Water vapour is of import to the conditions and clime because of their function in the planetary clime system. The clear interaction between H2O vapour and atmospheric events can explicate some physical mechanisms of how little graduated table of atmospheric environment could act upon the clime alteration form. To heighten this interaction, this work is aimed to detect the features of coreless winter event utilizing precipitable H2O vapour ( PWV ) derived from GPS technique, surface weather forecasting and solar radiation informations. The periods of observations are over 2009 for Antarctic and from July 2008 to June 2009 for Arctic. Results show that the happening of coreless winter was clearly detected in June and January for Antarctica and Arctic, severally. During the period of winter, the temperature, comparative humidness and PWV fluctuations at both parts demonstrates straight relative to each other than with surface force per unit area. At the center of winter when coreless event took topographic point as indicated by important unusual warming extremum of temperature, comparative humidness and PWV in both parts, their form was shown similar characters except for surface force per unit area. During this event, the increasing of 1A°C of temperature has increased the PWV of approximately 0.25 millimeters and 0.70 millimeter for Antarctica and Arctic, severally, verified that the PWV in Arctic was observed twice bigger compared to Antarctic. The increased PWV during winter suggests that the coreless winter feature was meaning when advection of warm or cold air multitudes over the part tend to increase the formation of cyclonal activity that frequently causes to hold the chilling in surface temperature.
Keywords: GPS PWV ; Coreless winter ; Antarctic and Arctic ; Climate
The Antarctic-Arctic parts ( bipolar ) have turning acknowledgment that polar clime conditions were strongly act upon the universe clime system. Because of bipolar being in head of clime alterations issues and a sensitive index of global-scale clime alteration, proper word picture of the polar ambiance is indispensable to better our apprehension of the matching mechanisms between bipolar and planetary climes, and between the atmospheric, land and pelagic constituents of the clime system. Consequently, atmospheric H2O vapour is peculiar of import because of their capableness to modulate the polar energy balances. For illustration, little alterations of atmospheric H2O vapour have much larger impact on the nursery consequence and thereby heat the Earth ‘s surface cause a heating. As can be seen, a portion of both parts in recent twelvemonth had shown most rapid rates of the warming impact. In the Arctic, the important warming commence during the twentieth century with magnitude of air temperatures over extended land countries was expected increased by up to 5A°C ( IPCC, 2007 ) . The ascriptions of recent alterations are from the natural variableness and anthropogenetic forcing, which concludes a significant proportion of the recent variableness and manifestation of nursery gas induced by human ( e.g. , Serreze and Francis, 2006 ) . The most recent ( 1980 to show ) heating of the Arctic is strongest ( about 1A°C/decade ) in winter and spring ( McBean et al. , 2005 ) , while in the South-polar part, there has been a pronounced most quickly warming tendency was in the Antarctic Peninsula over the past several decennaries ( Turner et al. , 2007 ) . South-polar Peninsula Stationss show a consistent regional rate of warming that is more than twice the norm for other South-polar Stationss. King and Harangozo ( 1998 ) suggest that this heating is associated with an addition in the northern constituent of the atmospheric circulation over the Peninsula and possibly alterations in the sea-ice extent.
The important warming tendencies during winter in Antarctic and Arctic parts have been attracted many research worker to analyze about the physical mechanism that contributed to the event. The warming temperature during winter in the inside of Antarctica was widely accepted, as the ‘coreless ‘ or ‘kernlose ‘ winter ( see definition by Wexler, 1958 ; Wendler and Kodama, 1993 ) . This phenomenon refer to the winters without cold nucleus, nevertheless the temperature tendency addition for a few months and lead to a upper limit in early winter after a important bead in fall season. Several writers ( Carroll, 1982 ; Stone et al. , 1989, and Stone and Kahl, 1991 ) studied that the increasing of temperature during austral winter was non monotone and strong sudden heating episodes has been occurred. More surveies on temperature behaviour during winter in Antarctica, for illustration, Connolley and Cattle ( 1994 ) uses force per unit area and temperature Fieldss to better the public presentation of the UKMO Unified Model and found the coreless characteristic was present in their theoretical account, although cloud covers appears to be a job to their theoretical account truth. Van Den Broeke ( 1998 ) studied the influence of semi-annual oscillation ( SAO ) on near-surface temperature in Antarctica for period from 1957 to 1979, and shown sea ice extent modifies the SAO influence during winter, peculiarly in Vostok station. StyszyA„ska ( 2004 ) examined the relationship between the air temperature at Arctowski station on the South Shetlands, with the sea ice extent and sea surface temperature ( SST ) in the Bellingshausen Sea, and the event of coreless winter was identified pronounced in July. In add-on, Hudson and Brandt ( 2005 ) study the relationship between the inversion temperature profile by radiosonde informations over the South-polar Plateau at different graduated tables with air currents and downward long-wave radiation. In these surveies, nevertheless the consequence of radiosonde informations was limited to show their temporal declaration because the informations merely accessible twice a twenty-four hours. Because winters are terrible in Antarctica and the period of coreless winter was singular different for each part, their beginning and causes are of import before it strikes. Furthermore, the physical procedures of coreless during the winter is still ill understood. Therefore, in this work H2O vapor monitoring from ground-based Global Positioning System ( GPS ) technique is proposed to qualify the coreless winter behaviour.
