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Lightning activity constitute the major destructive component of thunderstorms over India. Hence, an understanding of the long-term variability in lightning occurrence and intensity and their interrelation with various causative factors is required. Long-term (1998–2014) Tropical Rainfall Measuring Mission (TRMM) satellite-based lightning observations depict the most frequent lightning occurrences along the Himalayan foothills, the Indo-Gangetic plains and coastal regions, while the intensity of these lightning strikes is found to be strongest along the coastal regions and in the Bay of Bengal. In addition, both of the abovementioned lightning properties show a very strong intensification (∼ 1 %–2.5 % annually) across all Indian regions during the 1998–2014 period with the maximum trends along the coasts. Accordingly, a detailed statistical dominance analysis is performed which reveals total column water vapor (TCWV) to be the dominant factor behind the intensification in lightning events, while instability, measured by the convective available potential energy (CAPE), and aerosol optical depth (AOD) jointly control the lightning frequency trends. An increase in surface temperatures has led to enhanced instability and, hence, stronger moisture transport to the upper-troposphere and lower-stratosphere regions, especially along the coasts. This transported moisture helps deplete the ozone concentration, leading to reduced temperatures and elevated equilibrium levels, which finally results in stronger and more frequent lightning events, as also evidenced by the trend analysis. Consequently, the relationships between lightning and its causative factors have been expressed in the form of multilinear regression equations, which are then employed in multiple global circulation models (GCMs) to understand the long-term impact of urbanization on lightning over the period from 1950 to 2100. The analysis reveals a uniform increase in lightning occurrence and intensity using both urbanization scenarios; however, accelerated growth is observed in the RCP8.5 projections after the year 2050, as also observed from the surface warming trends. As a result, lightning frequency and intensity values across the Indian region are expected to increase ∼ 10 %–25 % and 15 %–50 %, respectively, by the end of the century with the highest risk along the coasts; hence, this requires immediate attention from policymakers.
Rohit Chakraborty; Arindam Chakraborty; Ghouse Basha; Madineni Venkat Ratnam. Lightning occurrences and intensity over the Indian region: long-term trends and future projections. Atmospheric Chemistry and Physics 2021, 21, 11161 -11177.
AMA StyleRohit Chakraborty, Arindam Chakraborty, Ghouse Basha, Madineni Venkat Ratnam. Lightning occurrences and intensity over the Indian region: long-term trends and future projections. Atmospheric Chemistry and Physics. 2021; 21 (14):11161-11177.
Chicago/Turabian StyleRohit Chakraborty; Arindam Chakraborty; Ghouse Basha; Madineni Venkat Ratnam. 2021. "Lightning occurrences and intensity over the Indian region: long-term trends and future projections." Atmospheric Chemistry and Physics 21, no. 14: 11161-11177.
A weak El Niño during 2014–2015 boreal winter developed as a strong boreal summer event in 2015 which continued and even enhanced during the following winter. In this work, the detailed changes in the structure, dynamics, and trace gases within the Asian summer monsoon anticyclone (ASMA) during the extreme El Niño of 2015–2016 is delineated by using Aura Microwave Limb Sounder (MLS) measurements, COSMIC radio occultation (RO) temperature, and National Centers for Environmental Prediction (NCEP) reanalysis products. Our analysis concentrates only on the summer months of July and August 2015 when the Niño 3.4 index started to exceed values of 1.5. The results show that the ASMA structure was quite different in summer 2015 as compared to the long-term (2005–2014) mean. In July, the spatial extension of the ASMA is greater than the long-term mean in all the regions except over northeastern Asia, where it exhibits a strong southward shift in its position. The ASMA splits into two, and the western Pacific mode is evident in August. Interestingly, the subtropical westerly jet (STJ) shifted southward from its normal position over northeastern Asia, and as a result midlatitude air moved southward in 2015. Intense Rossby wave breaking events along with STJ are also found in July 2015. Due to these dynamical changes in the ASMA, pronounced changes in the ASMA tracers are noticed in 2015 compared to the long-term mean. A 30 % (20 %) decrease in carbon monoxide (water vapor) at 100 hPa is observed in July over most of the ASMA region, whereas in August the drop is strongly concentrated at the edges of the ASMA. A prominent increase in O3 (> 40 %) at 100 hPa is clearly evident within the ASMA in July, whereas in August the increase is strongly located (even at 121 hPa) over the western edges of the ASMA. Further, the temperature around the tropopause shows significant positive anomalies (∼ 5 K) within the ASMA in 2015. The present results clearly reveal the El-Niño-induced dynamical changes caused significant changes in the trace gases within the ASMA in summer 2015.
