Evaluation of TRMM PR Sampling Error Over a Subtropical Basin Using Bootstrap Technique

Indu, J and Kumar, Nagesh D (2014) Evaluation of TRMM PR Sampling Error Over a Subtropical Basin Using Bootstrap Technique. In: IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING, 52 (11). pp. 6870-6881.

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Abstract

Quantitative use of satellite-derived rainfall products for various scientific applications often requires them to be accompanied with an error estimate. Rainfall estimates inferred from low earth orbiting satellites like the Tropical Rainfall Measuring Mission (TRMM) will be subjected to sampling errors of nonnegligible proportions owing to the narrow swath of satellite sensors coupled with a lack of continuous coverage due to infrequent satellite visits. The authors investigate sampling uncertainty of seasonal rainfall estimates from the active sensor of TRMM, namely, Precipitation Radar (PR), based on 11 years of PR 2A25 data product over the Indian subcontinent. In this paper, a statistical bootstrap technique is investigated to estimate the relative sampling errors using the PR data themselves. Results verify power law scaling characteristics of relative sampling errors with respect to space-time scale of measurement. Sampling uncertainty estimates for mean seasonal rainfall were found to exhibit seasonal variations. To give a practical example of the implications of the bootstrap technique, PR relative sampling errors over a subtropical river basin of Mahanadi, India, are examined. Results reveal that the bootstrap technique incurs relative sampling errors < 33% (for the 2 degrees grid), < 36% (for the 1 degrees grid), < 45% (for the 0.5 degrees grid), and < 57% (for the 0.25 degrees grid). With respect to rainfall type, overall sampling uncertainty was found to be dominated by sampling uncertainty due to stratiform rainfall over the basin. The study compares resulting error estimates to those obtained from latin hypercube sampling. Based on this study, the authors conclude that the bootstrap approach can be successfully used for ascertaining relative sampling errors offered by TRMM-like satellites over gauged or ungauged basins lacking in situ validation data. This technique has wider implications for decision making before incorporating microwave orbital data products in basin-scale hydrologic modeling.

Item Type:	Journal Article
Publication:	IEEE TRANSACTIONS ON GEOSCIENCE AND REMOTE SENSING
Publisher:	IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
Additional Information:	http://dx.doi.org/ 10.1109/TGRS.2014.2304466 IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 445 HOES LANE, PISCATAWAY, NJ 08855-4141 USA
Keywords:	Basin; bootstrap; sampling error; Tropical Rainfall Measuring Mission (TRMM)
Department/Centre:	Division of Mechanical Sciences > Civil Engineering
Date Deposited:	06 Sep 2014 06:27
Last Modified:	06 Sep 2014 06:27
URI:	http://eprints.iisc.ac.in/id/eprint/49776

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