The GPS is an accurate and powerful technique to recover the precipitable H2O vapour ( PWV ) in all conditions conditions from individual station observations and/or in ground-based web with all right temporal and spacial declaration. This technique was foremost described by Bevis et Al. ( 1992, 1994 ) , Rocken et Al. ( 1993 ) and Duan et Al. ( 1996 ) , which GPS orbiter wireless signals are slowed caused by originates of both the ionosphere and the impersonal ambiance. To find the PWV from GPS signals holds, the procedure is accomplished by dividing the mistakes introduced into the computation by system-related and geometric factors caused the transition of the GPS signal through the ambiance ( Gutman et al. , 1994 ) . As the ionosphere hold is frequency dependant, it can be corrected by utilizing dual-frequency GPS receiving systems, and the staying hold, impersonal hold, which is depend on its components in the lower ambiance. The impersonal hold, alleged the entire tropospheric hold consists of a ‘hydrostatic ‘ hold and a ‘wet ‘ hold. The hydrostatic hold incorporating about 90 % of dry gases in the troposphere and the non-dipole constituent of H2O vapour refractiveness, while the wet hold is associated with the distribution of H2O vapour overlying from a GPS receiving system to the top of atmosphere. On the other manus, the entire tropospheric hold is the amount of the hydrostatic hold and wet hold. The PWV can be estimated from the zenith wet hold ( ZWD ) after the GPS signal mapped to satellite position. Section 2.3 gives briefly account of the PWV finding. Presently, the high impact of GPS PWV has been compared with radiosonde or microwave radiometers and found consistent at degree of 1~2 millimeter ( Rocken et al. , 1997 ; Businger et al. , 1996 ; Elgered et al. , 1998 ) . More soon, it can be used to better mesoscale NWP theoretical account ( Kuo et al. , 2000 ) and for clime monitoring ( Gradinarsky et al. , 2002 ) . The GPS PWV besides can be used as a placeholder of upper-lower atmospheric matching surveies as proposed by Suparta et Al. ( 2008 ) .
In this paper, the impact of GPS PWV is employed to analyze the response of coreless winter behaviour. In the analysis, the similarities or different of coreless winter in Antarctic and Arctic parts are observed. The location of survey for this work is focused at two braces of polar conjugate Stationss: Scott Base – Resolute, and Syowa – Reykjavik. Scott Base ( SBA ) and Syowa ( SYOG ) , and Resolute ( RESO ) and Reykjavik ( REYK ) are represents observations for Antarctic and Arctic parts, severally. For the analysis, the PWV and surface weather forecasting informations over the period of 2009 for Antarctic and from July 2008 to June 2009 for Arctic are processed. The measurings consequences are so analyzed on a day-to-day and monthly footing to give clear the response of surface parametric quantities on coreless winter event. In farther probe, solar radiation on monthly norm is analyzed to acquire clear seasonal of the happening of coreless winters.
Data sets and methodological analysis
In this survey the observations of coreless winter were focal points at high latitudes of Southern Hemisphere and Northern Hemisphere, in which the footings of both hemispheres for this work defined as the Antarctic and Arctic, severally. Two Stationss in each part, that are SBA and SYOG for Antarctic, and RESO and REYK for Arctic are selected. The location of each station in both parts is located above 60 grades, and coincidently identified as geomagnetic conjugate points, whereas the approximative conjugate braces are SBA – RESO and SYOG -REYK. The advantage of these coupled Stationss enabling us to larn many facets related to the similarities and/or dissymmetries of their belongingss phenomena between the parts. Figure 1 depicts the location of fixed GPS sites at both parts. SBA in the left of figure is located at Pram Point, near the tip of Hut Point Peninsula on Ross Island part within the latitudeA of 77A° 51A?S and 166A° 46A?E longitude. On the other manus, SBA is situated about 3 kilometers from McMurdo US base station at Discovery Point, or around 1,353 kilometer from the South Pole. SYOG is besides one lasting station managed by the National Institute of Polar Research Japan ( NIPR ) located on the Ongul Island in Lutzow-Holm bay, approximately 4 kilometers west from the seashore of East Antarctica ( NIPR, 2009 ) . The station is situated at co-ordinates 69A°00 ‘ S and 39A°35 ‘ Tocopherol.
