A New Methodology for Estimating the Surface Temperature Lapse Rate Based on Grid Data and Its Application in China

Yun Qin,Panfeng Zhang,Guoyu Ren,Tianlin Zhai,Kangmin Wen

doi:10.3390/rs10101617

Yun Qin, Panfeng Zhang + Show 3 more

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https://doi.org/10.3390/rs10101617

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Abstract

Land surface temperature (LST) is an important parameter in the study of the physical processes of land surface. Understanding the surface temperature lapse rate (TLR) can help to reveal the characteristics of mountainous climates and regional climate change. A methodology was developed to calculate and analyze land-surface TLR in China based on grid datasets of MODIS LST and digital elevation model (DEM), with a formula derived on the basis of the analysis of the temperature field and the height field, an image enhancement technique used to calculate gradient, and the fuzzy c-means (FCM) clustering applied to identify the seasonal pattern of the TLR. The results of the analysis through the methodology showed that surface temperature vertical gradient inversion widely occurred in Northeast, Northwest, and North China in winter, especially in the Xinjiang Autonomous Region, the northern and the western parts of the Greater Khingan Mountains, the Lesser Khingan Mountains, and the northern area of Northwest and North China. Summer generally witnessed the steepest TLR among the four seasons. The eastern Tibetan Plateau showed a distinctive seasonal pattern, where the steepest TLR happened in winter and spring, with a shallower TLR in summer. Large seasonal variations of TLR could be seen in Northeast China, where there was a steep TLR in spring and summer and a strong surface temperature vertical gradient inversion in winter. The smallest seasonal variation of TLR happened in Central and Southwest China, especially in the Ta-pa Mountains and the Qinling Mountains. The TLR at very high altitudes (>5 km) was usually steeper than at low altitudes, in all months of the year.

Highlights

Temperature lapse rate (TLR) is the rate at which temperature decreases with altitude
The lapse rate of land surface temperatures (LST) reflects the spatiotemporal variation of the thermal processes of land surface and the difference of regional climate, which can be used for the study of mountainous climates and probably for regional climate change, especially in remote mountainous areas where observations from ground meteorological stations are lacking
We developed a methodology to calculate and analyze the TLR based on grid data, and used China as a case study for the application of the methodology by using grid datasets of moderate-resolution imaging spectroradiometer (MODIS) LST and digital elevation model (DEM)

Summary

Introduction

Temperature lapse rate (TLR) is the rate at which temperature decreases with altitude. There are two kinds of TLRs, dynamic and static TLR The former describes the temperature change of the air parcel when it rises (e.g., dry adiabatic lapse rate); the latter indicates the temperature changes with space, which may be vertical (e.g., tropospheric free-air TLR) or along the earth’s surface with different altitudes. The lapse rate of LST reflects the spatiotemporal variation of the thermal processes of land surface and the difference of regional climate, which can be used for the study of mountainous climates and probably for regional climate change, especially in remote mountainous areas where observations from ground meteorological stations are lacking. Elevation-dependent warming in mountainous areas may result in a temporal change in the TLR, and the more rapid warming at high altitude may be related to the shallower land surface and near-surface air TLR [12]

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