far-infrared radiative properties of water vapor and clouds in antarctica: two years of spectral infrared measurements of downwelling radiation between 7 and 100 [micro]m in wavelength at high altitude over the antarctic plateau are presented. - absorpt

by:Demi     2019-09-05
far-infrared radiative properties of water vapor and clouds in antarctica: two years of spectral infrared measurements of downwelling radiation between 7 and 100 [micro]m in wavelength at high altitude over the antarctic plateau are presented.  -  absorption of water
Water vapor and cloud are the most important greenhouse gases, and their radiation features cover all the wide spectral ranges of atmospheric thermal emission.
Normally, more than 40% of the Earth's total heat emission occursinfrared (FIR)
Spectral regions from 100 to 667 [cm. sup. -1](
Wavelength from 100 to 15 [micro]m).
Nevertheless, this spectral region has never been fully covered to 100 cm-
1 through space missions, only a few ground-
The foundation experiment exists because it is difficult to measure from high altitude and very dry places where the atmosphere is very transparent and FIR emission features cannot be observed.
To compensate for this lack of observation, the Italian experiment "The radiation properties of water vapor and cloud in Antarctica" collected a2-
Annual data sets for spectral measurements from 100 to 1,400 [atmospheric and cloud, such as volume clouds and polar cloud radiation]cm. sup. -1](100-
Wavelength seven o'clock P. M)
Including the undetected FIR area, and polarization-
Sensitive lidarobservations observations, daily radio waves, and other auxiliary information to describe the atmosphere above the site.
Starting in Italy, measurements are carried out almost continuously, with a duty cycle of 6 hours out of 9 hours
Concordia's French base is located at the Dome C above the Antarctic Plateau, 3,230 in length.
Sky conditions since 2012
Due to the uniqueness of observations, this data set will be of great value in assessing the accuracy of the atmospheric absorption model (
Gas and Cloud)
In underdeveloped FIR and detect possible daily, seasonal and annual climate features.
Water vapor and the cloud are the most important components of the atmosphere, regulating the Earth's radiation budget by a strong contribution to the greenhouse effect and the planetary responsiveness.
They capture a large amount of heat wave thermal infrastructure from the underlying atmosphere and surface emissions (
Greenhouse effect
Reflect the short-wave solar radiation back into space (albedo effect).
Water vapor and clouds are generally not considered to be the cause of man-made climate forcing, but because of their strong greenhouse effect, they are key components of the feedback process (Stocker et al. 2014).
They are considered essential components and must be better understood for their radiation properties and their associated effects on the radiation budget in order to improve climate prediction.
Nevertheless, while broadband observations were made that could determine the overall radiation impact, due to the lack of spectral resolution measurements that could relate the radiation impact to the underlying components, the radiation properties of water vapor and the cloud were not sufficiently
The biggest uncertainty in the qualitative thelongwave atmospheric emissions came from the lack of spectrallyreturned measurements far awayinfrared (FIR)
Spectral region from 100to 667 [cm. sup. -1](100-15 [micro]m)(
Turner and Mlawer 2010).
Although the FIR spectral region contains more than 40% of the total wave energy emitted by the Earth, and about 60% of the relevant radiation cooling occurs in FIR (Clough et al. 1992)
, Only some spectral measurements and data sets have been collected in this area [
See Harris and others. (2008)for an in-
In-depth discussion.
1) explained this in part
Lack of onboard spectrometer operating in FIR-
In the 1970 s there was only one very early onboard sensor, the infrared interference spectrometer (IRIS)
On Nimbus-3and -
4 satellites, providing relatively low
Spanning part of FIR (Conrath et al. 1970)
At present, none of the missions are still deployed in space even if some missions are being studied (Rizzi et al. 2002; Mlynczak et al. 2002)--and 2)thatground-
Basic observations are hindered by strong water evaporation absorption in this spectral region, and therefore, meaningful ground-
Basic observations can only be made at high altitudes or very dry places (
As described in this article)
Or a balloon from the stratosphere (Palchetti etal. 2006; Mlynczak et al. 2006a,b).
