Variability in atmospheric circulation and moisture flux over the Arctic

1995 ◽  
Vol 352 (1699) ◽  
pp. 215-225 ◽  
Keyword(s):  
Water Vapour ◽  
North Atlantic ◽  
Temporal Distribution ◽  
Local Maximum ◽  
Precipitable Water ◽  
Moisture Flux ◽  
The Arctic ◽  
Polar Cap ◽  
Arctic Water ◽  
Spatio Temporal

Mean characteristics and variability in the spatio-temporal distribution of Arctic water vapour and vapour fluxes are examined using several different rawinsondederived databases. Precipitable water averaged over the polar cap, 70-90° N, peaks in July at 14.0 mm. Large poleward fluxes near the prime meridian reflect transport associated with north Atlantic cyclones and, for most months, a local maximum in available water vapour. The mean vapour flux convergence averaged for the polar cap peaks in September. There is a mean annual excess of precipitation minus evaporation ( P — E ) of 163 mm, with a 78 mm range between extreme years. High P — E is favoured by a meridional circulation accompanied by a more dominant North Atlantic cyclone track. No trend in annual P — E is apparent over the 1974-1991 period.

scholarly journals SPATIO-TEMPORAL ESTIMATION OF INTEGRATED WATER VAPOUR OVER THE MALAYSIAN PENINSULA DURING MONSOON SEASON

2017 ◽  
Vol XLII-4/W5 ◽  
pp. 165-175
Author(s):  
S. Salihin ◽  
T. A. Musa ◽  
Z. Mohd Radzi
Keyword(s):  
Water Vapour ◽  
Monsoon Season ◽  
Temporal Distribution ◽  
Southwest Monsoon ◽  
Northeast Monsoon ◽  
Path Delay ◽  
Zenith Path Delay ◽  
Temporal Estimation ◽  
Integrated Water Vapour ◽  
Spatio Temporal

This paper provides the precise information on spatial-temporal distribution of water vapour that was retrieved from Zenith Path Delay (ZPD) which was estimated by Global Positioning System (GPS) processing over the Malaysian Peninsular. A time series analysis of these ZPD and Integrated Water Vapor (IWV) values was done to capture the characteristic on their seasonal variation during monsoon seasons. This study was found that the pattern and distribution of atmospheric water vapour over Malaysian Peninsular in whole four years periods were influenced by two inter-monsoon and two monsoon seasons which are First Inter-monsoon, Second Inter-monsoon, Southwest monsoon and Northeast monsoon.

scholarly journals Enhancement of the North Atlantic CO<sub>2</sub> sink by Arctic Waters

2021 ◽  
Vol 18 (5) ◽  
pp. 1689-1701
Author(s):  
Jon Olafsson ◽  
Solveig R. Olafsdottir ◽  
Taro Takahashi ◽  
Magnus Danielsen ◽  
Thorarinn S. Arnarson
Keyword(s):  
North Atlantic ◽  
Thermohaline Circulation ◽  
Atlantic Water ◽  
Water Masses ◽  
The Arctic ◽  
Arctic Water ◽  
The North ◽  
The North Atlantic ◽  
Co2 Sink ◽  
The One

Abstract. The North Atlantic north of 50∘ N is one of the most intense ocean sink areas for atmospheric CO2 considering the flux per unit area, 0.27 Pg-C yr−1, equivalent to −2.5 mol C m−2 yr−1. The northwest Atlantic Ocean is a region with high anthropogenic carbon inventories. This is on account of processes which sustain CO2 air–sea fluxes, in particular strong seasonal winds, ocean heat loss, deep convective mixing, and CO2 drawdown by primary production. The region is in the northern limb of the global thermohaline circulation, a path for the long-term deep-sea sequestration of carbon dioxide. The surface water masses in the North Atlantic are of contrasting origins and character, with the northward-flowing North Atlantic Drift, a Gulf Stream offspring, on the one hand and on the other hand the cold southward-moving low-salinity Polar and Arctic waters with signatures from Arctic freshwater sources. We have studied by observation the CO2 air–sea flux of the relevant water masses in the vicinity of Iceland in all seasons and in different years. Here we show that the highest ocean CO2 influx is to the Arctic and Polar waters, respectively, -3.8±0.4 and -4.4±0.3 mol C m−2 yr−1. These waters are CO2 undersaturated in all seasons. The Atlantic Water is a weak or neutral sink, near CO2 saturation, after poleward drift from subtropical latitudes. These characteristics of the three water masses are confirmed by data from observations covering 30 years. We relate the Polar Water and Arctic Water persistent undersaturation and CO2 influx to the excess alkalinity derived from Arctic sources. Carbonate chemistry equilibrium calculations clearly indicate that the excess alkalinity may support at least 0.058 Pg-C yr−1, a significant portion of the North Atlantic CO2 sink. The Arctic contribution to the North Atlantic CO2 sink which we reveal was previously unrecognized. However, we point out that there are gaps and conflicts in the knowledge about the Arctic alkalinity and carbonate budgets and that future trends in the North Atlantic CO2 sink are connected to developments in the rapidly warming and changing Arctic. The results we present need to be taken into consideration for the following question: will the North Atlantic continue to absorb CO2 in the future as it has in the past?

