http://hdl.handle.net/20.500.11765/14266 2026-06-30T10:40:27Z http://hdl.handle.net/20.500.11765/17967 Título : Three-Year Characterization of Boundary Layer Dynamics From GNSS Zenith Wet Delay Spectral Analysis Autor : Kermarrec, Gaël; Calbet, Xavier; Deng, Zhiguo Resumen : Continuous monitoring of boundary layer turbulence remains a challenge due to sparse conventional instrumentation. Here we suggest that spectral analysis of Global Navigation Satellite System (GNSS) zenith wet delay (ZWD) fluctuations yields physically meaningful diagnostics of boundary layer state. From 3 years of co-located GNSS and Doppler lidar observations (January 2022–December 2024) at Payerne, Switzerland, we extract the variance σ², a measure of integrated water vapor turbulence intensity, and the cutoff frequency fc, which marks the spectral extent of turbulent mixing. Annual harmonic analysis reveals that σ² captures 54% of its variance through the seasonal cycle (R² = 0.54, peak in January), while fc peaks in August (R² = 0.49). The inverse σ²–fc coupling (r = -0.61) tightens to r = -0.77 under summer convective conditions, consistent with regime-dependent physical correspondence. Cross-instrument comparison with Doppler lidar turbulent kinetic energy (TKE) integrated over 100–550 m is compatible with the fundamental vertical sampling mismatch between troposphere-weighted GNSS and profile-limited lidar measurements. These results establish GNSS networks as a globally available sensing system for boundary layer turbulence monitoring. 2026-01-01T00:00:00Z http://hdl.handle.net/20.500.11765/17966 Título : Comparing v11.2 OCO‐2 and v11 OCO‐3 XCO2 Retrievals With Ground‐Based COCCON Measurements Autor : Das, Saswati; Sha, Mahesh Kumar; Dubravica, Darko; Taylor, Thomas E.; Kiel, Matthaeus; Laughner, Joshua; Osterman, Gregory; O'Dell, Christopher; Fisher, Brendan; Nelson, Robert R.; Alberti, Carlos; Baier, Bianca C.; Balis, Dimitris; Bösch, Hartmut; Butz, André; Cai, Zhaonan; Chen, Jia; Chevallier, Frédéric; Dandocsi, Alexandru; Deutscher, Nicholas Michael; Dubey, Manvendra K.; Feist, Dietrich G.; Feld, Lena; Franklin, Jonathan E.; Frey, Matthias; García Rodríguez, Omaira Elena; Gribanov, Konstantin; Gottlieb, Elaine; Griffith, David W. T.; Grutter, Michel; Hase, Frank; Sepúlveda Hernández, Eliezer; Humpage, Neil; Iraci, Laura; Jacobs, Nicole; Jeong, Sujong; Jeseck, Pascal; Karppinen, Tomi; Kivi, Rigel; Lopez, Morgan; Luther, Andreas; Makarova, Maria; Makowski, Moritz; McGee, Erin; Mermigkas, Marios; Morino, Isamu; Notholt, Justus; Ohyama, Hirofumi; Panou, Thomas; Park, Hayoung; Parker, Robert J.; Pollard, David F.; Rettinger, Markus; Roche, Sébastien; Roehl, Coleen M.; Rousogenous, Constantina; Shiomi, Kei; Simpson, William R.; Stremme, Wolfgang; Strong, Kimberly; Sussmann, Ralf; Taquet, Noémie; Te, Yao; Topaloglou, Chrysanthi; Toon, Geoffrey C.; Tu, Qiansi; Vrekoussis, Mihalis; Wang, Pucai; Warneke, Thorsten; Wofsy, Steven C.; Wunch, Debra; Zhou, Minqiang; Spicer, Elizabeth; Eldering, Annmarie; Kulawik, Susan; Chatterjee, Abhishek; Payne, Vivienne H. Resumen : The Orbiting Carbon Observatory-2 (OCO-2) and -3 (OCO-3) (collectively referred to as OCO-2/3) are NASA missions that study atmospheric carbon dioxide (CO2) globally with a high degree of precision and accuracy. Measurements from the Total Carbon Column Observing Network (TCCON), a global network of ground-based Fourier Transform Spectrometers (FTS) dedicated to measuring the column-averaged concentrations of GHGs (including CO2), have been historically used for validation of satellite observations. The new COllaborative Carbon Column Observing Network (COCCON) complements TCCON by expanding the network of ground-based CO2 measurements using portable and cost-effective FTSs. We provide the first global comparison between OCO-2/3 with COCCON observations to evaluate the mean differences between the ground- and space-based data sets and identify regions where these differences are most pronounced. Global comparisons suggest bias values (in ppm) of 0.42 (0.03), 0.94 (0.18), 0.88 (−0.01) for OCO-2, and 0.65 (0.03), 0.95 (0.09), 0.67 (0.16) for OCO-3 in the land nadir/glint, ocean glint, and target modes, respectively, against version (v) 1 COCCON, with corresponding values against TCCON listed within the parentheses. For sites with v2.x COCCON data available, reduced biases are observed against OCO-2/3, suggesting the need to update the data at all COCCON sites using the latest PROFFAST v2.4. 