Related Experiment Video
Updated: Aug 18, 2025
12:21
Stimulated Stokes and Antistokes Raman Scattering in Microspherical Whispering Gallery Mode Resonators
Published on: April 4, 2016
11.3K
Rossby wave second harmonic generation observed in the middle atmosphere
Maosheng He1, Jeffrey M Forbes2
1Key Laboratory of Solar Activity and Space Weather, National Space Science Center, Chinese Academy of Sciences, Beijing, P. R. China. hmq512@gmail.com.
Nature Communications
|December 8, 2022
Summary
Scientists observed second harmonic generation of atmospheric Rossby waves for the first time. This nonlinear wave-wave interaction explains how low-frequency Rossby waves generate higher-frequency waves in the middle atmosphere.
Area of Science:
- Atmospheric science
- Geophysics
- Wave physics
Background:
- Second harmonic generation is a fundamental wave-wave nonlinear interaction observed in various physical systems.
- It is theorized to be a key mechanism for generating high-frequency Rossby waves from low-frequency waves in the atmosphere.
Purpose of the Study:
- To report the first observational evidence of second harmonic generation of Rossby waves in Earth's atmosphere.
- To confirm the role of Rossby wave nonlinearity in atmospheric wave dynamics.
Main Methods:
- Utilized meteor-radar wind observations from European and Asian sectors during the 2018-2019 winter.
- Analyzed transient wave signatures with periods of 16 and 8 days.
- Employed bicoherence and biphase analyses to investigate frequency, wavenumber relations, and phase couplings.
Main Results:
- Identified distinct wave signatures with 16-day and 8-day periods in the terrestrial middle atmosphere.
- Diagnosed the 16-day wave as a Rossby wave normal mode.
- Confirmed that the second harmonic generation of the 16-day wave produces the observed 8-day wave signature.
Conclusions:
- The study provides the first direct observation of Rossby wave second harmonic generation in the atmosphere.
- This finding validates the long-standing theoretical prediction of Rossby wave nonlinearity driving high-frequency wave generation.
- The observed phenomenon contributes to understanding energy transfer and cascade processes in atmospheric waves.
Related Concept Videos
01:10Generating Electromagnetic Radiations
3.4K
The German physicist Heinrich Hertz (1857–1894) was the first to generate and detect certain types of electromagnetic waves in the laboratory. Starting in 1887, he performed a series of experiments that confirmed the existence of electromagnetic waves and verified that they travel at the speed of light. Hertz used an alternating-current RLC (resistor-inductor-capacitor) circuit that resonated at a known frequency and connected it to a loop of wire. High voltages induced across the gap in...
3.4K
01:03Modes of Standing Waves - I
3.0K
A close look at earthquakes provides evidence for the conditions appropriate for resonance, standing waves, and constructive and destructive interference. A building may vibrate for several seconds with a driving frequency matching the building's natural frequency of vibration; this produces a resonance that results in one building collapsing while the neighboring buildings do not. Often, buildings of a certain height are devastated, while other taller buildings remain intact. This...
3.0K
01:04Modes of Standing Waves: II
901
The starting point for expressing the modes of standing waves is understanding the boundary conditions that the waves must follow. The boundary conditions are derived from the physical understanding of how the standing waves are sustained, that is, how the vibrating particles of the medium behave at the boundaries imposed on them.
For a tube open at one end and closed at the other filled with air, the modes are such that there is always an antinode at the open end and a node at the closed end....
For a tube open at one end and closed at the other filled with air, the modes are such that there is always an antinode at the open end and a node at the closed end....
901
01:14Sound Waves: Resonance
2.7K
Resonance is produced depending on the boundary conditions imposed on a wave. Resonance can be produced in a string under tension with symmetrical boundary conditions (i.e., has a node at each end). A node is defined as a fixed point where the string does not move. The symmetrical boundary conditions result in some frequencies resonating and producing standing waves, while other frequencies interfere destructively. Sound waves can resonate in a hollow tube, and the frequencies of the sound...
2.7K
01:16Shock Waves
2.1K
While deriving the Doppler formula for the observed frequency of a sound wave, it is assumed that the speed of sound in the medium is greater than the source's speed through it. When this condition is breached, a shock wave occurs.
When the source's speed approaches the speed of sound, constructive interference between successive wavefronts emitted by the source occurs immediately behind it. Initially, scientists believed that this constructive interference would result in such high...
When the source's speed approaches the speed of sound, constructive interference between successive wavefronts emitted by the source occurs immediately behind it. Initially, scientists believed that this constructive interference would result in such high...
2.1K
01:10Wave Parameters
7.9K
The simplest mechanical waves are associated with simple harmonic motion and repeat themselves for several cycles. These simple harmonic waves can be modeled using a combination of sine and cosine functions. Consider a simplified surface water wave that moves across the water's surface. Unlike complex ocean waves, in surface water waves, water moves vertically, oscillating up and down, whereas the disturbance of the wave moves horizontally through the medium. If a seagull is floating on the...
7.9K