Rudolph Clausius (1822–1888) and His Concept of Mathematical Physics

Rudolph Clausius is well known as a pioneer of the mechanical theory of heat (1857) and as the creator of the concept of entropy (1865). Oftentimes, he is also called the discoverer of the second law of thermodynamics although some argue that this law was already established by Sadi Carnot in 1824 (while still based on the caloric theory). But beyond any doubt, it was Clausius who gave in 1850 the first mathematically correct formulation of the first law (in its differential form that is still valid today, dQ = dU + pdV) and a particularly stringent exposition of both the necessity and independence of the two laws, indeed a logical masterpiece. This paper focuses on his concept of mathematical physics for the development of theoretical physics, contributions that have changed physics well beyond the field of thermodynamics

Retrieval of O₂(¹Σ) and O₂(¹Δ) volume emission rates in the mesosphere and lower thermosphere using SCIAMACHY MLT limb scans

We present the retrieved volume emission rates (VERs) from the airglow of both the daytime and twilight O2(1Σ) band and O2(1Δ) band emissions in the mesosphere and lower thermosphere (MLT). The SCanning Imaging Absorption SpectroMeter for Atmospheric CHartographY (SCIAMACHY) onboard the European Space Agency Envisat satellite observes upwelling radiances in limb-viewing geometry during its special MLT mode over the range 50–150 km. In this study we use the limb observations in the visible (595–811 nm) and near-infrared (1200–1360 nm) bands. We have investigated the daily mean latitudinal distributions and the time series of the retrieved VER in the altitude range from 53 to 149 km. The maximal observed VERs of O2(1Δ) during daytime are typically 1 to 2 orders of magnitude larger than those of O2(1Σ). The latter peaks at around 90 km, whereas the O2(1Δ) emissivity decreases with altitude, with the largest values at the lower edge of the observations (about 53 km). The VER values in the upper mesosphere (above 80 km) are found to depend on the position of the sun, with pronounced high values occurring during summer for O2(1Δ). O2(1Σ) emissions show additional high values at polar latitudes during winter and spring. These additional high values are presumably related to the downwelling of atomic oxygen after large sudden stratospheric warmings (SSWs). Accurate measurements of the O2(1Σ) and O2(1Δ) airglow, provided that the mechanism of their production is understood, yield valuable information about both the chemistry and dynamics in the MLT. For example, they can be used to infer the amounts and distribution of ozone, solar heating rates, and temperature in the MLT

Analysis of an 18O and D enhanced water spectrum and new assignments for HD18O and D218O in the near-infrared region (6000–7000 cm−1) using newly calculated variational line lists

An experimental infrared spectrum due to Orphal and Ruth (2008) [10] recorded using isotopically enriched water in the 6000–7000 cm−1 region is analysed and assigned. The assignment procedure is based on the use of known transition frequencies for H216O and H218O, existing variational line lists for HD16O and D216O, and newly calculated variational line lists for HD18O and D218O. These new variational line lists are presented herein. The main absorption comes from HD16O and HD18O, for which there are few previous assignments in the region. Assignments to 426 new HD18O lines are presented. In all 3254 of the 4768 lines observed in the spectrum are assigned, resulting in a number of newly determined energy levels. These assignments are in agreement with the recent work of Mikhailenko et al. (2012) [41]

Incoherent broadband cavity-enhanced absorption spectroscopy in the near-ultraviolet: application to HONO and NO2

The first application of incoherent broadband cavity-enhanced absorption spectroscopy (IBBCEAS) in the near-ultraviolet for the simultaneous detection of two key atmospheric trace species, HONO and NO2, is reported. For both compounds the absorption is measured between 360 and 380 nm with a compact cavity-enhanced spectrometer employing a high power light-emitting diode. Detection limits of similar to 4 ppbv for HONO and similar to 14 ppbv for NO2 are reported for a static gas cell setup using a 20 s acquisition time. Based on an acquisition time of 10 min and an optical cavity length of 4.5 m detection limits of similar to 0.13 ppbv and similar to 0.38 ppbv were found for HONO and NO2 in a 4 m(3) atmospheric simulation chamber, demonstrating the usefulness of this approach for in situ monitoring of these important species in laboratory studies or field campaigns

