Paul Hartogh - Academia.edu (original) (raw)

Papers by Paul Hartogh

ABSTRACT Herschel has observed Mars with its three instruments, the Heterodyne Instrument for the... more ABSTRACT Herschel has observed Mars with its three instruments, the Heterodyne Instrument for the Far Infrared (HIFI), the Photodetector Array Camera & Spectrometer (PACS) and the Spectral and Photometric Imaging Receiver (SPIRE) as part of the HssO Key programme. SPIRE provided for the first time a far infrared spectrum of Mars from 0.45 to 1.55 THz. From these observations during Ls = 5°, water vapor and carbon monoxide mixing ratios of 100 ppm and 900 ppm respectively were derived. PACS observed Mars twice during Ls = 340 ° and Ls = 108 ° in the frequency range from 1.43 to 5.26 THz. The spectra show high signal-to-noise- ratio (SNR) carbon monoxide and water lines including water isotopes. HIFI has observed Mars around Ls = 78° and Ls = 108° and performed line scans from band 1a to 6b (for technical reasons excluding band 5b). Furthermore dedicated observations on carbon- and oxygen isotopes in carbon monoxide and oxygen- and hydrogen isotopes in water vapor as well as hydrogen peroxide, hydrogen chloride and molecular oxygen were executed. The latter presents the first observation of molecular oxygen in the submm wave regime. From the very high SNR spectrum a (constant with altitude) volume mixing ratio of 1400 ppm has been derived, consistent with ground-based observations in the oxygen A band (around 763 nm) from the early 1970s. Finally from the analysis of 2 carbon monoxide isotopes a globally averaged volume mixing ratio of constant 980 ppm and a vertical temperature profile have been retrieved. Compared to general circulation model calculations the observations show up to 10 K lower temperatures in the middle atmosphere of Mars.

2006 IEEE Ultrasonics Symposium, 2006

Three wideband SAW chirp filters are reported. They are 1 GHz central frequency with 400 MHz band... more Three wideband SAW chirp filters are reported. They are 1 GHz central frequency with 400 MHz bandwidth and 10 mus chirp duration, 1.5 GHz central frequency with 600 MHz bandwidth and 10 mus chirp duration, and 2 GHz central frequency with 800 MHz bandwidth and 6 mus chirp duration, respectively. With our regular design and fabrication, the passband has a

We developed a new efficient and accurate routine for calculating the non-LTE radiative cooling/h... more We developed a new efficient and accurate routine for calculating the non-LTE radiative cooling/heating (C/H) rates in CO2 bands in the Martian atmosphere. This routine: a) relies on the exact accelerated lambda itera-tion (ALI) solution of the vibrational non-LTE problem in CO2; b) utilizes opacity distribution function (ODF) technique; c) allows varying all input collisional rate and spectroscopic parameters; d) calculates C/H with a prescribed accuracy. New routine is about 10 4 times faster than the line by line (LBL) approach when reproducing C/H data with ∼15– 20% accuracy. This allowed implementing the routine to the general circulation and climate model of the Mar-tian atmosphere developed in the Max-Planck Institute for Solar System Research, and running the model at the computers of moderate performance. The difference between the "standard cooling to space" approximation and the new radiative transfer routine are discussed.

Geophysical Research Letters

1] Seasonal changes in baroclinic wave activity during northern autumns (L s = 195–225°) and wint... more 1] Seasonal changes in baroclinic wave activity during northern autumns (L s = 195–225°) and winters (L s = 280– 300°) are studied with a Martian general circulation model. For the weak dust load, the simulated s = 2 harmonic with 3.1 sols period dominates near the surface, while s = 1 (5.5 sols period) is more prominent at higher altitudes during autumns. In winters, the s = 1 wave has stronger amplitudes and a deep (up to 0.1 mb) vertical structure. These simulations are consistent with observations from MGS. We provide a simple explanation for the planetary wave changes in terms of seasonal variations of the background zonal mean fields. In particular, the observed and simulated significant reduction of the baroclinic wave activity during strong solstitial season dust storms occurs due to the stabilization of the jet stream with respect to baroclinic disturbances, and due to the associated weakening of the wave excitation. Citation: Kuroda, T., A. S. Medvedev, P. Hartogh, and M. ...

