Evaluation of the TRMM Multi-satellite Precipitation Analysis (TMPA) and its utility in

hydrologic prediction in La Plata Basin

Dennis P. Lettenmaier and Fengge Su

Department of Civil and Environmental EngineeringUniversity of Washington, Seattle,

WA 98195, USA

1. Background

• Objective of this study: Evaluate TRMM-based precipitation

estimates, and their utility in hydrologic (streamflow)

predictions.

• This initial hydrologic effectiveness assessment of TRMM

products for La Plata Basin can provide useful insights into

the potential hydrologic utility of the Global Precipitation

Measurement mission (GPM)

• A first step in development of a global hydrologic assessment

framework for satellite-based precipitation products.

• The TRMM product evaluated in this study is the TRMM

Multi-satellite Precipitation Analysis (TMPA) research

product Version 6 3B42 for the years of 1998-2006.

• V6 3B42 combines precipitation estimates from multiple

satellites, as well as gauge analyses, where available, at a

3-hour time step and 0.25° degree spatial resolution.

• The data set covers the latitude band 50°N-S for the

period 1998 to the delayed present.

2. Data sets and methodology

Huffman et al., 2007, The TRMM Multi-satellite Precipitation Analysis (TMPA): Quasi-Global, Multi-Year, Combined-Sensor Precipitation Estimates at Fine Scales (Journal of Hydrometeorology 8, 38-55 )

Brazil

Uruguay

Bolivia

Paraguay

Argentina

Parana Basin

Uruguay basin

Paraguay basin

Brazil

Uruguay

Bolivia

Paraguay

Argentina

Parana Basin

Uruguay basin

Paraguay basin

Brazil

Uruguay

Bolivia

Paraguay

Argentina

Parana Basin

Uruguay basin

Paraguay basinLa Plata Basin and gauge-based gridded daily precipitation for the years of 1998-2006

Sources: South American gridded daily precipitation (0.25° ) which was constructed from daily meteorological stations (Liebmann and Allured, 2005).

Rain gauge distributions in 2005. Blue triangles are streamflow stations. Colored areas highlight four subbasins with relative dense station coverage.

Methodology

1. Basin average precipitation estimates from the TRMM

Satellite precipitation product (Version 6 3B42) and gauge

estimates for 1998-2006 are compared with each other at

both daily and monthly time scales.

2. The Variable Infiltration Capacity (VIC) land surface

hydrology model is forced by the daily 3B42 and gridded

gauged precipitation estimates over several subbasions of

La Plata. The two streamflow simulations are compared

with each other and with available observed streamflow.

3. Precipitation evaluation

Scattergrams of daily basin-averaged precipitation from gauged and TRMM V.6 3B42 estimates for La Plata basin tributaries for the period January 1998 to August 2006.

R2=0.63Rrmse=0.94

R2=0.42Rrmse=1.70

R2=0.39Rrmse=1.69

R2=0.0.45Rrmse=1.51

R2=0.58Rrmse=0.86

R2=0.54Rrmse=1.02

R2=0.41Rrmse=1.38

Daily time series of precipitation for basin 3802

Gauged

TRMM1998

1999

2000

2001

2002

FBI can indicate whether there is a tendency to underestimate (FBI<1) or overestimate (FBI>1) rainy events.

POD gives a proportion of observed rain events successfully estimated by the TRMM data.

FAR provides a measure of the 3B42’s tendency to estimate rain where none was observed.

Statistical evaluation over different subbasinsFrequency Bias Index

0

0.5

1

1.5

2

2.5

0.1 0.5 1 2 5 10 20

Threshold (mm)

FB

I

3861

6301

6682

Probability of Detection

0

0.2

0.4

0.6

0.8

1

0.1 0.5 1 2 5 10 20

Threshold (mm)P

OD

3861

6301

6682

False Alarms Ratio

0

0.2

0.4

0.6

0.8

1

0.1 0.5 1 2 5 10 20

Thresholds (mm)

FA

R

3861

6301

6682

Frequency Bias index

Probability of Detection

False Alarms Ratio

Scattergrams of monthly basin-averaged precipitation estimated from gauged and TRMM for seven subbasins in La Plata (Jan 1998-Aug 2006).

