1. Bob Kuligowski, Clay Davenport, Rod Scofield, Gilberto Vicente
Hydro-Estimator (HE)
Bob Kuligowski, Clay Davenport, Rod Scofield, Gilberto Vicente
NOAA/NESDIS/ORA

2. Theory / Schematic Algorithm Inputs (IR, MW, NWP):
10.7-µm IR window Tb’s from GOES-9, -10, -12, Meteosat-5 and -7
NAM or GFS PW, hPa mean RH, u, v, convective EL computed from T, q profile
Satellite inputs are from GVAR feeds; model inputs come from NCEP
Algorithm Process (how the inputs are converted to rainfall estimates)
Adjust Tb (Tadj) by reducing values where convective EL temperature>213 K
Z=-(Tadj-µT)/σT: rain only where Z>0
Rain rate=f(Tadj, Z, PW)
Reduce rain rate in low-RH environments

3. Theory / Schematic Strengths and Weaknesses of Underlying Assumptions
Standard IR assumption that Tb is a proxy for cloud depth / updraft strength and hence for rain rate; works best for convective precipitation
Assumes rainfall only in areas of positive Z (local Tb minima); effective screening of cirrus by using Z
Adjusts for environments with low convective EL by adjusting Tb downward based on convective EL temperature, but still underestimates warm-cloud rainfall
Underestimates rainfall early in convective life cycle where updrafts are strong and clouds are rapidly cooling, but still relatively warm
Planned Modifications / Improvements
Currently undergoing recalibration using 6 weeks of CONUS data from summer 2003 with bias-adjusted radar as target data; should be completed by end of summer
Inclusion of Lagrangian ΔTb to improve performance in early stages of convection; work planned for this fall

4. Algorithm Output Information
Spatial Resolution: 4 km Western Hemisphere, 6 km elsewhere
Spatial Coverage: global (60°S – 60°N)
Update Frequency: same as IR update frequency
15 min over CONUS
Generally 30 min elsewhere, but up to 3 h in parts of Southern Hemisphere
Data Latency: ~10 min after data received at ORA
Source of Real-Time Data:
(graphic)
(digital) ftp://

5. Algorithm Output Information
Source of Archive Data:
limited online archive at real-time ftp site
offline global archive back to 25 May 2005
offline CONUS archive back to April 2003
Capability of Producing Retrospective Data (data and resources required / available)
CONUS: tape archive of component files back to 1997
Northern Hemisphere: can get GOES IR data from CLASS (back to December 2003) and use archive Eta adjustment files
Elsewhere: need 10.7-µm data and AVN/GFS fields (PW, RH, T, u, v)