We introduce a new coupled global 3D-model of the dynamics and chemistry of the Martian atmospher... more We introduce a new coupled global 3D-model of the dynamics and chemistry of the Martian atmosphere. The model is an adjustment of the model COMMA-IAP (Cologne Model of the Middle Atmosphere of the Institute of Atmospheric Physics in Kühlungsborn) to the relation of the Martian atmosphere. It consists of a dynamical model calculating the dynamical fields of wind components and temperature and a chemistry transport model (CTM) using these dynamical fields. The model is not self- consistent thus far meaning there is no online feedback from the CTM to the dynamical model. We present first results got from the model and compare them with available observations. The outcomes will be discussed in terms of dynamics and chemistry. A particular problem consist in the stability of the Mars atmosphere. We introduce three new catalytic cycles of the oxidation of CO returning to CO2 and estimate their efficiency in different atmospheric regions and during different seasons and local times. The im...

Astronomy and Astrophysics

We report on the initial analysis of Herschel/HIFI carbon monoxide (CO) observations of the Marti... more We report on the initial analysis of Herschel/HIFI carbon monoxide (CO) observations of the Martian atmosphere performed between 11 and 16 April 2010. We selected the (7-6) rotational transitions of the isotopes ^{13}CO at 771 GHz and C^{18}O at 768 GHz in order to retrieve the mean vertical profile of temperature and the mean volume mixing ratio of carbon monoxide. The derived temperature profile agrees within less than 5 K with general circulation model (GCM) predictions up to an altitude of 45 km, however, show about 12-15 K lower values at 60 km. The CO mixing ratio was determined as 980 \pm 150 ppm, in agreement with the 900 ppm derived from Herschel/SPIRE observations in November 2009. Comment: Accepted for publication in Astronomy and Astrophysics (special issue on HIFI first results); minor changes to match published version

Journal of Geophysical Research: Atmospheres, 2014

Based on an advanced model of excited hydroxyl relaxation we calculate trends of number densities... more Based on an advanced model of excited hydroxyl relaxation we calculate trends of number densities and altitudes of the OH*-layer during the period 1961-2009. The OH*-model takes into account all major chemical processes such as the production by H + O 3 , deactivation by O, O 2 , and N 2 , spontaneous emission, and removal by chemical reactions. The OH*-model is coupled with a chemistry-transport model (CTM). The dynamical part (Leibniz Institute Model of the Atmosphere, LIMA) adapts ECMWF/ERA-40 data in the troposphere-stratosphere. The change of greenhouse gases (GHGs) such as CH 4 , CO 2 , O 3 , and N 2 O is parameterized in LIMA/CTM. The downward shift of the OH*-layer in geometrical altitudes occurs entirely due to shrinking (mainly in the mesosphere) as a result of cooling by increasing CO 2 concentrations. In order to identify the direct chemical effect of GHG changes on OH*-trends under variable solar cycle conditions, we consider three cases: (a) variable GHG and Lyman-α fluxes, (b) variable GHG and constant Lyman-α fluxes, and (c) constant GHG and Lyman-α. At midlatitudes, shrinking of the middle atmosphere descends the OH*-layer by~À300 m/decade in all seasons. The direct chemical impact of GHG emission lifts up the OH*-layer by~15-25 m/decade depending on season. Trends of the thermal and dynamical state within the layer lead to a trend of OH* height by~±100 m/decade, depending on latitude and season. Trends in layer altitudes lead to differences between temperature trends within the layer, at constant pressure, and at constant altitude, respectively, of typically 0.5 to 1 K/decade.

Measurements of isotopic ratios provide key information about the formation of cometary materials... more Measurements of isotopic ratios provide key information about the formation of cometary materials. We will present the first Herschel D/H measurement in the water of a long-period comet to be compared to the Ocean's like value in 103P/Hartley 2.

Saturn's usually slowly evolutive seasonal cycle has been disrupted in December 2010 between ... more Saturn's usually slowly evolutive seasonal cycle has been disrupted in December 2010 between 20° N and 50° N by the outbreak of an unexpected planetary-scale storm system. First Cassini/CIRS and ground-based observations have shown that temperatures, winds and chemistry have been rapidly affected by the storm in the stratosphere. Subsidence of warmer stratospheric air around the initial vortex at 1 mbar caused a dramatic increase in the infrared emission. Initially, a 16 K difference between these warm stratospheric regions, referred to as "beacons", and the cool central vortex was reported. Data taken in May 2011 by Cassini/CIRS show that the "beacons" have merged into a single hot spot. The temperature at 1 mbar had reached 190 K over a wide region according Cassini/CIRS. In this paper, we will present observations of water in Saturn carried out with the Herschel Space Observatory during the storm, in July 2011. These observations will be analyzed and diffe...

