Role of Arabian Sea Surface Pressure on Indian Northeast Monsoon

2016 ◽  
pp. 849-853
Author(s):  
Ramesh Kumar Yadav
Keyword(s):  
Surface Pressure ◽  
Arabian Sea ◽  
Sea Surface ◽  
Northeast Monsoon

scholarly journals ‘Eastern African Paradox’ rainfall decline due to shorter not less intense Long Rains

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Caroline M. Wainwright ◽  
John H. Marsham ◽  
Richard J. Keane ◽  
David P. Rowell ◽  
Declan L. Finney ◽  
...  
Keyword(s):  
Surface Pressure ◽  
Arabian Sea ◽  
Daily Rainfall ◽  
Eastern Africa ◽  
Future Climate Change ◽  
Climate Projections ◽  
Partial Recovery ◽  
African Climate ◽  
Rain Band

Abstract An observed decline in the Eastern African Long Rains from the 1980s to late 2000s appears contrary to the projected increase under future climate change. This “Eastern African climate paradox” confounds use of climate projections for adaptation planning across Eastern Africa. Here we show the decline corresponds to a later onset and earlier cessation of the long rains, with a similar seasonal maximum in area-averaged daily rainfall. Previous studies have explored the role of remote teleconnections, but those mechanisms do not sufficiently explain the decline or the newly identified change in seasonality. Using a large ensemble of observations, reanalyses and atmospheric simulations, we propose a regional mechanism that explains both the observed decline and the recent partial recovery. A decrease in surface pressure over Arabia and warmer north Arabian Sea is associated with enhanced southerlies and an earlier cessation of the long rains. This is supported by a similar signal in surface pressure in many atmosphere-only models giving lower May rainfall and an earlier cessation. Anomalously warm seas south of Eastern Africa delay the northward movement of the tropical rain-band, giving a later onset. These results are key in understanding the paradox. It is now a priority to establish the balance of mechanisms that have led to these trends, which are partially captured in atmosphere-only simulations.

scholarly journals Variability of surface fields in different branches of monsoon

MAUSAM ◽  
2022 ◽  
Vol 46 (3) ◽  
pp. 313-324
Author(s):  
P. K. MOHANTY ◽  
S. K. DASH
Keyword(s):  
Heat Flux ◽  
Surface Temperature ◽  
Latent Heat ◽  
Latent Heat Flux ◽  
Surface Pressure ◽  
South China ◽  
Bay Of Bengal ◽  
Arabian Sea ◽  
Sea Surface ◽  
Surface Fields

ABSTRACT. Characteristics of the surface fields. such as zonal and meridional components of pseudostress. surface pressure, latent and sensible heat fluxes, sea surface temperature (SST) and air temperature for the years 1985 and 1986, are studied using ECMWF model-analysed data and FSU data obtained from TOGA CD-ROM (1990). Three branches of monsoon. Viz. (i) Arabian Sea; (ii) Bay of Bengal and (iii) South China 1 Sea are observed in pseudostress, surface pressure and latent heat flux. However, the other three surface fieldsdo not reflect the branching phenomenon. The Arabian Sea and Bay of Bengal branches depict strong signals of variability in the surface fields in association with the monsoon variability compared to the south China Sea branch. Arabian Sea branch is observed to have the strongest signals in the pseudostress and latent heat flux transfer whereas surface pressure is having the lowest value over the Bay of Bengal. Southern Indian Ocean shows significant variability in surface pressure in comparison to the three branches of monsoon. Strong positive radient of pseudostress in association with sudden increase of latent heat flux front May to June, and the pre-monsoonal pressure drop (March to April) in 1985 are the most prominent features associated with better monsoon activity. Inter-annual variability in sea surface temperature (SST) is not well marked but differences in SST amongst the three branches are significant.  

Impact of surface warming over Equatorial Pacific ocean in western disturbances precipitation

2020 ◽  
Author(s):  
Asiya Badarunnisa Sainudeen ◽  
Prasanta Sanyal
Keyword(s):  
Pressure Gradient ◽  
Surface Pressure ◽  
Indian Subcontinent ◽  
Sea Surface ◽  
Northeast Monsoon ◽  
Western Disturbances ◽  
Increasing Trend ◽  
Indian Landmass ◽  
Northern Atlantic

