scholarly journals The ground-based FTIR network's potential for investigating the atmospheric water cycle

2009 ◽  
Vol 9 (6) ◽  
pp. 26199-26235 ◽  
Author(s):  
M. Schneider ◽  
K. Yoshimura ◽  
F. Hase ◽  
T. Blumenstock
Keyword(s):  
Water Transport ◽  
General Circulation ◽  
Water Cycle ◽  
Lower Troposphere ◽  
Circulation Model ◽  
Hadley Circulation ◽  
The Arctic ◽  
Atmospheric Water ◽  
Transport Pathways ◽  
Northern Atlantic

Abstract. We present tropospheric H216O and HD16O/H216O vapour profiles measured by ground-based FTIR (Fourier Transform Infrared) spectrometers between 1996 and 2008 at a northern hemispheric subarctic and subtropical site (Kiruna, Northern Sweden, 68° N and Izaña, Tenerife Island, 28° N, respectively). We compare these measurements to an isotope incorporated atmospheric general circulation model (AGCM). If the model is nudged towards meteorological fields of reanalyses data the agreement is very satisfactory on time scales ranging from daily to inter-annual which demonstrates the good quality of the FTIR data. Taking the Izaña and Kiruna measurements as an example we document the FTIR network's unique potential for investigating the atmospheric water cycle. For the subtropical site the FTIR observations confirm the central role of the Hadley circulation, but in addition they reveal a strong connection between the Northern Atlantic Oscillation (NAO) and the middle/upper tropospheric water vapour transport pathways. Concerning the subarctic site the observations indicate that water transport to the lower troposphere is affected by the northern Atlantic sea surface temperature and correlated to the Arctic Oscillation (AO). For the middle troposphere we observe that spring and autumn water transport pathways are different. We document in detail where the AGCM is able to capture these complexities of the water cycle and where it fails.

scholarly journals The ground-based FTIR network's potential for investigating the atmospheric water cycle

2010 ◽  
Vol 10 (7) ◽  
pp. 3427-3442 ◽  
Author(s):  
M. Schneider ◽  
K. Yoshimura ◽  
F. Hase ◽  
T. Blumenstock
Keyword(s):  
General Circulation ◽  
Water Cycle ◽  
Circulation Model ◽  
Hadley Circulation ◽  
Reanalysis Data ◽  
The Arctic ◽  
Atmospheric Water ◽  
Arctic Oscillation Index ◽  
Northern Atlantic ◽  
The Arctic Oscillation

Abstract. We present tropospheric H216O and HD16O/H216O vapour profiles measured by ground-based FTIR (Fourier Transform Infrared) spectrometers between 1996 and 2008 at a northern hemispheric subarctic and subtropical site (Kiruna, Northern Sweden, 68° N and Izaña, Tenerife Island, 28° N, respectively). We compare these measurements to an isotope incorporated atmospheric general circulation model (AGCM). If the model is nudged towards meteorological fields of reanalysis data the agreement is very satisfactory on time scales ranging from daily to inter-annual. Taking the Izaña and Kiruna measurements as an example we document the FTIR network's unique potential for investigating the atmospheric water cycle. At the subarctic site we find strong correlations between the FTIR data, on the one hand, and the Arctic Oscillation index and the northern Atlantic sea surface temperature, on the other hand. The Izaña FTIR measurements reveal the importance of the Hadley circulation and the Northern Atlantic Oscillation index for the subtropical middle/upper tropospheric water balance. We document where the AGCM is able to capture these complexities of the water cycle and where it fails.

scholarly journals Effects of Cloud Microphysics on Tropical Atmospheric Hydrologic Processes and Intraseasonal Variability

2005 ◽  
Vol 18 (22) ◽  
pp. 4731-4751 ◽  
Author(s):  
K. M. Lau ◽  
H. T. Wu ◽  
Y. C. Sud ◽  
G. K. Walker
Keyword(s):  
General Circulation ◽  
Large Scale ◽  
Water Cycle ◽  
Deep Convection ◽  
Intraseasonal Variability ◽  
Lower Troposphere ◽  
Circulation Model ◽  
Cloud Microphysics ◽  
Hydrologic Processes ◽  
Warm Rain