Disk averaged observations of several H2O far infrared lines in Titan’s atmosphere were performed... more Disk averaged observations of several H2O far infrared lines in Titan’s atmosphere were performed with the Herschel Space Observatory, as part of the guaranteed time key program "Water and related chemistry in the Solar System" (HssO, see Hartogh et al 2011). Two instruments were used: (i) HIFI, a heterodyne instrument (R~ 106 ) in the sub-millimeter, which measured the H2O(110-101) rotational transition at 557 GHz on June 10 and Dec. 31, 2010 (ii) PACS, a photoconductor spectrometer (R~103) which measured three water lines at 108.1, 75.4 and 66.4 microns on June 22, 2010. Additional PACS measurements at 66.4 microns on Dec. 15 and 22, 2010 and on July 09, 2011, do not show any significant line intensity variation with time, nor between the leading/trailing sides (i.e. longitude). Spectra were analyzed with a line-by-line radiative transfer code accounting for spherical geometry (Moreno et al. 2011). This model considers the H2O molecular opacity from JPL catalog (Pickett ...

As a species subject to photolytic, chemical and condensation losses, H2O present in Titan's ... more As a species subject to photolytic, chemical and condensation losses, H2O present in Titan's stratosphere must be of external origin. The discovery of CO2 by Voyager (Samuelson et al. 1981) pointed to an external supply of oxygen to Titan's atmosphere. Indeed, CO2, which also condenses, was recognized to be formed via CO+OH, where OH was likely produced by H2O photolysis. This view was supported by the ground-based discovery of CO (Lutz et al. 1983) and subsequent measurements confirming an abundance of ~50 ppm. The source of CO itself remained elusive, but inspired by the Cassini/CAPS discovery of a O+ influx rate (Hartle et al. 2006), Hörst et al. (2008) showed that an external source of O or O+ leads to the formation of CO, also pointing to the likely external origin of this compound. The most up-to-date model of Titan's oxygen chemistry by Hörst et al. (2008) adjusted the OH/H2O deposition rate as a function of the eddy diffusion coefficient below 200 km to match the...

176P/LINEAR was observed with the Heterodyne Instrument for the Far Infrared (HIFI) on-board Hers... more 176P/LINEAR was observed with the Heterodyne Instrument for the Far Infrared (HIFI) on-board Herschel. The line emission from the fundamental transition of water at 557 GHz was searched for and an upper limit on its production was inferred.

CO2 snow forms in the high-latitude atmosphere of Mars in regular patches coinciding with passage... more CO2 snow forms in the high-latitude atmosphere of Mars in regular patches coinciding with passages of baroclinic planetary waves (periodic oscillations of temperature and other meteorological fields). Our simulations using a Mars general circulation model (MGCM) show that about a half of the snow cover on the northern polar cap is created by such snowfalls. This discovery would allow to forecast snow storms in future robotic and manned missions to Mars [1].

Planetary and Space Science, 2009

a b s t r a c t ''Water and related chemistry in the Solar System'' is a Herschel Space Observato... more a b s t r a c t ''Water and related chemistry in the Solar System'' is a Herschel Space Observatory Guaranteed-Time Key Programme. This project, approved by the European Space Agency, aims at determining the distribution, the evolution and the origin of water in Mars, the outer planets, Titan, Enceladus and the comets. It addresses the broad topic of water and its isotopologues in planetary and cometary atmospheres. The nature of cometary activity and the thermodynamics of cometary comae will be investigated by studying water excitation in a sample of comets. The D/H ratio, the key parameter for constraining the origin and evolution of Solar System species, will be measured for the first time in a Jupiter-family comet. A comparison with existing and new measurements of D/H in Oort-cloud comets will constrain the composition of pre-solar cometary grains and possibly the dynamics of the protosolar nebula. New measurements of D/H in giant planets, similarly constraining the composition of protoplanetary ices, will be obtained. The D/H and other isotopic ratios, diagnostic of Mars' atmosphere evolution, will be accurately measured in H 2 O and CO. The role of water vapor in Mars' atmospheric chemistry will be studied by monitoring vertical profiles of H 2 O and HDO and by searching for several

