arXiv subjects

Wenbo Gu

Publications and source records attributed to Wenbo Gu.

4 recordsLinked to original sources

arXiv2026

Shigatse Astronomical Site Testing. I. Cloud-cover Climatology and Selected Local Meteorological Conditions

As the first paper in a Shigatse astronomical site-testing series, we present a multi-source assessment of cloud cover and selected local meteorological conditions at the Shigatse 40 m site on the southern Tibetan Plateau. The study combines CALIPSO-GOCCP active-lidar climatology, ISCCP HXG passive-satellite cloud fields, conventional total-cloud-amount observations from the Shigatse Meteorological Station, and on-site Weather Station measurements. Together, these records characterize Shigatse as a southern-plateau monsoon-transition cloud regime: the active-lidar climatology gives a moderate-to-low annual cloud fraction, and the cloudier months are concentrated in the June--September monsoon interval. In GOCCP, the annual mean cloud fraction is 42.1%, while the October--May low-cloud season has a mean cloud fraction of 26.3%, compared with 73.7% during the June--September monsoon interval. ISCCP gives higher absolute cloud fractions but supports the same seasonal phase and local spatial placement. The aligned 1988--2013 meteorological-station record gives a total-cloud-amount <=40% fraction of 80.7% during October--May, rising to 90.7% in the November--January core, and decreasing to 39.9% during June--September. The 2024--2025 Weather Station archive further shows high fractions of valid samples satisfying the adopted meteorological criteria during the low-cloud months: 92.6% for the October--May night-time proxy and 94.6% for the corresponding 24 h samples. These results identify Shigatse as a measured lower-latitude southern-plateau cloud-cover reference within China's site-testing network, with a well-defined October--May low-cloud observing period and a Shigatse--Ali low-cloud corridor for subsequent regional site testing.

astro-ph.IM↗

arXiv2026

ASCNet: Research on all-sky camera images classification at the Muztagh-ata site

Cloud coverage is one of the crucial elements of site testing in astronomy. All-sky camera (ASC) images are beneficial for our research on cloud coverage. In this paper, we propose ASCNet, an innovative model specifically designed for classifying nighttime ASC images collected at the Muztagh-ata site from 2022 March to 2024 June. ASCNet integrates ResNet34 with an ASCModule, which employs Depthwise Dilated Convolution and embeds lightweight Squeeze-and-Excitation attention within its branches to extract fine-grained texture information from the luminance channel. The data set is partitioned by category, with 70% of images assigned to the training set and 30% to the test set. The model's performance is assessed by comparing its predictions on the test set with manually annotated labels, yielding a consistency rate of 92.7%. All evaluation metrics of ASCNet are as follows: Accuracy 92.66%, Precision 83.26%, Recall 84.25%, and F1-Score 83.67%, and both ablation and comparative experiments demonstrate significant superiority over other models. A confusion matrix is utilized to analyze the differences between manual classification and model classification. The statistical results demonstrate the model's excellent classification performance and its robust generalization ability, illustrating that ASCNet has potential for application in future astronomical image classifications.

astro-ph.IM↗

arXiv2025

Seeing and Meteorological Analysis at the North-1 and North-2 Points of Muztagh-Ata Site on the Pamir Plateau

To support the selection of large optical/infrared telescope sites in western China, long-term monitoring of atmospheric conditions and astronomical seeing has been conducted at the Muztagh-Ata site on the Pamir Plateau since 2017. With the monitoring focus gradually shifting northward, three stations were established: the South Point, North-1 point, and North-2 point. The North-1 point,selected as the site for the Muztagh-Ata 1.93 m Synergy Telescope (MOST), has recorded seeing and meteorological parameters since late 2018. In 2023,the North-2 point was established approximately 1.5 km northeast of North-1 point as a candidate location for a future large-aperture telescope. A 10m DIMM tower and a PC-4A environmental monitoring system were installed to evaluate site quality. This study presents a comparative analysis of data from the North-1 and North-2 points during 2018-2024.The median seeing is 0.89 arcsecs at North-1 and 0.78 arcsecs at North-2. Both points show clear seasonal and diurnal variations,with winter nights offering optimal observing conditions.On average, about 64% of the nighttime duration per year is suitable for astronomical observations. Nighttime temperature variation is low :2.03 at North-1 and 2.10 at North-2 .Median wind speeds are 5-6 m/s, with dominant directions between 210 and 300, contributing to stable airflow. Moderate wind suppresses turbulence, while strong shear and rapid fluctuations degrade image quality. These findings confirm that both the North-1 and North-2 points offer high-quality atmospheric conditions and serve as promising sites for future ground-based optical/infrared telescopes in western China.

astro-ph.IM↗

arXiv2024

Optical turbulence in the atmospheric surface layer at the Pamir Plateau Muztagh-ata site

In this paper, we conducted a detailed analysis of optical turbulence in the Atmospheric Surface Layer (ASL) at Muztagh-ata site during on-site testing. We utilized ultrasonic anemometers positioned on a 30-meter tower to collect and process data at five height levels, obtaining data from October 1, 2021 to the present. We investigated the behavior of optical turbulence parameters (\(C_n^2\) and seeing \(\varepsilon\)) in the ASL. Nighttime \(C_n^2\) primarily fluctuated in the range of \(10^{-16}\) to \(10^{-14}\), exhibiting an exponential decrease with height. During the day, it showed a \(h^{-0.82}\) dependency, while at night, it displayed a \(h^{-0.48}\) dependency. Additionally, we presented the distribution of seeing across different layers within the ASL, showing a gradual decrease with increasing height, with a median seeing of 0.24 arcseconds at nighttime and 0.48 arcseconds at daytime between 6-30m. We investigated the relationship between surface temperature inversion, seeing in the ASL, and wind speed at the site. Our results show that under temperature inversion conditions, seeing significantly improves and is often accompanied by low to moderate wind speeds, while high wind speeds are usually associated with poorer seeing. Preliminary calculations and observational results, combined with the high altitude and unique geographical location, suggest that Muztagh-ata site has the potential to be an outstanding optical astronomical observatory in the western plateau of china.

physics.ao-ph↗