Terrain sensitive climate mapping for the Arequipa Department in Peru

Abstract

Climate is a powerful driver of agricultural and natural systems, and spatial climate datasets are currently in great demand. This is especially true in the Arequipa Department of Peru, a region with low seasonal precipitation, remarkable topographic variability, and significant water demand in a highly managed water system. This paper presents the Arequipa Climate Maps (ACM) datasets, a high resolution (1 km) spatial 30-year (1988-2017) climate dataset for the Arequipa Region, in Peru. Four interpolation methods, and combinations of those methods, were tested to produce 30 years of daily precipitation, maximum and minimum air temperature: Ordinary Kriging (OK), Thin Plate Splines (TPS), Regression Kriging (RK), and Regression Thin Plate Splines (RTPS). The mixed method RTPS-TPS and RTPS using locally fitted polynomial and potential regressions were found to best represent the spatial variability of precipitation and daily extreme temperatures, respectively, and helped compensate the bias resulting from the lack of weather stations at higher elevations. These methods were then selected to create the ACM dataset, which contains climate maps of 30-year annual and monthly climate normals (ACM-Normals) and 30 years of annual, monthly, and daily climate maps (ACM-YMD). In addition, insights on weather station gap filling in mountainous areas and bias corrections for avoidance of anomalous precipitation and to assure consistency between annual, monthly and daily data are presented, together with discussion about the quality and limitations of the dataset, and its comparison with other datasets.

The fast‐changing climate reality of Arequipa, Peru

“…A region marked by substantial topographic and climate variability. Within the Department, elevation varies from sea level to 6,405 m (Figure 1), while average annual precipitation varies from 1.5 to 1,100.0 mm∙year −1 , average annual temperature varies from −11.4 to 22.7°C (Figure 2) (Moraes et al ., 2022). The region can be roughly divided into two topographic/climatic regions: the Andean Altiplano and the desert.…”

“…The Andean Altiplano is a wide, high‐altitude region with average elevations of more than 3,500 m, occupying parts of Peru, Chili, Bolivia and Argentina. The Andean Altiplano in the south of Peru experiences a semiarid climate with more than 70% of the precipitation occurring during austral summer (December–March) (Moraes et al ., 2022), with precipitation mostly fed by moist easterly winds from the Amazon basin (Garreaud et al ., 2003; Garreaud, 2009).…”

“…Map of (a) annual average precipitation, (b) annual average daily maximum air temperature, and (c) annual average daily minimum air temperature for the period 1988–2017 (Moraes et al ., 2022). Gridded data is clipped to the boundary of the Arequipa Department [Colour figure can be viewed at wileyonlinelibrary.com]…”

“…All the data went through a data cleaning process for removal of implausible values as described in Moraes et al (2022). Precipitation gaps were filled by nearest neighbour bounded by elevation (NNBE) and temperatures were filled by intra-station interpolation (ISI) (Moraes et al, 2022). From the full dataset, stations were selected that had less than 10% missing data before gap filling for the 30-year period between 1988 and 2017.…”

“…This results in substantial competition for the limited water supply from the Andean mountains (Maos, 1985;Stensrud, 2016). The region is known for its strong seasonality at very high altitudes with more than 75% of annual precipitation occurring from December to March (Moraes et al, 2022). Much of the rain and snow is initially stored in glaciers and high-altitude wetlands ('Paramos') and then gradually released over time.…”