bluuebunny/crossref_metadata_2025_split huggingface dataset:
Daily summer monsoon rainfall over northeast India due to synoptic scale systems
Authors: MOHAPATRA M. , BISWAS H. R. , SAWAISARJE G. K. 
Published: November 2021

The summer monsoon rainfall over northeast India mostly depends on the synoptic systems over the region and neighbourhood and the convection due to the interaction of orography with the synoptic and sub-synoptic scale systems. Hence, an attempt is made to analyse the mean daily rainfall distribution over northeast India due to different synoptic systems like Low Pressure Systems (LPS) and cyclonic circulations (cycir) extending upto lower/middle tropospheric levels over different regions. The mean daily rainfall due to monsoon trough over various locations in northeast India is also analysed. For the above purpose, the rainfall data over 50 uniformly distributed stations in northeast India during summer monsoon season (June-September) for a period of 10 years (1991-2000) are considered. The principal objective of the study is to find out the contribution of the different synoptic systems to the spatial variability of monsoon rainfall over northeast India.

The developed synoptic analog maps may be useful to the forecasters for 24 hours rainfall forecast with the knowledge of location, intensity and movement of the synoptic systems. Based on larger data set, the results confirm the earlier findings (Srinivasan et al., 1972) with respect to rainfall due to monsoon trough and LPS. The Low Level Cycir (LLC) also plays significant role on the rainfall variability over northeast India, as the number of LLC days is significantly higher over the region, contrary to the days of occurrence of LPS. The study finds out the regions of excess/deficient rainfall and active/weak monsoon conditions due to different synoptic systems.
Intensification and movement of cyclonic storm in the Bay of Bengal during post monsoon season
Authors: MUTHUCHAMI A. , SRIDHARAN S. 
Published: November 2021

Using NCEP/NCAR reanalysis data and from the available data on tracks of the storms from India Meteorological Department for the period 1981-2005 an attempt is made to understand the intensification of storms and their movements in the Bay of Bengal during post-monsoon season. It is noticed that in the month of October only 12 % of the cyclonic storms weakened whereas in November and December it is 28 % and 41 % respectively. Cyclonic storms moving in a northeast direction weaken in all the months of post-monsoon season. Most of the westward moving storms do not undergo weakening. In the Bay of Bengal, SST and relative humidity are not responsible for weakening of the storms except in December but wind shear is responsible for weakening. The orientation of isotherms of SST of Bay of Bengal influences the direction of motion. During the years when the storms are predominantly moving west/northwest the SST over the Bay of Bengal is about 1.0° C warmer than the years when the storms are predominantly moving in north/northeastward. If the isotherms of SST are oriented southwest-northeast with higher value in the east then system may move in north or northeastward and on such occasions east Bay of Bengal is warmer than west Bay of Bengal.
Generation of district level rice crop inventory, growth profile and yield estimation in Orissa using spot-vegetation data
Authors: DUTTA SUJAY , DADHWAL V. K. , PATEL N. K. , PARIHAR J. S. 
Published: November 2021

Spot-vegetation 10 day NDVI composites over Orissa state were analysed to study rice crop inventory and condition assessment. A total of 17 images from July to December during the monsoon (kharif) season of 1998 (S1) and 2001 (S2) a drought and normal year, respectively were analysed. A hierarchical decision rule-based approach that successively eliminated data loss, non vegetated land, forest cover, fallow and other crops was adopted for rice inventory. NDVI temporal profiles of rice could distinguish autumn and winter rice. The total monsoon rice area identified by RS in the state was 4.5 M ha in 1998 and 4.05 M ha in 2001 and was within 7 percent of the state level rice estimate given by Directorate of Economic Survey (DES) i.e., 4.26 and 4.22 M ha, respectively. A new profile fit i.e., a six parameter modified Gaussian approach was adopted. The spectral profile indicated higher mean NDVI at peak growth profile of lowland winter rice (sown in June-July) in 2001-02 compared to 1998-1999. Thus, 2001-2002 rice was seen to be normal while in 1998-1999 a drought affected year. District-wise NDVI profiles of rice were generated and peak NDVI and date at peak profile were found to be correlated with rice yield at district and agro-climatic zone level. Use of rainfall with spectral profile parameters in yield model group of districts or zonal level improved coefficient of determination. This study demonstrates the utility of 1 km and 10 day NDVI composite data for rice crop assessment during monsoon season.
Recent variations and trends in potential evapotranspiration (PET) over India
Authors: VERMA I.  J. , JADHAV V. N. , S. ERANDE R. 
Published: November 2021