scholarly journals Moisture origin, transport pathways, and driving processes of intense wintertime moisture transport into the Arctic

2021 ◽  
Author(s):  
Lukas Papritz ◽  
David Hauswirth ◽  
Katharina Hartmuth
Keyword(s):  
North Atlantic ◽  
Moisture Transport ◽  
Large Scale ◽  
The Arctic ◽  
Polar Cap ◽  
Transport Pathways ◽  
Moisture Sources ◽  
The North ◽  
Total Transport ◽  
Air Streams

Abstract. Poleward moisture transport occurs in episodic, high-amplitude events with strong impacts on the Arctic and its climate system components such as sea ice. This study focuses on the origin of such events and examines the moisture sources, moisture transport pathways, and their linkage to the large-scale circulation. For that purpose, 597 events of intense zonal mean poleward moisture transport at 70° N (exceeding the 90th anomaly percentile) are identified and kinematic backward trajectories from 70° N are computed to pinpoint the moisture sources and characterize the air-streams accomplishing the transport. The bulk of the moisture transported into the polar cap during these events originates in the eastern North Atlantic with an uptake maximum poleward of 50° N. This asymmetry between ocean basins is a direct consequence of the fact that most of the moisture transport into the polar cap occurs in this sector. As a result of the fairly high-latitude origin of the moisture, the median time moisture spends in the atmosphere prior to reaching 70° N amounts to about 2.5 days. Trajectories further reveal an inverse relationship between moisture uptake latitude and the level at which moisture is injected into the polar cap, consistent with ascent of poleward flowing air in a baroclinic atmosphere. Focusing on events for which 75 % of the zonal mean moisture transport takes place in the North Atlantic east of Greenland (424 events) reveals that lower tropospheric moisture transport results predominantly from two types of air-streams: (i) cold, polar air advected from the Canadian Arctic over the North Atlantic and around Greenland, whereby the air is warmed and moistened by surface fluxes, and (ii) air subsiding from the mid-troposphere into the boundary layer. Both air-streams contribute about 36 % each to the total transport. The former dominates the moisture transport during events associated with an anomalously high frequency of cyclones east of Greenland (218 events), whereas the latter is more important in the presence of atmospheric blocking over Scandinavia and the Ural (145 events). A substantial portion of the moisture sources associated with both types of air-streams are located between Iceland, the British Isles, and Norway. Long-range moisture transport, accounting for 17 % of the total transport, is the dominant type of air-stream during events with weak forcing by baroclinic weather systems (64 events). Finally, mid-tropospheric moisture transport is invariably associated with (diabatically) ascending air and moisture origin in the central and western North Atlantic, including the Gulf Stream front, accounting for roughly 10 % of the total transport. In summary, our study reveals that moisture injections into the polar atmosphere are not primarily caused by the poleward transport of warm and humid air from low latitudes – a conclusion that applies in particular to cases where the transport is driven by baroclinic weather systems such as extratropical cyclones. Instead, it results from a combination of air-streams with pre-dominantly high-latitude or high-altitude origin and their interplay with large-scale weather systems (e.g., cyclones, blocks).

scholarly journals Estimation of spatio-temporal distribution of precipitable water using MODIS and AVHRR data: a case study for Cyprus

2011 ◽  
Vol 30 ◽  
pp. 23-29 ◽  
Author(s):  
D. Hadjimitsis ◽  
Z. Mitraka ◽  
I. Gazani ◽  
A. Retalis ◽  
N. Chrysoulakis ◽  
...  
Keyword(s):  
Near Infrared ◽  
Temporal Distribution ◽  
Grid Cell ◽  
Precipitable Water ◽  
Avhrr Data ◽  
Moderate Resolution ◽  
Resolution Imaging ◽  
Spatio Temporal ◽  
Moderate Resolution Imaging Spectroradiometer

