Significance Non–line-of-sight (NLOS) imaging can recover details of a hidden scene from the indirect light that has scattered multiple times. Despite recent advances, NLOS remained at short-range verifications. Here, both experimental and conceptual innovations yield hardware software solutions to increase meter kilometer range. This range is about three orders magnitude longer than previous experiments. The results will open avenues for development techniques relevant applications...

Observations with the Venus Express magnetometer and low-energy particle detector revealed magnetic field plasma behavior in near-Venus wake that is symptomatic of reconnection, a process occurs Earth's magnetotail but not expected nonmagnetized planet such as Venus. On 15 May 2006, flow this region was toward planet, component transverse to reversed. Magnetic reconnection changes topology results energy exchange between plasma. Thus, energetics resembles terrestrial tail, where stored later...

Abstract In this study, multiple data sets from Beidou geostationary orbit satellites total electron contents (TECs), ionosonde, meteor radar, magnetometer, and model simulations have been used to investigate the ionospheric responses in Asian‐Australian sector during September 2017 geomagnetic storm. It was found that long‐duration daytime TEC enhancements lasted 7 12 were observed by satellite constellation. This is a unique event as prominent persisted storm recovery phase when activity...

We present a fully integrated InGaAs/InP negative feedback avalanche diode (NFAD) based free-running single-photon detector (SPD) designed for accurate lidar applications.A freepiston Stirling cooler is used to cool down the NFAD with large temperature range, and an active hold-off circuit implemented in field programmable gate array applied further suppress afterpulsing contribution.The key parameters of SPD including photon detection efficiency (PDE), dark count rate (DCR), afterpulse...

Seasonal and interannual variations of the Quasi‐Two‐Day wave s = −3 (W3) −4 (W4) modes were studied with global temperature wind data sets during 2002–2012, observed respectively by Sounding Atmosphere using Broadband Emission Radiometry (SABER) TIMED Doppler Imager (TIDI) instruments onboard Thermosphere Ionosphere Mesosphere Electric Dynamics (TIMED) satellite. The amplitudes W3 W4 are significantly enhanced austral boreal summer respectively. Strong January 2006 in all three components...

A mobile Rayleigh Doppler lidar based on double-edge technique is developed for mid-altitude wind observation. To reduce the systematic error, a system-level optical frequency control method proposed and demonstrated. The emission of seed laser at 1064 nm used to synchronize FPI in domain. servo loop stabilizing formed by measuring absolute second harmonic against an iodine absorption line. And, third detection. stability 1.6 MHz over 2 minutes. locking accuracy 0.3 realized. In comparison...

A dual-frequency direct detection Doppler lidar is demonstrated using a superconducting nanowire single-photon detector (SNSPD) at 1.5 μm. The so-called double-edge technique implemented by laser pulse, rather than double-channel Fabry-Perot interferometer. Such modification to the reported lidars enhances frequency stability in system level. Using time-division multiplexing method, only one piece of SNSPD used optical receiver, making simplified and robust. adopted enhance temporal...

Abstract It is commonly believed that solar eclipses have a great impact on the ionosphere‐thermosphere (I‐T) system within eclipse shadow, but little attention has been paid to global response these events. In this study, we investigate upper atmospheric responses recent Great American Solar Eclipse occurred 21 August 2017 using high‐resolution coupled ionosphere‐thermosphere‐electrodynamics model. The simulation results show ionosphere and thermosphere not just local global. Large‐scale...

A micro-pulse lidar at eye-safe wavelength is constructed based on an upconversion single-photon detector. The ultralow-noise detector enables using integration technique to improve the signal-to-noise ratio of atmospheric backscattering even daytime. With pulse energy 110 μJ, repetition rate 15 kHz, optical antenna diameter 100 mm and time 5 min, a horizontal detection range 7 km realized. In demonstration experiment, visibility over 24 h monitored continuously, with results in accordance...

Abstract. On the basis of S4max data retrieved from COSMIC GPS radio occultation measurements, long-term climatology intensity Es layers is investigated for period December 2006 to January 2014. Global maps show high-spatial-resolution geographical distribution and strong seasonal dependence layers. The maximum occurs over mid-latitudes, its value in summer 2–3 times larger than that winter. A relatively layer observed at North Pole South Pole, with a distinct boundary dividing mid-latitudes...

Doppler wind lidar is an effective tool for detection with high temporal and spatial resolution. However, precise profile measurement under rainy conditions a challenge, due to the interfering signals from raindrop reflections. In this work, compact all-fiber coherent (CDL) at working wavelength of 1.5 µm applied simultaneous precipitation detection. The performance validated by comparison weather balloons. Thanks ability spectrum measurement, both aerosol rainfall can be detected CDL...

Abstract In the Southern Hemisphere (SH) polar region, satellite observations reveal a significant upper-mesosphere cooling and lower-thermosphere warming during warm ENSO events in December. An opposite pattern is observed tropical mesopause region. The agrees with climate model simulation. Analysis of simulation suggests that enhanced planetary wave (PW) dissipation Northern (NH) high-latitude stratosphere El Niño strengthens Brewer–Dobson circulation cools equatorial stratosphere. This...