Thirty years meteorological time series data (1971-2000), for twenty two well distributed locations in India, have been utilized to compute potential evapotranspiration using FAO recommended Penman-Monteith equation. Annual, seasonal and monthly PET trends have been studied using linear trend analysis technique. Suitable graphs have been plotted to study the variations and changes in PET trends and to identify the specific periods as and when significant changes occur.

The mean annual PET has been found to be lowest (1100 mm) at Buralikson and highest (2109 mm) at Bellary. Out of twenty two locations, significant decreasing trend in annual PET has been observed at seventeen locations and no significant trend at five locations. The mean annual dEo/dt over India has been found to be -9.36 mm/year. Linear relationship has been obtained to quantitatively estimate annual dEo/dt, at a given location, using annual PET range. Non linear relationships have been obtained (a) to quantitatively estimate the mean monthly dEo/dt values over India, (b) to quantitatively estimate the average cumulative dEo/dt values over India (mm/year) up to any particular month and (c) to quantitatively estimate the contribution (percent) towards average annual dEo/dt over India, up to any particular month.
A study on recent changes in weekly evaporation at selected locations in India
Authors: VERMA I. J. , DAS H. P. , JADHAV V. N. 
Published: November 2021

Thirty years evaporation time series data (1971-2000) recorded from US class-A evaporation pans for ten well distributed locations in India, have been utilized in the present study. For these locations, basic statistical parameters of weekly evaporation [minimum, maximum, range, mean, standard deviation (S.D.) and coefficient of variation (C.V.)] have been computed. Variations in average weekly evaporation in different weeks and at different locations have been plotted and discussed. Changes in weekly evaporation have been studied using linear trend analysis technique on weekly evaporation time series data for standard meteorological weeks (1 to 52). Graphs have been plotted, for all ten different locations, to study week wise distribution of changes in weekly evaporation trends and to identify the specific periods when significant changes occur.

The highest average weekly evaporation of 107.5 mm has been observed at Jodhpur in standard week 21(21 – 27 May). The lowest average weekly evaporation of 14.5 mm has been observed at Karimganj in standard week 3 (15 – 21 January). The peak in average weekly evaporation, at most of these locations is achieved around standard week 20 (14 – 20 May). The coefficient of variation (C.V.) at these locations varied between 18.7 and 51.8 percent. The highest C.V. of 51.8 % has been observed at Bikramganj, whereas the lowest C.V. of 18.7 % has been observed at Rajamundry. Out of 52 weeks, Pune and Rajamundry have shown significant decreasing trend in weekly evaporation in maximum number of weeks (37) and Bhubaneshwar has shown significant decreasing trend in weekly evaporation in minimum number of weeks (10). At six locations (Bikramganj, Hissar, Jodhpur, Pattambi, Pune and Rajamundry), the number of weeks showing significant decreasing trend in weekly evaporation have been found to be more than 23 weeks. At more than five locations significant decreasing trend in weekly evaporation occur, in almost all weeks, between standard weeks 1 to 19 (1 January - 13 May) and also between standard weeks 40 to 52 (1 October - 31 December). In almost all the locations, significant decreasing trend in weekly evaporation occur, in standard week numbers 1-2, 9-10, 13 and 15.
Water requirement and water use efficiency of Sorghum and its irrigation planning under limited water resources in arid and semi arid regions of India
Authors: SAMUI R. P. , JOHN GRACY , PILLAI M. P. S. , RANSURE S. P. 
Published: November 2021

Water requirement and water use efficiency of sorghum was studied at Akola, Parbhani, Rahuri and Coimbatore. The study enables to understand the consumptive water demand of sorghum and water use efficiency in relation to yield. The results can be used for efficient management of both rainfall and limited water resources available for sorghum production.

