Standardized Drought Indices for Pre-Summer Drought Assessment in Tropical Areas

David Romero,Eric Alfaro,Maria-Engracia Hernandez Cerda,Roger Orellana

doi:10.3390/atmos11111209

Abstract

The main climatic indices used for the determination of pre-summer drought severity were developed for temperate zones with very different climatic conditions from those found in the tropical climate zones, particularly with respect to seasonal rainfall variations. The temporal evolution of pre-summer drought leads the authors to compute the indices for each year over a defined period according to the climatic normals of each meteorological station and to consider the months inside the dry episode differently, according to the law of emptying the water reserves. As a function of this, standardized drought indices are proposed for the evaluation of the pre-summer drought in tropical zone. Two new indices were tested: one developed from precipitation and the other also considering temperature. These indices were validated by correlation with Advanced very-high-resolution radiometer (AVHRR) normalized difference vegetation index (NDVI) time series and used to identify the most severe drought conditions in the Yucatan Peninsula. The comparison between the indices and their temporal variations highlighted the importance of temperature in the most critical events and left indications of the impact of global warming on the phenomenon.

Highlights

The cost of natural disasters grows continuously worldwide [1] and among these disasters, drought impacts the widest areas [2] as it is exacerbated by overextraction of freshwater aquifers [3]even in areas with a humid tropical climate [4]
The computation of the Palmer drought severity index (PDSI) requires, in addition to precipitation data, information regarding evapotranspiration, runoff, and soil moisture [13], which is generally difficult to obtain in Mexico and tropical areas since it implies spatially detailed information of the water and soil characteristics of the areas studied
The year 2009, which stood out in the series studied for having negative index considering precipitation (ISPP) and ISPB indices throughout the Yucatan peninsula, was recorded as the most

Summary

Introduction

The cost of natural disasters grows continuously worldwide [1] and among these disasters, drought impacts the widest areas [2] as it is exacerbated by overextraction of freshwater aquifers [3]even in areas with a humid tropical climate [4]. The computation of the PDSI requires, in addition to precipitation data, information regarding evapotranspiration, runoff, and soil moisture [13], which is generally difficult to obtain in Mexico and tropical areas since it implies spatially detailed information of the water and soil characteristics of the areas studied. For this reason, the PDSI is rarely used to measure drought in Mexico. The calculation of the SPI only requires the precipitation data, which are accessible from national databases such as CliCom (Climate Computing Project), administered by the National Meteorological. The SPI is commonly used and is Atmosphere 2020, 11, 1209; doi:10.3390/atmos11111209 www.mdpi.com/journal/atmosphere

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