Southern Argentina Agile Meteor Radar: System design and initial measurements of large-scale winds and tides

The Southern Argentina Agile Meteor Radar (SAAMER) was installed at Rio Grande on Tierra del Fuego (53.8°S, 67.8°W) in May 2008 and has been operational for ∼24 months. This paper describes the motivations for the radar design and its placement at the southern tip of South America, its operating modes and capabilities, and observations of the mean winds, planetary waves, and tides during its first ∼20 months of operation. SAAMER was specifically designed to provide very high resolution of large-scale motions and hopefully enable direct measurements of the vertical momentum flux by gravity waves, which have only been possible previously with dual- or multiple-beam radars and lidars or in situ measurements. SAAMER was placed on Tierra del Fuego because it was a region devoid of similar measurements, the latitude was anticipated to provide high sensitivity to an expected large semidiurnal tide, and the region is now recognized to be a "hot spot" of small-scale gravity wave activity extending from the troposphere into the mesosphere and lower thermosphere, perhaps the most dynamically active location on Earth. SAAMER was also intended to permit simultaneous enhanced meteor studies, including "head echo" and "nonspecular" measurements, which were previously possible only with high-power large-aperture radars. Initial measurements have defined the mean circulation and structure, exhibited planetary waves at various periods, and revealed large semidiurnal tide amplitudes and variability, with maximum amplitudes at higher altitudes often exceeding 60 m s-1 and amplitude modulations at periods from a few to ∼30 days.Universidad Nacional De La Plat

Southern Argentina Agile Meteor Radar: System design and initial measurements of large-scale winds and tides

The Southern Argentina Agile Meteor Radar (SAAMER) was installed at Rio Grande on Tierra del Fuego (53.8°S, 67.8°W) in May 2008 and has been operational for ∼24 months. This paper describes the motivations for the radar design and its placement at the southern tip of South America, its operating modes and capabilities, and observations of the mean winds, planetary waves, and tides during its first ∼20 months of operation. SAAMER was specifically designed to provide very high resolution of large-scale motions and hopefully enable direct measurements of the vertical momentum flux by gravity waves, which have only been possible previously with dual- or multiple-beam radars and lidars or in situ measurements. SAAMER was placed on Tierra del Fuego because it was a region devoid of similar measurements, the latitude was anticipated to provide high sensitivity to an expected large semidiurnal tide, and the region is now recognized to be a "hot spot" of small-scale gravity wave activity extending from the troposphere into the mesosphere and lower thermosphere, perhaps the most dynamically active location on Earth. SAAMER was also intended to permit simultaneous enhanced meteor studies, including "head echo" and "nonspecular" measurements, which were previously possible only with high-power large-aperture radars. Initial measurements have defined the mean circulation and structure, exhibited planetary waves at various periods, and revealed large semidiurnal tide amplitudes and variability, with maximum amplitudes at higher altitudes often exceeding 60 m s-1 and amplitude modulations at periods from a few to ∼30 days.Universidad Nacional De La Plat

Southern Argentina Agile Meteor Radar: System design and initial measurements of large-scale winds and tides

The Southern Argentina Agile Meteor Radar (SAAMER) was installed at Rio Grande on Tierra del Fuego (53.8°S, 67.8°W) in May 2008 and has been operational for ∼24 months. This paper describes the motivations for the radar design and its placement at the southern tip of South America, its operating modes and capabilities, and observations of the mean winds, planetary waves, and tides during its first ∼20 months of operation. SAAMER was specifically designed to provide very high resolution of large-scale motions and hopefully enable direct measurements of the vertical momentum flux by gravity waves, which have only been possible previously with dual- or multiple-beam radars and lidars or in situ measurements. SAAMER was placed on Tierra del Fuego because it was a region devoid of similar measurements, the latitude was anticipated to provide high sensitivity to an expected large semidiurnal tide, and the region is now recognized to be a "hot spot" of small-scale gravity wave activity extending from the troposphere into the mesosphere and lower thermosphere, perhaps the most dynamically active location on Earth. SAAMER was also intended to permit simultaneous enhanced meteor studies, including "head echo" and "nonspecular" measurements, which were previously possible only with high-power large-aperture radars. Initial measurements have defined the mean circulation and structure, exhibited planetary waves at various periods, and revealed large semidiurnal tide amplitudes and variability, with maximum amplitudes at higher altitudes often exceeding 60 m s-1 and amplitude modulations at periods from a few to ∼30 days.Universidad Nacional De La Plat

Detrital events and hydroclimate variability in the Romanian Carpathians during the mid-to-late Holocene

The Romanian Carpathians are located at the confluence of three major atmospheric pressure fields: the North Atlantic, the Mediterranean and the Siberian. Despite its importance for understanding past human impact and climate change, high-resolution palaeoenvironmental reconstructions of Holocene hydroclimate variability, and in particular records of extreme precipitation events in the area, are rare. Here we present a 7500-year-long high-resolution record of past climatic change and human impact recorded in a peatbog from the Southern Carpathians, integrating palynological, geochemical and sedimentological proxies. Natural climate fluctuations appear to be dominant until 4500 years before present (yr BP), followed by increasing importance of human impact. Sedimentological and geochemical analyses document regular minerogenic deposition within the bog, linked to periods of high precipitation. Such minerogenic depositional events began 4000 yr BP, with increased depositional rates during the Medieval Warm Period (MWP), the Little Ice Age (LIA) and during periods of societal upheaval (e.g. the Roman conquest of Dacia). The timing of minerogenic events appears to indicate a teleconnection between major shifts in North Atlantic Oscillation (NAO) and hydroclimate variability in southeastern Europe, with increased minerogenic deposition correlating to low NAO index values. By linking the minerogenic deposition to precipitation variability, we state that this link persists throughout the mid-to-late Holocene

Climatology of quasi-2-day wave structure and variability at middle latitudes in the northern and southern hemispheres.

Climatological structure of the quasi-2-day wave (Q2DW) at middle latitudes in temperature and horizontal winds in the mesosphere and lower thermosphere (MLT) was compared between the northern and southern hemispheres. Determination of the Q2DW in temperature was based on observation data by the Microwave Limb Sounder (MLS) onboard NASA's Earth Observing System (EOS) Aura satellite over 17 years from 2004 to 2021 and the Q2DW in horizontal winds was derived from Aura/MLS geopotential height data using balance equations. Amplitudes were maximized in summer in the southern hemisphere and in the meridional wind in the northern hemisphere, but in winter in the zonal wind in the northern hemisphere. Summer amplitudes were larger in the meridional wind than the zonal wind in the southern hemisphere, but zonal amplitudes in winter were larger than meridional amplitudes in summer in the northern hemisphere. Westward propagating zonal wavenumber 3 (W3) was largest in both hemispheres, but in addition to well-known W4, W3, W2 and eastward propagating zonal wavenumber 2 (E2), we also found W1, zonally symmetric standing (S0), and E1. Eliassen-Palm fluxes were derived for each mode. W3, W2, W1, and E2 fluxes were exhibited upward and poleward in January in the southern hemisphere while only W3 fluxes were exhibited clearly upward and poleward in July in the northern hemisphere. Comparison between Q2DW balance winds and radar winds showed modulations in amplitudes and phase of the Q2DW from the W3 by accumulating other modes. Furthermore, the balance winds and radar winds agreed in both amplitude and phase in the southern hemisphere and at lower latitudes in the northern hemisphere in January, and at lower latitudes in both hemispheres in July