1] We report on the first detection of the semiannual oscillation (SAO) in the Martian atmosphere... more 1] We report on the first detection of the semiannual oscillation (SAO) in the Martian atmosphere. The semiannual periodicity is found in the difference between day-and night-time atmospheric temperatures, a good proxy for solar tides, measured from Mars Global Surveyor. Simulations with a general circulation model proved that this modulation of tidal amplitudes is a manifestation of the SAO of zonal winds in Martian tropics. Our numerical experiments revealed significant differences in driving mechanisms of the SAO between Mars and Earth. On Mars, unlike on Earth, equatorial Kelvin waves supply only small retrograde torque to the mean circulation. Instead, thermal tides and quasi-stationary planetary waves induced by Martian topography contribute strongly to the prograde (super-rotation) acceleration. The existence of the SAO on Mars suggests that this phenomenon is not a result of the unique terrestrial environment, but a more general consequence of wave-mean flow interactions in atmospheres of fast-rotating planets. Citation: Kuroda, T., A. S. Medvedev, P. Hartogh, and M. Takahashi (2008), Semiannual oscillations in the atmosphere of Mars, Geop hy s. Res . Let t. , 35 , L23 20 2,

Temperature inversions and the warmings over the winter poles in the Martian atmosphere occur due... more Temperature inversions and the warmings over the winter poles in the Martian atmosphere occur due to the adiabatic heating associated with the downward branch of the Hadley circulation. We present results of simulations with a recently developed GCM which suggest that the warmings are the manifestations of the global meridional transport, and are strongly related to atmospheric eddies (planetary waves and tides). To date, sets of data required for the validation of the predicted warmings and the corresponding circulation patterns do not extend far enough into the middle atmosphere of Mars. This motivated our radiative and retrieval simulations to demonstrate that sub-millimeter observations can provide the required fields to validate and constrain the GCM results. r (P. Hartogh), medvedev@mps.mpg.de (A.S. Medvedev), jarchow@mps.mpg.de (C. Jarchow).

ABSTRACT Herschel has observed Mars with its three instruments, the Heterodyne Instrument for the... more ABSTRACT Herschel has observed Mars with its three instruments, the Heterodyne Instrument for the Far Infrared (HIFI), the Photodetector Array Camera & Spectrometer (PACS) and the Spectral and Photometric Imaging Receiver (SPIRE) as part of the HssO Key programme. SPIRE provided for the first time a far infrared spectrum of Mars from 0.45 to 1.55 THz. From these observations during Ls = 5°, water vapor and carbon monoxide mixing ratios of 100 ppm and 900 ppm respectively were derived. PACS observed Mars twice during Ls = 340 ° and Ls = 108 ° in the frequency range from 1.43 to 5.26 THz. The spectra show high signal-to-noise- ratio (SNR) carbon monoxide and water lines including water isotopes. HIFI has observed Mars around Ls = 78° and Ls = 108° and performed line scans from band 1a to 6b (for technical reasons excluding band 5b). Furthermore dedicated observations on carbon- and oxygen isotopes in carbon monoxide and oxygen- and hydrogen isotopes in water vapor as well as hydrogen peroxide, hydrogen chloride and molecular oxygen were executed. The latter presents the first observation of molecular oxygen in the submm wave regime. From the very high SNR spectrum a (constant with altitude) volume mixing ratio of 1400 ppm has been derived, consistent with ground-based observations in the oxygen A band (around 763 nm) from the early 1970s. Finally from the analysis of 2 carbon monoxide isotopes a globally averaged volume mixing ratio of constant 980 ppm and a vertical temperature profile have been retrieved. Compared to general circulation model calculations the observations show up to 10 K lower temperatures in the middle atmosphere of Mars.