As for the water vapor spectrum, there is still some uncertainty in the knowledge of the shape of the frequency line in the far offline center in FIR.
The contribution of this component to the total absorption of water vapor is called "continuous absorption" and has a great influence on the total absorption of water vapor. An in-
Discuss in depth the importance of FIR spectral localization and find clear explanations of continuous absorption in Turner and Mlawer (2010).
In addition, the radiation properties of ice particles in the cloud, such as Cirrus or polar cloud (PSC)
, Is not known in fir, only a few models have been developed to cover this spectral region (Yang et al. 2003, 2013).
The FIR spectral range will provide unique information about the volume cloud.
Because the radiation properties of ice particles drive the radiation balance of the cloud, thus modulated the radiation from the earth, their assessment is very important, and many studies have shown that, FIR can also be used to improve the sound of the micro-physical properties of the cloud (e. g. , Baran 2007).
It is expected that observations of underexplored FIR spectral regions will provide new information on the radiation properties of water evaporation and the cloud and their role in global warming, and improve our ability to simulate and evaluate climate processes, like forcing and feeding.
The first two floors
The basic experiment developed to cover the first spectral region is the Earth cooling of water vapor radiation (ECOWAR)experiment (Bhawar et al. 2008)
This happened in the Alps of Italy, 500 MSL in 2-
During the week of March 2007, almost at the same time, radiation heating in band motion was not fully explored (RHUBC-I)of the U. S.
Measurement of atmospheric radiation (ARM)
Project of ARM Climate Research Institute (ACRF)
The Northern Slope of Alaska site inbarrow (
Turner and Mlawer 2010). A second RHUBC-
The II movement occupied placeat Cerro Toco in the Atacama Desert of Chile in October 2009 at a speed of 5,380 m MSL (Turner et al. 2012a).
These three experiments are mainly focused on clear measurements.
The main purpose is to improve the water vapor spectrum in the FIR area.
The results of these experiments help to improve the spectral representation of the pure rotating water vapor band and make the continuous absorption coefficient in FIR between 80 and 600 cur1 (55. 6-16. 7 [micro]m)(Serio et al. 2008; Delamere et al. 2010; Masiello et al. 2012; Liuzzi et al. 2014). Turner et al. (2012b)
Prove the water vapor continuation of the reform model, after RHUBC-
I and ecobar experiments have had a significant impact on the radiation and dynamics of global climate model simulations.
However, the complete representation of the fir composition of atmospheric thermal emission needs to be in all-
Sky conditions and sufficient time include daily, seasonal and annual signatures.
This can be done from highaltitudeground-
Base station characterized by low level
Humidity values throughout the year, which occur in the Antarctic Plateau, are therefore ideal for permanent installation of instruments capable of such measurements.
This paper describes the radiation properties of water vapor and cloud in Antarctica (PRANA;
The abbreviation name of Italianproject "Proprieta radiation dell 'ateliera e delle Nubiin Antartide ")
This happened from a height.
Concordia's elevation Antarctic station, close to the Dome C site, has been characterized by spectral representation of wave radiation sinking in the atmosphere (DLR)
From 100 to 1,400 [cm. sup. -1](100-7. 1 [micro]m).
The project started in December 2011, and the measurement continued until the end of 2015, making systematic acquisitions every day under different sky conditions.
The PRANA experiment provides the first complete data set of the spectral DLR, which can be obtained through the web interface, including unique measurements in FIR.
The spectral measurement of DLR is performed by a radiation detector in far infrared--
Prototype for application and development (REFIR-PAD)
The splitter, which was developed at home for on-site applications on remote sites.
In order to support the spectral measurement, acwid coverage representation was performed using a reverse scattering and depolarized lidar system.