On the right panel of Fig. 1 presents the REYK and RESO Stationss in Arctic part. REYK is located in Southwestern of Iceland, on the southern shore of Faxafloi Bay at geographic: 64.08A°N and 21.57°W. The last station, RESO ( 74.41°N, 94.53°W ) is located between the northern terminal of Resolute Bay and the Northwest Passage of the Qikiqtaaluk part, situated on the Coast of Cornwallis Island in Nunavut, Canada.
Fig. 1. Location of fixed GPS sites in this survey for both parts, adapted from hypertext transfer protocol: //gdl.cdlr.strath.ac.uk/scotia/vserm/vserm0103.htm
The chief base of measurement systems for Antarctica is at SBA. The system employed at SBA consists of a GPS receiving system and a land meteoric system. The GPS receiving system was installed in November 2002 under the Malaysian Antarctic Research Programme ( MARP ) and was maintained by Antarctica New Zealand ( ANZ ) . At this station, GPS informations are collected continuously utilizing a Trimble GPS receiving system and a Zephyr Geodetic aerial. The GPS receiving system was set to track GPS signals at 1s trying rate and the cut-off lift angles was set to 13A° to extinguish possible multipath effects on GPS informations. The surface meteoric information was supported by the National Institute of Water and Atmospheric Research Ltd. , New Zealand ( NIWA ) and ANZ. Both measurement systems housed at Hatherton Geosciences Lab are employed to find PWV. Further inside informations of measurement systems at SBA can be found in Suparta et Al. ( 2008 ) . The GPS informations apart from SBA were obtained from the International GNSS Service ( IGS ) at SOPAC home page ( hypertext transfer protocol: //sopac.ucsd.edu ) , except GPS informations for RESO station, which is from the Canadian Spatial Reference System ( CSRS ) database. Table 1 gives the instrument apparatus of GPS receiving systems and geographical co-ordinates for four Stationss in both parts. The GPS informations at SOPAC were recorded at 30 2nd intervals and supplied as RINEX files of 24 hours continuance. The all observation files are available in Hanataka format ( d-file compaction ) to cut down the storage size of RINEX files. The surface meteoric informations for SYOG, RESO and REYK are obtained from the British Antarctic Survey ( BAS ) , the Environment Canada Weather Office database and the SOPAC web sites, severally. In this work, surface meteoric informations for PWV computation consists of surface force per unit area ( in mbar ) , temperature ( in A°C ) and comparative humidness ( in per centum ) . The sampling cyclicity for all surface meteoric informations for SBA, SYOG, RESO and REYK are 10 min, 3h, 1h and 15 min, severally.
The geographical co-ordinates and instrument apparatus of GPS receiving systems for both parts
( state )
( Deg )
( Deg )
( m )
Types of GPS receiving system and twelvemonth installed
Cut-off lift angle ( Deg )
Resolute ( CAN )
Reykjavik ( ICL )
Syowa ( JPN )
Scott Base ( NZ )
Small business administration
ASHTECH UZ-12 ( 2006 )
TPS E_GGD ( 2008 )
Trimble NETRS ( 2007 )
Trimble TS5700 ( 2002 )
To place a clear seasonal fluctuation of polar clime, solar radiation measured at both parts is employed. The solar radiation informations at SBA and Tartu-Toravere ( TRV ) are obtained from NIWA and the Estonian Meteorological and Hydrological Institute at WRDC ( World Radiation Data Center ) , severally. The solar radiation consists of direct, diffuse and planetary, which are measured in unit of W/m2. At SBA, the solar radiation systems are measured with a Kipp and Zonen CM 11 pyranometer to steps direct, diffuse and planetary radiation. At TRV station, direct solar radiation is measured utilizing the Actinograph, while for diffuse and planetary solar radiations are measured utilizing the Yanishevsky pyranometer M-150.
