scholarly journals Evaluation of ozonesondes, HALOE, SAGE II and III, Odin-OSIRIS and SMR, and ENVISAT-GOMOS, -SCIAMACHY and -MIPAS ozone profiles in the tropics from SAOZ long duration balloon measurements in 2003 and 2004

2006 ◽  
Vol 6 (5) ◽  
pp. 10087-10152 ◽  
Author(s):  
F. Borchi ◽  
J.-P. Pommereau
Keyword(s):  
Southern Hemisphere ◽  
Ozone Concentration ◽  
Measuring Instruments ◽  
Near Ir ◽  
Solar Occultation ◽  
Long Duration ◽  
Stellar Occultation ◽  
Tropical Troposphere ◽  
The Tropics ◽  
Balloon Measurements

Abstract. The performances of satellite and sondes ozone measuring instruments available in the tropics between 10 and 26 km during the southern hemisphere summer in 2003 and 2004, have been investigated by comparison with series of profiles obtained by solar occultation in the visible Chappuis bands using a SAOZ UV-Vis spectrometer carried by circumnavigating long duration balloons. When compared to SAOZ, systematic positive or negative altitude shifts could be observed in satellite profiles, varying from <50 m for the GOMOS stellar occultation instrument, followed by +100/200 m for solar occultation systems (SAGE II, HALOE above 22 km), but as large as −900 m or +2000 m for limb viewing systems (OSIRIS, SCIAMACHY). The ozone relative biases are generally limited, between −4% and +4%, for measurements in the visible Chappuis bands (SAGE II and III, GOMOS above 22 km and OSIRIS), the near IR (HALOE above 22 km) and the ozonesondes, but increase to −7% in the UV (SCIAMACHY), and +7% in the mid-IR (MIPAS) and the submillimetric range (SMR). Regarding precision, evaluated statistically from the zonal variability of ozone concentration, the best measurements are found to be those of SAGE II (2%), followed by HALOE above 22 km (3–4%), then the ozonesondes, SAGE III moon and OSIRIS (4–5%), GOMOS above 22 km and SCIAMACHY (~6%), MIPAS (8.5%) and finally SMR (16%). Overall, all satellite ozone measurements appear little reliable in the tropical troposphere except those of SAGE II (and eventually SAGE III), though low biased by 50% and of limited (50%) precision.

scholarly journals Evaluation of ozonesondes, HALOE, SAGE II and III, Odin- OSIRIS and -SMR, and ENVISAT-GOMOS, -SCIAMACHY and -MIPAS ozone profiles in the tropics from SAOZ long duration balloon measurements in 2003 and 2004

2007 ◽  
Vol 7 (10) ◽  
pp. 2671-2690 ◽  
Author(s):  
F. Borchi ◽  
J.-P. Pommereau
Keyword(s):  
Southern Hemisphere ◽  
Ozone Concentration ◽  
Measuring Instruments ◽  
Near Ir ◽  
Solar Occultation ◽  
Long Duration ◽  
Stellar Occultation ◽  
Tropical Troposphere ◽  
The Tropics ◽  
Balloon Measurements

Abstract. The performances of satellite and sondes ozone measuring instruments available in the tropics between 10 and 26 km during the southern hemisphere summer in 2003 and 2004, have been investigated by comparison with series of profiles obtained by solar occultation in the visible Chappuis bands using a SAOZ UV-Vis spectrometer carried by long duration balloons. When compared to SAOZ, systematic positive or negative altitude shifts are observed in the satellite profiles, varying from <50 m for the GOMOS v6.0b stellar occultation instrument, followed by +100/200 m for solar occultation systems (SAGE II v6.2, HALOE v19 above 22 km), but as large as −900 m for the OSIRIS limb viewing system. The ozone relative biases are generally limited, between −4% and +4%, for measurements in the visible Chappuis bands (SAGE II and SAGE III moon v3, GOMOS above 22 km and OSIRIS), the near IR (HALOE above 22 km) and the ozonesondes, but increase to +5.5% (SCIAMACHY IUP v1.63) though still in the visible, and +7% in the mid-IR (MIPAS NL v4.61) and the submillimetric range (SMR v222). Regarding precision, evaluated statistically from the zonal variability of ozone concentration, the best measurements are found to be those of SAGE II (2%), followed by HALOE above 22 km (3–4%), then the ozonesondes, SAGE III moon, SCIAMACHY and OSIRIS (4–5%), GOMOS above 22 km (~6%), MIPAS (8.5%) and finally SMR (16%). Overall, all satellite ozone measurements appear to be of little utility in the tropical troposphere except those of SAGE II (and eventually SAGE III), though low biased by 50% and of limited (50%) precision.