Both instruments have long records of measurement activity: REFIR-
PAD was deployed in Brazil for the first time in 2005 and carried out a balloon flight in the stratosphere (Palchetti, etc. 2006,2008a)
And then in a few places
Activity-based from high-
Altitude location with Eco Park and RHUBC-
II or above 2007 campaign-11 period;
The lidar system was operated on the "Italy" ship in the Ross Sea on 2006 and has been operating at Concordia station since 2007.
Both instruments allow full-automatic operation 24 hours a year and have an Italian remote to adjust the configuration parameters.
Measuring instruments on site and deployed.
Concordia station is an Antarctic research base located in Area C of dome. 75[degrees]06'S, 123[degrees]23'E)
3,230 above sea level on the Antarctic Plateau (Fig. 1).
The international cooperation project between the station and the Italian national project for Antarctic research in 2005 (PNRA)
Paul Emile Victor College (IPEV).
Concordia station is open all year round, with about 65 people in summer and about 16 people in winter.
Learning from glaciers atmospheric physics and astrophysics, experiments and instruments carried out within the station range are deployed in different facilities 1,500 m² kilometers around the main building (Fig. 2). The REFIR-
A lidar system used in PAD spectrometer and PRANAproject is installed in the "physical Sanctuary (PS)
So-about half a kilometer south of the main station building-
Known as the clearing area, usually relative to the main south wind direction wind, to minimize air pollution caused by exhaust gas discharged by the generator.
Measurement by roof hole: Figure
3 shows the picture from above the roof of the sanctuary where different viewing ports can be seen. REFIR-
The PAD observes the sky through a clear aperture without any window, because in the infrared spectrum, any material introduces important absorption/reflection effects, thus reducing the calibration accuracy.
The insulating material chimney connects the inside of the instrument to the measuring port to protect the shelter from outdoor cold air.
There is a wooden fence on the roof that protects the port of REFIRPAD from wind and snow.
Two pairs of lidar
Glass windows mounted on the roof of the sanctuary.
Through the dry air flow, both windows are kept clean and free from snow and ice.
Figure 3 also shows the sight position of other instruments installed on the ps roof, which will be briefly presented in the next section "Other instruments on site. " The REFIR-
PAD spectrometerThe REFIR-
PAD instruments are based on aspectrometer designed for the satellite mission proposed in the fourth European framework plan in 1998, known as the far infrared radiation detector (Rizzi et al. 2002).
REFIRPAD is a prototype of the main instrument of the REFIR mission, a compact and easy-to-use conversion spectrometer developed for laboratory and field applications (Not only enjoy. 2006)
With the support of the Italian and European space agencies.
The spectrometer works at room temperature using a thermoelectric detector and a double-layer amplitude beam splitter, which enables good performance throughout the IR.
In the Antarctic deployment, REFIR-
The PAD works 24 hours in a row through an automated program, controlling acquisition, preliminary analysis and data transfer to Italy.
The acquisition is performed in a 9 h cycle of 66% duty cycle, where 3 h is used to calibrate the spectrum (level-1 analysis)
Email to the main server in Italy. The 9-
The H loop is chosen to cover different local times of the year, avoiding the creatures of the system, thus capturing possible Daily signatures. The REFIR-
The main specifications of the mats during the Antarctic movement are shown in Table 1.
Instrument coverage 100-1,400 crm1 (100-7. 1 pm)
The nominal spectral resolution is 0. 4 cnr1.
The measurement sequence consists of four calibration collections and four sky observations, in which the instrument observes the internal reference body source and four sky observations.
Each acquisition takes about 80 seconds, and the duration of the whole process is about 14 minutes, including the delay in detector settlement after the scene changes. The REFIR-
The PAD standard product is a calibration spectrum of the DLR obtained from a single measurement sequence, averaging on two detectors and four sky observations (
A total of 8 spectra
There are associated random and calibration errors.
