Meteorological observation plays a critical role in climatic study, and in situ measurements are the foundation of meteorological observation, especially in the Tibetan Plateau, the surface of which is fairly complex. Several field stations in the Northern Tibetan Plateau, which features relatively homogeneous surface, were selected as the study area. A detailed description on the significance of site observation for climate prediction was given in this paper. Data from weather stations can be used to verify satellite data and provide parameters for initial mode field in the study of weather and climate changes. The field observation data in the Northern Tibetan Plateau from 2001 to 2013 is analyzed. The results show that in El Nino year, values of land surface temperature (
It is well recognized that the Tibetan Plateau plays an important role in the East Asian and global climate because of its high evaluation and complex surface conditions. The land surface of the Tibetan Plateau reaches evaluations of greater than 4000 m above sea level, which is about a third of the height of the troposphere. It interacts with the atmosphere through radiation, sensible heat flux, and latent heat flux, and because of its topographic condition, the Tibetan Plateau exerts profound dynamical and thermal influences on Asian monsoon, the atmospheric circulation, and global climate change [
Decades of research on the Tibetan Plateau indicates that the plateau plays a vital part in the East Asian and global weather and climate prediction. Then the long-term meteorological observation in the plateau is essential and crucial for the research. Scientists have started to observe the atmospheric condition over the Tibetan Plateau systematically since 1970s. The first atmospheric science experiment on the Tibetan Plateau in 1979 (QXPMEX-1979) was performed by Ye and Gao. In that field experiment, the variation and distribution characteristics of each component in the land surface radiation balance and heat balance were analyzed, and the changing process of the heat source has been well understood [
However, the Tibetan Plateau covers a vast geographic area with various landforms, and the research is largely deficient only by a few of weather stations. But the remote sensing observation features large coverage and can obtain different surface parameters simultaneously, and it makes up the deficiency for the conventional observation data. With the developing of the satellite remote sensing, using satellite data to research various weather systems over the plateau has been a popular way. Meanwhile, an important method of estimating the air temperature by satellite data has been put forward, and it benefits the research on the land-atmosphere interaction [
As is shown in Figure
The basic information of all sites.
Stations | Longitude and latitude | Elevation | Underlying surface |
---|---|---|---|
NewD66 | 35.43°N, 93.59°E | 4465 m | Alpine sparse grassland |
D105 | 33.06°N, 91.94°E | 5039 m | Alpine meadow |
NPAM | 31.93°N, 91.71°E | 4620 m | Alpine meadow |
BJ | 31.37°N, 91.90°E | 4509 m | Alpine meadow |
MS3608 | 31.23°N, 91.78°E | 4589 m | Alpine grassland |
Map for the observation area and locations of stations in the Northern Tibetan Plateau.
Data applied in this study come from the observational data of the six stations, D66, NewD66, D105, NPAM, BJ, and MS3608. Daily meteorological data were obtained from the six stations and all these stations had complete records of meteorological factors from 2001 to 2013. The daily meteorological data included air temperature, land surface temperature, soil moisture, wind speed, and long-wave radiation. A few missing data (mainly in 2004, 2005 at BJ station) were estimated by averaging the value of other years observed at the same station.
Because of the poor quality data of land surface temperature observed, long-wave radiation data were used to calculate land surface temperature, and the formula is as follows:
Generally, the first-hand data for meteorology are provided by in situ measurements, and these data are widely used to validate the satellite data and model data for studying climate changes. For example, in situ measurements are compared with air temperature data estimated from the MODIS land surface data to verify the use of MODIS data for studying the spatial distribution of the air temperature by Sun et al. [
Comparisons between the estimated and measured
Thermodynamic structure from balloon soundings for June–August. (The figure is cited from Boos and Kuang [
As shown in Table
The annual and seasonal linear trend of
Annual | Spring | Summer | Autumn | Winter | ||||||
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| |
NewD66 | 0.12 | 0.03 | 0.11 | 0.04 | 0.02 | 0.08 | 0.01 | 0.08 | 0.09 | 0.03 |
D105 | 0.12 | 0.02 | 0.04 | 0.02 | 0.02 | 0.09 | 0.07 | 0.09 | 0.05 | 0.01 |
NPAM | 0.01 | 0.01 | 0.01 | 0.02 | 0.01 | 0.07 | −0.07 | 0.05 | 0.01 | 0.01 |
BJ | 0.07 | 0.10 | 0.07 | 0.14 | 0.03 | 0.13 | 0.002 | 0.07 | 0.11 | 0.07 |
MS3608 | 0.01 | 0.03 | 0.02 | 0.06 | 0.06 | 0.10 | 0.03 | 0.01 | 0.01 | 0.01 |
Take BJ station as an example. Figure
Averaged land surface temperature and air temperature change curves for seasons and years at BJ (curved lines are observed values, and straight lines are liner trend).
The interannual variation of wind speed and soil moisture in each season at BJ.
In addition, according to some researches [
For the sake of monitoring the weather changes, a number of autoweather stations (AWSs) were set up in the Tibetan Plateau. Figure
The diurnal variation of land surface temperature (
The process of making weather forecast consists of observation, data acquisition, data processing, data analysis, and forecast. All of them are based on the observation, and surface observation is absolutely necessary and it provides initial and reference value for the numerical forecasting. It is obvious that daily observation has an effect on weather forecast in the Northern Tibetan Plateau.
The underlying surface in the Tibetan Plateau is complex and heterogeneous, and it makes all the difference to the East Asian and even global climate change. So based on the in situ measurements, weather and climate prediction is dependable and convincing. As the first-hand data, data from weather stations are widely used to validate the satellite data and model data for studying climate changes. And in situ measurements are essential to the climate and weather forecast.
Long-term observations in the Tibetan Plateau exert an important influence on the regional and global climate prediction. In the Northern Tibetan Plateau,
The daily variations of
According to these observations, amount of weather and climate research in the plateau can be done continuously. As the foundation of climate prediction, long-term meteorological observations are worthy to be paid more attention.
The authors declare no conflict of interests.
This study was funded by CAS “Hundred Talent” program (Dr. Weiqiang Ma), National Natural Science Foundation of China (NSFC) (41375009, 91337212, 41275010, and 41275028). Special thanks are given to the anonymous reviewers and the editor for very constructive comments. The authors also thank all the participations for their very hard field work during the field observations in Tibetan Plateau.