The PWV sum is determined from both GPS and come up meteoric informations. As GPS information from SOPAC available in Hatanaka format, to change over a RINEX file to or from Hatanaka format requires particular package. This can be obtained from file transfer protocol: //terras.gsi.go.jp/software/RNXCMP. When RINEX files gettable in observation and pilotage files, the following measure is so appraisal of entire atmospheric hold. Basically there are five stairss to deduce the PWV from GPS observations. First, the entire tropospheric hold is estimated by restraining the places of widely-spaced GPS receiving systems and mensurating the evident mistake in place every 30s. When all system related mistakes are accounted, the residuary mistake is presumed to come merely from the impersonal ambiance. Second, the entire signal holds measured by the GPS receiving system from all orbiters in position are mapped to the zenith way utilizing a hydrostatic appropriate function map, and combined to give the zenith entire hold ( ZTD ) . In add-on to the precise ZTD appraisal truth, the residuary tropospheric hold was cancelled by implementing a individual differencing technique in the pre-processing with baseline length below 10 kilometer. On the other manus, the ZTD in this work is calculated based on the Modified Hopfield theoretical account. Third, the zenith hydrostatic hold ( ZHD ) is calculated utilizing surface force per unit area measuring and the precise geographic place at the GPS site. In this work, ZHD is used to rectify the mistakes caused by atmospheric holds on the GPS signals. Fourth, the Zenith Wet Delay ( ZWD ) is obtained by deducting the ZHD from ZTD. Finally, PWV is derived from ZWD signals and a transition factor that proportional to the leaden average surface temperature. The average air temperature is presently estimated from a surface temperature measuring at the site. In this work, the Tropospheric Water Vapor Program ( TroWav ) written in Matlab developed by the first writer was used to treat and analyse all the above parametric quantities. Further inside informations of GPS derived PWV above can be found in Suparta et Al. ( 2008 ) . For this work, the existent PWV information ( in kg/m2 or millimetre ) at SBA has been calculated at a 10-min interval. The ZTD merchandise at this station had an truth of about 1.0 ~ 1.20 centimeters degree, which corresponds to 1~2 millimeters in PWV prejudice.
To detect one-year oscillation of winter season for both parts, the informations collected from January to December 2009 and from July 2008 to June 2009 for two Stationss in Antarctic and Arctic, severally, were processed. Overall, the GPS PWV consequences at SBA, RESO, REYK and SYOG for this analysis are calculated at 10 min, 1h, 2h and 3h intervals, severally. In farther probe, the monthly norm of all parametric quantities with solar radiation was analyzed in order to acquire clear form of coreless winter behaviour. The analyses are to detect the temporal fluctuations of surface meteoric measurings and PWV to correlate their influence on the coreless winter.
3. Consequences and treatments
To detect the features of coreless winter between the parts, the atmospheric variables: surface meteoric measurings ( force per unit area, temperature and comparative humidness ) , PWV and solar radiation constituents ( direct, diffuse and planetary ) during the winter are presented. The dynamic responses of coreless winter on the above variables are discussed through in the physical procedures at the beginning of these coreless.
3. 1 Daily surface meteoric and GPS PWV fluctuations between the parts
Figure 2 shows the day-to-day fluctuations of surface parametric quantities for Antarctic and Arctic, severally. The top panel of Fig. 2 presents the surface force per unit area for SBA and SYOG vary from 939 mbar to 1029 mbar. At each station, their average values are recorded around 991 mbar and 985 mbar, severally. For RESO and REYK, they have similar mean values that are about 1000 mbar. The lowest and highest force per unit areas for Arctic are recorded in January and April with values 950 mbar and 1035 mbar, severally. As shown in the figure, the surface force per unit area fluctuations at both parts exhibits extremely irregular and their sums are depending on the weight of atmospheric mass on top of peculiar measuring point. The air force per unit area at sea degree usually varies between 970 mbar and 1040 mbar ( Sing and Aung, 2005 ) with standard atmospheric force per unit area at sea degree is taken as 1013.25 mbar. The in-between panel of Fig. 2 nowadayss the day-to-day fluctuations of surface temperature. The mean values for South-polar ranging from -50°C to 4°C with average values for SBA and SYOG are about -19A°C and -10A°C, severally. The scope temperature for REYK was between -9.9A°C and 24.4A°C with a average value of about 5A°C. At RESO, the scope values vary from -40A°C to 18A°C ( -14.6A°C, on norm ) with an utmost minimal value recorded was -40.2A°C in March. From temperature recorded, temperature for Arctic demonstrates a big sum of heat compared to Antarctic temperature with difference mean value was 10.31°C. The bottom panel of Fig. 2 presents the fluctuations of comparative humidness for each station with average values for SBA and SYOG are about 63 % and 73 % , severally, and for REYK and RESO are 77 % and 71 % , severally. The comparative humidness at REYK shown little fluctuations compared to RESO, whereas the humidness at RESO demonstrated addition from July to November and started lessening in December. The comparative humidness in Antarctic was more fluctuating compared to Arctic fluctuation because of the driest ambiance in Antarctica. Overall, the day-to-day fluctuation of surface meteoric parametric quantities at both parts showed a similar seasonal fluctuation, which highest during summer and lowest for winter periods.