Figure 4 shows some examples of spectra obtained in clear and cloudy skies (toppanel)
For the volume cloud, for the low
High-grade thick clouds, as well as typical noise performance (bottom panel)
Within the entire spectrum of the instrument.
Measurements of the entire range of atmospheric thermal emission spectra allow people to obtain information about the relevant atmospheric components that contribute to the energy balance of Langbo.
Emittedradiance is modulated by the spectral features of water vapor (H,0)
Carbon dioxide (C02), ozone (03)
And the cloud that has a huge impact. In clear-
Under sky conditions, the measured radiation of the fully transparent spectral region of the atmosphere is equal to the launch of deep space (
Blue curve in figure4)--
This can be ignored.
In other cases, the presence of the cloud increases the launch, and this contribution is mainly visible in the transparent window mouth, judging from the small effect of the thin roll cloud (
Red curve in figure4)
Strong emission of a typical oflow cloud in a completely opaque atmosphere (
Black curve in figure4).
As shown in the figure.
4. all atmospheric spectral features are passed by REFIR-Padmeasures.
The positive signal peak above the black body curve responding to the thick cloud is a local effect, due to the emission of the first part of the measurement path, which is located inside the protective chimney, just above the instrument, so, at a higher temperature than outside (chimney effect).
According to the methods outlined in Bianchini and Palchetti, the measurement errors for each mean spectrum are estimated (2008)
By calculating the radiation noise equivalent spectral radiation brightness (NESR)
Calibration error due to detector noise (Cal Err)
Due to the standard deviation of calibration uncertainty and mean value (STD).
STD is including instrument NESR (cited above)
It also considers possible scenario changes during the acquisition process under cloudy conditions.
As shown in the figure, the noise component is usually between 0. 001 and 0. 002 W[m. sup. 2]cm [sr. sup. -1]
Increase of strong absorption line of pure rotation [H. sub. 2]
O band below 600 【cm. sup. -1](above 16. 7[micro]m)and C[O. sub. 2]
With about 667 [:cm. sup. -1](15 [micro]m)
The efficiency is reduced due to the gas in the instrument path.
Strong absorption band of Pet (PET)
The substrate for making the broadband beam splitter also reduces the efficiency of the instrument.
Especially PET absorption interval 1,095-1,140 and 1,230-1,285 [cm. sup. -1](9. 13-8. 77 and 8. 13-7. 78[micro]M respectively.
Since the measured noise value is high, it has been removed from the drawn spectrum. Lidar system.
Lidar is a reverse scattering and depolarization system currently operating at Concordia station under different project frameworks (
Http:/lidarmax. altervista.
Org/englidar/_ Antarctic lidar. php).
It allows continuous measurement of the vertical profile and cloud structure of faerosol and determination of the physical phase of the particles.
Daily plots of false colors obtained through automated procedures are shipped to Italy to monitor the site and check the instrument operation.
Table 2 shows the main specifications for characterizing lidar.
Weather Station.
Atmospheric conditions on the ground are provided by weather stations (Vaisala WXT520)
Mounted on a PS ata roof a few meters away from REFIR
Pad view aperture.
The station is configured to provide measurements of six weather parameters every 10 seconds: wind speed and wind direction, precipitation, atmospheric pressure P, temperature T and relative humidity U.
These auxiliary parameters can be used to constrain the ground atmosphere seen by the spectrometer.
Other instruments on site.
As far as atmospheric research is concerned, the Concordia station has hosted many projects that typically provide a large amount of atmospheric parameters.
Here we summarize the available data sets (see Table 3)
This can add additional or collaborative information to take advantage of the scientific objectives of the thePRANA project.
RAdio Detection (RS)
In the "conventional meteorological observation at Concordia station" project, observations were conducted daily at 1200 UTCby IPEV/PNRA (www. climantartide. it/index . php? lang=en).
Measurements include pressure from the ground to 25-high altitude, temperature, humidity, and vertical distribution of wind speed and wind direction
Usually 30 km.