Seasonal Evapotranspiration (ET) losses were studied for non- irrigated kharif sorghum at Akola and Parbhani and for Rahuri and Coimbatore seasonal ET losses were studied for rabi sorghum for well distributed normal and deficit rainfall years. In the normal rainfall years ET losses were more compared to deficit rainfall years. However, water use efficiency was found higher during deficit rainfall years than normal rainfall years. The seasonal ET- yield relationship was found positively correlated but insignificant for Akola, Parbhani, Rahuri and significant for Coimbatore (5% level). At Akola and Parbhani optimum yields were observed for seasonal ET of around 486 mm and 470 mm respectively. At Coimbatore maximum yield was observed for seasonal ET of 416 mm whereas at Rahuri yield was maximum when ET loss was about 475 mm. Water Use Efficiency (WUE) ranged from 6.3 to 12.2 mm for kharif season and 5.5 to 10.1 mm for rabi sorghum. Crop coefficient Kc was found negligible during early growth stages and reached peak during flowering stage and declined subsequently during maturity to harvesting stage.

The study revealed that during deficit rainfall years life saving irrigation need to be applied for all stations under consideration. If limited irrigation is available irrigations at vegetative stage (25-35 days after sowing) and at boot- flowering stage (55-65 days after sowing) be given. The boot stage is found to be the most critical stage and if only one irrigation is available, it may be given at this stage. Water stress at this stage is found to cause reduction in yield by 35 to 40%.
Understanding the mechanism of land-cover related climate change in the low latitudes
Authors: PAETH HEIKO 
Published: November 2021

Rainfall variability in the low latitudes in general and over tropical and sub-tropical Africa in particular, is largely affected by land surface characteristics like, vegetation cover, albedo and soil moisture. Understanding the local and dynamical effects of land-cover changes is crucial to future climate prediction, given ongoing population growth and increasing agricultural needs in Africa. Here, a set of sensitivity studies with a synoptic-scale regional climate model is presented, prescribing idealized scenarios of reduced vegetation cover over Africa. Beside the vegetation ratio itself, the leaf area index, forest ratio, surface albedo and roughness length are changed as well, in order to obtain a consistent scenario of land surface degradation. In addition, a second set of experiments is realized with altered soil parameters as expected to be coming alongwith a reduction in vegetation cover.

Seasonal rainfall amount decreases substantially when the present-day vegetation continuously disappears. The strongest changes are found over the Congo Basin and subsaharan West Africa, where the summer monsoon precipitation diminishes by up to 2000 mm and 600 mm, respectively. The rainfall response to vegetation changes is non-linear and statistically significant over large parts of subsaharan Africa. Convective precipitation is more sensitive than large-scale precipitation.

The most prominent effect of land degradation is a decrease (increase) of latent (sensible) heat fluxes. As a consequence, the large-scale thermal gradients, as a key factor in the monsoonal flow over Africa, are modified leading to a southward shift of the intertropical convergence zone and enhanced moisture advection over the southernmost part of West Africa and the central Congo Basin. The mid-tropospheric jet and wave dynamics are barely affected by land-cover changes. Although the large-scale dynamical response is favourable to increasing rainfall amount, the moisture budget is predominantly governed by reduced evapotranspiration, overcompensating the positive dynamical effect and inducing a weakening of the regional-scale water recycling. The related changes in the soil properties may additionally contribute to a reduction in rainfall amount, albeit of lower amplitude.
Activity of Madden Julian Oscillation during 2002 and 2006 – A comparative analysis
Authors: KHOLE MEDHA 
Published: November 2021

The Indian summer monsoon is characterized by very significant intra-seasonal variability. Madden-Julian Oscillation (MJO) is one of the dominant modes of the intra-seasonal variability of the Indian summer monsoon rainfall. The activity of Madden Julian Oscillation during the monsoon seasons of the two years of contrasting intra-seasonal rainfall variability has been examined in terms of rainfall activity over India and eastward propagation of convection in the near-equatorial region. The study shows the contrasting nature, viz., in the monsoon season of 2002, eastward mode dominated whereas in 2006, it remained suppressed.
Sub-divisional summer monsoon rainfall over India in relation to low pressure systems over the Bay of Bengal and adjoining land regions during 1982-1999
Authors: MOHAPATRA M. 
Published: November 2021