scholarly journals Evaluation of SHADOZ sondes, HALOE and SAGE II ozone profiles at the tropics from SAOZ UV-Vis remote measurements onboard long duration balloons

2004 ◽  
Vol 4 (5) ◽  
pp. 4945-4997 ◽  
Author(s):  
F. Borchi ◽  
J.-P. Pommereau ◽  
A. Garnier ◽  
M. Pinharanda
Keyword(s):  
Stratospheric Ozone ◽  
American Samoa ◽  
Reunion Island ◽  
Solar Occultation ◽  
Long Duration ◽  
Remote Measurements ◽  
Réunion Island ◽  
Tropical Troposphere ◽  
The Tropics ◽  
The Western Pacific

Abstract. Long series of ozone profiles from 6 to 28 km at the Southern Tropics have been obtained from solar occultation measurements at twilight using a SAOZ spectrometer borne by long duration balloons. Two flights have been performed from Bauru in Brazil both in the summer, in February and March 2001 and 2003, from where the balloons are moving westward at almost constant latitude (20°±5° S). The flight in 2001 passed right over Reunion Island where the SAOZ measurements could be compared to those of both tropospheric and stratospheric ozone lidars. In the stratosphere, compared to that of SAOZ, the measurements of the SHADOZ ozonesondes network, and the HALOE and SAGE II instruments in orbit are found a little noisier (2–3% for SAGE II, 3–4% for HALOE, 4–5% for the sondes), and of insignificant or small high biased (SAGE II). No differences in altitude could be found between SAOZ and SAGE II at all levels, and HALOE above 22 km. But the ozonesondes appear to be systematically displaced upwards by some 400–700 m at all levels, and the HALOE profiles do show an increasing altitude bias at decreasing altitude below 22 km. In the upper troposphere, the SAOZ measurements are found consistent with those of the sondes at Reunion Island and high biased on average over the Western Pacific, at American Samoa and Fiji. Compared to SAOZ, SAGE II shows a 50–60% low bias similar to that already found with the ozonesondes, and a 2–2.5 times larger zonal variability, suggesting a degradation of its precision below the tropopause. Finally, the unrealistic large offsets and variability in the HALOE data compared to all others suggest that its measurements are no reliable in the tropical troposphere below 17 km.

scholarly journals Accuracy of analyzed temperatures, winds and trajectories in the Southern Hemisphere tropical and midlatitude stratosphere as compared to long-duration balloon flights

2006 ◽  
Vol 6 (4) ◽  
pp. 7499-7518
Author(s):  
B. M. Knudsen ◽  
T. Christensen ◽  
A. Hertzog ◽  
A. Deme ◽  
F. Vial ◽  
...  
Keyword(s):  
Zonal Wind ◽  
Cold Bias ◽  
Night Time ◽  
Zonal Winds ◽  
Tropical Tropopause ◽  
Wrong Side ◽  
Long Duration ◽  
Infra Red ◽  
The Tropics ◽  
Balloon Measurements

Abstract. Eight super-pressure balloons floating at constant level between 50 and 80 hPa and three Infra-Red Montgolfier balloons of variable altitude (15 hPa daytime, 40–80 hPa night time) have been launched at 22° S from Brazil in February–May 2004 in the frame of the HIBISCUS project. The flights lasted for 7 to 79 days residing mainly in the tropics, but some of them passed the tropical barrier and went to southern midlatitudes. Compared to the balloon measurements just above the tropical tropopause the ECMWF operational temperatures show a systematic cold bias of 0.9 K and the easterly zonal winds are too strong by 0.7 m/s. This bias in the zonal wind adds to the ECMWF trajectory errors, but they still are relatively small with e.g. about an error of 700 km after 5 days. The NCEP/NCAR reanalysis trajectory errors are substantially larger (1300 km after 5 days). In the southern midlatitudes the cold bias is the same, but the zonal wind bias is almost zero. The trajectories are generally more accurate than in the tropics, but for one balloon a lot of the calculated trajectories end up on the wrong side of the tropical barrier and this leads to large trajectory errors.

scholarly journals Evaluation of ECMWF ERA-40 temperature and wind in the lower tropical stratosphere since 1988 from past long-duration balloon measurements