Abstract The sensitivity of tropical atmospheric hydrologic processes to cloud microphysics is investigated using the NASA Goddard Earth Observing System (GEOS) general circulation model (GCM). Results show that a faster autoconversion rate leads to (a) enhanced deep convection in the climatological convective zones anchored to tropical land regions; (b) more warm rain, but less cloud over oceanic regions; and (c) an increased convective-to-stratiform rain ratio over the entire Tropics. Fewer clouds enhance longwave cooling and reduce shortwave heating in the upper troposphere, while more warm rain produces more condensation heating in the lower troposphere. This vertical differential heating destabilizes the tropical atmosphere, producing a positive feedback resulting in more rain and an enhanced atmospheric water cycle over the Tropics. The feedback is maintained via secondary circulations between convective tower and anvil regions (cold rain), and adjacent middle-to-low cloud (warm rain) regions. The lower cell is capped by horizontal divergence and maximum cloud detrainment near the freezing–melting (0°C) level, with rising motion (relative to the vertical mean) in the warm rain region connected to sinking motion in the cold rain region. The upper cell is found above the 0°C level, with induced subsidence in the warm rain and dry regions, coupled to forced ascent in the deep convection region. It is that warm rain plays an important role in regulating the time scales of convective cycles, and in altering the tropical large-scale circulation through radiative–dynamic interactions. Reduced cloud–radiation feedback due to a faster autoconversion rate results in intermittent but more energetic eastward propagating Madden–Julian oscillations (MJOs). Conversely, a slower autoconversion rate, with increased cloud radiation produces MJOs with more realistic westward-propagating transients embedded in eastward-propagating supercloud clusters. The implications of the present results on climate change and water cycle dynamics research are discussed.

scholarly journals Influence of atmospheric internal variability on the long-term Siberian water cycle during the past 2 centuries

2018 ◽  
Vol 9 (2) ◽  
pp. 497-506 ◽  
Author(s):  
Kazuhiro Oshima ◽  
Koto Ogata ◽  
Hotaek Park ◽  
Yoshihiro Tachibana
Keyword(s):  
General Circulation ◽  
Large Scale ◽  
Water Cycle ◽  
Circulation Model ◽  
Internal Variability ◽  
The Arctic ◽  
The Past ◽  
Term Variation ◽  
East West

Abstract. River discharges from Siberia are a large source of freshwater into the Arctic Ocean, whereas the cause of the long-term variation in Siberian discharges is still unclear. The observed river discharges of the Lena in the east and the Ob in the west indicated different relationships in each of the epochs during the past 7 decades. The correlations between the two river discharges were negative during the 1980s to mid-1990s, positive during the mid-1950s to 1960s, and became weak after the mid-1990s. More long-term records of tree-ring-reconstructed discharges have also shown differences in the correlations in each of the epochs. It is noteworthy that the correlations obtained from the reconstructions tend to be negative during the past 2 centuries. Such tendency has also been obtained from precipitations in observations, and in simulations with an atmospheric general circulation model (AGCM) and fully coupled atmosphere–ocean GCMs conducted for the Fourth Assessment Report of the IPCC. The AGCM control simulation further demonstrated that an east–west seesaw pattern of summertime large-scale atmospheric circulation frequently emerges over Siberia as an atmospheric internal variability. This results in an opposite anomaly of precipitation over the Lena and Ob and the negative correlation. Consequently, the summertime atmospheric internal variability in the east–west seesaw pattern over Siberia is a key factor influencing the long-term variation in precipitation and river discharge, i.e., the water cycle in this region.

