Spatio-temporal variation of temperature for the recent 40 years in Lhasa

TL;DR

This study analyzes 40 years of temperature data in Lhasa, revealing a significant upward trend, periodic oscillations, and the likelihood of continued temperature rise, especially in winter.

Contribution

It provides a comprehensive spatio-temporal analysis of temperature variation in Lhasa using multiple statistical methods, highlighting long-term trends and cyclic patterns.

Findings

Annual mean temperature is rising at 0.5°C per decade.

No significant abrupt change in temperature around 1995.

Main temperature cycle is approximately 28 years.

Abstract

It was all known that Lhasa went through a high temperature of 30.8$^{\circ}$C in late June 2019, which hit record highs. To better understand the reasons, based on observations recorded at automatic weather stations in Lhasa, we studied the characteristics of temperature variation at multiple time scales using the linear trend method, Mann-Kendall mutation test, morlet wavelet analysis, R/S analysis and so on. The results showed that: (a) The annual mean temperature (AMT) is rising at a rate of 0.5$^{\circ}$C/10yr, and the average temperature for different seasons also increased significantly, especially in winter. (b) Although there was an intersection in 1995, we found that AMT, did not pass the reliability test of significance level ${\alpha}$ =0.05, this means there are no abrupt changes for AMT, the values are 7.97$^{\circ}$C and 9.15$^{\circ}$C respectively before and after the intersection point. (c) AMT has a periodic oscillation for 18~25yr and 25~32yr based on a mass of data and the wavelet variance diagrams in Lhasa. AMT has a main cycle of 28yr, cyclic Patterns of temperature changes in spring, summer and autumn is similar to AMT, but it is relatively complex in winter. (d) The Hurst index of AMT and different seasons demonstrates that the temperature are likely to continue to rise in the future in Lhasa.