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Figure 5: Scatter between wind speed and CO) mixing ratios during (a) October 2011, (b) November 2011, (c) December 2011 and (d) January 2012. radiation by CO). The instrument is calibrated at the factory with 5 known concentration of CO) values (0-1000 ppm). The graph between the CO, measured by the instrument and the standard values are shown in Figure 2. Most of our observations are below 500 ppm and the difference between two observations varies from 1 and 3 ppm. This calibration is carried out at 26.2°C and the pressure varying between 1016.4 to 1016.7 hpa. These differences are much within the permissible limit. As per the Vaisala standard calibration procedure, the accuracy of the instrument is +2 ppm for a temperature range of -40 to 60°C and for concentration range 0-1000 ppm. The precision of the instrument at 370 ppm with 30sec output averaging is +1 ppm. The instrument (reference cylinder) drift in one year is < 2% (+ 0.5%) of the reading (Vaisala GMP-343 user guide and calibration report). The station has two towers of 100 m and 50 m. The 100 m tower has wind sensors at 100 m, 80 m, 60 m, 40 m, 30 m, 20 m and 10 m height. The 50 m tower has temperature and humidity sensors at 50 m, 32 m, 16 m, 8 m and 4 m. The continuous CO), observations were collected through a panoptic data logger at 5 min interval. The technical details and schematic diagram of the instrument are given in [3]. These CO) mixing ratios and wind vectors are analyzed for four months during October 2011 to January 2012. Methodology 1.844 082 59, a3 = —11.786 6497, a4 = 22.680 7411, a5 = —15.961 8719, a6 = 1.801 225 02 and t = 1-(T+273.15)/T,

Figure 5 Scatter between wind speed and CO) mixing ratios during (a) October 2011, (b) November 2011, (c) December 2011 and (d) January 2012. radiation by CO). The instrument is calibrated at the factory with 5 known concentration of CO) values (0-1000 ppm). The graph between the CO, measured by the instrument and the standard values are shown in Figure 2. Most of our observations are below 500 ppm and the difference between two observations varies from 1 and 3 ppm. This calibration is carried out at 26.2°C and the pressure varying between 1016.4 to 1016.7 hpa. These differences are much within the permissible limit. As per the Vaisala standard calibration procedure, the accuracy of the instrument is +2 ppm for a temperature range of -40 to 60°C and for concentration range 0-1000 ppm. The precision of the instrument at 370 ppm with 30sec output averaging is +1 ppm. The instrument (reference cylinder) drift in one year is < 2% (+ 0.5%) of the reading (Vaisala GMP-343 user guide and calibration report). The station has two towers of 100 m and 50 m. The 100 m tower has wind sensors at 100 m, 80 m, 60 m, 40 m, 30 m, 20 m and 10 m height. The 50 m tower has temperature and humidity sensors at 50 m, 32 m, 16 m, 8 m and 4 m. The continuous CO), observations were collected through a panoptic data logger at 5 min interval. The technical details and schematic diagram of the instrument are given in [3]. These CO) mixing ratios and wind vectors are analyzed for four months during October 2011 to January 2012. Methodology 1.844 082 59, a3 = —11.786 6497, a4 = 22.680 7411, a5 = —15.961 8719, a6 = 1.801 225 02 and t = 1-(T+273.15)/T,

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Carbon dioxide (CO ), one of the major Greenhouse Gases (GHG) in the atmosphere, plays a prominent role in climate change. The global mean concentration of CO, in 2005 was 379 ppm, leading to a Radiative Forcing (RF) of +1.66 [+ 0. 17] W m-2 [1]. Recently, the CO, levels have gone up to a daily mean of 400 ppm in May 2013 at Mauna Loa, Hawaii [2]. Local meteorological and environmental factors control the CO, mixing ratios. During night times, temperature inversions prevent thorough mixing of the atmosphere. There is also an absence of photosynthetic activity consuming CO). Due to these two processes, CO, mixing ratios increase at night. During the daytime due to increase in photosynthesis activity, CO, mixing ratio decreases [3].
Carbon dioxide (CO ), one of the major Greenhouse Gases (GHG) in the atmosphere, plays a prominent role in climate change. The global mean concentration of CO, in 2005 was 379 ppm, leading to a Radiative Forcing (RF) of +1.66 [+ 0. 17] W m-2 [1]. Recently, the CO, levels have gone up to a daily mean of 400 ppm in May 2013 at Mauna Loa, Hawaii [2]. Local meteorological and environmental factors control the CO, mixing ratios. During night times, temperature inversions prevent thorough mixing of the atmosphere. There is also an absence of photosynthetic activity consuming CO). Due to these two processes, CO, mixing ratios increase at night. During the daytime due to increase in photosynthesis activity, CO, mixing ratio decreases [3].
