin Aerosols (usually in tropical or sub-tropical areas) or Water Vapor / Ice clouds (usually in polar or sub-polar areas)