Saginela Ravindra Babu; Madineni Venkat Ratnam; Ghouse Basha; Shantanu Kumar Pani; Neng-Huei Lin. Structure, dynamics, and trace gas variability within the Asian summer monsoon anticyclone in the extreme El Niño of 2015–2016. Atmospheric Chemistry and Physics 2021, 21, 5533 -5547.
AMA StyleSaginela Ravindra Babu, Madineni Venkat Ratnam, Ghouse Basha, Shantanu Kumar Pani, Neng-Huei Lin. Structure, dynamics, and trace gas variability within the Asian summer monsoon anticyclone in the extreme El Niño of 2015–2016. Atmospheric Chemistry and Physics. 2021; 21 (7):5533-5547.
Chicago/Turabian StyleSaginela Ravindra Babu; Madineni Venkat Ratnam; Ghouse Basha; Shantanu Kumar Pani; Neng-Huei Lin. 2021. "Structure, dynamics, and trace gas variability within the Asian summer monsoon anticyclone in the extreme El Niño of 2015–2016." Atmospheric Chemistry and Physics 21, no. 7: 5533-5547.
Rohit Chakraborty; Arindam Chakraborty; Ghouse Basha; Madineni Venkat Ratnam. Supplementary material to "Lightning occurrences and intensity over the Indian region: Long-term trends and future projections". 2021, 1 .
AMA StyleRohit Chakraborty, Arindam Chakraborty, Ghouse Basha, Madineni Venkat Ratnam. Supplementary material to "Lightning occurrences and intensity over the Indian region: Long-term trends and future projections". . 2021; ():1.
Chicago/Turabian StyleRohit Chakraborty; Arindam Chakraborty; Ghouse Basha; Madineni Venkat Ratnam. 2021. "Supplementary material to "Lightning occurrences and intensity over the Indian region: Long-term trends and future projections"." , no. : 1.
Lightning activities constitute the major destructive component of thunderstorms over India. Hence, understanding the long-term variabilities of lightning occurrence and intensity and their inter-relation with various causative factors is required. Long-term (1998–2014) Tropical Rainfall Measuring Mission (TRMM) satellite-based lightning observations depict the most abundant lightning occurrences along the Himalayan foothills, the Indo-Gangetic plains and coastal regions, while the intensity of these lightning strikes are found to be strongest along the coastal regions and Bay of Bengal. In addition, both the lightning properties show a very strong intensification (~1–2.5 % annually) across all Indian regions during 1998–2014 with the maximum trends along the coasts. Accordingly, a detailed statistical dominance analysis is performed which reveals total column water vapor (TCWV) to be the dominant factor behind the intensification in lightning events, while instability, measured by the convective available potential energy (CAPE), and aerosols optical depth (AOD) jointly control the lightning frequency trends. An increase in surface temperatures has led to enhanced instability hence stronger moisture transport to the upper troposphere lower stratosphere regions especially in the along the coasts. This transported moisture helps deplete the ozone concentration leading to reduced temperatures and elevated equilibrium levels which finally results in stronger and more abundant lightning events as also evidenced from the trend analysis. Consequently, the relationship between lightning and its causative factors have been expressed in form of multi-linear regression equations which are then employed on multiple global circulation models (GCM) to understand the long-term impact of urbanization on lightning over a period of 1950–2100. The analysis reveals a uniform increase in lightning occurrences, and intensity from both urbanization scenarios; however, an accelerated growth is observed in the RCP8.5 projections after the year 2050 as also observed from the surface warming trends. As a result, lightning frequency and intensity values across the Indian region are expected to increase alarmingly by ~10–25 % and 15–50 %, respectively, by the end of this century with highest risks along the coasts and hence it requires immediate attention from policy makers.
Rohit Chakraborty; Arindam Chakraborty; Ghouse Basha; Madineni Venkat Ratnam. Lightning occurrences and intensity over the Indian region: Long-term trends and future projections. 2021, 2021, 1 -27.
AMA StyleRohit Chakraborty, Arindam Chakraborty, Ghouse Basha, Madineni Venkat Ratnam. Lightning occurrences and intensity over the Indian region: Long-term trends and future projections. . 2021; 2021 ():1-27.