A Closer Comparison of Early and Late-Winter Atmospheric Trends in the Northern Hemisphere

2005 ◽  
Vol 18 (16) ◽  
pp. 3204-3216 ◽  
Author(s):  
Yongyun Hu ◽  
Ka Kit Tung ◽  
Jiping Liu
Keyword(s):  
Northern Hemisphere ◽  
General Circulation ◽  
Polar Vortex ◽  
Circulation Model ◽  
Hadley Circulation ◽  
Reanalysis Data ◽  
Hadley Cell ◽  
The Arctic ◽  
Late Winter ◽  
Positive Trend

Abstract Decadal trends are compared in various fields between Northern Hemisphere early winter, November–December (ND), and late-winter, February–March (FM), months using reanalysis data. It is found that in the extratropics and polar region the decadal trends display nearly opposite tendencies between ND and FM during the period from 1979 to 2003. Dynamical trends in late winter (FM) reveal that the polar vortex has become stronger and much colder and wave fluxes from the troposphere to the stratosphere are weaker, consistent with the positive trend of the Arctic Oscillation (AO) as found in earlier studies, while trends in ND appear to resemble a trend toward the low-index polarity of the AO. In the Tropics, the Hadley circulation shows significant intensification in both ND and FM, with stronger intensification in FM. Unlike the Hadley cell, the Ferrel cell shows opposite trends between ND and FM, with weakening in ND and strengthening in FM. Comparison of the observational results with general circulation model simulations is also discussed.

scholarly journals Ground-based remote sensing of tropospheric water vapour isotopologues within the project MUSICA

2012 ◽  
Vol 5 (12) ◽  
pp. 3007-3027 ◽  
Author(s):  
M. Schneider ◽  
S. Barthlott ◽  
F. Hase ◽  
Y. González ◽  
K. Yoshimura ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Water Vapour ◽  
General Circulation ◽  
Lower Troposphere ◽  
Circulation Model ◽  
Complex Nature ◽  
Atmospheric Water ◽  
Mid Infrared ◽  
The Cross

Abstract. Within the project MUSICA (MUlti-platform remote Sensing of Isotopologues for investigating the Cycle of Atmospheric water), long-term tropospheric water vapour isotopologue data records are provided for ten globally distributed ground-based mid-infrared remote sensing stations of the NDACC (Network for the Detection of Atmospheric Composition Change). We present a new method allowing for an extensive and straightforward characterisation of the complex nature of such isotopologue remote sensing datasets. We demonstrate that the MUSICA humidity profiles are representative for most of the troposphere with a vertical resolution ranging from about 2 km (in the lower troposphere) to 8 km (in the upper troposphere) and with an estimated precision of better than 10%. We find that the sensitivity with respect to the isotopologue composition is limited to the lower and middle troposphere, whereby we estimate a precision of about 30‰ for the ratio between the two isotopologues HD16O and H216O. The measurement noise, the applied atmospheric temperature profiles, the uncertainty in the spectral baseline, and the cross-dependence on humidity are the leading error sources. We introduce an a posteriori correction method of the cross-dependence on humidity, and we recommend applying it to isotopologue ratio remote sensing datasets in general. In addition, we present mid-infrared CO2 retrievals and use them for demonstrating the MUSICA network-wide data consistency. In order to indicate the potential of long-term isotopologue remote sensing data if provided with a well-documented quality, we present a climatology and compare it to simulations of an isotope incorporated AGCM (Atmospheric General Circulation Model). We identify differences in the multi-year mean and seasonal cycles that significantly exceed the estimated errors, thereby indicating deficits in the modeled atmospheric water cycle.

scholarly journals Influence of atmospheric internal variability on the long-term Siberian water cycle during the past two centuries

2017 ◽  
Author(s):  
Kazuhiro Oshima ◽  
Koto Ogata ◽  
Hotaek Park ◽  
Yoshihiro Tachibana
Keyword(s):  
General Circulation ◽  
Water Cycle ◽  
Circulation Model ◽  
Internal Variability ◽  
The Arctic ◽  
Coupled Models ◽  
The Past ◽  
Term Variation ◽  
East West