Fig. 2. Daily norm of surface meteoric fluctuations for two Stationss in both parts, severally. The month label in the figure represents center of the month in UT.
Figure 3 presents the GPS PWV fluctuations for Antarctic and Arctic, severally. The day-to-day form of PWV in both parts showed U-distribution, which minimum in winter and upper limit in summer. This suggests the development of PWV variableness was dependance to the Sun. As shown on the left of Fig. 3, the mean values of PWV measurings observed at Antarctic runing from 0.35 millimeters to 11.54 millimeters, with average values are 3.27 millimeters and 5.26 millimeter for SBA and SYOG, severally. While for Arctic on the right of Fig. 3, the mean PWV values vary from 0.75 millimeters to 31.75 millimeters, with average values are 5.42 millimeters and 12.35 millimeter for RESO and REYK, severally. The PWV fluctuation at REYK shown a extremely variable compared to the PWV at RESO. This high fluctuations is perchance because its location that inclination have stormy conditions influenced by the conflict of the Irminger Current and East Greenland Current ( see Nowotarski et al. , 2006 ) . Thus the PWV value in Arctic was observed about twice bigger compared to the PWV at Antarctica. In add-on to the conditions status, the air current velocities at SBA and SYOG were windiest, with one-year norms of about 5.2 m/s and 6.5 m/s, severally. The wind way for SBA, the most frequent air current way coming from easterly to Northeast between 45° and 90° ( see Suparta et al. , 2009 ) . For SYOG, the air current dominantly blows northeasterly ( sou’-west ) with directional stability of air current about 0.78 ( Sato and Hirasawa, 2007 ) . While one-year mean air current velocities for RESO and REYK were approximately 5.9 m/s and 4 m/s, severally. Both wind waies at both Stationss from Southeast to Southwest directional ( see Einarsson, 1984 ) and flow from North to Northwest ( NW ) directional ( hypertext transfer protocol: //www.theweathernetwork.com ) , severally.
Fig. 3. Daily norm of GPS PWV fluctuations at both parts
Coreless winter analysis
3.2.1 Solar radiation form between the parts
As introduced in Section 2.2, solar radiation for this work is employed to place a clear seasonal fluctuation of polar clime in both parts. Because of lack handiness of recent solar radiation informations at RESO, solar informations at TRV station ( 58A°15’N, 26A°28’E ) for period from July 2008 to June 2009 was chosen alternatively of RESO informations. Although solar informations from TRV used in this work, solar informations at RESO ( hypertext transfer protocol: //wrdc.mgo.rssi.ru ) for the period of 1998/1999 was compared to TRV, and shown that the one-year norms for diffused and planetary constituents for RESO was about 585 W/m2. The lower solar radiation recorded at RESO for 1998/1999 with about zero values was received from November to February. While mean solar radiation at TRV at the same period was recorded lower between October and April for diffuse and direct constituents about 467 W/m2. In add-on, mentioning to the Earth receives a entire sum of radiation in one cross country ( one-fourth ) about 342A W/mA? of solar invariable, the happening of dark ( winter period ) for Arctic can be assumed occurs between October and April. The low solar radiation forms for diffuse, direct and planetary constituents recorded at SBA are employed to stand for winter period in Antarctic.
