The Hydro-Estimator
The Hydro-Estimator is a fully automated method that uses an empirical exponential relationship between precipitation (estimated by radar) and cloud-top brightness temperature (obtained from the infrared channel of the GOES satellite), generating real-time precipitation rates. Cloud temperature trends (and texture information) are used to adjust the area covered by precipitation. Variables such as precipitable water, relative humidity, orography, parallax, and an adjustment of the convective equilibrium level for warm cloud-top events (Scofield 2001) are used to automatically adjust precipitation rates.
The Hydro-Estimator was developed to address problems previously associated with the Auto-Estimator, which used a temperature trend curve rather than texture information (assuming zero precipitation for pixels in regions of low spatial variability beneath cirrus clouds). Therefore, the Hydro-Estimator uses different criteria to distinguish between rainy and non-rainy areas, along with new adjustments to account for the effects of available moisture.
The implemented estimation model is an adaptation of the one used by NEDIS (Vicente et al. 1998 and 2001). This model underwent several modifications and was fully adapted to the precipitation conditions and structure over South America (Vila, 2001) for operational implementation at the Division of Environmental Satellites and Systems (DISSM).
The products displayed on this website show the precipitation estimated from the most recent GOES image received by DISSM and the accumulated precipitation during the period between 12:00 p.m. on the previous day and 12:00 p.m. on the current day. The absence of products at a particular time or on a particular day is due to missing GOES images or wind data generated by the CPTEC model.
More information about the Hydro-Estimator and Auto-Estimator can be found in:
Scofield, R. A., 1987: The NESDIS operational convective precipitation technique. Mon.Wea. Rev., 115, 1773-1792.
Scofield, R. A., 2001: Comments on "A quantitative assessment of the NESDIS Auto-Estimator." Wea. Forecasting., 16, 277-278.
The Adjusted Hydro-Estimator
A new technique for real-time precipitation estimation based on the Hydro-Estimator algorithm is being applied. The new rainfall estimates are calibrated using a new histogram adjustment methodology based on historical estimates obtained from the DPR (Dual Precipitation Radar) sensor aboard the GPM satellite.
More information can be found in:
Siqueira, R. A. D. and Vila, D., 2019: Hybrid methodology for precipitation estimation using Hydro-Estimator over Brazil. International Journal of Remote Sensing, 40(11), 4244-4263.
Redes Sociais