Diurnal cycle of precipitation based on cmorph
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Diurnal Cycle of Precipitation Based on CMORPH. Vernon E. Kousky, John E. Janowiak and Robert Joyce Climate Prediction Center, NOAA. CMORPH (CPC Morphing technique).

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Diurnal Cycle of Precipitation Based on CMORPH

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Diurnal cycle of precipitation based on cmorph

Diurnal Cycle of Precipitation Based on CMORPH

Vernon E. Kousky, John E. Janowiak

and

Robert Joyce

Climate Prediction Center, NOAA


Cmorph cpc morphing technique

CMORPH (CPC Morphing technique)

Uses IR data along with passive microwave data to create global rainfall analyses (60N-60S) at high spatial and temporal resolution.

CMORPH uses IR only as a transport vehicle, i.e. IR data are NOT used to make estimates of rainfall when passive microwave data are not available.

The underlying assumption is that the error in using IR to transport precipitation features is less than the error in using IR to estimate precipitation.


Rationale

Rationale

  • Passive microwave (PMW) data provide much better rainfall estimates than IR but these data are spatially and temporally incomplete (instruments on polar orbiting platforms)

  • IR data are abundant both in space & time (polar & geostationary platforms)

  • CMORPH combines the superior quality of the PMW-derived precipitation estimates with the excellent sampling characteristics of the IR data


Specifics

Specifics

  • Spatial Grid: 0.0728o lat/lon (8 km at equator)

  • Temporal Resolution: 30 minutes

  • Domain: Global (60o N - 60o S)

  • Period of record: Dec. 2002 – present

    For more information about CMORPH:

    http://www.cpc.ncep.noaa.gov/products/janowiak/cmorph.html


Comparison cmorph and gridded analyses djf 0203 0304

Comparison: CMORPH and Gridded Analyses (DJF 0203+0304)

CMORPH

Gridded

CMORPH over estimates precipitation by 40-50% over Brazil.


South america djf 02 03 03 04 1mm d mask

South America: DJF 02-03+03-04 (1mm/d mask)


Djf south america 1mm mask

DJF - South America (1mm mask)


Djf south america 1mm mask1

DJF - South America (1mm mask)


Time utc of max precipitation south america djf 2002 03

Time (UTC) of Max. Precipitation: South America – DJF 2002-03

18-21 UTC

00-03 UTC

12-15 UTC

06-09 UTC

06-09 UTC

12-15 UTC

00-03 UTC

18-21 UTC


Time lst of max precipitation south america djf 2002 03

Time (LST) of Max. Precipitation: South America – DJF 2002-03

15-18 LST

21-24 LST

08-11 LST

03-06 LST

02-05 LST

09-12 LST

20-23 LST

15-18 LST


Percent total precipitation diurnal cycle djf 2002 03

Percent Total Precipitation: Diurnal Cycle DJF 2002-03

4

5

6

La Plata Basin

4

5

6

Daytime maximum

Nighttime maximum

1

2

3

2

1

3


Diurnal cycle djf 02 03 03 04

Diurnal Cycle DJF 02-03 + 03-04


Time longitude diurnal cycle eq djf 2002 03 2003 04

Time-Longitude Diurnal Cycle EQ DJF 2002-03 +2003-04

Rainfall develops along coast during the day and propagates westward through the night and into the next day.

Early morning maximum in rainfall over tropical Atlantic.


Mam mean diurnal cycle eq 5n

MAM Mean Diurnal Cycle – EQ-5N

Convective rainfall systems start along east coast on day-1 propagate westward, reaching western Amazon on day-3.

West Coast

East Coast


Time longitude diurnal cycle 30s djf 2002 03 2003 04

Time-Longitude Diurnal Cycle 30S DJF 2002-03 +2003-04

Rainfall develops over Andes Mts. During late afternoon, then shifts eastward during the night and following day.

Andes

East Coast SA


Conclusions

Conclusions

  • CMORPH precipitation analyses are useful in obtaining a detailed description of the diurnal cycle.

  • A pronounced diurnal cycle in precipitation is found in many areas of South America.

    • Daytime peak over high terrain (e.g., Andes Mts., Brazilian Planalto).

    • Daytime peak near the coast, especially NE South America, associated with sea breeze.

    • Nocturnal peak in the central La Plata Basin, and inland areas affected by westward propagating sea breeze-induced convection (Amazon Basin).


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