Figure 4 shows the fluctuations of solar radiation constituents at SBA and TRV over the period of 2009 and from July 2008 to June 2009, severally. On the left of Fig. 4 shown that SBA received low solar radiation around six back-to-back months from March ( polar sundown ) to October ( polar forenoon ) with about about nothing values. Thus the solar radiation form in Antarctic represented by SBA, which the period of winter was defined between March and October. While at TRV, solar radiation was recorded low at around five months which considered below 500 W/m2 occurred from October to April. As shown in Fig. 4, solar radiation penetrates higher in Arctic compared to Antarctic, with norm of planetary constituents at TRV larger about 33 times than with SBA. Similar to SBA, solar radiation at TRV show increasing in spring and upper limit in summer, whereas in fall the fluctuations were worsening. The mean differences of direct, diffuse and planetary constituents during winter between both parts are about 300, 216 and 309 W/m2, severally. On the other manus, the fluctuations of solar radiation in both parts were characteristically U-distribution. From the low sum of solar radiation in Fig. 4, the premise for the period of winter in both parts used to analyse the features of coreless winter can be decently expected.
Fig. 4. Monthly norm of solar radiation fluctuations at both parts
Features of coreless winter
To supervise the coreless winter behaviour in both parts, the surface parametric quantities ( force per unit area, temperature and comparative humidness ) and PWV fluctuations were analyzed in a monthly norm, as presented in Fig. 5. As shown in the figure, the important unusual warm temperature extremums perceptibly occurred during winter was identified as a coreless winter event. For illustration, the coreless winter event pronounced in Antarctica occurred when the surface temperature has a important extremum for one or two months during winter season ( Wexler, 1958 ; van Loon, 1967 ; King and Turner, 1997 ; StyszyA„ska, 2004 ) . To detect clearly the features of coreless winter, the analyses are focused during the period of winter as indicated by two episodes as F1 and F2. The first episodes ( F1 ) were from March to June of 2009 and October 2008 to January 2009 for Antarctic and Arctic, severally. The 2nd episode ( F2 ) for Antarctic and Arctic were in June to October 2009, and from January to April of 2009, severally.
The left panel of Fig. 5 showed the coreless winter behaviour in Antarctic started from March to October. June is considered as a coreless winter because of unusual little warming during the period of winter. In the first episode ( F1 ) , the surface force per unit area fluctuations at both Stationss have shown bit by bit increased with peaked in May. The temperature and PWV fluctuations were in worsening stage, through comparative humidness at SBA was peaked in April. However, there was important warm extremum of temperature at SBA in April through the beginning of winter clip, together with the lifting extremum in PWV, which the addition values of about 0.83°C and 0.32 millimeter, severally. Thus the temperature, comparative humidness and PWV were drop together in May before it peaked in June. From May to June, when surface force per unit area bit by bit decreased to 992 mbar on norm, the norms of temperature, comparative humidness and PWV shown bit by bit increased, with gradient values of approximately 5°C, 4 % and 1 millimeter, severally. However at SBA, comparative humidness was shown decreased in June. Further, one or more can sum up during the F1 episode, foremost, the norms of temperature and PWV fluctuations exhibit semi-seasonal oscillation, or opposed to the surface force per unit area fluctuation, while comparative humidness reveal a sinusoidal oscillation. Second, the Antarctic is starts chilling, although temperature and PWV shown increased about 4.6°C and 1.02 millimeter, correspondingly. On the other manus at this episode the cyclonal activity is weak, since the meridian fluctuation in temperature in the center troposphere is reduced.
In the 2nd episode ( F2 ) , both Stationss had shown diminishing in surface temperature, comparative humidness and PWV fluctuations from June to August, which correspond to the continuous of winter season. However, the force per unit area fluctuation at both Stationss showed a difference form. The force per unit area in SBA demoing increasing from June to July and so starts to diminish, while SYOG force per unit area was bead from June to July but the fluctuation started increasing in August. After that, the temperature and PWV fluctuations begin increased during late winter and quickly rises from September to October, while surface force per unit area fluctuation tend to diminish easy. On the other manus, the comparative humidness fluctuation at SBA showed a important bead in September and so increased back in October. The increasing of temperature was continuously until December/January in summer, when the Sun is revolving the skyline continuously at approximately 20A° lift ( Warren and Town, 2009 ) . During the F2 episode, it entirely noted that the temperature and PWV fluctuations shown closely related to each other than to come up force per unit area, while comparative humidness was dropped in September. The South-polar conditions in F2 episode is shown colder than F1 episode due to sea ice reaches its maximal extent at the terminal of the winter. The September-October is considered as an earlier Austral spring in which heating is faster than the autumnal chilling because the formation of the sea ice that takes longer clip. On the whole, the coreless winter for Antarctic on the left of Fig. 5 was clearly occurred in June, with the difference in monthly norm during the period of winter respective to the peak value of coreless winter for all observation parametric quantities are increased of approximately 3 mbar, 3.4°C, 1.6 % and 0.65 millimeter, severally. Figure 6a summarizes the responses of surface parametric quantities and PWV observations during each episode of coreless winter event.