The near infrared cavity-enhanced absorption spectrum of methyl cyanide

The absorption spectrum of methyl cyanide (CH3CN) has been measured in the near IR between 6000 and 8000 cm(-1) with a resolution of 0.12 cm(-1) using Fourier transform incoherent broadband cavity-enhanced absorption spectroscopy. The spectrum contains several weakly perturbed spectral regions: potential vibrational combination bands contributing to the spectrum are outlined. Line positions and cross-sections of CH3CN between 6814 and 7067 cm(-1) have been measured at high-resolution of 0.001 cm(-1) using diode laser based off-axis cavity-enhanced absorption spectroscopy. A total of 4630 new absorption lines of CH3CN are identified in this region. A value for the self-broadening coefficient has determined to be (3.3 +/- 0.2) X 10(-3) cm(-1) mbar(-1) for one isolated line at 7034.171 cm(-1). Several line series have been identified in these regions and an autocorrelation analysis performed with a view to aiding future assignments of the rotational-vibrational transitions

High sensitivity in situ monitoring of NO3 in an atmospheric simulation chamber using incoherent broadband cavity-enhanced absorption spectroscopy

We describe the application of incoherent broadband cavity-enhanced absorption spectroscopy (IBBCEAS) for the in situ detection of atmospheric trace gases and radicals (NO3, NO2, O-3, H2O) in an atmospheric simulation chamber under realistic atmospheric conditions. The length of the optical cavity across the reaction chamber is 4.5 m, which is significantly longer than in previous studies that use high finesse optical cavities to achieve high absorption sensitivity. Using a straightforward spectrometer configuration, we show that detection limits corresponding to typical atmospheric concentrations can be achieved with a measurement time of seconds to a few minutes. In particular, with only moderate reflectivity mirrors, we report a measured sensitivity of 4 pptv to NO3 in a 1 min acquisition time. The high spatial and temporal resolution of the IBBCEAS method and its pptv sensitivity to NO3 makes it useful in laboratory studies of atmospheric processes as well as having obvious potential for field measurements.We describe the application of incoherent broadband cavity-enhanced absorption spectroscopy (IBBCEAS) for the in situ detection of atmospheric trace gases and radicals (NO3, NO2, O-3, H2O) in an atmospheric simulation chamber under realistic atmospheric conditions. The length of the optical cavity across the reaction chamber is 4.5 m, which is significantly longer than in previous studies that use high finesse optical cavities to achieve high absorption sensitivity. Using a straightforward spectrometer configuration, we show that detection limits corresponding to typical atmospheric concentrations can be achieved with a measurement time of seconds to a few minutes. In particular, with only moderate reflectivity mirrors, we report a measured sensitivity of 4 pptv to NO3 in a 1 min acquisition time. The high spatial and temporal resolution of the IBBCEAS method and its pptv sensitivity to NO3 makes it useful in laboratory studies of atmospheric processes as well as having obvious potential for field measurements

A new cavity ring-down instrument for airborne monitoring of N2O5, NO3, NO2 and O3 in the upper troposphere lower stratosphere

A new airborne instrument based on pulsed cavity ring-down spectroscopy for simultaneous detection of N2O5, NO3, NO2 and O3 in the upper troposphere lower stratosphere is being developed for global atmospheric monitoring. OCIS codes: 010.0010, 120.0120, 140.0140, 280.0280, 300.0300, 300.6260, 300.6360

First detection of ammonia (NH₃) in the Asian summer monsoon upper troposphere

Ammonia (NH3) has been detected in the upper troposphere by the analysis of averaged MIPAS (Michelson Interferometer for Passive Atmospheric Sounding) infrared limb-emission spectra. We have found enhanced amounts of NH3 within the region of the Asian summer monsoon at 12–15 km altitude. Three-monthly, 10° longitude  ×  10° latitude average profiles reaching maximum mixing ratios of around 30 pptv in this altitude range have been retrieved, with a vertical resolution of 3–8 km and estimated errors of about 5 pptv. These observations show that loss processes during transport from the boundary layer to the upper troposphere within the Asian monsoon do not deplete the air entirely of NH3. Thus, ammonia might contribute to the so-called Asian tropopause aerosol layer by the formation of ammonium aerosol particles. On a global scale, outside the monsoon area and during different seasons, we could not detect enhanced values of NH3 above the actual detection limit of about 3–5 pptv. This upper bound helps to constrain global model simulations