scholarly journals On variability of total ozone derived from TOVS data over peninsular Indian sub-continent and adjoining oceanic area

MAUSAM ◽  
2022 ◽  
Vol 53 (4) ◽  
pp. 503-514
Author(s):  
R. SURESH
Keyword(s):  
Total Ozone ◽  
Monsoon Season ◽  
Lower Troposphere ◽  
Southwest Monsoon ◽  
Retrieval Algorithm ◽  
Tropospheric Temperature ◽  
Minimum Concentration ◽  
Upper Troposphere ◽  
Positive Correlation Coefficient ◽  
Longitudinal Variability

The total ozone derived from TOVS data from NOAA 12 satellite through one step physical retrieval algorithm of  International TOVS Processing Package (ITPP) version 5.0 has been used to identify  its diurnal, monthly, latitudinal and longitudinal variability during 1998 over the domain Equator to 26° N / 60-100° E. The linkage of  maximum total ozone with warmer tropopause and lower stratosphere has been re-established. The colder upper tropospheric temperature which is normally associated with maximum ozone concentration throughout the year elsewhere in the world  has also been identified in this study but the relationship gets reversed during southwest  monsoon months(June-September) over the domain considered. The moisture  available in abundance in the lower troposphere gets precipitated due to the convective instability prevailing in the atmosphere during monsoon season and very little moisture is only available for vertical transport into the upper troposphere atop 500 hPa. The latent heat released by the  precipitation processes warms up the middle and upper atmosphere. The warm and dry upper troposphere could be the reason for less depletion of ozone in the upper troposphere during monsoonal  months and this is supported by the positive correlation coefficient prevailing in monsoon season between  total ozone and upper tropospheric (aloft 300 hPa) temperature. The warmness in middle and upper troposphere which is associated with less depletion and/or production of more  ozone in the upper troposphere may  perhaps contribute  for the  higher total ozone during monsoon months than in other seasons over peninsular Indian region.  The minimum concentration is observed during January (226 DU) over 6° N and the maximum (283DU) over 18° N during August. Longitudinal variability is less pronounced than the latitudinal variability.

scholarly journals Evaluating moist physics for Antarctic mesoscale simulations

1997 ◽  
Vol 25 ◽  
pp. 282-286 ◽  
Author(s):  
Keith M. Hines ◽  
David H. Bromwich ◽  
R. I. Cullather
Keyword(s):  
Mesoscale Model ◽  
Cloud Condensation Nuclei ◽  
Inversion Layer ◽  
Lower Troposphere ◽  
Tropospheric Temperature ◽  
Winter Climate ◽  
Cold Temperatures ◽  
Upper Troposphere ◽  
Downward Longwave Radiation ◽  
Cloud Ice

The performance of an explicit cloud physics parameterization is examined with simulations of high southern latitude winter climate using a version of the Pennsylvania State University/National Center for Atmospheric Research Mesoscale Model, version 4. The results reveal that there are three moist physics regimes in the vertical over the elevated interior of Antarctica: the very cold upper troposphere, the relatively warm middle troposphere and the cold boundary layer. Deficiencies for these layers include excessive cloud ice in the upper troposphere, excessive cloud ice in the inversion layer near the ice surface, overly warm temperatures in the lower troposphere, overly cold temperatures in the upper troposphere and excessive downward longwave radiation at the Earth’s surface. Three sensitivity experiments were performed to investigate possible improvements in the cloud parameterization. The results indicate that a reduction of the numerous cloud condensation nuclei, while reducing some errors, appears to be insufficient to improve the simulation. A reduction in the excessive cloud ice in the upper troposphere significantly improves the simulation of upper-tropospheric temperature.

scholarly journals Evaluating moist physics for Antarctic mesoscale simulations

1997 ◽  
Vol 25 ◽  
pp. 282-286 ◽  
Author(s):  
Keith M. Hines ◽  
David H. Bromwich ◽  
R. I. Cullather
Keyword(s):  
Mesoscale Model ◽  
Cloud Condensation Nuclei ◽  
Inversion Layer ◽  
Lower Troposphere ◽  
Tropospheric Temperature ◽  
Winter Climate ◽  
Cold Temperatures ◽  
Upper Troposphere ◽  
Downward Longwave Radiation ◽  
Cloud Ice

