Increasing incidence of Arabian Sea cyclones during the monsoon onset phase: Its impact on the robustness and advancement of Indian summer monsoon

2021 ◽  
pp. 105915
Author(s):  
P.P. Baburaj ◽  
S. Abhilash ◽  
C.S. Abhiram Nirmal ◽  
A.V. Sreenath ◽  
K. Mohankumar ◽  
...  
Keyword(s):  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
Arabian Sea ◽  
Monsoon Onset ◽  
Onset Phase

scholarly journals On the Detection of Onset and Activity of the Indian Summer Monsoon Using GPS RO Refractivity Profiles

2013 ◽  
Vol 141 (6) ◽  
pp. 2096-2106 ◽  
Author(s):  
V. V. M. Jagannadha Rao ◽  
M. Venkat Ratnam ◽  
Y. Durga Santhi ◽  
M. Roja Raman ◽  
M. Rajeevan ◽  
...  
Keyword(s):  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
Arabian Sea ◽  
Active Phase ◽  
Monsoon Onset ◽  
Tropospheric Temperature ◽  
Sudden Increase ◽  
Atmospheric Conditions ◽  
Good Relation ◽  
Onset Phase

Abstract Global positioning system (GPS) radio occultation (RO) data available during 2001–10 have been used to examine the variations in the refractivity during the onset of Indian summer monsoon (ISM) over the east Arabian Sea (5°–15°N, 65°–75°E). An enhancement of 5–10 N-units in the refractivity is observed around 4.8 km (~600 hPa) a few days (9.23 ± 3.6 days) before onset of the monsoon over Kerala, India. This is attributed to moisture buildup over the Arabian Sea during the monsoon onset phase. A sudden increase (1.5–2 K) in mean upper-tropospheric temperature at the time of onset and during the active phase of the monsoon is attributed to convective activity and the release of latent heat. On the day of monsoon onset over Kerala, an appreciable dip in the refractivity is observed that persisted for 1–3 days followed by an enhancement in refractivity with the active phase of the monsoon. An arbitrary value of 128 N-units difference between 4.8 km (~600 hPa) and 16 km (~100 hPa) coupled with a dip in refractivity on the day of monsoon arrival might give an indication of clear transition of atmospheric conditions and the detection of monsoon onset. Further, a good relation is also found between the activity of monsoon and variability in the refractivity.

scholarly journals Objective Definition of the Indian Summer Monsoon Onset*

2009 ◽  
Vol 22 (12) ◽  
pp. 3303-3316 ◽  
Author(s):  
Bin Wang ◽  
Qinghua Ding ◽  
P. V. Joseph
Keyword(s):  
Indian Ocean ◽  
Excellent Agreement ◽  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
Time Scale ◽  
Rainy Season ◽  
Arabian Sea ◽  
Monsoon Onset ◽  
Indian Peninsula ◽  
The Past

Abstract The onset of the Indian summer monsoon (ISM) over the southern tip of the Indian peninsula [also known as monsoon onset over Kerala (MOK)] has been considered the beginning of India’s rainy season. The Indian Meteorological Department (IMD) makes an official prediction of ISM onset every year using a subjective method. Based on an analysis of the past 60-yr (1948–2007) record, the authors show that the onset date can be objectively determined by the beginning of the sustained 850-hPa zonal wind averaged over the southern Arabian Sea (SAS) from 5° to 15°N, and from 40° to 80°E. The rapid establishment of a steady SAS westerly is in excellent agreement with the abrupt commencement of the rainy season over the southern tip of the Indian peninsula. In 90% of the years analyzed, this simple and objective index has excellent agreement with the onset dates that are subjectively defined by the IMD. There are only 3 yr of the past 60 yr during which the two onset dates differ by more than 10 days, and none of them perfectly reflects the MOK. A prominent onset precursor on the biweekly time scale is the westward extension of the convection center from the equatorial eastern Indian Ocean toward the southeast Arabian Sea. On the intraseasonal time scale, the onset tends to be led by northeastward propagation of an intraseasonal convective anomaly from the western equatorial Indian Ocean. The objective determination of the onset based on the SAS low-level westerly is a characteristic representation of the complex process of the ISM onset. Given its objectiveness and its representation of the large-scale circulation, the proposed new onset definition provides a useful metric for verifying numerical model performance in simulating and predicting the ISM onset and for studying predictability of interannual variations of the onset.