These measurements can be used to provide auxiliary information about the state of the atmosphere and verify that from REFIR-PAD spectra (
See section "initial results).
Given the importance of using this information to make better use of REFIR
PAD observation, RS profile provided with REFIR-PAD dataset.
A series of standard radians located about 100 metres from refir
Pad to measure the downward and upward flow radiation in the short and short wave range within the Baseline Surface Radiation Network (BSRN)
World Climate Research Program
These measurements provide information on the ground level radiation budget, which has been available for both the falling part and the rising part since 2006 (
Lanconelli and others. 2011)(
Interest in these measurements relates to the possibility of comparing BSRN long-wave home measurements and similar quantities from REFIR-performed special-resolution observationsPAD.
This comparison will allow the identification of contributions of different species in the surface radiation budget by spectral measurement. The [H. sub. 2]
O. Antarctic microwave radiometers (HAMSTRAD)
The microwave radiator was deployed on 2009 (
Two of 60 and 183 GHz)
Provide a vertical distribution of water evaporation and temperature every 7 minutes, from 0 above the ground to about 10 km, the vertical resolution of the planetary boundary layer from about 30 to 50 m, about 500 m above the upper layer
To study the lower layer of the possible trend (Ricaud et al. 2013)(www. cnrm-game-meteo . fr/? lang=en).
The profile of the measurement can be cross-checked with similar products derived from theREFIR-
Pad measurement.
System d analysis, par observation, Zenithale (SAOZ)
Run in Dome C from 2007 and in indaytime (
Pommereau and Goutail 1988)(. fr/).
For the PRANA project, ozone measurements can be used to limit specific concentrations in REFIR-AnalysisPAD spectra.
Finally, the ice scan camera (ICE-CAMERA)
The image scanner installed in 2012 was modified to capture high
Resolution image of the crystal shape precipitated on the instrument (
Http:/lidarmax. altervista.
In Org/radar/_ Precipitazioni Antartide. php). TheICE-
The precipitation is automatically classified by the camera instrument and can be used to identify REFIR-
PAD thermal infrared spectra of precipitated particles.
Preliminary results
In the two years of the PRANA project, REFIR-
PADwas is operating almost every day.
After the summer event, only a few interruptions due to a helicopter main power failure or instrument maintenance failure.
The most important loss of several days of measurement occurred in July 2012 and March 2013.
To estimate the absolute accuracy of the measurement, in the spectral channel between 828 and 839 [the mean of the radiation measured in the atmospheric window]cm. sup. -1](12. 077-11. 919[micro]m)
, Calculated for each measurement of the entire data set.
In this narrow spectral region, the atmosphere is completely transparent because there is no emission line;
Therefore, in the clear
The radiation intensity measured by sky conditions is equal to zero, corresponding to almost zero emission in deep space.
In cloudy cases, the measured radiation is due to the launch of the cloud, which is very different from zero.
Average brightness map at 828-839-[cm. sup. -1]
The channel shown in the figure
5, therefore, is an estimate of skycloudiness, in the case of clear air, is an estimate of the absolute calibration error of the measurement.
Since most of the observations are in clear skies and most of the measurements are 828-839-[cm. sup. -1]
Channel below 00015 W [m. sup. -2]
For the estimation of calibration error, only the spectrum with 828-839-[cm. sup. -1]
The glory below this value has been considered.
Not only can this condition be chosen clear-
In the case of the sky, but there are also some very thin cloud caseswith.
However, the frequency of very thin clouds is very low, with an average of 828-839-[cm. sup. -1]
Even with small overestimates, channel scanning is considered a good estimate of calibration errors.
The figure of the monthly average of this number is shown in black in the figure
The error bar corresponding to the standard deviation of the average value.
Curve display, in 2-
The annual measurement is about 0. 0005 W [([m. sup. 2]sr[cm. sup. -1]). sup. -1]
Corresponding to 0.
For boldface at 240 K, 5 k exists.