The performance of an explicit cloud physics parameterization is examined with simulations of high southern latitude winter climate using a version of the Pennsylvania State University/National Center for Atmospheric Research Mesoscale Model, version 4. The results reveal that there are three moist physics regimes in the vertical over the elevated interior of Antarctica: the very cold upper troposphere, the relatively warm middle troposphere and the cold boundary layer. Deficiencies for these layers include excessive cloud ice in the upper troposphere, excessive cloud ice in the inversion layer near the ice surface, overly warm temperatures in the lower troposphere, overly cold temperatures in the upper troposphere and excessive downward longwave radiation at the Earth’s surface. Three sensitivity experiments were performed to investigate possible improvements in the cloud parameterization. The results indicate that a reduction of the numerous cloud condensation nuclei, while reducing some errors, appears to be insufficient to improve the simulation. A reduction in the excessive cloud ice in the upper troposphere significantly improves the simulation of upper-tropospheric temperature.

scholarly journals Cluster analysis of midlatitude oceanic cloud regimes – Part 1: Mean cloud and meteorological properties

2010 ◽  
Vol 10 (1) ◽  
pp. 1559-1593 ◽  
Author(s):  
N. D. Gordon ◽  
J. R. Norris
Keyword(s):  
Large Scale ◽  
Clustering Algorithm ◽  
Storm Track ◽  
Lower Troposphere ◽  
Shortwave Radiation ◽  
Tropospheric Temperature ◽  
Free Troposphere ◽  
Upper Troposphere ◽  
Cloud Data ◽  
Cloud Regimes

Abstract. Clouds play an important role in the climate system by reducing the amount of shortwave radiation reaching the surface and the amount of longwave radiation escaping to space. Although dependent on type and location, clouds produce more cooling than warming in the global average. Accurate simulation of clouds in computer models remains elusive, however, pointing to a lack of understanding of the connection between large-scale dynamics and cloud properties. This study uses a k-means clustering algorithm to group 21-years of satellite cloud data over midlatitude oceans into seven clusters and demonstrates that the cloud clusters are associated with distinct large-scale dynamical conditions. Three clusters correspond to low-level cloud regimes with different cloud fraction and cumuliform or stratiform characteristics, but all occur under large-scale descent and a relatively dry free troposphere. The "small cumulus" regime is most prevalent equatorward of 40° in all seasons; the "large cumulus" regime is associated with a relatively cold troposphere and primarily occurs during winter; and the "stratocumulus/stratus" regime occurs under a temperature inversion and relatively warm free troposphere and predominates during summer. Three clusters correspond to vertically extensive cloud regimes with tops in the middle or upper troposphere. They differ according to the strength of large-scale ascent and enhancement of tropospheric temperature and humidity: "deep altostratus" has the smallest forcing, "weak frontal" is in the middle, and "strong frontal" has the largest forcing. The frontal cloud regimes occur most frequently in storm track regions. The final cluster, "cirrus" is associated with a lower troposphere that is dry and an upper troposphere that is moist and experiencing weak ascent and horizontal moist advection. This information builds a foundation for producing an observational estimate of the midlatitude ocean cloud response to warming that is independent of confounding meteorological influences.

scholarly journals On the tropospheric zonal and meridional fluxes of moisture in relation to nor’westers in Bangladesh during the pre-monsoon season

MAUSAM ◽  
2021 ◽  
Vol 58 (1) ◽  
pp. 67-74
Author(s):  
SAMARENDRA KARMAKAR ◽  
MD. MAHBUB ALAM
Keyword(s):  
Spatial Distribution ◽  
Monsoon Season ◽  
Lower Troposphere ◽  
Maximum Frequency ◽  
Upper Troposphere ◽  
Middle Troposphere ◽  
Surrounding Areas