scholarly journals Simulation of the Indian summer monsoon onset-phase rainfall using a regional model

2015 ◽  
Vol 33 (9) ◽  
pp. 1097-1115 ◽  
Author(s):  
C. V. Srinivas ◽  
D. Hari Prasad ◽  
D. V. Bhaskar Rao ◽  
R. Baskaran ◽  
B. Venkatraman
Keyword(s):  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
Onset Time ◽  
India Meteorological Department ◽  
Regional Model ◽  
Monsoon Onset ◽  
Scale Model ◽  
Wave Radiation ◽  
Climate Zones ◽  
Onset Phase

Abstract. This study examines the ability of the Advanced Research WRF (ARW) regional model to simulate Indian summer monsoon (ISM) rainfall climatology in different climate zones during the monsoon onset phase in the decade 2000–2009. The initial and boundary conditions for ARW are provided from the NCEP/NCAR Reanalysis Project (NNRP) global reanalysis. Seasonal onset-phase rainfall is compared with corresponding values from 0.25° IMD (India Meteorological Department) rainfall and NNRP precipitation data over seven climate zones (perhumid, humid, dry/moist, subhumid, dry/moist, semiarid and arid) of India to see whether dynamical downscaling using a regional model yields advantages over just using large-scale model predictions. Results show that the model could simulate the onset phase in terms of progression and distribution of rainfall in most zones (except over the northeast) with good correlations and low error metrics. The observed mean onset dates and their variability over different zones are well reproduced by the regional model over most climate zones. It has been found that the ARW performed similarly to the reanalysis in most zones and improves the onset time by 1 to 3 days in zones 4 and 7, in which the NNRP shows a delayed onset compared to the actual IMD onset times. The variations in the onset-phase rainfall during the below-normal onset (June negative) and above-normal onset (June positive) phases are well simulated. The slight underestimation of onset-phase rainfall in the northeast zone could be due to failure in resolving the wide extent of topographic variations and the associated multiscale interactions in that zone. Spatial comparisons showed improvement of pentad rainfall in both space and quantity in ARW simulations over NNRP data, as evident from a wider eastward distribution of pentad rainfall over the Western Ghats, central and eastern India, as in IMD observations. While NNRP under-represented the high pentad rainfall over northeast, east and west coast areas, the ARW captured these regional features showing improvement upon NNRP reanalysis, which may be due to the high resolution (30 km) employed. The onset-phase rainfall characteristics during the contrasting ISM of 2003 and 2009 are well simulated in terms of the variations in the strength of low-level jet (LLJ) and outgoing long-wave radiation (OLR).

scholarly journals Oceanic factors controlling the Indian summer monsoon onset in a coupled model

2014 ◽  
Vol 44 (3-4) ◽  
pp. 977-1002 ◽  
Author(s):  
Chloé Prodhomme ◽  
Pascal Terray ◽  
Sébastien Masson ◽  
Ghyslaine Boschat ◽  
Takeshi Izumo
Keyword(s):  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
Coupled Model ◽  
Monsoon Onset ◽  
Summer Monsoon Onset

scholarly journals Relationship between monsoon onset over Thiruvananthapuram and Mumbai and rainfall over Kerala and Konkan

MAUSAM ◽  
2021 ◽  
Vol 57 (3) ◽  
pp. 445-450
Author(s):  
M. P. SHEWALE ◽  
A. S. PONKSHE
Keyword(s):  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
Significant Relationship ◽  
Monsoon Rainfall ◽  
Indian Summer Monsoon Rainfall ◽  
Summer Monsoon Rainfall ◽  
Monsoon Onset ◽  
Onset Date ◽  
Simultaneous Occurrence