<p>Indian subcontinent receives precipitation from the southwest monsoon, northeast monsoon, and western disturbances. Unlike southwest and northeast monsoon, precipitation by western disturbances is less studied in terms of understanding its forcing factors and future behavior. Synoptic weather phenomena that originate in temperate north-Atlantic and the Mediterranean sea are primarily responsible for the moisture convergence towards the Indian landmass through an eastward movement and cause Western Disturbance Precipitation (WDP) in Turkey, Iran, Pakistan, Afghanistan, and northwestern India during winter (December-March). Long term (116 years) WDP shows an increasing trend over most of the regions. To understand the forcing factors in WDP, a long term pressure gradient between the Indian landmass and northern Atlantic has been calculated. This pressure gradient also shows an increasing trend, thereby suggesting its direct influence on WDP. This influence is observed not only in the long term WDP but for each winter month as well. Previous studies showed the impact of Pacific ocean sea surface temperature (SST)  on the modulation of northern Atlantic ocean SST and surface pressure. However, no quantitative estimation on the relation of Pacific SST with WDP is known. Here, an attempt has been made to understand the role of Pacific SST in the long term trend of WDP.</p><p>Changes in SST and convection in the tropical Pacific region determines the interannual variability as well as seasonal climate forecasting all over the world by modulating the air-sea coupling and sea level pressure. Therefore, the potential impact of Pacific SST on WDP has been tested, and a significant correlation between them has been observed. To understand the causal factors behind such relation, statistical analysis like Pearson's correlation analysis was performed by taking the SST of the Nino 3.4 region with the surface pressure of the northern Atlantic and Indian subcontinent. This analysis gave a significant positive correlation (R=0.24) among NINO 3.4 SST and surface pressure over the northern Atlantic and negative correlation (R=-0.28) between NINO 3.4 SST and surface pressure of the Indian region. From this analysis, it is inferred that the Pacific warm pool primarily drives the lower and higher surface pressure over Indian landmass and northern Atlantic, respectively, by modulating the local meridional and zonal circulation, which further dictates WDP.</p><p>References</p><p>Dimri, A. P., et al. "Western disturbances: a review."Reviews of Geophysics 53.2 (2015): 225-246.    </p><p>Enfield, DAVID B., and ALBERTO M. Mestas-Nuñez. "Global modes of ENSO and non-ENSO sea surface temperature variability and their associations with climate."El-Niño and the Southern Oscillation: multiscale variability and global and regional impacts (2000): 89-112.</p><p>    </p>

Role of suspended matter in controlling beryllium-7 (7Be) in the Black Sea surface layer

2021 ◽  
pp. 103513
Author(s):  
Dmitrii A. Kremenchutskii ◽  
Gennady F. Batrakov ◽  
Illarion I. Dovhyi ◽  
Yury A. Sapozhnikov
Keyword(s):  
Surface Layer ◽  
Black Sea ◽  
Suspended Matter ◽  
Sea Surface ◽  
The Black Sea

scholarly journals Role of sea surface temperature responses in simulation of the climatic effect of mineral dust aerosol

2011 ◽  
Vol 11 (12) ◽  
pp. 6049-6062 ◽  
Author(s):  
X. Yue ◽  
H. Liao ◽  
H. J. Wang ◽  
S. L. Li ◽  
J. P. Tang
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Radiative Forcing ◽  
Mineral Dust ◽  
Dust Aerosol ◽  
Sea Surface ◽  
Climatic Effect ◽  
Radiative Effects ◽  
Climate Simulations

Abstract. Mineral dust aerosol can be transported over the nearby oceans and influence the energy balance at the sea surface. The role of dust-induced sea surface temperature (SST) responses in simulations of the climatic effect of dust is examined by using a general circulation model with online simulation of mineral dust and a coupled mixed-layer ocean model. Both the longwave and shortwave radiative effects of mineral dust aerosol are considered in climate simulations. The SST responses are found to be very influential on simulated dust-induced climate change, especially when climate simulations consider the two-way dust-climate coupling to account for the feedbacks. With prescribed SSTs and dust concentrations, we obtain an increase of 0.02 K in the global and annual mean surface air temperature (SAT) in response to dust radiative effects. In contrast, when SSTs are allowed to respond to radiative forcing of dust in the presence of the dust cycle-climate interactions, we obtain a global and annual mean cooling of 0.09 K in SAT by dust. The extra cooling simulated with the SST responses can be attributed to the following two factors: (1) The negative net (shortwave plus longwave) radiative forcing of dust at the surface reduces SST, which decreases latent heat fluxes and upward transport of water vapor, resulting in less warming in the atmosphere; (2) The positive feedback between SST responses and dust cycle. The dust-induced reductions in SST lead to reductions in precipitation (or wet deposition of dust) and hence increase the global burden of small dust particles. These small particles have strong scattering effects, which enhance the dust cooling at the surface and further reduce SSTs.

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