2026-01-01T00:00:00Z http://hdl.handle.net/20.500.11765/17965 Título : GNSS Zenith Wet Delay as a Boundary Layer Diagnostic: Regime‐Dependent Turbulence Signatures From LargeEddy Simulation and Observations Autor : Kermarrec, Gaël; Schrader, Tim; Calbet, Xavier; Deng, Zhiguo Resumen : Global Navigation Satellite Systems (GNSS) signals, used routinely for satellite positioning, are slightly delayed as they cross the moist atmosphere. Beyond the slow variations associated with weather forecasting, these delays exhibit rapid fluctuations on timescales of seconds to minutes that are caused by turbulent mixing of water vapor in the lowest kilometers of the atmosphere. We investigate whether two properties of these fluctuations, the total variance and the cutoff frequency of their power spectrum, carry quantitative information on the state of the atmospheric boundary layer. The difficulty is that all the variables of interest, including the wind speed, the humidity variance and the spectral parameters are dominated by a common diurnal cycle which inflates ordinary correlations and makes them physically meaningless. To address this, we develop a coherence analysis that compares the shape of diurnal cycles independently of amplitude and timing offsets. When tested on a high-resolution simulation of a convective boundary layer, the analysis recovers the expected dynamical relations between turbulence intensity, wind speed and the spectral parameters. Run on 3 years of co-located GNSS and wind LiDAR observations from Payerne, Switzerland, the same patterns emerge under summer conditions, while they disappear in winter when the diurnal cycle of turbulence is muted. Spectral parameters can be retrieved from existing GNSS networks with a relative uncertainty below 5% throughout the day, including at night. These results support the use of GNSS as a complementary observing system for boundary-layer dynamics in regions lacking dedicated meteorological instrumentation. 2026-01-01T00:00:00Z http://hdl.handle.net/20.500.11765/17964 Título : Overview: The Network for the Detection of Atmospheric Composition Change at 35 years: achievements and future strategy Autor : Petropavlovskikh, Irina; De Mazière, Martine; Thompson, Anne M.; Wild, Jeannette; Hannigan, James W.; Selkirk, Henry; Hannun, Reem A.; Steinbrecht, Wolfgang; Lambert, Jean-Christopher; Van Malderen, Roeland; Asher, Elizabeth; Cordero, Raul R.; Godin-Beekmann, Sophie; Hubert, Daan; Khaykin, Sergey; Kreher, Karin; Leblanc, Thierry; Mahieu, Emmanuel; Maillard Barras, Eliane; McConville, Glen; Nedoluha, Gerald; Ortega, Ivan; Redondas, Alberto; Seckmeyer, Gunther; Stauffer, Ryan M.; Strode, Sarah A.; Strong, Kimberly; Sugita, Takafumi; Roozendael, Michel Van; Velazco, Voltaire A.; Vigouroux, Corinne; Vogel, Bärbel Resumen : Since 1991, continuous, consistently calibrated and openly archived ground-based measurements from the Network for the Detection of Atmospheric Composition Change (NDACC) have been collected to investigate processes responsible for decadal-scale changes, anomalies in atmospheric composition, and to validate satellite observations and model simulations. These measurements, from nearly 120 stations, support fundamental research in the area of stratospheric and tropospheric processes impacting ozone chemistry, greenhouse gases, atmospheric radiative forcing, air quality, and interactions with solar radiation and the entire Earth system. NDACC data are supplemented by observations from eleven global Cooperating Networks. The operational principles of Cooperating Networks are well aligned with NDACC objectives and protocols, focusing on data that (a) are high-quality, uniformly processed and traceable to reference standards; and (b) capture short-term (daily to interannual) anomalies and long-term trends. This paper summarizes the NDACC organizational structure. We also review the major accomplishments of NDACC since De Mazière et al. (2018), collaborative research with Cooperating Networks, and interactions with the satellite and modeling communities. Ground-based atmospheric composition monitoring is at a crossroads. Challenges include sustainability of human and financial resources required for complex and intensive data collection, technical issues including aging instrumentation, requirements for FAIR (findable, accessible, interoperable, reusable) data, and lack of data over large parts of Asia, Africa and South America. NDACC is well-positioned to adopt a three-pronged strategy going forward: protecting and modernizing existing stations; promoting the growing use of NDACC data; expanding the number of measured species and network coverage in under-sampled or under-reporting regions. 2026-01-01T00:00:00Z