Abstract. River discharges from Siberia are a large source of freshwater into the Arctic Ocean, although the cause of the long-term variation in discharge is still unclear. The observed river discharges of the Lena in the east and the Ob in the west indicated different relationships in each of the epochs during the past seven decades. The correlations between the two river discharges were negative during the 1980s to mid-1990s, positive during the mid-1950s to 1960s, and became weak after the mid-1990s. Long-term records of tree-ring-reconstructed discharges during the past two centuries have also shown differences in the correlations in each epoch. However, it is noteworthy that the correlations obtained from the reconstructions tend to be negative. Such negative correlations have also been obtained from precipitations over the Lena and Ob in observation, and in simulations with an atmospheric general circulation model (AGCM) and multi-coupled models conducted for the Fourth Assessment Report of the IPCC. The AGCM control simulation further demonstrated that an east–west seesaw pattern of summertime atmospheric large-scale circulation frequently emerges over Siberia as an atmospheric internal variability, resulting in the negative correlation between the Lena and Ob. Consequently, the summertime atmospheric internal variability of east–west seesaw pattern over Siberia is a key factor influencing the long-term variation in precipitation and river discharge, i.e., the water cycle in this region.

scholarly journals Ground-based remote sensing of tropospheric water vapour isotopologues within the project MUSICA

2012 ◽  
Vol 5 (4) ◽  
pp. 5357-5418 ◽  
Author(s):  
M. Schneider ◽  
S. Barthlott ◽  
F. Hase ◽  
Y. González ◽  
K. Yoshimura ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Water Vapour ◽  
General Circulation ◽  
Lower Troposphere ◽  
Circulation Model ◽  
Atmospheric Composition ◽  
Complex Nature ◽  
Atmospheric Water ◽  
Mid Infrared

Abstract. Within the project MUSICA (MUlti-platform remote Sensing of Isotopologues for investigating the Cycle of Atmospheric water), long-term tropospheric water vapour isotopologues data records are provided for ten globally distributed ground-based mid-infrared remote sensing stations of the NDACC (Network for the Detection of Atmospheric Composition Change). We present a new method allowing for an extensive and straightforward characterisation of the complex nature of such isotopologue remote sensing datasets. We demonstrate that the MUSICA humidity profiles are representative for most of the troposphere with a vertical resolution ranging from about 2 km (in the lower troposphere) to 8 km (in the upper troposphere) and with an estimated precision of better than 10%. We find that the sensitivity with respect to the isotopologue composition is limited to the lower and middle troposphere, whereby we estimate a precision of about 30‰ for the ratio between the two isotopologues HD16O and H216O. The measurement noise, the applied atmospheric temperature profiles, the uncertainty in the spectral baseline, and interferences from humidity are the leading error sources. We introduce an a posteriori correction method of the humidity interference error and we recommend applying it for isotopologue ratio remote sensing datasets in general. In addition, we present mid-infrared CO2 retrievals and use them for demonstrating the MUSICA network-wide data consistency. In order to indicate the potential of long-term isotopologue remote sensing data if provided with a well-documented quality, we present a climatology and compare it to simulations of an isotope incorporated AGCM (Atmospheric General Circulation Model). We identify differences in the multi-year mean and seasonal cycles that significantly exceed the estimated errors, thereby indicating deficits in the modeled atmospheric water cycle.

scholarly journals The Rossby radius in the Arctic Ocean

Ocean Science ◽  
2014 ◽  
Vol 10 (6) ◽  
pp. 967-975 ◽  
Author(s):  
A. J. G. Nurser ◽  
S. Bacon
Keyword(s):  
Arctic Ocean ◽  
General Circulation ◽  
Circulation Model ◽  
Ocean General Circulation Model ◽  
High Arctic ◽  
The Arctic ◽  
Hudson Bay ◽  
Ocean Eddies ◽  
Shelf Seas ◽  
The Impact

Abstract. The first (and second) baroclinic deformation (or Rossby) radii are presented north of ~60° N, focusing on deep basins and shelf seas in the high Arctic Ocean, the Nordic seas, Baffin Bay, Hudson Bay and the Canadian Arctic Archipelago, derived from climatological ocean data. In the high Arctic Ocean, the first Rossby radius increases from ~5 km in the Nansen Basin to ~15 km in the central Canadian Basin. In the shelf seas and elsewhere, values are low (1–7 km), reflecting weak density stratification, shallow water, or both. Seasonality strongly impacts the Rossby radius only in shallow seas, where winter homogenization of the water column can reduce it to below 1 km. Greater detail is seen in the output from an ice–ocean general circulation model, of higher resolution than the climatology. To assess the impact of secular variability, 10 years (2003–2012) of hydrographic stations along 150° W in the Beaufort Gyre are also analysed. The first-mode Rossby radius increases over this period by ~20%. Finally, we review the observed scales of Arctic Ocean eddies.