Lkkj & bl ’kks/k&Ik= esa nks LFkkuksa uker% fFk:ouUriqje vkSj eqEcbZ dk p;u djds ;g irk yxkus dk iz;kl fd;k x;k gS fd D;k ekulwu ds vkxeu dh rkjh[k dk Øze’k% dsjy vkSj dksad.k esa gksus okyh o"kkZ ds lkFk dksbZ laca/k gS A lewps ns’k ds fy, Hkkjrh; xzh"edkyhu ekulwu o"kkZ ¼vkbZ- ,l- ,e- vkj-½ ds lkFk ekulwu ds vkxeu dh rkjh[k ds laca/k dh Hkh tk¡p dh xbZ gS A bl v/;;u ds fy, 100 o"kksaZ ¼1901&2000½ ds vk¡dM+ksa dk mi;ksx fd;k x;k gS A             fo’ys"k.k dh lgk;rk ls vk¡dM+ksa dh ,d:irk vkSj o"kkZ ds vU; y{k.kksa dh tk¡p dh xbZ gS A dsjy vkSj dksad.k esa vdky vkSj ekSle laca/kh ck<+ dh ledkfyd ?kVukvksa dh vko`fr dk irk yxk;k x;k gS vkSj mldh tk¡p dh xbZ gS A             bl v/;;u ls ;g irk pyk gS fd ekulwu ds vkxeu ds laca/k esa fFk:ouUriqje vkSj eqEcbZ ds chp egRoiw.kZ laca/k gS A fFk:ouariqje vFkok eqEcbZ vkSj vkbZ- ,l- ,u- vkj- ds chp ekulwu ds vkxeu ds ckjs esa fdlh egRoiw.kZ laca/k dk irk ugha pyk gS A dsjy dh rqyuk eas dksad.k esa ekSle laca/kh ck<+ vf/kd vkrh gS A In this paper, choosing two locations viz., Thiruvananthapuram and Mumbai, an attempt has been made to find whether the onset date of monsoon has any bearing on monsoon rainfall over Kerala and Konkan respectively.   Association of the onset dates with Indian Summer Monsoon Rainfall (ISMR) for the country as a whole has also been explored.  The study utilizes 100 years’ (1901-2000) data. Homogeneity of the data and other rainfall features have been examined with the help of  analysis.  Frequency of simultaneous occurrence of droughts and meteorological floods at Kerala and Konkan have been determined and examined.    The study showed that onset over Thiruvananthapuram and Mumbai are significantly related.  It revealed absence of any significant relationship between onset over Thiruvananthapuram or Mumbai and the ISMR. Meteorological floods seem to be more frequent over Konkan compared to Kerala.

Influence of the Arabian Sea on the Indian summer monsoon

Tellus ◽  
1978 ◽  
Vol 30 (2) ◽  
pp. 117-125 ◽  
Author(s):  
S. K. Ghosh ◽  
M. C. Pant ◽  
B. N. Dewan
Keyword(s):  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
Arabian Sea

Long-term history of sediment inputs to the eastern Arabian Sea and its implications for the evolution of the Indian summer monsoon since 3.7 Ma

2018 ◽  
Vol 157 (6) ◽  
pp. 908-919 ◽  
Author(s):  
Mingjiang Cai ◽  
Zhaokai Xu ◽  
Peter D. Clift ◽  
Boo-Keun Khim ◽  
Dhongil Lim ◽  
...  
Keyword(s):  
Clay Minerals ◽  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
Arabian Sea ◽  
Sediment Supply ◽  
Deccan Traps ◽  
Indus River ◽  
Eastern Arabian Sea ◽  
Monsoon Intensity ◽  
History Of

AbstractWe present a new set of clay mineral and grain-size data for the siliciclastic sediment fraction from International Ocean Discovery Program (IODP) Site U1456 located in the eastern Arabian Sea to reconstruct the variabilities in the continental erosion and weathering intensity in the western Himalaya, elucidate the sediment source-to-sink processes and discuss the potential controls underlying these changes since 3.7 Ma. The clay minerals mainly consist of smectite (0–90%, average 44%) and illite (3–90%, average 44%), with chlorite (1–26%, average 7%) and kaolinite (0–19%, average 5%) as minor components. The compositional variations in the clay minerals at IODP Site U1456 suggest four phases of sediment provenance: the Indus River (phase 1, 3.7–3.2 Ma), the Indus River and Deccan Traps (phase 2, 3.2–2.6 Ma), the Indus River (phase 3, 2.6–1.2 Ma) and the Indus River and Deccan Traps (phase 4, 1.2–0 Ma). These provenance changes since 3.7 Ma can be correlated with variations in the Indian summer monsoon intensity. The siliciclastic sediments in the eastern Arabian Sea were mainly derived from the Indus River when the Indian summer monsoon was generally weak. In contrast, when the Indian summer monsoon intensified, the siliciclastic sediment supply from the Deccan Traps increased. In particular, this study shows that the smectite/(illite+chlorite) ratio is a sensitive tool for reconstructing the history of the variation in the Indian summer monsoon intensity over the continents surrounding the Arabian Sea since 3.7 Ma.

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