Chicago/Turabian StyleRohit Chakraborty; Arindam Chakraborty; Ghouse Basha; Madineni Venkat Ratnam. 2021. "Lightning occurrences and intensity over the Indian region: Long-term trends and future projections." 2021, no. : 1-27.
In this work, the detailed changes in the structure, dynamics and trace gases within the Asian summer monsoon anticyclone (ASMA) during extreme El Niño of 2015–16 is delineated by using Aura Microwave Limb Sounder (MLS) measurements, COSMIC Radio Occultation (RO) temperature, and NCEP reanalysis products. We have considered the individual months of July and August 2015 for the present study. The results show that the ASMA structure was quite different in 2015 as compared to the long-term (2005–2014) mean. In July, the spatial extension of the ASMA shows larger than the long-term mean in all the regions except over northeastern Asia, where, it exhibits a strong southward shift in its position. The ASMA splits into two and western Pacific mode is evident in August. Interestingly, the subtropical westerly jet (STJ) shifted southward from its normal position over northeastern Asia as resulted mid latitude air moved southward in 2015. Intense Rossby wave breaking events along with STJ are also found in July 2015. Due to these dynamical changes in the ASMA, pronounced changes in the ASMA tracers are noticed in 2015 compared to the long-term mean. A 30 % (20 %) decrease in carbon monoxide (water vapor) at 100 hPa is observed in July over most of the ASMA region, whereas in August the drop is strongly concentrated in the edges of the ASMA. Prominent increase of O3 (> 40 %) at 100 hPa is clearly evident within the ASMA in July, whereas in August the increase is strongly located (even at 121 hPa) over the western edges of the ASMA. Further, the temperature around the tropopause shows significant positive anomalies (~ 5 K) within the ASMA in 2015. Overall, warming of the tropopause region due to the increased O3 weakens the anticyclone and further supported the weaker ASMA in 2015 reported by previous studies.
Saginela Ravindra Babu; Madineni Venkat Ratnam; Ghouse Basha; Shantanu Kumar Pani; Neng-Huei Lin. Structure, dynamics, and trace gases variability within the Asian summer monsoon anticyclone in extreme El Niño of 2015–16. 2020, 2020, 1 .
AMA StyleSaginela Ravindra Babu, Madineni Venkat Ratnam, Ghouse Basha, Shantanu Kumar Pani, Neng-Huei Lin. Structure, dynamics, and trace gases variability within the Asian summer monsoon anticyclone in extreme El Niño of 2015–16. . 2020; 2020 ():1.
Chicago/Turabian StyleSaginela Ravindra Babu; Madineni Venkat Ratnam; Ghouse Basha; Shantanu Kumar Pani; Neng-Huei Lin. 2020. "Structure, dynamics, and trace gases variability within the Asian summer monsoon anticyclone in extreme El Niño of 2015–16." 2020, no. : 1.
The Asian summer monsoon anticyclone (ASMA) has been a topic of intensive research in recent times regarding its variability in dynamics, chemistry and radiation. This work explores the spatial variability and the trends of the ASMA using observational and reanalysis data sets. Our analysis indicates that the spatial extent and magnitude of the ASMA is greater during July and August than in June and September. The decadal variability of the anticyclone is very large at the edges of the anticyclone compared with the core region. Significant decadal variability is observed in the northeastern and southwestern parts of the ASMA with reference to the 1951–1960 period. The strength of the ASMA shows a drastic increase in zonal wind anomalies in terms of temporal variation. Furthermore, our results show that the extent of the anticyclone is greater during the active phase of the monsoon, strong monsoon years, and La Niña events. Significant warming with strong westerlies is observed exactly over the Tibetan Plateau from the surface to the tropopause during the abovementioned periods. Our results support the existence of transport process over the Tibetan Plateau and the Indian region during active, strong monsoon years and during strong La Niña years. Therefore, it is recommended that the different phases of the monsoon be taken into account when interpreting the variability of pollutants and trace gases in the anticyclone.
Ghouse Basha; M. Venkat Ratnam; Pangaluru Kishore. Asian summer monsoon anticyclone: trends and variability. Atmospheric Chemistry and Physics 2020, 20, 6789 -6801.
AMA StyleGhouse Basha, M. Venkat Ratnam, Pangaluru Kishore. Asian summer monsoon anticyclone: trends and variability. Atmospheric Chemistry and Physics. 2020; 20 (11):6789-6801.