scholarly journals Stratospheric temperatures and tracer transport in a nudged 4-year middle atmosphere GCM simulation

2005 ◽  
Vol 5 (1) ◽  
pp. 961-1006 ◽  
Author(s):  
M. K. van Aalst ◽  
J. Lelieveld ◽  
B. Steil ◽  
C. Brühl ◽  
P. Jöckel ◽  
...  
Keyword(s):  
Interannual Variability ◽  
General Circulation ◽  
Middle Atmosphere ◽  
Circulation Model ◽  
Detailed Comparison ◽  
The Arctic ◽  
Cold Bias ◽  
Tracer Transport ◽  
Quasi Biennial Oscillation ◽  
The Antarctic

Abstract. We have performed a 4-year simulation with the Middle Atmosphere General Circulation Model MAECHAM5/MESSy, while slightly nudging the model’s meteorology in the free troposphere (below 113 hPa) towards ECMWF analyses. We show that the nudging 5 technique, which leaves the middle atmosphere almost entirely free, enables comparisons with synoptic observations. The model successfully reproduces many specific features of the interannual variability, including details of the Antarctic vortex structure. In the Arctic, the model captures general features of the interannual variability, but falls short in reproducing the timing of sudden stratospheric warmings. A 10 detailed comparison of the nudged model simulations with ECMWF data shows that the model simulates realistic stratospheric temperature distributions and variabilities, including the temperature minima in the Antarctic vortex. Some small (a few K) model biases were also identified, including a summer cold bias at both poles, and a general cold bias in the lower stratosphere, most pronounced in midlatitudes. A comparison 15 of tracer distributions with HALOE observations shows that the model successfully reproduces specific aspects of the instantaneous circulation. The main tracer transport deficiencies occur in the polar lowermost stratosphere. These are related to the tropopause altitude as well as the tracer advection scheme and model resolution. The additional nudging of equatorial zonal winds, forcing the quasi-biennial oscillation, sig20 nificantly improves stratospheric temperatures and tracer distributions.

Eastward-Propagating Intraseasonal Oscillation Represented by Chikira–Sugiyama Cumulus Parameterization. Part II: Understanding Moisture Variation under Weak Temperature Gradient Balance

2014 ◽  
Vol 71 (2) ◽  
pp. 615-639 ◽  
Author(s):  
Minoru Chikira
Keyword(s):  
Temperature Gradient ◽  
Vertical Velocity ◽  
General Circulation ◽  
Intraseasonal Oscillation ◽  
Lower Troposphere ◽  
Circulation Model ◽  
Velocity Anomaly ◽  
Mature Phase ◽  
Moisture Variation ◽  
Heating Profile

Abstract The eastward-propagating intraseasonal oscillation represented by the Chikira–Sugiyama cumulus scheme in a general circulation model was investigated focusing on the variation of the free-tropospheric humidity. The net effect of the vertical advection and cloud process amplifies the positive moisture anomaly in the mature phase, supporting the moisture-mode theory. The horizontal advection causes the eastward propagation of the field. The variation of the moisture profile is accurately understood by using environmental vertical velocity outside cumuli. The velocity is regulated by a thermodynamic balance under a weak temperature gradient. A nondimensional parameter α plays an important role in the moisture variation, which characterizes the efficiency of moistening (drying) induced by external heating (cooling). In the middle and lower troposphere, the major moistening factor is the radiative warming anomaly, which induces the upward environmental vertical velocity anomaly. The reevaporation of the precipitation works as drying, since its cooling effect induces the downward environmental vertical velocity anomaly. Snow melting significantly cools and thereby dries the midtroposphere. The moistening of the midtroposphere is important for moistening the lower troposphere through the reduction of α. The efficiency of moistening depends on the heating profile, and congestus clouds play an important role in it. The heating profile, which maximizes the moistening of the free troposphere, is realized in the mature phase. The atmosphere is marginally unstable even in the mature phase, which is a favorable condition for the congestus clouds to occur.

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