A study is undertaken to find out characteristic features of relationship of the low pressure system (LPS) over the Bay of Bengal and adjoining land regions with the rainfall over different meteorological sub-divisions of India during summer monsoon season (June-September). For this purpose, rainfall over 35 meteorological sub-divisions in India and LPS days over west central (WC) Bay, northwest (NW) Bay, northeast (NE) Bay, Bangladesh (BDS), Gangetic West Bengal (GWB), Orissa, north coastal Andhra Pradesh (NCAP), east Madhya Pradesh and Chattisgarh (EMPC) and Jharkhand (JKD) during different monsoon months and the season as a whole over a period of 18 years (1982-1999) are analysed. There is large month to month variation in the impact of the LPS on the sub-divisional monsoon rainfall over India. However, the results presented in the study including developed correlation maps may be helpful to predict 24 hours rainfall based on the location of the LPS and associated monsoon trough.

The frequent development and persistence of LPS over NW Bay are favourable for higher seasonal monsoon rainfall over east central India. The development and persistence of LPS over WC Bay adversely affect the seasonal rainfall over this region. On the other hand, the frequent development and persistence of LPS over WC Bay and its subsequent westward movement across NCAP are favourable for higher seasonal rainfall over the peninsular region excluding west coast. The seasonal rainfall over northwest India decreases with increase in LPS days over EMPC. The seasonal rainfall over west central India, northeast India and west coast are not significantly related with the number of LPS days over the regions under consideration.
Effect of weather on growth and yield of cotton grown in the dry farming tract of peninsular India
Authors: CHATTOPADHYAY N. , SAMUI R. P. , BANERJEE S. K. 
Published: November 2021

In the present study the effect of meteorological parameters on cotton growth at three different stations in the dry farming tract of peninsular India were studied critically. Increase in minimum temperature (above normal) particularly at vegetative and flowering stages favoured the yield of three varieties of cotton (AHH - 468, MCU - 9 and MCU - 10) under study. Decrease in maximum temperature at flowering and boll development stages was found to be conducive for the higher yield of AHH – 468 variety of cotton at Akola. In general, relative humidity was positively correlated with the yield of AHH – 468 varieties at Akola and MCU – 10 varieties at Kovilpatti. Lower values of bright sunshine hours (<5 hours) during vegetative and flowering were found to be helpful for increased yield of cotton at Akola. Rainfall at the beginning of the season favoured the yield of the crop.
Variability in dynamic and thermodynamic parameters in cyclogenesis over north Indian ocean
Authors: MUTHUCHAMI A. 
Published: November 2021

The two basins Arabian sea (ARS) and Bay of Bengal (BOB) of the North Indian Ocean (NIO) are having different dynamic and thermodynamic character and therefore ARS has subdued cyclone activity than BOB. In order to examine the difference between these basins in respect of various meteorological parameters, using NCEP/NCAR reanalysis data for the period 1971-2005 during the months of September to December the distribution of the dynamic and thermodynamic parameters are discussed. It is seen that sea surface temperature (SST) is not responsible for subdued activity over ARS as the SST over ARS and BOB is mostly above minimum threshold level. In respect of wind shear, during October in ARS north of 10° N is favourable for storm formation unlike September where the whole of Arabian sea except the region north of 20° N is inert to cyclone formation. The humidity factor is more pronounced in ARS for prohibiting storm formation than shear factor. In all the months static instability at 90° E is least and so the atmosphere is neutral throughout the period and consequence of it any small trigger in the lower level will induce the system to grow further. The BOB is more barotropic than ARS. There is a considerable difference exists in precipitation rate as a consequence of more stable atmosphere over Arabian sea than in Bay of Bengal even at the lower level.
Application of Neural Network Technique to improve the location specific forecast of temperature over Delhi from MM5 model
Authors: BHOWMIK S. K. ROY , NATH SANKAR , MITRA A. K. , HATWAR H. R. 
Published: November 2021