2006 IEEE Ultrasonics Symposium, 2006

Three wideband SAW chirp filters are reported. They are 1 GHz central frequency with 400 MHz band... more Three wideband SAW chirp filters are reported. They are 1 GHz central frequency with 400 MHz bandwidth and 10 mus chirp duration, 1.5 GHz central frequency with 600 MHz bandwidth and 10 mus chirp duration, and 2 GHz central frequency with 800 MHz bandwidth and 6 mus chirp duration, respectively. With our regular design and fabrication, the passband has a

We developed a new efficient and accurate routine for calculating the non-LTE radiative cooling/h... more We developed a new efficient and accurate routine for calculating the non-LTE radiative cooling/heating (C/H) rates in CO2 bands in the Martian atmosphere. This routine: a) relies on the exact accelerated lambda itera-tion (ALI) solution of the vibrational non-LTE problem in CO2; b) utilizes opacity distribution function (ODF) technique; c) allows varying all input collisional rate and spectroscopic parameters; d) calculates C/H with a prescribed accuracy. New routine is about 10 4 times faster than the line by line (LBL) approach when reproducing C/H data with ∼15– 20% accuracy. This allowed implementing the routine to the general circulation and climate model of the Mar-tian atmosphere developed in the Max-Planck Institute for Solar System Research, and running the model at the computers of moderate performance. The difference between the "standard cooling to space" approximation and the new radiative transfer routine are discussed.

Geophysical Research Letters

1] Seasonal changes in baroclinic wave activity during northern autumns (L s = 195–225°) and wint... more 1] Seasonal changes in baroclinic wave activity during northern autumns (L s = 195–225°) and winters (L s = 280– 300°) are studied with a Martian general circulation model. For the weak dust load, the simulated s = 2 harmonic with 3.1 sols period dominates near the surface, while s = 1 (5.5 sols period) is more prominent at higher altitudes during autumns. In winters, the s = 1 wave has stronger amplitudes and a deep (up to 0.1 mb) vertical structure. These simulations are consistent with observations from MGS. We provide a simple explanation for the planetary wave changes in terms of seasonal variations of the background zonal mean fields. In particular, the observed and simulated significant reduction of the baroclinic wave activity during strong solstitial season dust storms occurs due to the stabilization of the jet stream with respect to baroclinic disturbances, and due to the associated weakening of the wave excitation. Citation: Kuroda, T., A. S. Medvedev, P. Hartogh, and M. ...

We introduce a new coupled global 3D-model of the dynamics and chemistry of the Martian atmospher... more We introduce a new coupled global 3D-model of the dynamics and chemistry of the Martian atmosphere. The model is an adjustment of the model COMMA-IAP (Cologne Model of the Middle Atmosphere of the Institute of Atmospheric Physics in Kühlungsborn) to the relation of the Martian atmosphere. It consists of a dynamical model calculating the dynamical fields of wind components and temperature and a chemistry transport model (CTM) using these dynamical fields. The model is not self- consistent thus far meaning there is no online feedback from the CTM to the dynamical model. We present first results got from the model and compare them with available observations. The outcomes will be discussed in terms of dynamics and chemistry. A particular problem consist in the stability of the Mars atmosphere. We introduce three new catalytic cycles of the oxidation of CO returning to CO2 and estimate their efficiency in different atmospheric regions and during different seasons and local times. The im...

Astronomy and Astrophysics

We report on the initial analysis of Herschel/HIFI carbon monoxide (CO) observations of the Marti... more We report on the initial analysis of Herschel/HIFI carbon monoxide (CO) observations of the Martian atmosphere performed between 11 and 16 April 2010. We selected the (7-6) rotational transitions of the isotopes ^{13}CO at 771 GHz and C^{18}O at 768 GHz in order to retrieve the mean vertical profile of temperature and the mean volume mixing ratio of carbon monoxide. The derived temperature profile agrees within less than 5 K with general circulation model (GCM) predictions up to an altitude of 45 km, however, show about 12-15 K lower values at 60 km. The CO mixing ratio was determined as 980 \pm 150 ppm, in agreement with the 900 ppm derived from Herschel/SPIRE observations in November 2009. Comment: Accepted for publication in Astronomy and Astrophysics (special issue on HIFI first results); minor changes to match published version

