Annual Report 2004-2005

Scientific Research

Himalayan Glaciology

The programme is aimed at understanding the behavior of glaciers in general and their interaction with climate and hydrological systems in the region as also to train manpower and create research and development related facilities in this vital area of societal relevance. The programme is overseen by the Programme Advisory and Monitoring Committee on Himalayan Glaciology (PAMC-HG). During the period under report, the PAMC-HG met twice. The PAMC-HG reviewed progress of the on-going projects as also achievements made under the completed projects. The Committee also considered new proposals for funding and deliberated on various issues for overall development of the Himalayan Glaciology Programme. A brief account of the progress made in respect of individual projects under Gangotri Glacier and Dokriani Bamak Glacier is given below:

Studies on Gangotri Glacier

The Gangotri Glacier was studied through multi-disciplinary projects particularly dealing with remote sensing, microwave remote sensing, isotopic and chemical studies, palaeo-climatology, climate change, microbial-biodiversity and environmental quality studies etc. Most of the projects sanctioned in above mentioned areas have been completed. Significant field data have been acquired and useful infrastructure facilities on glacier site have been created for further research purpose.

A permanent station at Gangotri near Bhojbasa has been built by Snow & Avalanche Study Establishment (SASE), a DRDO set up. Weather data is being acquired through the observatory at Bhojbasa. All weather parameters are recorded twice a day as per WMO standards manually by the trained observers. Three Automatic Weather Stations (AWS) have been established in the area: Bhojbasa, Kalindipass and Nandaban. One VHF radio communication link has been established between the observatory at Bhojbasa and R.D.C., SASE.

Integrated Studies on Dokriani Bamak Glacier

The studies on Dokriani Bamak in the Bhagirthi River catchment have focused on atmospheric deposition on Dokriani Bamak Glacier, glacier mass balance, glacier runoff and its effects on the river hydrologic regime, sediment transfer from glacierised and non-glacierised regions and hydrometeorology on Din Gad catchment. Three discharge and three meteorological stations were established in the Din Gad catchment to monitor discharge, suspended sediment concentrations (SSC) and meteorological parameters.

New Projects

• Training course on Microwave Remote Sensing data processing and analysis for glacier and snow studies.
• Optical & Microwave remote sensing of snow variations in Gangotri and Satopanth Glacier areas in Uttaranchal Himalayas.
• Paleo-glaciation studies of upper Alaknanda catchment (upstream to Mana) with special reference to pro-glacial geomorpholgy of Satopanth and Bhagirath Kharak glaciers.
  
• Seasonal characterization of ablation, storage and drainage of melt run-off and simulation of stream flow for the Gangotri glacier.
• SAR data analysis for snow packs characteristics and glacier movement studies on angotri glacier.
• Geohydrological studies and quantification of sediment load of Gangotri glacier system, Uttarancal Himalayas.

Atmospheric Dynamics and Modelling

The analysis of the space-time variations of the heat sources over India during the monsoon season has brought out intra-seasonal variations of heating rate and drying rates over north-west India and Tibetan region. Increased convection in this belt, north of the monsoon trough area due to increased activity of the eastward moving cyclonic circulations over north-west India during monsoon 2002 changed the normal east-west heating gradient across the monsoon trough and affected the monsoon circulation over India adversely. These features were not seen during monsoon 1997 and the season turned out to be a normal monsoon season. The study confirmed the earlier results for monsoon 1979.

Modelling studies were carried out using T80 spectral GCM and a Regional Climate Model (RegCM3). Model simulations demonstrate that high (low) Eurasian snow depth in spring is followed by deficient (excess) IMR. Model simulations also show weak (strong) seasonal mean lower level monsoon westerlies and upper level easterlies in response to high (low) April snow over Eurasia. The simulations by spectral GCM indicate that area weighted average rainfall over India during June to September months are close to the observed rainfall. However, spatial distribution of rainfall over different parts of India does not agree well with the observations. RegCM3 over the Indian region was integrated with two different convective schemes at a resolution of 55Km. Preliminary results showed that the model was able to simulate the monsoon circulation over India reasonably well. Studies are underway to explore the significance of physiographic features in the land surface processes and feasibility of their parameterization to use in a GCM, in the perspective of Indian monsoon. Expansion of forest over north-west India is identified to influence the Indian summer monsoon circulation.