Attempts have been made to study the zonal and meridional fluxes of moisture of the troposphere prior to the occurrence of nor’westers in Bangladesh during the pre-monsoon season. The study reveals that the westerly fluxes (positive) of moisture (WFM) dominate in the troposphere over Dhaka at 0000 UTC from 925 to 200 hPa level having maximum frequency of WFM from 61.68 to 96.26% in the layer from 925 to about 300 hPa level. The maximum WFM over Dhaka at 0000 UTC on the dates of occurrence of nor’westers may be more than 200 gm kg-1 × ms-1 in the lower troposphere and the maximum easterly (negative) fluxes of moisture (EFM) over Dhaka at 0000 UTC may be -128.3 gm kg-1 × ms-1 at 1000 hPa. In the upper troposphere the zonal fluxes of moisture (ZFM) become nil in most of the cases. The ZFM over Dhaka at 0000 UTC are mainly westerly and more westerly in the lower and middle troposphere on the dates of occurrence of nor’westers as compared to the fluxes on the dates of non-occurrence. The southerly fluxes (positive) of moisture (SFM) dominate in the troposphere over Dhaka at 0000 UTC from 1000 to 300 hPa level. The meridional fluxes of moisture (MFM) are mainly southerly and more southerly in the lower and middle troposphere on the dates of occurrence of nor’westers as compared to the dates of non-occurrence. In the upper troposphere the MFM become nil in most of the cases.The vertically integrated ZFM and MFM from 1000 to 100 hPa over Dhaka at 0000 UTC on the dates of occurrence of nor’westers in Bangladesh have been computed, compared and inference has been drawn. The present study also deals with the spatial distribution of the vertically integrated ZFM and MFM from 925 to 400 hPa level over Bangladesh and its surrounding areas. The range of the vertically integrated ZFM and MFM for the layer is about (2-12) × 105 and (3-14) × 105 kg × ms-1 respectively over Bangladesh in most of the cases.

scholarly journals NOAA/TOVS DERIVED UPPER TROPOSPHERIC TEMPERATURE CHANGES ASSOCIATED WITH THE ONSET OF SOUTHWEST MONSOON OVER KERALA COAST

MAUSAM ◽  
2022 ◽  
Vol 45 (2) ◽  
pp. 155-160
Author(s):  
P. C. JOSHI ◽  
B. SIMON
Keyword(s):  
Temperature Profile ◽  
Southwest Monsoon ◽  
Tropospheric Temperature ◽  
Temperature Changes ◽  
Upper Troposphere ◽  
Kerala Coast

Th e NOAA· scries of pol ar urbiting meteorological JalellitC"J cany cnboent an instrumentTOYSOlROS Operational Vertical Sounder). The temperature profile da la from thi! instrument over Pakistan beatlow region and Tibetan pla teau region i5 examined in relatio n to the onset of sout h~ mnruoon OWf Kent. coast.A si,nificanl temperatu re increase in upper troposphere nead y rv.u ·~u in a.1V11ncfO of onset of monsoonh.. been observed.

scholarly journals Profiles of CH<sub>4</sub>, HDO, H<sub>2</sub>O, and N<sub>2</sub>O with improved lower tropospheric vertical resolution from Aura TES radiances

2012 ◽  
Vol 5 (2) ◽  
pp. 397-411 ◽  
Author(s):  
J. Worden ◽  
S. Kulawik ◽  
C. Frankenberg ◽  
V. Payne ◽  
K. Bowman ◽  
...  
Keyword(s):  
Lower Troposphere ◽  
Retrieval Algorithm ◽  
Profile Measurement ◽  
Vertical Resolution ◽  
Spectral Window ◽  
Upper Troposphere ◽  
Carbon Cycles ◽  
Peak Sensitivity ◽  
Window Approach ◽  
The Tropics

