Bob Joyce : RSIS, Inc.

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0000Z, 30Nov 2001
Bob Joyce RSIS, Inc. John Janowiak
Climate Prediction Center/NWS Phil Arkin
ESSIC/Univ. Maryland Pingping Xie
Climate Prediction Center/NWS
AMSU
TRMM
SSM/I
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Two primary types of precipitation algorithms

• Infrared (GPI, convective-stratiform, OPI)
• (-) indirect - can only sense cloud-top
  temperature
• () very good sampling characteristics
  (time space)

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Our Approach

• Use the IR and microwave data but do NOT mix them
• Use the IR only as a transport and morphing
• mechanism
• Here we use precipitation algorithms developed by
  
• Ferraro (NESDIS AMSU-B SSM/I) and
• Kummerow (CSU TRMM) but method is algorithm
• independent.
• Enables the generation of spatially and
  temporally
• complete precipitation fields while maintaining
• a pure, albeit manipulated, microwave-based
• analysis

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Advection vectors are computed from IR for each
2.5ogridbox andall microwave pixels contained in
that grid box are propagated in the direction of
that vector
2.5o
2.5o
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IR Spatial Correlation Domain for Computation of
Advection Vectors
2.5o
IR (t0)
2.5o
precip
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Advection Rates for 00Z 30 Nov 2001
. EAST WEST
(pixels/hour)
MERIDIONAL
. NORTH ...SOUTH
(pixels/hour)
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Actual Microwave Observations
t0
t2 hrs
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Validation
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Initial microwave pass
Next microwave pass
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Microwave-Advected
GPCP 1DD
GPI (IR)
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Potential Applications

• Real-time quantitative global precipitation
  monitoring
• Disaster mitigation
• Provide timely updates for U.S. interests abroad
• Numerical model initialization validation
• Improve diurnal cycle in the models
• Diagnostic studies diurnal cycle in particular

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Continuing Work

• Account for precipitation that forms and
  dissipates
• between microwave overpasses
• Refine advection vector computation
• Continue validation effort
• Test/Include new precipitation products as they
• become available method is not restricted to
• particular algorithms or sensors

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Finis
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mm/day
Figure 5
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Microwave propagated by IR
Another test this one is over The South
Atlantic Convergence Zone (SACZ)
Valid time is 1.5 hours after the initial pass
and 6 hours before the next pass
Initial microwave pass
Next microwave pass
Validating microwave data
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Spatial Lag Correlation of IR pixel temperature
among nearby 5o x 5o grid boxes to determine
propagation direction
(t 1/2 hr)
(t 0 hr)
5o 12 pixels
5o
5o
5o 12 pixels