India Meteorological Department (IMD) has been using direct model output (2 meters height temperature) of MM5 model as numerical guidance for forecasting maximum and minimum temperature of Delhi in short range time scale (up to 72 hours). Performance statistics of the direct model outputs of the model for maximum and minimum temperature show that forecast skill of the model is reasonably good, particularly for the minimum temperature. For further improving the model forecast, Neural Network (NN) as well as regression techniques are applied so that the systematic errors of the direct model output of the model for maximum and minimum temperature could be reduced. The study shows that both Neural Network approach and regression technique are capable to improve the forecast skill of maximum and minimum temperature. Daily modified forecasts are found persistently closer to the observations when the method is tested with the independent sample. The methods are found to be promising for operational application.
Excess and deficient summer monsoon rainfall over Orissa in relation to low pressure systems
Authors: MOHAPATRA M. , MOHANTY U. C. 
Published: November 2021

A study has been undertaken to find out different characteristics like frequency, intensity, movement, region of occurrence etc. of low pressure systems (LPS) including low, depression and cyclonic storm etc. developing over Orissa and neighbouring sea and land regions during excess and deficient monsoon rainfall months (June – September) over Orissa. The study is based on data of 20 years (1980-1999). The principal objective of this study is to find out the contribution of LPS to extreme monsoon rainfall activity over Orissa.

The number of LPS days rather than frequency of formation of LPS over different regions better explain the excess and deficient rainfall over Orissa. The excess rainfall over Orissa during June is not significantly related with the number of LPS days. Significantly less than normal number of LPS days over northwest (NW) Bay of Bengal and Gangetic West Bengal (GWB) and higher number of LPS days over west central (WC) Bay off north coastal Andhra Pradesh (NCAP) cause deficient rainfall over Orissa during June. While significantly higher than normal number of LPS days over NW Bay and Orissa leads to excess rainfall during July, less than normal number of LPS days over WC Bay off NCAP is associated with excess rainfall during August. The less number of LPS days over Orissa due to less frequent movement of LPS across Orissa from the Bay of Bengal leads to deficient rainfall over Orissa during both July and August. Significantly higher/less than normal number of LPS days over NW Bay leads to excess/deficient rainfall over Orissa during September.
Simulations of frequency, intensity and tracks of cyclonic disturbances in the Bay of Bengal and the Arabian Sea
Authors: SINGH O. P. 
Published: November 2021

The paper presents the results of simulation experiments conducted for the assessment of likely changes in the cyclogenesis pattern in the Bay of Bengal (BOB) and the Arabian Sea (AS) resulting from global climate change. Two experiments were performed, namely the ‘control’ (CTL) experiment in which the greenhouse gas concentration in the atmosphere was fixed as per 1990 levels and the ‘greenhouse gas’ (GHG) experiment in which an annual compound increase of 1% from 1990 onwards was introduced. CTL and GHG experiments of 20 years length were performed for the period 2041-2060. The model used is the regional climate model Had RM2 of the Hadley Centre of Climate Prediction and Research, U.K.

The results have brought out some significant changes in the cyclogenesis pattern in the North Indian Ocean (BOB and AS). The most significant likely change is the increase in the frequency of post-monsoon storms in the Bay of Bengal. The experiments show an increase of about 50% in the post-monsoonal cyclogenesis by 2041-2060 as a result of increased greenhouse gas concentrations in the atmosphere. The frequency of monsoon depressions / storms in the BOB is likely to decrease considerably during June-August. Due to varying impacts in different seasons, the annual frequency of cyclonic disturbances may change marginally in the BOB. In the Arabian Sea, however the model has simulated a significant reduction in the frequency which may be halved by the period 2041-2060.
The results show intensification of storms during May-June and September-November. The monsoon depressions during July-August are likely to become less intense.

In GHG experiment most of the post-monsoon storms have a tendency to strike north Andhra-Orissa coasts whereas in CTL experiment the storms strike coast from Tamilnadu to south Orissa. Thus, the focus of post-monsoon storms in the BOB is likely to shift northwards from Tamilnadu-Andhra Pradesh coast to north Andhra Pradesh-south Orissa coast. Another important simulated change in storm tracks is that more number of pre-monsoon storms in the BOB may have a tendency to recurve north or northeastwards by 2041-2060.