Abstract. Thermal infrared (IR) radiances measured near 8 microns contain information about the vertical distribution of water vapor (H2O), the water isotopologue HDO, and methane (CH4), key gases in the water and carbon cycles. Previous versions (Version 4 or less) of the TES profile retrieval algorithm used a "spectral-window" approach to minimize uncertainty from interfering species at the expense of reduced vertical resolution and sensitivity. In this manuscript we document changes to the vertical resolution and uncertainties of the TES version 5 retrieval algorithm. In this version (Version 5), joint estimates of H2O, HDO, CH4 and nitrous oxide (N2O) are made using radiances from almost the entire spectral region between 1100 cm−1 and 1330 cm−1. The TES retrieval constraints are also modified in order to better use this information. The new H2O estimates show improved vertical resolution in the lower troposphere and boundary layer, while the new HDO/H2O estimates can now profile the HDO/H2O ratio between 925 hPa and 450 hPa in the tropics and during summertime at high latitudes. The new retrievals are now sensitive to methane in the free troposphere between 800 and 150 mb with peak sensitivity near 500 hPa; whereas in previous versions the sensitivity peaked at 200 hPa. However, the upper troposphere methane concentrations are biased high relative to the lower troposphere by approximately 4% on average. This bias is likely related to temperature, calibration, and/or methane spectroscopy errors. This bias can be mitigated by normalizing the CH4 estimate by the ratio of the N2O estimate relative to the N2O prior, under the assumption that the same systematic error affects both the N2O and CH4 estimates. We demonstrate that applying this ratio theoretically reduces the CH4 estimate for non-retrieved parameters that jointly affect both the N2O and CH4 estimates. The relative upper troposphere to lower troposphere bias is approximately 2.8% after this bias correction. Quality flags based upon the vertical variability of the methane and N2O estimates can be used to reduce this bias further. While these new CH4, HDO/H2O, and H2O estimates are consistent with previous TES retrievals in the altitude regions where the sensitivities overlap, future comparisons with independent profile measurement will be required to characterize the biases of these new retrievals and determine if the calculated uncertainties using the new constraints are consistent with actual uncertainties.

scholarly journals Observation of aerosol induced ‘lower tropospheric cooling’ over Indian core monsoon region

2021 ◽  
Author(s):  
Manish Jangid ◽  
Amit Kumar Mishra ◽  
Ilan Koren ◽  
Chandan Sarangi ◽  
Krishan Kumar ◽  
...  
Keyword(s):  
Monsoon Season ◽  
Regional Scale ◽  
Lower Troposphere ◽  
Radiation Budget ◽  
Cloud Formation ◽  
Tropospheric Temperature ◽  
Monsoon Region ◽  
Remote Sensors ◽  
Aerosol Cloud ◽  
Aerosol Cloud Interactions

Abstract Aerosols play a significant role in regional scale pollution that alters the cloud formation process, radiation budget, and climate. Here, using long-term (2003-2019) observations from multi-satellite and ground-based remote sensors, we show robust aerosol-induced instantaneous daytime lower tropospheric cooling during the pre-monsoon season over the Indian core monsoon region (ICMR). Quantitatively, an average cooling of -0.82±0.11 °C to -1.84±0.25 °C is observed in the lower troposphere. The observed cooling is associated with both aerosol-radiation and aerosol-cloud-radiation interactions processes. The elevated dust and polluted-dust layers cause extinction of the incoming solar radiation, thereby decreasing the lower tropospheric temperature. The aerosol-cloud interactions also contribute to enhancement of cloud fraction which further contributes to the lower tropospheric cooling. The observed cooling results in a stable lower tropospheric structure during polluted conditions, which can also feedback to cloud systems. Our findings suggest that aerosol induced lower tropospheric cooling can strongly affect the cloud distribution and circulation dynamics over the ICMR, a region of immense hydroclimatic importance.

scholarly journals GPS radio occultation with TerraSAR-X and TanDEM-X: sensitivity of lower troposphere sounding to the Open-Loop Doppler model

