Types of climate indices

After scrutinising the models and their selection, province based core climate indices are calculated (Table 4.1). We have calculated and analyzed 25 indices – 15 indices related to the temperature and 10 indices related to the precipitation. Indices are driven from maximum temperature, minimum temperature, and precipitation. The climate indices are of five different types:

Percentile-based indices

Occurrence of cold nights, occurrence of warm nights, occurrence of cold days, occurrence of warm daysvery wet days, and extremely wet days, are all percentile based indices.

Absolute indices

These indices represent maximum or minimum values within a season or a year. Maximum of daily maximum temperature, maximum of daily minimum temperature, minimum of daily maximum temperature, minimum of daily minimum temperature, maximum 1-day precipitation amount, and maximum 5-day precipitation amount, are all absolute indices.

Threshold indices

The indices are those in which the number of days on which a temperature or precipitation value falls above or below a fixed threshold. Annual occurrence of frost days, annual occurrence of ice days, annual occurrence of summer days, annual occurrence of tropical nights, number of heavy precipitation days, and number of very heavy precipitation days, are all threshold indices.

Duration indices

These indices signify periods of excessive warm, cold, wetness or dryness in the climate. Cold spell duration indicator, warm spell duration indicator, consecutive dry days, and consecutive wet days, are all duration indices.

Societal Impact indices

The indices could have significant societal impacts. Annual precipitation total, diurnal temperature range, simple daily intensity index, and annual contribution from very wet days, all fall into societal impact indices.

Table 4.1: Core climate indices calculated and analyzed in this study.

RClimDex is employed for index calculation in this study. The RClimDex provides a friendly graphical user interface to compute 27 core indices (see e.g., Karl et al., (1999); Peterson et al., (2001); Zhang et al. (2005)). It also conducts simple quality control on the input daily data. It has been developed and maintained by Xuebin Zhang and Yang Feng at Climate Research Division.