Chicago/Turabian StyleGhouse Basha; M. Venkat Ratnam; Pangaluru Kishore. 2020. "Asian summer monsoon anticyclone: trends and variability." Atmospheric Chemistry and Physics 20, no. 11: 6789-6801.
Ghouse Basha. Replies to Reviewer #1 Comments/Suggestions. 2020, 1 .
AMA StyleGhouse Basha. Replies to Reviewer #1 Comments/Suggestions. . 2020; ():1.
Chicago/Turabian StyleGhouse Basha. 2020. "Replies to Reviewer #1 Comments/Suggestions." , no. : 1.
Ghouse Basha. Replies to Reviewer #2 Comments/Suggestions. 2020, 1 .
AMA StyleGhouse Basha. Replies to Reviewer #2 Comments/Suggestions. . 2020; ():1.
Chicago/Turabian StyleGhouse Basha. 2020. "Replies to Reviewer #2 Comments/Suggestions." , no. : 1.
Ghouse Basha. Replies to Reviewer #3 Comments/Suggestions. 2020, 1 .
AMA StyleGhouse Basha. Replies to Reviewer #3 Comments/Suggestions. . 2020; ():1.
Chicago/Turabian StyleGhouse Basha. 2020. "Replies to Reviewer #3 Comments/Suggestions." , no. : 1.
Ghouse Basha. Replies to Reviewer #2 Comments/Suggestions. 2020, 1 .
AMA StyleGhouse Basha. Replies to Reviewer #2 Comments/Suggestions. . 2020; ():1.
Chicago/Turabian StyleGhouse Basha. 2020. "Replies to Reviewer #2 Comments/Suggestions." , no. : 1.
The Asian Summer Monsoon Anticyclone (ASMA) persisting during monsoon season in the upper troposphere and lower stratosphere (UTLS) region play an important role in confining the trace gases and aerosols for a longer period thus affects regional and global climate. Our understanding on these trace gases and aerosols variability in the ASMA is limited. In this study, the effect of the ASMA on the trace gases (Water Vapour (WV), Ozone (O3), Carbon Monoxide (CO)) and aerosols (Attenuated Scattering Ratio (ASR)) obtained from long-term (2006–2016) satellite measurements is investigated. Since the ASMA is present in the UTLS region, its influence on the tropopause characteristics is also explored. Higher tropopause altitude, WV, CO and ASR confining to the ASMA region is observed, whereas tropopause temperatures and O3 are found low. There exists large inter-annual variation in the ASMA and hence its effect on these trace gases and aerosols are also seen clearly. A significant relationship is also observed between the phases of Quasi-Biannual Oscillation (QBO) and El Niño Southern Oscillation (ENSO) on the trace gases and ASR, including the tropopause when measurements in the ASMA region are subject to multivariate regression analysis. Further, the influence of the Indian summer monsoon (ISM) activity on the ASMA trace gases and aerosols is studied with respect to active and break spells of monsoon, strong and weak monsoon years, strong La Niña, El Niño years. Results show a significant increase in WV, CO and decrease in O3 during the active phase of the ISM, strong monsoon years and strong La Niña years in the ASMA. Enhancement in the ASR values during the strong monsoon years and strong La Niña years is observed. Thus, it is prudent to conclude that the dynamics of the ASMA play an important role in the confinement of several trace gases and aerosols and suggested to consider the activity of summer monsoon while dealing with them at sub-seasonal scales.
Ghouse Basha; M. Venkat Ratnam; Pangaluru Kishore; S. Ravindrababu; Isabella Velicogna. Influence of Asian Summer Monsoon Anticyclone on the Trace gases and Aerosols over Indian region. 2019, 1 -33.
AMA StyleGhouse Basha, M. Venkat Ratnam, Pangaluru Kishore, S. Ravindrababu, Isabella Velicogna. Influence of Asian Summer Monsoon Anticyclone on the Trace gases and Aerosols over Indian region. . 2019; ():1-33.
Chicago/Turabian StyleGhouse Basha; M. Venkat Ratnam; Pangaluru Kishore; S. Ravindrababu; Isabella Velicogna. 2019. "Influence of Asian Summer Monsoon Anticyclone on the Trace gases and Aerosols over Indian region." , no. : 1-33.
Ghouse Basha; M. Venkat Ratnam; Pangaluru Kishore. Supplementary material to "Asian Summer Monsoon Anticyclone: Trends and Variability". 2019, 1 .