Abstract. In this paper, the atmospheric precipitable water (PW) over the area of Cyprus was estimated by means of Advanced Very High Resolution Radiometer (AVHRR) thermal channels brightness temperature difference (ΔT). The AVHRR derived ΔT was calculated in a grid of 5 × 5 km cells; the corresponding PW value in each grid cell was extracted from Moderate Resolution Imaging Spectroradiometer (MODIS) Level 2 product (near-infrared algorithm). Once the PW – ΔT relationship coefficients corresponding to the area of Cyprus were calculated, the relationship was applied to AVHRR data for one month period. Radiosonde derived PW values, as well as MODIS independent PW values were used to validate the estimations and a good agreement was noted.

scholarly journals Propagation of Thermohaline Anomalies and their predictive potential along the Atlantic water pathway

2021 ◽  
pp. 1-60
Keyword(s):  
North Atlantic ◽  
Physical Mechanism ◽  
Atlantic Water ◽  
The Arctic ◽  
North Atlantic Current ◽  
The North ◽  
Spatio Temporal ◽  
Prediction Systems ◽  
Water Pathway ◽  
Atlantic Current

Abstract We assess to what extent seven state-of-the-art dynamical prediction systems can retrospectively predict winter sea surface temperature (SST) in the subpolar North Atlantic and the Nordic Seas in the period 1970-2005. We focus on the region where warm water flows poleward, i.e., the Atlantic water pathway to the Arctic, and on interannual-to-decadal time scales. Observational studies demonstrate predictability several years in advance in this region, but we find that SST skill is low with significant skill only at lead time 1-2 years. To better understand why the prediction systems have predictive skill or lack thereof, we assess the skill of the systems to reproduce a spatio-temporal SST pattern based on observations. The physical mechanism underlying this pattern is a propagation of oceanic anomalies from low to high latitudes along the major currents; the North Atlantic Current and the Norwegian Atlantic Current. We find that the prediction systems have difficulties in reproducing this pattern. To identify whether the misrepresentation is due to incorrect model physics, we assess the respective uninitialized historical simulations. These simulations also tend to misrepresent the spatio-temporal SST pattern, indicating that the physical mechanism is not properly simulated. However, the representation of the pattern is slightly degraded in the predictions compared to historical runs, which could be a result of initialization shocks and forecast drift effects. Ways to enhance predictions, could be through improved initialization, and better simulation of poleward circulation of anomalies. This might require model resolutions in which flow over complex bathymetry and physics of mesoscale ocean eddies and their interactions with the atmosphere are resolved.

Spatio-Temporal Variability of Seasonal Drought Over the Dobrogea Region

2020 ◽  
pp. 590-617
Author(s):  
Monica Ionita ◽  
Silvia Chelcea
Keyword(s):  
North Atlantic Oscillation ◽  
North Atlantic ◽  
Temporal Variability ◽  
Potential Evapotranspiration ◽  
Phase Relationship ◽  
Dominant Mode ◽  
The Arctic ◽  
Spatial And Temporal Variability ◽  
Drought Conditions ◽  
Spatio Temporal

In this study we have examined the spatial and temporal variability of seasonal short-term drought over Dobrogea region over the period 1965 -2005. The dominant mode of spatial variability captures an in-phase relationship of drought conditions over the entire analyzed region, for all the seasons. We show that the Arctic/North Atlantic Oscillation patterns control a significant part of the interannual drought variability over the Dobrogea region in all seasons. Dry (wet) periods in Dobrogea region are associated with geopotential height anomalies at 850mb that project onto the negative (positive) phase of Arctic/North Atlantic Oscillation. Moreover, the SST anomalies from the Atlantic Ocean realm and potential evapotranspiration anomalies over the south eastern part of Romania play also a significant role on the variability of drought conditions over Dobrogea region.