Journal of Geophysical Research: Atmospheres, 2014

Based on an advanced model of excited hydroxyl relaxation we calculate trends of number densities... more Based on an advanced model of excited hydroxyl relaxation we calculate trends of number densities and altitudes of the OH*-layer during the period 1961-2009. The OH*-model takes into account all major chemical processes such as the production by H + O 3 , deactivation by O, O 2 , and N 2 , spontaneous emission, and removal by chemical reactions. The OH*-model is coupled with a chemistry-transport model (CTM). The dynamical part (Leibniz Institute Model of the Atmosphere, LIMA) adapts ECMWF/ERA-40 data in the troposphere-stratosphere. The change of greenhouse gases (GHGs) such as CH 4 , CO 2 , O 3 , and N 2 O is parameterized in LIMA/CTM. The downward shift of the OH*-layer in geometrical altitudes occurs entirely due to shrinking (mainly in the mesosphere) as a result of cooling by increasing CO 2 concentrations. In order to identify the direct chemical effect of GHG changes on OH*-trends under variable solar cycle conditions, we consider three cases: (a) variable GHG and Lyman-α fluxes, (b) variable GHG and constant Lyman-α fluxes, and (c) constant GHG and Lyman-α. At midlatitudes, shrinking of the middle atmosphere descends the OH*-layer by~À300 m/decade in all seasons. The direct chemical impact of GHG emission lifts up the OH*-layer by~15-25 m/decade depending on season. Trends of the thermal and dynamical state within the layer lead to a trend of OH* height by~±100 m/decade, depending on latitude and season. Trends in layer altitudes lead to differences between temperature trends within the layer, at constant pressure, and at constant altitude, respectively, of typically 0.5 to 1 K/decade.

Measurements of isotopic ratios provide key information about the formation of cometary materials... more Measurements of isotopic ratios provide key information about the formation of cometary materials. We will present the first Herschel D/H measurement in the water of a long-period comet to be compared to the Ocean's like value in 103P/Hartley 2.

Saturn's usually slowly evolutive seasonal cycle has been disrupted in December 2010 between ... more Saturn's usually slowly evolutive seasonal cycle has been disrupted in December 2010 between 20° N and 50° N by the outbreak of an unexpected planetary-scale storm system. First Cassini/CIRS and ground-based observations have shown that temperatures, winds and chemistry have been rapidly affected by the storm in the stratosphere. Subsidence of warmer stratospheric air around the initial vortex at 1 mbar caused a dramatic increase in the infrared emission. Initially, a 16 K difference between these warm stratospheric regions, referred to as "beacons", and the cool central vortex was reported. Data taken in May 2011 by Cassini/CIRS show that the "beacons" have merged into a single hot spot. The temperature at 1 mbar had reached 190 K over a wide region according Cassini/CIRS. In this paper, we will present observations of water in Saturn carried out with the Herschel Space Observatory during the storm, in July 2011. These observations will be analyzed and diffe...

Disk averaged observations of several H2O far infrared lines in Titan’s atmosphere were performed... more Disk averaged observations of several H2O far infrared lines in Titan’s atmosphere were performed with the Herschel Space Observatory, as part of the guaranteed time key program "Water and related chemistry in the Solar System" (HssO, see Hartogh et al 2011). Two instruments were used: (i) HIFI, a heterodyne instrument (R~ 106 ) in the sub-millimeter, which measured the H2O(110-101) rotational transition at 557 GHz on June 10 and Dec. 31, 2010 (ii) PACS, a photoconductor spectrometer (R~103) which measured three water lines at 108.1, 75.4 and 66.4 microns on June 22, 2010. Additional PACS measurements at 66.4 microns on Dec. 15 and 22, 2010 and on July 09, 2011, do not show any significant line intensity variation with time, nor between the leading/trailing sides (i.e. longitude). Spectra were analyzed with a line-by-line radiative transfer code accounting for spherical geometry (Moreno et al. 2011). This model considers the H2O molecular opacity from JPL catalog (Pickett ...

As a species subject to photolytic, chemical and condensation losses, H2O present in Titan's ... more As a species subject to photolytic, chemical and condensation losses, H2O present in Titan's stratosphere must be of external origin. The discovery of CO2 by Voyager (Samuelson et al. 1981) pointed to an external supply of oxygen to Titan's atmosphere. Indeed, CO2, which also condenses, was recognized to be formed via CO+OH, where OH was likely produced by H2O photolysis. This view was supported by the ground-based discovery of CO (Lutz et al. 1983) and subsequent measurements confirming an abundance of ~50 ppm. The source of CO itself remained elusive, but inspired by the Cassini/CAPS discovery of a O+ influx rate (Hartle et al. 2006), Hörst et al. (2008) showed that an external source of O or O+ leads to the formation of CO, also pointing to the likely external origin of this compound. The most up-to-date model of Titan's oxygen chemistry by Hörst et al. (2008) adjusted the OH/H2O deposition rate as a function of the eddy diffusion coefficient below 200 km to match the...