To understand the carbon cycle in the atmosphere, several surface CO, measuring network stations have been established across the county under National Carbon Project (NCP). NCP is a component of Geosphere Biosphere Programme (IGBP) of the Indian Space Research Organization (ISRO). Under this program terrestrial, ocean and atmospheric components of carbon balance are studied. Instruments are installed to measure the atmospheric CO, [3], flux measurements in forests [4] and in soil [5]. As a part of this program, GMP-343 is installed in 2011 at Sriharikota High Altitude Range (SHAR). Since this is a coastal station, we report the impact of the wind vector, particularly the land and sea breezes, on CO) variations from October 2011 to January 2012. While pure water has pH of 7.0, normal rain is slightly acidic with pH range from 5.0-5.6 [6] because of dissolving of CO in water droplets forming a weak carbonic acid. The dissolution of CO) in rain drop depends upon the partial pressure of CO, and the atmospheric temperature. Since the study region influenced by North East (NE) monsoon, we also studied the impact of rainfall on CO, mixing ratios. Carbon dioxide (CO2) observations collected at 5 min interval at Sriharikota during October 2011-January 2012 from the Vaisala GMP-343 sensor were averaged on an hourly basis. The baseline of atmospheric CO, during study period is 382 ppm. Minimum (maximum) mixing ratios were observed during the afternoon (night times) indicating the role of photosynthetic activity and the atmospheric boundary layer on this parameter. Sriharikota being a coastal station, the land and sea breezes mainly control CO, mixing ratios. The correlation between CO, and the wind speed is significantly less during sea breeze than during land breeze in October, compared to other months, where the correlations are more during sea breeze. The less correlation during sea breeze in October is due to the heavy rainfall in this month during daytime.
To understand the carbon cycle in the atmosphere, several surface CO, measuring network stations have been established across the county under National Carbon Project (NCP). NCP is a component of Geosphere Biosphere Programme (IGBP) of the Indian Space Research Organization (ISRO). Under this program terrestrial, ocean and atmospheric components of carbon balance are studied. Instruments are installed to measure the atmospheric CO, [3], flux measurements in forests [4] and in soil [5]. As a part of this program, GMP-343 is installed in 2011 at Sriharikota High Altitude Range (SHAR). Since this is a coastal station, we report the impact of the wind vector, particularly the land and sea breezes, on CO) variations from October 2011 to January 2012. While pure water has pH of 7.0, normal rain is slightly acidic with pH range from 5.0-5.6 [6] because of dissolving of CO in water droplets forming a weak carbonic acid. The dissolution of CO) in rain drop depends upon the partial pressure of CO, and the atmospheric temperature. Since the study region influenced by North East (NE) monsoon, we also studied the impact of rainfall on CO, mixing ratios. Carbon dioxide (CO2) observations collected at 5 min interval at Sriharikota during October 2011-January 2012 from the Vaisala GMP-343 sensor were averaged on an hourly basis. The baseline of atmospheric CO, during study period is 382 ppm. Minimum (maximum) mixing ratios were observed during the afternoon (night times) indicating the role of photosynthetic activity and the atmospheric boundary layer on this parameter. Sriharikota being a coastal station, the land and sea breezes mainly control CO, mixing ratios. The correlation between CO, and the wind speed is significantly less during sea breeze than during land breeze in October, compared to other months, where the correlations are more during sea breeze. The less correlation during sea breeze in October is due to the heavy rainfall in this month during daytime.
Figure 3: Baseline determination using Savitzky-Golay filter technique over SHAR region during the study period
Figure 3: Baseline determination using Savitzky-Golay filter technique over SHAR region during the study period
Figure 4: Diurnal variation of hourly mean CO), mixing ratios during October 2011-January 2012
Figure 4: Diurnal variation of hourly mean CO), mixing ratios during October 2011-January 2012
Figure 6: Wind direction from (a) AWS and (b) HYSPLIT model. interval along the axis [9]. The 5 min observations have been averaged to hourly daily values. Along with the 100 m and 50 m tower observations, we have also computed 5-day back trajectory analysis at an altitude of 100 m for the study period using Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model [10].
Figure 6: Wind direction from (a) AWS and (b) HYSPLIT model. interval along the axis [9]. The 5 min observations have been averaged to hourly daily values. Along with the 100 m and 50 m tower observations, we have also computed 5-day back trajectory analysis at an altitude of 100 m for the study period using Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model [10].
Figure 7: The prevailing mean wind direction from land and Ocean during the study period.
Figure 7: The prevailing mean wind direction from land and Ocean during the study period.
Table 2: Correlation between CO, mixing ratios and wind speed during land-sea breezes. Table 1: Correlation between CO, mixing ratios and wind speed with and without including months as a dummy variable. Wind direction Wind speed
Table 2: Correlation between CO, mixing ratios and wind speed during land-sea breezes. Table 1: Correlation between CO, mixing ratios and wind speed with and without including months as a dummy variable. Wind direction Wind speed
Table 3: Rainfall during October 2011 to January 2012.
Table 3: Rainfall during October 2011 to January 2012.
To have a quality control of the data, setting the background level (baseline) is required. For this purpose, we first filtered all the data following Savitazky-Golay technique [8]. The original data (black curve) and the data after filtering (red curve) are shown in Figure 3. These filtered values are used to compute the hourly means. These hourly observations were checked for consistency and only those observations, where the difference between the two consecutive values is less than 0.5 ppm are considered (4 % of the observations were removed in this way). Then the regional background level (baseline) was computed as a means of the hourly data following Zhou [11]. Thus, the baseline of this region is 382 ppm with a standard deviation of 8.1 ppm.
To have a quality control of the data, setting the background level (baseline) is required. For this purpose, we first filtered all the data following Savitazky-Golay technique [8]. The original data (black curve) and the data after filtering (red curve) are shown in Figure 3. These filtered values are used to compute the hourly means. These hourly observations were checked for consistency and only those observations, where the difference between the two consecutive values is less than 0.5 ppm are considered (4 % of the observations were removed in this way). Then the regional background level (baseline) was computed as a means of the hourly data following Zhou [11]. Thus, the baseline of this region is 382 ppm with a standard deviation of 8.1 ppm.
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