For Arctic, the period of winter is identified between October and April as shown on the right panel of Fig. 5. January is considered as a coreless winter, though the norm of surface force per unit area was important bead in their month due to depressions of circumpolar whirl. In the F1 episode, the norm of surface force per unit area was increasing in November, and the norms of temperature, comparative humidness and PWV was diminishing at the same time. At surface force per unit area extremum in November, the temperature, comparative humidness and PWV at REYK was shown increased than at RESO. Then these three parametric quantities drop together in December, and at the same clip surface force per unit area lessening bit by bit to 1000 mbar and 996 mbar for RESO and REYK, severally. From December to January, the three parametric quantities were shown a somewhat increased, which is indicated as a heating at the center of winter. As can be seen at RESO, the temperature and PWV lessening significantly compared to REYK. REYK showed a somewhat difference in PWV, which the fluctuation was bit by bit increased of 0.22 millimeter. This due to the interaction of North Atlantic Current with other Ocean Current that may convey strong storms and it would act upon the rate of precipitation. During coreless winter in January, both Stationss had increased in temperature and comparative humidness, when the force per unit area was decreased. Thus the warm temperature of about 2.2°C during winter tends to coerce the PWV fluctuation to increase to 1.83 millimeter. In drumhead, the norms of temperature, comparative humidness and PWV demonstrates lessening faster, bead in December before bit by bit increased in January. Surface force per unit area in this episode was peaked in November and their tendency shown opposite to F1 episode in Antarctic. The comparative humidness fluctuation at both parts shown crossed each other in the F1 episode during early winter which Antarctic in April and Arctic in November was due to the passage summer to winter season.
In the F2 episode, fluctuation of force per unit area at both Stationss had a similar form which increased in February. At the same clip the temperature, comparative humidness and PWV profiles at both Stationss had shown diminishing. Then, the surface force per unit area fluctuation for both Stationss had shown difference form. The force per unit area at RESO demonstrated increasing from February to April, while force per unit area at REYK shown significantly bead in March and subsequently increased back in April. The surface temperature, comparative humidness and PWV fluctuations at REYK demonstrated increasing from February to April, whereas at RESO these three fluctuations uninterrupted diminishing until March but increased back in April. From March to April, all the parametric quantities at both Stationss demonstrated increasing in their values, which correspond to the seasonal passage to summer. For F2 episode, we can sum up that the surface force per unit area was opposed fluctuation to the temperature, comparative humidness and PWV profiles. The alteration of temperature and comparative humidness in Arctic demonstrated more reduced in F2 than F1 which same as in South-polar part. The coreless winter for Arctic on the right of Fig. 5 was shown clearly occurred in January at REYK, with the difference in monthly norm during the period of winter respective to the peak value of coreless winter for all observation parametric quantities were increased of approximately 9 mbar, 0.9°C, 2.5 % and 0.40 millimeter, severally. However, RESO shown less important heating of temperature and PWV extremums during this winter period due to the sea ice covered through the twelvemonth and therefore the uninterrupted chilling was comparatively high than warmer rate.
Fig. 5. Monthly norms of surface weather forecasting and PWV fluctuations for both parts. The interval clip between perpendicular dashlines show the instance for the period of winter, which both divided into two episodes of coreless event, and the perpendicular dashlines in June and January show a important little warming in the center of the winter ( called “ coreless winter ” ) . Note that mistake bars in each graph show the assurance intervals of informations or the divergence along a curve, which is obtained from norm between the two values at both Stationss.