AMA StyleGhouse Basha, M. Venkat Ratnam, Pangaluru Kishore. Supplementary material to "Asian Summer Monsoon Anticyclone: Trends and Variability". . 2019; ():1.
Chicago/Turabian StyleGhouse Basha; M. Venkat Ratnam; Pangaluru Kishore. 2019. "Supplementary material to "Asian Summer Monsoon Anticyclone: Trends and Variability"." , no. : 1.
The Asian Summer Monsoon (ASM) dynamics act as a pathway for the transport of trace gases and pollutants both vertically (through convection) and horizontally (through low-level jet and tropical easterly jet). These pollutants will be trapped in the anticyclone present during the same period in the upper troposphere and lower stratosphere (UTLS). Since the anticyclone extends from the Middle East to East Asia, trapped pollutants are expected to make a large radiative forcing to the background atmosphere. Thus, it is essential to understand the anticyclone features in detail and its relation to long-term oscillations. This work explores the spatial variability and the trends of the Asian Summer Monsoon Anticyclone (ASMA) using observational and reanalysis data sets. Emphasis is made to investigate the temporal, spatial, and long-term trends of ASMA. Our analysis indicates that the spatial extent and magnitude of ASMA is greater during July and August compared to June and September. The decadal variability of the anticyclone is very large at the edges of anticyclone than at the core region. Significant deviations in the northeast and southwest parts of ASMA are also observed in the decadal variability with reference to 1951−1960 period. The strength of the ASMA shows a drastic increase from the easterlies to the westerlies in terms of temporal variation. Further, our results show that the extent of anticyclone is greater during the active phase of the monsoon, strong monsoon years, and during La Niña events. Significant warming with strong westerlies is observed exactly over the Tibetan Plateau during the active phase of the monsoon, strong monsoon years, and during La Niña events. Over the Tibetan Plateau, there is strong elevated heating from the surface to the tropopause, which is observed with strong westerlies during active and strong monsoon years. Our results support the transport process over Tibetan Plateau and the Indian region during active, strong monsoon years and during strong La Niña years. It is suggested to consider different phases of monsoon while interpreting the pollutants/trace gases in the anticyclone.
Ghouse Basha; M. Venkat Ratnam; Pangaluru Kishore. Asian Summer Monsoon Anticyclone: Trends and Variability. 2019, 1 .
AMA StyleGhouse Basha, M. Venkat Ratnam, Pangaluru Kishore. Asian Summer Monsoon Anticyclone: Trends and Variability. . 2019; ():1.
Chicago/Turabian StyleGhouse Basha; M. Venkat Ratnam; Pangaluru Kishore. 2019. "Asian Summer Monsoon Anticyclone: Trends and Variability." , no. : 1.
It is well reported that the 2015–16 El Niño event is one of the most intense and long lasting events in the 21st century. The quantified changes in the trace gases (Ozone (O3), Carbon Monoxide (CO) and Water Vapour (WV)) in the tropical upper troposphere and lower stratosphere (UTLS) region are delineated using Aura Microwave Limb Sounder (MLS) and Atmosphere Infrared Radio Sounder (AIRS) satellite observations from June to December 2015. Prior to reaching its peak intensity of El Niño 2015–16, large anomalies in the trace gases (O3 and CO) were detected in the tropical UTLS region, which is a record high in the 21st century. A strong decrease in the UTLS (at 100 and 82 hPa) ozone (~200 ppbv) in July-August 2015 was noticed over the entire equatorial region followed by large enhancement in the CO (150 ppbv) from September to November 2015. The enhancement in the CO is more prevalent over the South East Asia (SEA) and Western Pacific (WP) regions where large anomalies of WV in the lower stratosphere are observed in December 2015. Dominant positive cold point tropopause temperature (CPT-T) anomalies (~5 K) are also noticed over the SEA and WP regions from the high-resolution Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC) Global Position System (GPS) Radio Occultation (RO) temperature profiles. These observed anomalies are explained in the light of dynamics and circulation changes during El Niño.
S. Ravindrababu; M. Venkat Ratnam; Ghouse Basha; Yuei-An Liou; N. Narendra Reddy. Large Anomalies in the Tropical Upper Troposphere Lower Stratosphere (UTLS) Trace Gases Observed during the Extreme 2015–16 El Niño Event by Using Satellite Measurements. Remote Sensing 2019, 11, 687 .