This value obtained in 828-839-[cm. sup. -1]
For other spectral regions, the spectral channel can also be considered a good estimate, as the primary source of calibration errors is the uncertainty known to refer to the temperature of the black body (Palchetti, etc. 2008b).
We note that the accuracy of the summer is higher after the annual maintenance (December-January)
Optimize the operation of alignment and optical systems.
This effect is more evident in the Cal Err estimates for each single measurement, with the monthly average in the red curve of the figure
6, this is based on a prior estimate of the accuracy of a single measurement based on the efficiency of the effective instrument, and therefore strongly depends on the misalignment and quality of the optical system, especially at 828-839[cm. sup. -1].
Figure 7 shows the seasonal average (3-month average)
Acquired spectrai in clear circumstances
Sky conditions of 2012
In the spectral region where the atmosphere is opaque--
That is, in C [O. sub. 2]
Ring belt 667 [:cm. sup. -1](15 [micro]m)and the [H. sub. 2]
O band below 400 【cm. sup. -1](25 [micro]m)--
The brilliance is higher, because it mainly comes from the emission in the lowest layers of atmosphere near the surface, and follows the typical emission curve of the black body at the temperature near the instrument, as shown in the figure, in the case of spring, green curve through figure7.
In autumn and winter, when the vertical temperature structure has a strong inversion layer (up to 25 K)
Near the typical surface of the Antarctic atmosphere, the measured spectrum shows a decrease near the C [central peak]O. sub. 2]
The band due to the lower Cold level. The black (fall)and blue (winter)curves inFig.
7 shows the occurrence of this effect.
Another detail revealed by the seasonal mean is the higher transparency of the FIR Region, which allows us to observe the spectral features of the pure rotating water vapor band down to 180 [1]cm. sup. -1](55. 6 [micro]m)
In winter, the precipitation can be as low as 0. 1 mm. A 2-
Clear map-
Sky spectrum converted at Bright temperature (BT)
As shown in the figure. 8.
This map shows the temperature rise of the [launch] on the wave in the summerH. sub. 2]O, C[O. sub. 2]
, And 03 is located.
The figure also shows that for many days of winter, 5 to September, BT in FIR is very low due to the high transparency of the atmospheric window.
Large number of transparent windows from 230 to 1,200 [cm. sup. -1](43. 5-8. 3 [micro]m pm)
Not only can the properties of the rotating water vapor band be improved (Liuzzi et al. 2014)
The representation of cloud radiation effects is also extended to the FIR Region.
There are some models in this area (Yang et al. 2013)
, But due to the evaporation and absorption of water, the atmosphere is highly opaque, and only several measurements have been made from the ground. Finally, Fig.
8 also shows a very interesting difference in the downward radiation observed in the ozone band of 1,043 [cm. sup. -1](9. 6 [micro]m)
In two winter months, data near September 2012 showed that the signal was lower than the same period in 2013.
In fact, at 2012, the ozone hole in the Antarctic is larger than in 2013, extending almost every day over the Concordia station.
In fact, radiation depends not only on the ozone concentration, but also on the temperature of the stratosphere, which must be restored by independent measurements.
However, this example shows how the spectral resolution measurement of the DLR can also help to study the stratosphere processes in the polar vortex in the Antarctic, such as ozone chemistry and its relationship with the polar stratosphere cloud, throughout the year, standard measurements of ultraviolet radiation measurements that are possible only during solar lighting are supplemented.
Major Atmospheric parameters that have an impact in the measurement spectral range--that is, [H. sub. 2]
O and temperature (through C[O. sub. 2])
Profile, ozone column volume and cloud microphysics--
It can be achieved by fitting the measurements with the radiation provided by the radiation transmission model.
For example, REFIR-
PAD measurement for retrieving the vertical profile [H. sub. 2]
O and temperature, through at 230-980-[cm. sup. -1](43. 5-10. 2 [micro]m)
Spectral range of the line-By-
Model of line radiation transmission (LBLRTM,v12. 2; Clough et al. 2005)in clear-sky conditions.