The features of coreless winter induce to the surface weather forecasting and PWV parametric quantities are shown in Fig. 6. As shown in Fig. 6a, in the F1 episode the surface force per unit area are increased for all Stationss, nevertheless, the temperature and comparative humidness had shown similar form to each other, which increased at all Stationss except for SYOG. On the other manus, PWV demonstrated increased for SBA and REYK, and decreased for SYOG and RESO. In the F2 episode, the surface force per unit area at all Stationss shown similar form as force per unit area in F1 episode. However, the temperature, comparative humidness and PWV profiles shown decreased between the norm and extremum values for each station. Based on the feature of all parametric quantities during both episodes, we can reason that the coreless winter was significantly induced during F1 episode. Figure 6b summarizes the important response of coreless winter for Antarctic and Arctic during the period of winter with regard to coreless winter phenomenon. As shown in the figure, the surface force per unit area at both parts was shown opposite fluctuation to each other which coreless winter extremums in Antarctic shown increasing and Arctic demonstrated diminishing. Average values of all parametric quantities for force per unit area, temperature, comparative humidness and PWV during winter are about 989 mbar, -20°C, 67 % and 3.0 millimeter for Antarctic which are all lower by about 12 mbar, 9°C, 4 % and 3.1 millimeter for Arctic, severally. Comparing to their extremum values, the norms of temperature and PWV for Antarctic are observed increased of approximately 4A°C and 0.36 millimeter for SBA and 2.8A°C and 0.93 millimeter for SYOG, severally. While for Arctic, the important heating had increasing the temperature of 0.92A°C and PWV of 0.41 millimeter for REYK, in contrast there is less response at RESO. Relative humidness was increased merely at SYOG and REYK for approximately 4.9 % and 2.5 % , severally. The temperature, comparative humidness and PWV profiles had shown similar features, which the coreless winter extremum values are higher than their mean value during the whole winter, except at RESO the coreless winter extremum was lower than the mean value. The less response of all parametric quantities at RESO in peculiar surface temperature and PWV possibly uninterrupted chilling that may decelerate the heating. On the happening of coreless winter, much clime at RESO is moderated by the ocean H2O, which is comparatively warm H2O keeps the North Pole from being the coldest topographic point. These declarative factors suggest that why climatic response at RESO during coreless winter event was different compared to other Stationss.
Fig. 6. Response of surface parametric quantities and PWV during ( a ) each episode and ( B ) the period of winter at both parts respect to the coreless winter event. Average and extremum in the fable stands for norm and peak values during each episode and the mean period of winter and extremum coreless, severally.
This paper success turn toing the features of coreless winter and their impacts on the GPS PWV variableness over Antarctic and Arctic parts. The observations carried out on short-run during winter for the period of 2008/2009 showed that June and January months were identified as the occurring of coreless winter event for Antarctic and Arctic, severally. During the period of winter in both parts the temperature, comparative humidness and PWV demonstrates straight relative to each other than with surface force per unit area. Temperature and PWV are the two parametric quantities had bigger impacts in the somewhat heating of the ambiance at the center of winter than with comparative humidness. At these coreless winter events, approximately, an increasing in 1A°C of temperature will increasing of PWV content of about 0.25 millimeters and 0.7 millimeter for Antarctic and Arctic, severally. In other words, the difference PWV values between Antarctic and Arctic has been quantified at about twice bigger compared to Antarctic, as the temperature in Arctic was warmer than with Antarctic. There are similarities features of atmospheric variables on the coreless winter event characterized during winter in both parts. Coreless winter was signified when the important heating in temperature during winter season related to the warm air advections to the difference temperature between the sea ice screen and sea surface temperature. The circulation will happen when the heater H2O surface flows over the cool air surface ; hence the heat exchange will increased the air temperature and H2O vapour. In add-on, the increasing of temperature and PWV may be affected by the increasing of blending heater or cold air mass advection from the strong air current velocities that will escalate cyclone activity and the traveling cyclones will convey precipitations as noted by Mahesh et Al. ( 2003 ) and Einarrson ( 1984 ) .
The analysis can be concluded that the increasing of PWV during winter in both parts signature the GPS signals had somewhat delayed that may job in positioning application. Although a little addition of PWV during winter because of no or really low solar radiation received in that part, its stage would be really important in order to heighten the capableness of ground-based GPS as a distant feeling tool to supervise atmospheric H2O vapour. The PWV variableness in both parts was closely follows the temperature patterns which are clearly identified a seasonal signal ; highest in summer and lowest in winter, and unusual heating at the center of winter is known as the coreless winter. The word picture of the response of surface weather forecasting and PWV parametric quantities during winter showed that PWV information has more capable and consistent to observe the period of coreless winter, alternatively of conventional assessment method from the inversion of surface air temperature. However, the prospective PWV information for clime surveies is non complement to traditional measurings. Although the clip happening of coreless winter may different in specific part due to influence of the air circulation factors, the high temporal and uninterrupted GPS PWV informations presented here has a great potency to supervise the features of the ambiance in peculiar in reasonable countries as the poles. To work comprehensive physical mechanism of H2O vapor distribution during coreless winter, new factors and with different event that may act upon its circulation employed for extenuating clime alteration anticipation are considered for farther surveies.