AMA StyleS. Ravindrababu, M. Venkat Ratnam, Ghouse Basha, Yuei-An Liou, N. Narendra Reddy. Large Anomalies in the Tropical Upper Troposphere Lower Stratosphere (UTLS) Trace Gases Observed during the Extreme 2015–16 El Niño Event by Using Satellite Measurements. Remote Sensing. 2019; 11 (6):687.
Chicago/Turabian StyleS. Ravindrababu; M. Venkat Ratnam; Ghouse Basha; Yuei-An Liou; N. Narendra Reddy. 2019. "Large Anomalies in the Tropical Upper Troposphere Lower Stratosphere (UTLS) Trace Gases Observed during the Extreme 2015–16 El Niño Event by Using Satellite Measurements." Remote Sensing 11, no. 6: 687.
Long-term trends of the parameters related to convection and instability obtained from 27 radiosonde stations across six subdivisions over the Indian region during the period 1980–2016 are presented. A total of 16 parcel and instability parameters along with moisture content, wind shear, and thunderstorm and rainfall frequencies have been utilized for this purpose. Robust fit regression analysis is employed on the regional average time series to calculate the long-term trends on both a seasonal and a yearly basis. The level of free convection (LFC) and the equilibrium level (EL) height are found to ascend significantly in all Indian subdivisions. Consequently, the coastal regions (particularly the western coast) experience increases in severe thunderstorms (TSS) and severe rainfall (SRF) frequency in the pre-monsoon period, while the inland regions (especially Central India) experience an increase in ordinary thunderstorms (TSO) and weak rainfall (WRF) frequency during the monsoon and post-monsoon periods. The 16–20-year periodicity is found to dominate the long-term trends significantly compared to other periodicities and the increase in TSS, and convective available potential energy (CAPE) is found to be more severe after the year 1999. The enhancement in moisture transport and associated cooling at 100 hPa along with the dispersion of boundary layer pollutants are found to be the main causes for the increase in CAPE, which leads to more convective severity in the coastal regions. However, in inland regions, moisture-laden winds are absent and the presence of strong capping effect of pollutants on instability in the lower troposphere has resulted in more convective inhibition energy (CINE). Hence, TSO and occurrences of WRF have increased particularly in these regions.
Rohit Chakraborty; Madineni Venkat Ratnam; Shaik Ghouse Basha. Long-term trends of instability and associated parameters over the Indian region obtained using a radiosonde network. Atmospheric Chemistry and Physics 2019, 19, 3687 -3705.
AMA StyleRohit Chakraborty, Madineni Venkat Ratnam, Shaik Ghouse Basha. Long-term trends of instability and associated parameters over the Indian region obtained using a radiosonde network. Atmospheric Chemistry and Physics. 2019; 19 (6):3687-3705.
Chicago/Turabian StyleRohit Chakraborty; Madineni Venkat Ratnam; Shaik Ghouse Basha. 2019. "Long-term trends of instability and associated parameters over the Indian region obtained using a radiosonde network." Atmospheric Chemistry and Physics 19, no. 6: 3687-3705.
This paper deals with the investigation of long-term variability of atmospheric dust over the United Arab Emirates (UAE). The climatology of dust episodes (dust events, dust storms, and severe dust storms) is compiled based on the hourly observations and synoptic codes recorded at four different stations over UAE between the years 1983–2014. The diurnal, temporal, monthly, and inter-annual variations of dust episodes and their relation with the mean wind speed, maximum wind speed, and temperature are discussed. Dust episodes show a clear diurnal variation in all the stations. The duration of dust storms is large compared to dust events. For instance, dust events over the UAE persist for 2–5 h while dust storms last for about 5–11 h. Dust storms also show clear seasonal variability with the maximum occurring during winter and the minimum during summer whereas most of the dust events occur during the months of March and April. The inter-annual variation of dust events shows a significant decrease while dust storms depict a moderate increase over the UAE. The synoptic scale climatology of all dust storms is also analyzed and shows changes in wind direction to the south-west prior to 2 days of the dust storm generation. The climatology of wind direction and wind speed during the dust episode indicates that 90% of dust episodes are coming from the southwest direction. These observed results are discussed in light of the current global warming scenarios with a special emphasis on the role of dust episodes on the regional enhancement of temperature.
