Publications

Orvos, Peter I.; Homonnai, Viktoria; Varai, Anita; Bozoki, Zoltan; Janosi, Imre M. (2014). Trend analysis of a new MODIS drought severity index with emphasis on the Carpathian Basin. IDOJARAS, 118(4), 323-333.

Abstract
Recently, Mu et al. (2013) have compiled an open access data base of a remotely sensed global drought severity index (DSI) based on MODIS satellite measurements. Observations cover a continuous period of 12 years between January 1, 2000 and December 31, 2011 with a temporal resolution of 8 days. The highest spatial resolution is around 5 km in the geographic band between 60 degrees S and 80 degrees N latitudes (more than 4.9 million locations over land). Here we extend the global trend analysis by Orvos et al. (2014) of these satellite based DSI time series in order to locate geographic areas where either positive or negative trends are statistically significant. Significance is established by a standard perturbation test, where each individual record is cut into annual pieces, and the statistics of 1000 randomly shuffled and glued time series is compared with the original record. We exhibit three regions of significant wetting and/or drying trends over extended geographic ranges and try to correlate them with recent reports of local climate shifts. We are fully aware of the fact that 12 years are too short for linking the findings to global climate change. Most probably, the identified significant trends can be considered as a component of natural climate variability on decadal time scales, however, a full explanation will require to identify a couple of explanatory variables. We demonstrate that drying and wetting trends are weakly significant in the Carpathian Basin. Nevertheless, the observations can serve as benchmark for regional climate simulations, projections can be accepted when the test period is properly reproduced considering also high resolution DSI data.

DOI:

ISSN:
0324-6329