Monthly and annual temperature extremes and their changes on the Tibetan Plateau and its surroundings during 1963–2015

Abstract

In this study, the spatiotemporal distributions of monthly and annual temperature minima (Tmin) and maxima (Tmax), extreme Tmin and Tmax, the highest (lowest) Tmin (Tmax), frost day (FD), icing day (ID), summer day (SD) and tropical night (TR) at 112 stations and over the ten large river basins on the Tibetan Plateau and its surroundings (TPS) during 1963–2015 are examined. Mann-Kendall test is applied for the trends. The analyses show: the northwest experiences the hottest summer while the central TPS has the coldest winter and most frequent frost and icing days. The northwest (southeast) features the highest (lowest) monthly extreme temperature ranges. The northwest has the most frequent hot summer days, whereas the southeast has the least frequent frost and icing days. The entire TPS displays few tropical nights. Most stations show positive trends for all monthly and annual Tmin and Tmax variables. February displays the most positive trends for both monthly Tmin and Tmax variables while April shows the highest number of stations with decreasing trends in monthly Tmax. The trends of FD and ID are negative, whereas the trends of SU and TR are positive. Over river basins, the trends of monthly Tmin are all positive and statistically significant and the trends of monthly Tmax are all positive except for one negative trend and around 1/3 of the positive trends are statistically significant. Relatively larger increases in monthly Tmin and Tmax are noted for the cold season than the warm. The monthly and annual Tmin variables increase more than Tmax variables.

Spatio‐temporal variability of the annual and monthly extreme temperature indices in Nepal

“…The result supports the general warming trend in Nepal and faster increase in T max compared to T min in the mountains as reported by Bhutiyani et al (2007), Khatiwada et al (2016) and Dhital et al (2013). On the other hand, the higher increasing trends in annual T max than in annual T min in the mountains and the decreasing trends in annual T max in the plains are apparently different from what is happening on the Tibetan Plateau (TP, Cuo et al, 2013;Liang et al, 2013;Ding et al, 2018) and around the globe that has caused the consistent downward trend in the diurnal temperature range (Alexander et al, 2006;Donat et al, 2013).…”

“…However, July and August have the most stations (11 and 13, respectively) with statistically significant increasing trends. December and January have the most decreasing trends (11 and 10, respectively) which is different from the Tibetan Plateau where the most stations tend to have high increasing trends in December and January (Ding et al, 2018). Kathmandu, a highly urbanized city, shows an increasing trend in T min for every month which is F I G U R E 7 The spatial distribution of the trends of monthly maximum temperature (T max ) from 1986 to 2015.…”

“…biodiversity and ecosystems (Meehl and Tebaldi, 2004;Sherwood and Huber, 2010). The analysis for indicators of climate change especially temperature has attracted extensive research over the last decades owing to the availability of long homogeneous records and the ability of temperature data to represent the energy exchange process over the earth's surface with reasonable accuracy (Vinnikov et al, 1990;Bhutiyani et al, 2007;Ding et al, 2018).…”

Rising mean and extreme near‐surface air temperature across Nepal

“…This typical diurnal warming pattern over the Himalaya seems to be a unique feature, which has been previously reported by Baidya et al (2008) and Shrestha et al (1999). In contrast, prominent warming of T min -based indices has been reported for the Tibetan plateau, inner Mongolia, indo-pacific regions, and whole globe (Alexander et al, 2006;Caesar et al, 2011;Donat et al, 2013;Shrestha et al, 2017;Ding et al, 2018;Tong et al, 2019). Furthermore, we noted that the magnitude of T max warming (0.04 CÁyear −1 ) detected over the 1980-2016 period in the present study is slightly lower than 0.06 CÁyear −1 as reported by Shrestha et al (1999) for the 1971-1994 period across Nepal.…”

Tackling the Tibetan Plateau in a down suit: insights into thermoregulation by bar-headed geese during migration

“…Bar-headed geese (Anser indicus) migrate annually from warm wintering grounds in south Asia to breeding grounds in Mongolia (Hawkes et al, 2011), crossing the Himalayas and Tibetan plateau (approximately 1000 km north to south with a mean elevation of 4500 m). The Tibetan Plateau can be inhospitable to migrants, with minimum monthly temperatures below −30°C for September to November (Ding et al, 2018), when bar-headed geese complete their southward migration. How these birds are able to thermoregulate in extreme cold both at stopover sites and during flight has not been investigated.…”