Ghouse Basha; M. Venkat Ratnam; K. Niranjan Kumar; T.B.M.J. Ouarda; P. Kishore; Isabella Velicogna. Long-term variation of dust episodes over the United Arab Emirates. Journal of Atmospheric and Solar-Terrestrial Physics 2019, 187, 33 -39.
AMA StyleGhouse Basha, M. Venkat Ratnam, K. Niranjan Kumar, T.B.M.J. Ouarda, P. Kishore, Isabella Velicogna. Long-term variation of dust episodes over the United Arab Emirates. Journal of Atmospheric and Solar-Terrestrial Physics. 2019; 187 ():33-39.
Chicago/Turabian StyleGhouse Basha; M. Venkat Ratnam; K. Niranjan Kumar; T.B.M.J. Ouarda; P. Kishore; Isabella Velicogna. 2019. "Long-term variation of dust episodes over the United Arab Emirates." Journal of Atmospheric and Solar-Terrestrial Physics 187, no. : 33-39.
Rohit Chakraborty; Madineni Venkat Ratnam; Ghouse Basha. Supplementary material to "Long-term trends of instability and associated parameters over the Indian region obtained using radiosonde network". 2018, 1 .
AMA StyleRohit Chakraborty, Madineni Venkat Ratnam, Ghouse Basha. Supplementary material to "Long-term trends of instability and associated parameters over the Indian region obtained using radiosonde network". . 2018; ():1.
Chicago/Turabian StyleRohit Chakraborty; Madineni Venkat Ratnam; Ghouse Basha. 2018. "Supplementary material to "Long-term trends of instability and associated parameters over the Indian region obtained using radiosonde network"." , no. : 1.
Long-term trends of the parameters related to convection and instability obtained from 27 radiosonde stations across 6 sub-divisions over Indian region during the period 1980–2016 is presented. A total of 16 parcel and instability parameters along with moisture content, wind shear, and thunderstorm and rainfall frequencies have been utilized for this purpose. Robust fit regression analysis is employed on the regional average time series to calculate the long-term trends on both seasonal and yearly basis. The Level of Free Convection (LFC) and Equilibrium Level (EL) height is found to ascend significantly in all Indian sub-divisions. Consequently, the coastal regions (particularly the western coasts) experience strengthening in Severe Thunderstorm (TSS) and Severe Rainfall Frequencies (SRF) in the pre-monsoon while the inland regions (especially central India) experience an increase in Ordinary Thunderstorm (TSO) and Weak Rain Frequency (WRF) during the monsoon and post-monsoon. The 16–20 year periodicity is found to dominate the long-term trends significantly compared to other periodicities and the increase in TSS, SRF and CAPE is found more severe after the year 1999. The enhancement in moisture transport and associated cooling at 100 hPa along with dispersion of boundary layer pollutants is found to be the main cause for the increase in Convective Available Potential Energy (CAPE) which leads to more convective severity in the coastal regions. However, in inland regions moisture-laden winds are absent and the presence of strong capping effect of pollutants on instability in the lower troposphere has resulted in more Convective Inhibition Energy (CINE). Hence, TSO and weak rainfall occurrences have increased particularly in these regions.
Rohit Chakraborty; Madineni Venkat Ratnam; Ghouse Basha. Long-term trends of instability and associated parameters over the Indian region obtained using radiosonde network. 2018, 2018, 1 -27.
AMA StyleRohit Chakraborty, Madineni Venkat Ratnam, Ghouse Basha. Long-term trends of instability and associated parameters over the Indian region obtained using radiosonde network. . 2018; 2018 ():1-27.
Chicago/Turabian StyleRohit Chakraborty; Madineni Venkat Ratnam; Ghouse Basha. 2018. "Long-term trends of instability and associated parameters over the Indian region obtained using radiosonde network." 2018, no. : 1-27.