The pattern of radiative heating and cooling in the troposphere and lower stratosphere

1956 ◽  
Vol 236 (1205) ◽  
pp. 148-156 ◽  
Keyword(s):  
Cooling Rate ◽  
Water Vapour ◽  
Middle Atmosphere ◽  
Precipitable Water ◽  
Radiative Heating ◽  
The Arctic ◽  
Trade Wind ◽  
Water Vapour Content ◽  
Middle Latitudes ◽  
Heating And Cooling

For any meteorological effects of radiation, only those constituents of the air which have a very strong absorption in the infra-red are involved; these are water vapour and carbon dioxide. Several methods have been developed (Mügge & Möller 1932 a, b ; Elsasser 1942; Yamamoto 1952) for computing the radiation flux, and numerous calculations of these fluxes and of the cooling rates have been performed in the last 25 years (Ludwig 1935; Kortiim 1939; Thompson & Neiburger 1955). The results are summarized in figure 1, which shows the distribution of the tem­perature and of the cooling rate by water vapour in some characteristic atmospheres. The lower levels of the tropical atmosphere have a small cooling rate because the higher layers are very humid and the lower layers are thus sheltered from radiation losses. A contrary effect occurs at 30° latitude, where a very dry subsiding middle atmosphere is observed above a very wet trade-wind layer. In the arctic atmosphere a high cooling rate results for 1.5 km as a consequence of the conduction-like effect of radiation. The maximum values of the cooling rate are attained in the higher troposphere; they shift to somewhat lower levels with decreasing temperature and decreasing water-vapour content, from 10.5 km in the tropics to 7 km in middle latitudes and 4 km in the arctic. Apart from the extreme conditions in the arctic, the curves do not show much difference, and it is probable that all the differences may be understood by considering only the different amount of precipitable water.

scholarly journals Signatures of the 2-day wave and sudden stratospheric warmings in Arctic water vapour observed by ground-based microwave radiometry

2015 ◽  
Vol 15 (9) ◽  
pp. 5099-5108 ◽  
Author(s):  
B. Tschanz ◽  
N. Kämpfer
Keyword(s):  
Time Series ◽  
Water Vapour ◽  
Temporal Resolution ◽  
Microwave Radiometer ◽  
Maximum Amplitude ◽  
Microwave Radiometry ◽  
The Arctic ◽  
Arctic Water ◽  
Measurement Period

Abstract. The ground-based microwave radiometer MIAWARA-C recorded the upper stratospheric and lower mesospheric water vapour distribution continuously from June 2011 to March 2013 above the Arctic station of Sodankylä, Finland (67.4° N, 26.6° E) without major interruptions and offers water vapour profiles with temporal resolution of 1 h for average conditions. The water vapour time series of MIAWARA-C shows strong periodic variations in both summer and winter related to the quasi-2-day wave. Above 0.1 hPa the amplitudes are strongest in summer. The stratospheric wintertime 2-day wave is pronounced for both winters on altitudes below 0.1 hPa and reaches a maximum amplitude of 0.8 ppmv in November 2011. Over the measurement period, the instrument monitored the changes in water vapour linked to two sudden stratospheric warmings in early 2012 and 2013. Based on the water vapour measurements, the descent rate in the vortex after the warmings is 364 m d−1 for 2012 and 315 m d−1 for 2013.

scholarly journals Satellite-Derived Spatio-Temporal Distribution and Parameters of North Atlantic Polar Lows for 2015–2017

Atmosphere ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 224
Author(s):  
Pavel Golubkin ◽  
Julia Smirnova ◽  
Leonid Bobylev
Keyword(s):  
North Atlantic ◽  
Barents Sea ◽  
Auxiliary Information ◽  
Low Frequency ◽  
Temporal Distribution ◽  
Study Region ◽  
Polar Lows ◽  
Mean Values ◽  
Polar Low ◽  
Spatio Temporal

A list of North Atlantic polar lows was compiled for 2015–2017. A total of 131 polar lows were found by analyzing the Moderate Resolution Imaging Spectroradiometer (MODIS) infrared imagery and auxiliary information. The study region was additionally divided by the 20° W meridian to assess possible differences in the polar lows occurring in the western and eastern parts of the region. The highest polar low activity was found over the Barents Sea and the northern Norwegian Sea. A large number of polar lows over this region were dual or multiple. When considering such systems as a single event, more polar lows were found in 2015 over the Labrador Sea and southern Davis Strait, which is the region with the second highest number of polar lows. High interannual variability of polar low frequency was noted, which was more pronounced in the western part of the region. During the analyzed period, the largest number of polar lows occurred in January for the western part of the region and in February for the eastern part. The main polar low parameters were similar within the region, with the mean values slightly higher in the western part of the region, but all extreme high values were observed in the eastern part.

Sign in / Sign up

Export Citation Format

Share Document