Spectroscopy is a well-established nonintrusive tool that has played an important role in identifying and quantifying substances, from quantum descriptions to chemical biomedical diagnostics. Challenges exist accurate spectrum analysis free space, which hinders us understanding the composition of multiple gases processes atmosphere. A photon-counting distributed free-space spectroscopy proposed demonstrated using lidar technique, incorporating comb-referenced frequency-scanning laser...

Abstract The effects of volcanic eruptions on the ionosphere have been well studied, however, evidence for anticipated upper atmospheric neutral variations and their exact extents change are rarely available. Here, we report dramatic thermospheric disturbances following 15 January 2022 Tonga eruption. GRACE‐FO Swarm‐C observations from accelerometers exhibited three successive density waves at ∼500 km altitudes propagating concentrically across globe 200–450 m/s phase speed two converged...

Non-line-of-sight (NLOS) imaging has the ability to reconstruct hidden objects, allowing a wide range of applications. Existing NLOS systems rely on pulsed lasers and time-resolved single-photon detectors capture information encoded in time flight scattered photons. Despite remarkable advances, time-of-flight LIDAR approach limited temporal resolution struggles detect frequency-associated directly. Here, we propose demonstrate coherent scheme-frequency-modulated continuous wave calibrated by...

In this study, we use an ice‐cream cone model to analyze the geometrical and kinematical properties of coronal mass ejections (CMEs). Assuming that in early phase CMEs propagate with near‐constant speed angular width, some useful CMEs, namely radial ( v ), width (α), location at heliosphere, can be obtained considering shapes a CME as cone. This is improved by (1) using show near real configuration CME, (2) determining via fitting projected speeds calculated from height‐time relation...

In this paper, we studied the possible relations between incoming meteors, sporadic E (Es) layers, and (or sudden) sodium atom layers (SSLs) using data from FORMOSAT‐3/COSMIC constellation, a meteor radar (Wuhan, 31°N, 114°E), fluorescent lidar (Hefei, 31.8°N, 117.3°E). From statistical point of view, seasonal dependence SSL correlates well with annual variation Es is also consistent deposition except for February March. It suggests that “meteor‐Es‐SSL” chain could be reasonable if...

In this paper, observations from CHAMP and GRACE during 2002–2010 are used to study the seasonal variations of thermospheric density by characterizing dominant modes variability as empirical orthogonal functions (EOFs). Our results showed that first three EOFs captured most variability, which can be large 98% total variability. Subsequently, obtained mean field, corresponding amplitudes applied construct a model at 400 km under geomagnetically quiet conditions. Thermospheric shows strong...

Infrared radiative emissions by carbon dioxide (CO 2 ) and nitric oxide (NO) are the major cooling mechanisms of lower thermosphere. During geomagnetically active periods, NO density rate in auroral regions increase significantly as a result particle precipitation Joule heating. Previous studies have shown that time for to recover quiet levels is longer than thermosphere temperature or recovery. This study explores implications these different recovery rates post‐storm Thermosphere densities...

We report two lower thermospheric‐enhanced sodium layer (TeSL) cases observed at a low‐latitude station, Lijiang, China (26.7°N, 100.0°E), on 10 March and April 2012, respectively. The TeSLs in the were located altitudes near 122 112 km, In addition, strong sporadic layers (SSLs) 100 km accompanied TeSL 2012. Both SSLs exhibited tidal‐induced downward motion. adjacent ground‐based space‐borne ionospheric radio observations showed E s before appearance of TeSLs, suggesting an “ – (SSLs)”...

We report the statistical features of sporadic sodium layers (SSLs) and thermospheric enhanced (TeSLs) observed by a lidar chain located at Beijing (40.2°N, 116.2°E), Hefei (31.8°N, 117.3°E), Wuhan (30.5°N, 114.4°E), Haikou (19.5°N, 109.1°E). The average SSL occurrence rate was approximately 46.0, 12.3, 13.8, 15.0 h per Beijing, Hefei, Wuhan, Haikou, respectively. However, TeSLs occurred relatively infrequently were more likely to appear low high latitudinal sites. Both SSLs four sites...

Abstract Topside ionospheric total electron content (TEC) observations from multiple low‐Earth orbit (LEO) satellites have been used to investigate the local time, altitudinal, and longitudinal dependence of topside storm effect during both main recovery phases March 2015 geomagnetic storm. The results this study show, for first that there was a persistent TEC depletion lasted more than 3 days after phase at most longitudes, except in Pacific Ocean region, where TECs were comparable quiet...

A mobile Rayleigh Doppler lidar based on the molecular double-edge technique is developed for measuring wind velocity in middle atmosphere up to 60 km. The uses three lasers with a mean power of 17.5 W at 355 nm each and 1 m diameter telescopes receive backscattered echo: one points zenith vertical component temperature measurement; two others pointing toward east north are titled 30° from zonal meridional component, respectively. shift echo measured by inter-comparing signal detected...

Abstract The ionospheric radio occultation measurements from Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) satellites during 2007–2012 are utilized to analyze variations of the hemispheric asymmetry in equatorial ionization anomaly (EIA) solstice seasons. A index ( h ) is introduced quantitatively characterize relative interhemispheric or north‐south differences EIA crests. seasonal, solar activity, longitudinal dependences investigated these low moderately...