Cloud vertical structure, including top and base altitudes, thickness of cloud layers, and the vertical distribution of multilayer clouds, affects large-scale atmosphere circulation by altering gradients in the total diabatic heating and cooling and latent heat release. In this study, long-term (11 years) observations of high-vertical-resolution radiosondes are used to obtain the cloud vertical structure over a tropical station at Gadanki (13.5∘ N, 79.2∘ E), India. The detected cloud layers are verified with independent observations using cloud particle sensor (CPS) sonde launched from the same station. High-level clouds account for 69.05 %, 58.49 %, 55.5 %, and 58.6 % of all clouds during the pre-monsoon, monsoon, post-monsoon, and winter seasons, respectively. The average cloud base (cloud top) altitudes for low-level, middle-level, high-level, and deep convective clouds are 1.74 km (3.16 km), 3.59 km (5.55 km), 8.79 km (10.49 km), and 1.22 km (11.45 km), respectively. Single-layer, two-layer, and three-layer clouds account for 40.80 %, 30.71 %, and 19.68 % of all cloud configurations, respectively. Multilayer clouds occurred more frequently during the monsoon with 34.58 %. Maximum cloud top altitude and cloud thickness occurred during the monsoon season for single-layer clouds and the uppermost layer of multiple-layer cloud configurations. In multilayer cloud configurations, diurnal variations in the thickness of upper-layer clouds are larger than those of lower-layer clouds. Heating and cooling in the troposphere and lower stratosphere due to these cloud layers are also investigated and peak cooling (peak warming) is found below (above) the cold-point tropopause (CPT) altitude. The magnitude of cooling (warming) increases from single-layer to four- or more-layer cloud occurrence. Further, the vertical structure of clouds is also studied with respect to the arrival date of the Indian summer monsoon over Gadanki.
Nelli Narendra Reddy; Madineni Venkat Ratnam; Ghouse Basha; Varaha Ravikiran. Cloud vertical structure over a tropical station obtained using long-term high-resolution radiosonde measurements. Atmospheric Chemistry and Physics 2018, 18, 11709 -11727.
AMA StyleNelli Narendra Reddy, Madineni Venkat Ratnam, Ghouse Basha, Varaha Ravikiran. Cloud vertical structure over a tropical station obtained using long-term high-resolution radiosonde measurements. Atmospheric Chemistry and Physics. 2018; 18 (16):11709-11727.
Chicago/Turabian StyleNelli Narendra Reddy; Madineni Venkat Ratnam; Ghouse Basha; Varaha Ravikiran. 2018. "Cloud vertical structure over a tropical station obtained using long-term high-resolution radiosonde measurements." Atmospheric Chemistry and Physics 18, no. 16: 11709-11727.
Accurate estimation of the planetary boundary layer (PBL) top is essential for air quality prediction, weather forecast, and assessment of regional and global climate models. In this article, the long-term climatology of seasonal, global distribution of PBL is presented by using global positioning system radio occultation (GPSRO) based payloads such as Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC), Communication/Navigation Outage Forecast System (C/NOFS), TerraSAR-X, and The Gravity Recovery and Climate Experiment (GRACE) from the year 2006–2015. We used Wavelet Covariance Transform (WCT) technique for precise PBL top identification. The derived PBL top from GPSRO data is rigorously evaluated with GPS radiosonde data over Gadanki. Significant seasonal variation is noticed in both radiosonde and GPSRO observations. Further, we compared the PBL obtained GPS RO with global radiosonde network and observed very good correlation. The number of occultations reaching down to 500 m and retrieval rate of PBL top from WCT method is very high in mid-latitudes compared to tropical latitudes. The global distribution of PBL top shows significant seasonal variation with higher during summer followed by spring, fall, and minimum in winter. In the vicinity of Inter Tropical Convergence Zone (ITCZ), the PBL top is high over eastern Pacific compared to other regions. The ERA-Interim reanalysis data underestimate the PBL top compared to GPS RO observations due to different measurement techniques. The seasonal variation of global averaged PBL top over land and ocean shows contrasting features at different latitude bands.
Ghouse Basha; P. Kishore; M. Venkat Ratnam; Ravindra Babu; Isabella Velicogna; Jonathan H. Jiang; Chi O. Ao. Global climatology of planetary boundary layer top obtained from multi-satellite GPS RO observations. Climate Dynamics 2018, 52, 2385 -2398.
AMA StyleGhouse Basha, P. Kishore, M. Venkat Ratnam, Ravindra Babu, Isabella Velicogna, Jonathan H. Jiang, Chi O. Ao. Global climatology of planetary boundary layer top obtained from multi-satellite GPS RO observations. Climate Dynamics. 2018; 52 (3-4):2385-2398.
Chicago/Turabian StyleGhouse Basha; P. Kishore; M. Venkat Ratnam; Ravindra Babu; Isabella Velicogna; Jonathan H. Jiang; Chi O. Ao. 2018. "Global climatology of planetary boundary layer top obtained from multi-satellite GPS RO observations." Climate Dynamics 52, no. 3-4: 2385-2398.