Monthly Basin-averaged Precipitation

R2=0.95Rrmse=0.23

R2=0.99Rrmse=0.13

R2=0.99Rrmse=0.17

R2=0.95Rrmse=0.16

R2=0.96Rrmse=0.14

R2=0.98Rrmse=0.10

R2=0.97Rrmse=0.12

Monthly time series of

precipitation from gauged and

TRMM V.6 3B42 estimates for

seven subbasins in La Plata

(Jan 1998-Aug 2006).

Gauged TMPA

6301 (Area: 478,000 km2)

6598 (Area: 63,236 km2)

6682 (Area: 459,990 km2)

3802 (Area: 189,300 km2)

7870 (Area: 240,000 km2)

3402 (Area: 975,000 km2)

2401 (Area: 1,100,000 km2)

4. Hydrological Modelling4. Hydrological Modelling

The VIC (Liang et al, 1994;1996) model is a grid-based land surface scheme designed both for inclusion in GCMs, and for use as a stand-alone macro-

scale hydrological model.

Model features:

• multiple vegetation classes in each cell;

• energy and water budget closure at each time step;

• subgrid infiltration and runoff variability;

• and non-linear baseflow generation.

Observed

Simulated with TRMM Prce.

Simulated with gauged Prce.

Nash-Sutcliffe efficiency (Ef)

Relative error (Er)

Daily streamflow for basin 3802 (Area: 189, 300 km2)

Red VS. Black: Ef = 0.45, Er = 24%

Red VS. Green: Ef = 0.71, Er = 24%

1998 1999 2000

1998 1999 2000

2001 2002 2003

m3

/s m

3/s m

3/s

Green VS. Black: Ef = 0.85, Er = 2%

Daily streamflow for basin 6301, Parana at Jupia (Area: 478,000km2)

Red VS. Green: Ef = 0.62, Er = 22%

Nash-Sutcliffe efficiency (Ef)

Relative error (Er)

Observed

Simulated with TRMM Prce.

Simulated with gauged Prce.

m3

/s m

3/s m

3/s

Daily streamflow for basin 6598, Iguazu at Estreito (Area: 63,236 km2)

Red VS. Green: Ef = 0.62, Er = 22%

Nash-Sutcliffe efficiency (Ef)

Relative error (Er)

Observed

Simulated with TRMM Prce.

Simulated with gauged Prce.

m3

/s m

3/s m

3/s

Observed

Simulated with TRMM Prce.

Simulated with gauged Prce.

Nash-Sutcliffe efficiency (Ef)

Relative error (Er)

Stream

flow

(m3

/s)

1998 1999 2000 2001 2002 2003 2004 2005 2006

(b) 6301, Parana at Jupia (Area: 478,000km2)

(c) 6598, Iguazu at Estreito (Area: 63,236 km2)

(a) 6682, Paraguay at Ladario (Area: 459,990 km2)

(d) 3802, Uruguay at Paso de los Libres (Area: 189,300 km2)

(e) 7870, Uruguay at Concordia (Area: 240,000 km2)

(f) 3402, Parana at Posadas (Area: 975,000 km2)

(g) 2401, Paraguay at Bermejo (Area: 1,100,000 km2)

Monthly time series of

streamflow at seven locations

within La Plata basin for the

years of 1998-2006.

• The Version 6 3B42 precipitation matches observations closely at monthly

time scale (essentially by construct) . Daily estimates show a good

performance for the low and medium precipitation thresholds. For higher

thresholds, satellite estimates tend to overestimate the frequency of rain

events, and to show low POD and high FAR.

• The 3B42-driven model results show reasonable ability to capture low and

mid-range daily flows, but tend to overestimate high flows.

• Monthly adjustment is key to getting streamflow volumes (about) right – is

there a viable way of doing this in the absence of gauge estimates?

• This study is encouraging to the extent that the rescaled satellite estimates

provide plausible estimates of area covered by precipitating events.

• Key caveat is that hydrological model was calibrated to gridded gauge

estimates – need to investigate hydrological prediction errors when model is

calibrated to satellite products

5. Conclusions