The calculation is done by minimizing the difference between the measurement and the simulation using the least squares (Not only enjoy. 2011).
High Vertical sensitivity is not allowed for measurement;
Only the fewindependent level can be retrieved.
Simulations were performed using 37 atmospheric levels, but [only] 5 independent levelsH. sub. 2]
Temperature is O and 4 (
Includes level 1 for description due to 2-m-
Long path of chimney propagation through observation within the shelter)were fitted.
Figure 9 shows the fitting results of the measurements performed during the winter of June 27, 2013.
Residual differences between measurement and model (green curve)
Within the range of noise estimation (black curves)with [chi square]=0. 75.
Fitting vertical section [H. sub. 2]
Figure 4 shows the O and temperature obtained for this condition.
10, compare them with the climate profile used as the initial guess to initialize the fitting procedure and the radio sounding instrument profile measured at the same time.
While the fitting process provides an outline of the entire atmosphere, observations are most sensitive to lower temperatures
Atmospheric Structure in water vapor and temperature.
The true contours are also strongly influenced by the warmer and wetter areas above the shelter and inside the observation chimney.
The existence of this layer, characterized by an extremely different condition relative to the outside, especially in winter, makes the geometry chosen for fitting complex.
Nevertheless, as shown in the figure, the comparison with the radio sounding instrument measurement
10. there.
The layer values generated due to the chimney effect are not drawn, which proves that the main features of the vertical profile can be considered even when low vertical resolution is taken into account.
Case study as cloudy weather
The sky conditions formed in October 6, 2013 were considered.
LIDAR map in the figure
11 shows the existence of different cloud structures during the day: The ice cloud was received early in the morning, and the high volume cloud began to precipitate around 1900 UTC in the afternoon.
Similar pictures can be observed in the spectrum BT diagram of the figure.
12, the presence of the cloud in it is identified by the increasing number of BT in the transparent window mouth, especially in 750 [above]cm. sup. -1](13. 3 [micro]m).
It should be noted that REFIR-
The PAD measured only 6 in 9 h, so the measurement was discontinuous.
Here we analyze the measurements at 1817 UTC as shown in the figure
11 fitting is carried out by a black vertical line by simultaneously measuring the vertical water vapor and temperature distribution of the atmosphere and the microphysics of the Cirrus.
Effects of radiation transfer using LBLRTM to simulate atmospheric state (
Water vapor and temperature distribution as described above)
And the available database of classification and absorption properties to simulate the properties of the Cirrus covering the REFIR-Extended spectral rangePAD.
In particular, for ice grains, we used a semi-empirical model developed by Fu et al. (1998)
For water droplets, we use the database provided by Hu and Stamnes (1993).
In this way, cloud microphysics is retrieved as effective particle size, ice water path, fractional ice content relative to liquid water, and effective cloud temperature.
In this model, the volume cloud is approximate to a single uniform layer, its thickness is given by lidar measurement, and the temperature is weighted by the vertical temperature profile by using lidar reverse scattering cloud profile
Left panel and center panel in figure 113).
In this way, the cloud differential temperature is closely related to the real atmospheric vertical temperature profile during the fitting process.
The case suitable for analysis gives an effective cloud temperature37. 8[degrees]
C effective diameter of ice 20 [micro]
M, total waterway 9g 【m. sup. -2]
84% of ice.
The results show that the corresponding optical depth is 1. 5.
Although these parameters cannot be fully verified due to the lack of direct measurement of cloud microphysics, full-spectrum resolution is used-spectral-
The band thermal emission measurement shows the feasibility of remote sensing of cloud parameters if avalanche cloud model is provided.
In terms of fitting the atmospheric state, the resulting vertical profiles are compared in the center and right panel of Figure 1
13 verification of positioning radio sounding instrument measurements performed at 1200 UTC.