2007 ◽  
Vol 7 (13) ◽  
pp. 3399-3409 ◽  
Author(s):  
T. Christensen ◽  
B. M. Knudsen ◽  
J.-P. Pommereau ◽  
G. Letrenne ◽  
A. Hertzog ◽  
...  
Keyword(s):  
Wind Speed ◽  
Lower Stratosphere ◽  
Equatorial Region ◽  
Satellite Measurements ◽  
Operational Analysis ◽  
Long Duration ◽  
The Tropics ◽  
Recent Evaluation ◽  
Balloon Measurements

Abstract. The temperature and wind of the ECMWF ERA-40 reanalysis in the tropical lower stratosphere during the period 1988–2001 has been evaluated by comparison with independent in situ measurements of 21 IR Montgolfier and superpressure long-duration balloon flights performed by CNES from Pretoria (26° S) in South Africa in 1988–1989, Latacunga (1° S) in Ecuador in 1991–1998 and Bauru (22° S) in Brazil in 2000–2001. The ERA-40 temperature displays a bias varying progressively from +1.16 K in 1988–1989, to +0.26 K in 1994–1996 and −0.46 K after 1998, the latter being fully consistent with recent evaluations of ECMWF operational analysis from radio occultation and in situ long-duration balloon observations. The amplitude of the bias and its evolution are very similar to the results of a previous evaluation from radiosondes in 1991–2003, suggesting that the origin of the drift of ERA-40 might be mainly due to errors in the series of satellite measurements of MSU, replaced by AMSU in 1998, assimilated in the model. The ERA-40 zonal wind speed in the lower stratosphere appears slightly overestimated by 0.7–1.0 m/s on average in both the tropics and equatorial region, that is by 5–10% compared to the average 10–20 m/s wind speed. This bias, fully consistent with a recent evaluation of ECMWF operational analysis in 2004, is found constant during the whole 1988–2001 period, suggesting a shortfall in the variabililty of ERA-40 horizontal winds in the lower stratosphere in the tropics and the equatorial region. Finally calculated trajectories using ERA-40, frequently used for analysing field observations, are found in error compared to that of the balloons by ±500 km after 5 days and ±1000 km after 10 days.

scholarly journals Ozone Variation Trends under Different CMIP6 Scenarios

Atmosphere ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 112
Author(s):  
Lin Shang ◽  
Jiali Luo ◽  
Chunxiao Wang
Keyword(s):  
Ozone Concentration ◽  
Radiative Forcing ◽  
Stratospheric Ozone ◽  
Lower Troposphere ◽  
Total Column Ozone ◽  
The Social ◽  
Tropical Troposphere ◽  
Column Ozone ◽  
The Tropics ◽  
Total Column

This study compares and analyzes simulations of ozone under different scenarios by three CMIP6 models (IPSL-CM6A, MRI-ESM2 and CESM-WACCM). Results indicate that as the social vulnerability and anthropogenic radiative forcing is increasing, the change of total column ozone in the tropical stratosphere is not linear. Compared to the SSP2-4.5 and SSP5-8.5 scenarios, the SSP1-2.6 and SSP3-7.0 are more favorable for the increase in stratospheric ozone mass in the tropics. Arctic ozone would never recover under the SSP1-2.6 scenario; however, the Antarctica ozone would gradually recover in all scenarios. Under the SSP1-2.6 and SSP2-4.5 scenarios, the trend of tropical total column ozone is mainly determined by the trend of column ozone in the tropical troposphere. Under the SSP3-7.0 scenario, tropospheric ozone concentration will significantly increase; under the SSP5-8.5 scenario, ozone concentration will distinctly increase in the middle and lower troposphere.

scholarly journals Accuracy of analyzed temperatures, winds and trajectories in the Southern Hemisphere tropical and midlatitude stratosphere as compared to long-duration balloon flights

2006 ◽  
Vol 6 (12) ◽  
pp. 5391-5397 ◽  
Author(s):  
B. M. Knudsen ◽  
T. Christensen ◽  
A. Hertzog ◽  
A. Deme ◽  
F. Vial ◽  
...  
Keyword(s):  
Zonal Wind ◽  
Cold Bias ◽  
Night Time ◽  
Zonal Winds ◽  
Tropical Tropopause ◽  
Wrong Side ◽  
Long Duration ◽  
Infra Red ◽  
The Tropics ◽  
Balloon Measurements