176P/LINEAR was observed with the Heterodyne Instrument for the Far Infrared (HIFI) on-board Hers... more 176P/LINEAR was observed with the Heterodyne Instrument for the Far Infrared (HIFI) on-board Herschel. The line emission from the fundamental transition of water at 557 GHz was searched for and an upper limit on its production was inferred.

CO2 snow forms in the high-latitude atmosphere of Mars in regular patches coinciding with passage... more CO2 snow forms in the high-latitude atmosphere of Mars in regular patches coinciding with passages of baroclinic planetary waves (periodic oscillations of temperature and other meteorological fields). Our simulations using a Mars general circulation model (MGCM) show that about a half of the snow cover on the northern polar cap is created by such snowfalls. This discovery would allow to forecast snow storms in future robotic and manned missions to Mars [1].

Planetary and Space Science, 2009

a b s t r a c t ''Water and related chemistry in the Solar System'' is a Herschel Space Observato... more a b s t r a c t ''Water and related chemistry in the Solar System'' is a Herschel Space Observatory Guaranteed-Time Key Programme. This project, approved by the European Space Agency, aims at determining the distribution, the evolution and the origin of water in Mars, the outer planets, Titan, Enceladus and the comets. It addresses the broad topic of water and its isotopologues in planetary and cometary atmospheres. The nature of cometary activity and the thermodynamics of cometary comae will be investigated by studying water excitation in a sample of comets. The D/H ratio, the key parameter for constraining the origin and evolution of Solar System species, will be measured for the first time in a Jupiter-family comet. A comparison with existing and new measurements of D/H in Oort-cloud comets will constrain the composition of pre-solar cometary grains and possibly the dynamics of the protosolar nebula. New measurements of D/H in giant planets, similarly constraining the composition of protoplanetary ices, will be obtained. The D/H and other isotopic ratios, diagnostic of Mars' atmosphere evolution, will be accurately measured in H 2 O and CO. The role of water vapor in Mars' atmospheric chemistry will be studied by monitoring vertical profiles of H 2 O and HDO and by searching for several

1] We report on the first detection of the semiannual oscillation (SAO) in the Martian atmosphere... more 1] We report on the first detection of the semiannual oscillation (SAO) in the Martian atmosphere. The semiannual periodicity is found in the difference between day-and night-time atmospheric temperatures, a good proxy for solar tides, measured from Mars Global Surveyor. Simulations with a general circulation model proved that this modulation of tidal amplitudes is a manifestation of the SAO of zonal winds in Martian tropics. Our numerical experiments revealed significant differences in driving mechanisms of the SAO between Mars and Earth. On Mars, unlike on Earth, equatorial Kelvin waves supply only small retrograde torque to the mean circulation. Instead, thermal tides and quasi-stationary planetary waves induced by Martian topography contribute strongly to the prograde (super-rotation) acceleration. The existence of the SAO on Mars suggests that this phenomenon is not a result of the unique terrestrial environment, but a more general consequence of wave-mean flow interactions in atmospheres of fast-rotating planets. Citation: Kuroda, T., A. S. Medvedev, P. Hartogh, and M. Takahashi (2008), Semiannual oscillations in the atmosphere of Mars, Geop hy s. Res . Let t. , 35 , L23 20 2,

Temperature inversions and the warmings over the winter poles in the Martian atmosphere occur due... more Temperature inversions and the warmings over the winter poles in the Martian atmosphere occur due to the adiabatic heating associated with the downward branch of the Hadley circulation. We present results of simulations with a recently developed GCM which suggest that the warmings are the manifestations of the global meridional transport, and are strongly related to atmospheric eddies (planetary waves and tides). To date, sets of data required for the validation of the predicted warmings and the corresponding circulation patterns do not extend far enough into the middle atmosphere of Mars. This motivated our radiative and retrieval simulations to demonstrate that sub-millimeter observations can provide the required fields to validate and constrain the GCM results. r (P. Hartogh), medvedev@mps.mpg.de (A.S. Medvedev), jarchow@mps.mpg.de (C. Jarchow).