Considering that the radio sounding instrument was launched a few hours ago, and the large difference in the next layer is due to the known local warming effect of the first layer in the helicopter, the comparison shows a good agreement.
Available data sets. The 2-
Yr acquisition data set provided by ThePRANA project by REFIR-
The PAD calibrated the dlr, the physical protection weather station, the lidar reverse scattering and depolarization ratio measurements, and the spectrum of the vertical profile of RS.
Table 4 shows a list of available measurements with acquisition time information. The REFIR-
PAD, weather station data, and RS data are used with UTC timestamps in ASCII format, while lidarparameters are provided in the daily color map as shown in the figure11.
The data set is being published on the REFIR website (
For emission spectra, weather parameters, and RS profiles and online (
Antarctic lidarphp)
Map of laser radar
Access to spectrum, weather, and RS data requires permission, which will be granted to everyone interested in processing this data. CONCLUSIONS.
We present a unique infrared spectrum measurement data set that covers the area of large waves with reduced atmospheric emissions, and the system collects from the coordinated Antarctic site of Dome C for almost two consecutive years.
Due to the extremely low temperature and humidity of the site, the obtained spectra have sufficient transparency to cover all the relevant spectral ranges of FIR of 100 [cm. sup. -1](100 [micro]m)
Up to 1,400 [intermediate IR]cm. sup. -1](7. 1 [micro]m).
This spectral range contains the features of the main absorption bodies of the atmosphere: water vapor, carbon dioxide and Cirrus from the atmosphere, ozone from the stratosphere and PSC.
Therefore, the measurements provide radiation information for all of these components, as well as radiation coupling between different layers from the surface to the atmosphere in the stratosphere.
For the first time on the very dry Antarctic Plateau, covering the range of fir trees in different seasons and atmospheric conditions, it can greatly improve our understanding of the radiation properties of these components in the longest wavelength range of emission.
We limit the measurement by calculating the calibration error of the whole data set measurement--
That is about 0.
The brightness temperature is 5 K relative to the emission of the black body at 240 k.
We also show how this measurement can be used to remove atmospheric states by retrieving the vertical distribution of water vapor and temperature and cloud microphysics.
The obtained atmospheric profile is also compared, both of which are clear
In the case of Sky and cloudy clouds, measurements are carried out by coordinate radiation, showing that the overall consistency between measurements is good.
Finally, after the PRANA project ended in May 2014, REFIR-
Padcontinue will continue to operate and provide the same type of measurement within the framework of a new project called Concordia Multi-
Study on process atmosphere (CoMPASs)
This is to study the vertical structure of the Antarctic atmosphere through the synergy of different remote sensing technologies.
In the new project, REFIR-
The PAD spectral data set will continue to expand with other measurements.
At present, after the online preliminary analysis, the collected spectrum is displayed every day (
It is expected that this measurement covers many years and different weather conditions and can better characterize the FIR spectra of water vapor and thin clouds, such as roll clouds and polar layer clouds, as well as ozone, it will help to improve the accuracy of climate model prediction.
Affiliation: Pachetti, bibicini, Denita and Del guesta--
Corresponding author: Lucca Pachetti, nazlonar Dior, Florence, Italy. 50019, Italy E-mail: luca. palchetti@ino.
It is a summary of the article that can be found on this issue, following the catalog. DOI: 10. 1175/BAMS-D-13-00286.
1 confirm.
The study was obtained by the Italian PNRA (
Nazionale di Ricerche project in Antide)
Paul Emile Victor College (IPEV).
More specifically, it was developed as part of the subproject PRANA (
Radiation in Proprieta dell 'ateroerae delle Nubi Antartide).
Data and information on radio sound measurement were obtained from the IPEV/PNRA project "conventional meteorological observations at Concordia station (www. climantartide. it/index. php? lang=en).
We thank all the agencies listed in Table 3 and their colleagues for providing information on other measurements at Concordia station.
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