Abstract. Eight super-pressure balloons floating at constant level between 50 and 80 hPa and three Infra-Red Montgolfier balloons of variable altitude (15 hPa daytime, 40–80 hPa night time) have been launched at 22° S from Brazil in February–May 2004 in the frame of the HIBISCUS project. The flights lasted for 7 to 79 days residing mainly in the tropics, but some of them passed the tropical barrier and went to southern midlatitudes. Compared to the balloon measurements just above the tropical tropopause the ECMWF operational temperatures show a systematic cold bias of 0.9 K and the easterly zonal winds are too strong by 0.7 m/s. This bias in the zonal wind adds to the ECMWF trajectory errors, but they still are relatively small with e.g. about an error of 700 km after 5 days. The NCEP/NCAR reanalysis trajectory errors are substantially larger (1300 km after 5 days). In the southern midlatitudes the cold bias is the same, but the zonal wind bias is almost zero. The trajectories are generally more accurate than in the tropics, but for one balloon a lot of the calculated trajectories end up on the wrong side of the tropical barrier and this leads to large trajectory errors.

scholarly journals Evaluation of SHADOZ sondes, HALOE and SAGE II ozone profiles at the tropics from SAOZ UV-Vis remote measurements onboard long duration balloons

2005 ◽  
Vol 5 (5) ◽  
pp. 1381-1397 ◽  
Author(s):  
F. Borchi ◽  
J.-P. Pommereau ◽  
A. Garnier ◽  
M. Pinharanda
Keyword(s):  
Ozone Concentration ◽  
American Samoa ◽  
South Pacific Convergence Zone ◽  
Tropical Tropopause Layer ◽  
Convective Clouds ◽  
Tropical Tropopause ◽  
Long Duration ◽  
Remote Measurements ◽  
Strong Gradient ◽  
The Tropics

Abstract. Ozone profiles from 10 to 26km have been obtained at almost constant latitude (20 ± 5° S) in the tropics using SAOZ UV-vis spectrometers flown onboard long duration balloons in 2001 and 2003. The precision of the measurements is estimate to be better than 2% in the stratosphere (3.5% accuracy) and 5-6% in the troposphere (12% and 25% accuracy at 15km and 10km respectively) with an altitude uncertainty of -30 ± 25m. The variability of ozone concentration along a latitudinal circle at 20° S in the SH summer is found smaller than 3-4% above 20km, but increasing rapidly below in the Tropical Tropopause Layer (TTL). The high correlation between PV and ozone suggests that most of this variability can be attributed to quasi-horizontal exchange with the mid-latitude stratosphere. The performances of the SHADOZ ozonesonde network, HALOE and SAGE II in the tropics have been studied by comparison with SAOZ measurements. In the stratosphere, the main discrepancies arise from differences in altitude registration, particularly sensitive between 20 and 26km in the tropics because of the strong gradient of ozone concentration. In the upper troposphere, the SAOZ measurements are consistent with those of the sondes and the lidar in cloud free conditions, but biased high by 60% on average compared to ozonesondes over the Western Pacific, at American Samoa and Fiji. The likely explanation is the frequent occurrence of near zero ozone layers in the convective clouds of the South Pacific Convergence Zone which cannot be seen by SAOZ as well as all ground-based and space borne remote sensing instruments. Compared to SAOZ, SAGE II displays a 50-60% low bias similar to that already known with the ozonesondes, and a larger zonal variability. However, the significant correlation with PV suggests that useful information on tropospheric ozone could be derived from SAGE II. Finally, the unrealistic large offsets and variability in the HALOE data compared to all others, indicates that the measurements of this instrument are of limited use below 17km.

scholarly journals Validation of SCIAMACHY limb NO<sub>2</sub> profiles using solar occultation measurements

2011 ◽  
Vol 4 (4) ◽  
pp. 4753-4800
Author(s):  
R. Bauer ◽  
A. Rozanov ◽  
C. A. McLinden ◽  
L. L. Gordley ◽  
W. Lotz ◽  
...  
Keyword(s):  
The Past ◽  
Middle Latitudes ◽  
Solar Occultation ◽  
Time Period ◽  
Vertical Distributions ◽  
Global Coverage ◽  
Scanning Imaging ◽  
Diurnal Effect ◽  
Better Than ◽  
Balloon Measurements

