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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 Engineering University of Washington, Seattle, WA 98195, USA. 1. Background. - PowerPoint PPT Presentation
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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