2014 ◽  
Vol 7 (12) ◽  
pp. 12719-12733 ◽  
Author(s):  
F. Zus ◽  
G. Beyerle ◽  
S. Heise ◽  
T. Schmidt ◽  
J. Wickert
Keyword(s):  
Radio Occultation ◽  
Weather Prediction ◽  
Lower Troposphere ◽  
Systematic Difference ◽  
Open Loop ◽  
Negative Bias ◽  
Upper Troposphere ◽  
Gps Radio Occultation ◽  
Global Positioning ◽  
Data Source

Abstract. The Global Positioning System (GPS) radio occultation (RO) technique provides valuable input for numerical weather prediction and is considered as a data source for climate related research. Numerous studies outline the high precision and accuracy of RO atmospheric soundings in the upper troposphere and lower stratosphere. In this altitude region (8–25 km) RO atmospheric soundings are considered to be free of any systematic error. In the tropical (30° S–30° N) Lower (<8 km) Troposphere (LT), this is not the case; systematic differences with respect to independent data sources exist and are still not completely understood. To date only little attention has been paid to the Open Loop (OL) Doppler model. Here we report on a RO experiment carried out on-board of the twin satellite configuration TerraSAR-X and TanDEM-X which possibly explains to some extent biases in the tropical LT. In two sessions we altered the OL Doppler model aboard TanDEM-X by not more than ±5 Hz with respect to TerraSAR-X and compare collocated atmospheric refractivity profiles. We find a systematic difference in the retrieved refractivity. The bias mainly stems from the tropical LT; there the bias reaches up to ±1%. Hence, we conclude that the negative bias (several Hz) of the OL Doppler model aboard TerraSAR-X introduces a negative bias (in addition to the negative bias which is primarily caused by critical refraction) in our retrieved refractivity in the tropical LT.

scholarly journals CMIP5 Simulations of Low-Level Tropospheric Temperature and Moisture over the Tropical Americas

2013 ◽  
Vol 26 (17) ◽  
pp. 6257-6286 ◽  
Author(s):  
Leila M. V. Carvalho ◽  
Charles Jones
Keyword(s):  
Daily Precipitation ◽  
Monsoon Season ◽  
Coupled Model ◽  
Specific Humidity ◽  
Cmip5 Models ◽  
North American Monsoon ◽  
Tropospheric Temperature ◽  
The North ◽  
Decadal Variations ◽  
Monsoon System

Abstract Global warming has been linked to systematic changes in North and South America's climates and may severely impact the North American monsoon system (NAMS) and South American monsoon system (SAMS). This study examines interannual-to-decadal variations and changes in the low-troposphere (850 hPa) temperature (T850) and specific humidity (Q850) and relationships with daily precipitation over the tropical Americas using the NCEP–NCAR reanalysis, the Climate Forecast System Reanalysis (CFSR), and phase 5 of the Coupled Model Intercomparison Project (CMIP5) simulations for two scenarios: “historic” and high-emission representative concentration pathway 8.5 (RCP8.5). Trends in the magnitude and area of the 85th percentiles were distinctly examined over North America (NA) and South America (SA) during the peak of the respective monsoon season. The historic simulations (1951–2005) and the two reanalyses agree well and indicate that significant warming has occurred over tropical SA with a remarkable increase in the area and magnitude of the 85th percentile in the last decade (1996–2005). The RCP8.5 CMIP5 ensemble mean projects an increase in the T850 85th percentile of about 2.5°C (2.8°C) by 2050 and 4.8°C (5.5°C) over SA (NA) by 2095 relative to 1955. The area of SA (NA) with T850 ≥ the 85th percentile is projected to increase from ~10% (15%) in 1955 to ~58% (~33%) by 2050 and ~80% (~50%) by 2095. The respective increase in the 85th percentile of Q850 is about 3 g kg−1 over SAMS and NAMS by 2095. CMIP5 models project variable changes in daily precipitation over the tropical Americas. The most consistent is increased rainfall in the intertropical convergence zone in December–February (DJF) and June–August (JJA) and decreased precipitation over NAMS in JJA.

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