Abstract. The increasing amounts of reactive nitrogen in the stratosphere necessitates accurate global measurements of stratospheric nitrogen dioxide (NO2). Over the past decade, the SCIAMACHY (SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY) instrument on ENVISAT (European Environmental Satellite) has been providing global coverage of stratospheric NO2 every 6 days, which is otherwise difficult to achieve with other systems (e.g. balloon measurements, solar occultation). In this study, the vertical distributions of NO2 retrieved from limb measurements of the scattered solar light from the SCIAMACHY instrument are validated using NO2 products from three different satellite instruments (SAGE II, HALOE and ACE-FTS). The retrieval approach, as well as the sensitivity of the SCIAMACHY NO2 limb data product are discussed, and the photochemical corrections needed to make this validation feasible, as well as the chosen collocation criteria are described. For each instrument, a time period of two years is analyzed with several hundreds of collocation pairs for each year and instrument. The agreement between SCIAMACHY and each instrument is found to be better than 10 % between 22–24 km and 40 km. Additionally, NO2 amounts in three different latitude regions are validated individually, with considerably better agreements in high and middle latitudes compared to tropics. Differences with SAGE II and ACE-FTS below 20 km are consistent with those expected from the diurnal effect.

scholarly journals Triggering the Indian Ocean Dipole from the Southern Hemisphere

2021 ◽  
Author(s):  
Lian-Yi Zhang ◽  
Yan Du ◽  
Wenju Cai ◽  
Zesheng Chen ◽  
Tomoki Tozuka ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Southern Hemisphere ◽  
Indian Ocean Dipole ◽  
Southern Oscillation ◽  
Southern Annular Mode ◽  
Triggering Mechanism ◽  
Phase Development ◽  
The Indian Ocean ◽  
High System ◽  
The Tropics

&lt;p&gt;This study identifies a new triggering mechanism of the Indian Ocean Dipole (IOD) from the Southern Hemisphere. This mechanism is independent from the El Ni&amp;#241;o/Southern Oscillation (ENSO) and tends to induce the IOD before its canonical peak season. The joint effects of this mechanism and ENSO may explain different lifetimes and strengths of the IOD. During its positive phase, development of sea surface temperature cold anomalies commences in the southern Indian Ocean, accompanied by an anomalous subtropical high system and anomalous southeasterly winds. The eastward movement of these anomalies enhances the monsoon off Sumatra-Java during May-August, leading to an early positive IOD onset. The pressure variability in the subtropical area is related with the Southern Annular Mode, suggesting a teleconnection between high-latitude and mid-latitude climate that can further affect the tropics. To include the subtropical signals may help model prediction of the IOD event.&lt;/p&gt;

scholarly journals Southern Hemisphere Blocking Onsets Associated with Upper-Tropospheric Divergence Anomalies

2005 ◽  
Vol 62 (5) ◽  
pp. 1614-1625 ◽  
Author(s):  
F. Javier Sáez de Adana ◽  
Stephen J. Colucci
Keyword(s):  
Southern Hemisphere ◽  
Nonlinear Effect ◽  
Local Development ◽  
Relative Vorticity ◽  
Convective Activity ◽  
Early Winter ◽  
Horizontal Advection ◽  
Blocking Activity ◽  
The Tropics ◽  
Blocking Index

Abstract Upper-tropospheric divergence anomalies and divergence tendencies prior to and during the onset of blocking have been investigated for selected cases over the Southern Hemisphere in search of links between the upper-tropospheric response to tropical convective activity and the onset of blocking in midlatitudes. Climatologies of blocking, defined by an objective index, and divergence are established for the Southern Hemisphere and the southern Pacific, respectively. Relative blocking frequency versus longitude reveals a region of maximum blocking activity between 160°E and 75°W. Blocking frequencies for each ENSO phase indicate a shift toward the late austral fall and early winter during the warm phase, whereas during the cold and neutral phases the highest frequencies are in June and July, respectively. Composites of area-averaged divergence anomalies for the selected blocking cases reveal more anomalous divergence than during nonblocking periods over the blocking regions and the immediate upstream regions in midlatitudes. A full divergence tendency equation is utilized to diagnose the local development of divergence preceding the onset of blocking. Results indicate that divergence tendencies over midlatitudes in the block-onset region were forced primarily by horizontal advection, ageostrophic relative vorticity, and a nonlinear effect. In the region directly upstream from the block-onset region, ageostrophic relative vorticity had the greatest contribution followed by the horizontal advection. In the Tropics, divergence tendencies appear to be driven primarily by horizontal advection. Correlations of calculated divergence tendencies with the blocking index suggest that ageostrophic vorticity may locally generate divergence that in turn may force anticyclonic vorticity associated with blocking. Lag correlations with a blocking index during blocking reveal the importance of horizontal advection in driving divergence anomalies, implying divergence-induced vorticities, toward the incipient block.

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