Ocean –Atmosphere Coupling

A two dimensional numerical model was developed to study the upper ocean dynamics and thermodynamics. The model was used to simulate mixed layer temperature, depth and inter-annual variability in the sea surface temperature. The model could simulate the observed dipole mode events. Study of air-sea interaction using Bay of Bengal Monsoon Experiment (BOBMEX) data was initiated.

Atmospheric Chemistry

Monitoring of ambient air quality and surface ozone in Kullu Manali Tourist Complex is being carried out. High concentrations of total suspended particulate matter (TSP) and particulate matter below 10 microns in size (PM10) in a particular month or season at Mohal and Kullu may be due to vehicular emission during peak tourist season and biomass burning during winter. Washout effect due to rain results in minimum level of TSP and PM10. The monthly SO2 level recorded at Mohal and Kullu are less than the ambient air quality standards. Precipitation samples were collected in eight different environments around National Capital Region of Delhi during the monsoon season and analyzed. Rain water was found to be alkaline in nature with an average pH value of 6.22. Study to assess the impact of urban air pollution and climate variability on respiratory health in Delhi, indicated a weak association between air pollution and respiratory health.

A study on the aerosol optical properties over Kanpur region was initiated. The seasonal difference between inter-annual variability of Aerosol Optical Depth (AOD) at 500nm wavelength reveals the fact that the nature of dust loading during the pre-monsoon season is not changing in recent period, whereas local pollution level showed marked increase. The volume concentration of aerosol particles is similar during post monsoon and winter seasons, which is very unusual in an urban site. Studies of aerosol, black carbon, ozone and carbon monoxide load and their sources and impacts in Chattisgarh were initiated. Seasonal and temporal variation of SPM is being studied. A decrease in SPM concentration during the study period is observed.

Agrometeorology

The Expert Committee on Agrometeorology has submitted the national status report on Agrometeorology. Development of short-term aphid forecasting models at Ludhiana was initiated.

The weekly aphid population data and corresponding meteorological data during the crop season is being collected. Organized field experiments on Brassica, Sunflower and Groundnut at Ludhiana, to calibrate and validate the simulation models and conduct sensitivity analysis under Punjab conditions. A Soil-Plant- Atmosphere-Water (SPAW) model was used to simulate soil moisture profile in sandy loam soil at Anand under wheat crop. The required information was incorporated in the model. The simulated values indicated more fluctuations of soil moisture in the upper layer. The study revealed that SPAW model could be successfully used for simulating the moisture content of the soil profile under wheat crop.

Crop-weather interaction studies in sole crops and inter-crops in Coconut based cropping system are being carried out. The initial results indicate that both banana and ginger are the best companion crops with respect to each other and also in coconut garden. A study aimed at quantitative understanding of ‘Crop-climate interactions’ of soybean genotypes under field conditions was completed at Jabalpur. Crop growth, development and yield were recorded for different phases along with meteorological parameters. Cardinal limits and sensitivity of soybean genotypes to temperature and photoperiod were estimated. The study indicates that temperature is the most dominating factor that controls the development.

Studies on the influence of micro-climatic changes on the economic losses in layers in Namakkal area of Tamilnadu were completed. The study revealed that the ambient temperature significantly influence hen day egg production of birds. Feed consumption decreased as ambient temperature increased. High humidity is not favorable to egg type chicken. Under moderate humidity, the egg production was found to be satisfactory. High humidity resulted significantly in more egg breakage. Dry weather is favorable for layers, but, more mortality was recorded at low humidity.

Technology Development

The indigenously developed Wind Profiler - Radio Acoustic Sounding System (WP/RASS) for continuous atmospheric monitoring was made operational at Pune. Wind Profiler data archival and utilization centre was established. Necessary software was developed for analyzing the data. A web site for WP/RASS has been designed and is being uploaded as a part of IITM website.

Studies related to temporal and spatial variability of climate, past climate and climate change and relationships between climate and agriculture are being coordinated under ICRP. Special emphasis was given to evolve and implement multi-agency, multi-disciplinary coordinated field experimental campaigns to investigate the land-ocean-atmosphere interactions and their role in monsoon variability. Successfully planned and completed the observational campaigns of the Arabian Sea Monsoon Experiment (ARMEX) under ICRP. The initial results of the ARMEX were published as a special issue of Journal ‘Mausam’, January 2005. The salient achievements under the programme are as follows:

Prediction of the Indian Summer Monsoon

Long range monsoon forecasting is an important problem with implications in varied socioeconomic sectors. Modeling the monsoon behavior towards developing an efficient monsoon prediction from 10-30 days and seasonal scale is very much essential. To deliberate on this, a ‘Workshop on Extended Range Monsoon Prediction (ERMP)’ with focus on application of General Circulation Models, was organized at Space Applications Centre, Ahmedabad, during March, 2004. It was observed that considerable R&D effort is required towards understanding the physics and dynamics in modifying existing models to the level at which they could simulate realistically the sub-seasonal variation of the monsoon, so that they can be used for generating extended range predictions. In order to prepare the Science and Implementation Plans for ERMP, four Working Groups were constituted on the following i) Observational Systems; ii) Models and Diagnostics; iii) Computing and Human Resources; and iv) Field Campaigns. The reports of the Working Groups are being prepared to finalize the action plan.

Role of teleconnections in the prediction of monsoon rainfall

Impact of ENSO (El Nino Southern Oscillation) events on Indian summer monsoon rainfall (ISMR) is modulated by the decadal behavior of monsoon rainfall and depends on the prevailing epoch. Snow depth variations over Western (Eastern) Eurasia are negatively (positively) correlated with ISMR. Smaller snow cover area over Western Himalayan region during May and faster snow melt from winter to spring is conducive for good monsoon.

Monsoon variability in relation to NAO (North Atlantic Oscillation) and ENSO, and its use for predicting monsoon rainfall on smaller spatial and temporal scale was completed. The relationship between NAO and Southern Oscillation (SO) is found to be very strong and can be used as a predictor for the seasonal prediction of monsoon. The winter time NAO modes seem to be quite useful in many occasions for predicting extreme monsoon years. The Regional Pressure Index (RPI) over the north-western region, in the month of May can be used as a predictor for monsoon rainfall over Central North East India. For extreme monsoon years, NAO and SO are in favor of monsoon circulation and in deficient monsoon years, either one or both of them are not in favor of monsoon circulation. The Effective Strength Index (ESI) during December-February and March- May seasons show an inverse association with cyclogenesis over North Indian Ocean.

Palaeoclimatology

The increment core samples of Himalayan cedar and Silver Fir were collected from various moisture stressed as well as mesic sites in Uttaranchal and Himachal Pradesh and analyzed. The longest chronology of Himalayan Cedar prepared so far, in the context of India, spans from AD 797-2002 (1206 years). The 1200 year long chronology shows the lowest growth during the late 9th to 11th centuries and the highest growth during the 12th century. The ring width chronology showed negative correlation with temperature and positive correlation with precipitation.

Preparation of rainfall Atlas

An Atlas on the spatial features of moisture regions and rainfall of India during 19th and 20th centuries is under preparation. Prepared longest instrumental monthly, seasonal and annual rainfall for the whole country, seven homogeneous rainfall zones, different states, different meteorological sub divisions and different major river basins. The preparation of Atlas is in final stage.

Arabian Sea Monsoon Experiment (ARMEX)

The second phase of the Arabian Sea Monsoon Experiment (ARMEX) was completed successfully. The main aim of this large-scale land-ocean-atmosphere field experiment was toobtain more insight into the intricacies involved in the formation and development of the off-shore vortex and the warm pool over the Arabian Sea. About 24 organizations participated in this national endeavor. All the observational data sets are collated as per the ARMEX data management plan. The quality checked data sets were made available to the Indian scientific community for detailed analysis. A national Workshop on ARMEX was organized to discuss the initial results.

The genesis, intensification and movement of off-shore trough/off-shore vortex and associated heavy rainfall events was synoptically analyzed using observations from ARMEX field campaign and available satellite data sets. Numerical experiments were carried out using the MM5 model with double nested domain to study the heavy rainfall events. The data was analysed to understand the atmospheric and oceanic conditions that prevailed during July 2002 and the mechanism that possibly led to this. Sea Surface Temperature (SST) and atmospheric temperature was well above the convection threshold. A persistent atmospheric inversion near 800hpa level inhibited during July, weak phase of convection associated with the intra-seasonal oscillation resulted in deficit monsoon. The MM5 model with improved initial conditions was able to reasonably capture the location and intensity of the mid-tropospheric cyclonic circulation.

Automatic weather stations were installed for obtaining high spatio-temporal resolution data required for ARMEX. Realising the importance of a reliable and large capacity data logger, efforts are on to develop a data logger. Weather summary during the ARMEX period was prepared. Data obtained during ARMEX was processed and distributed to the participating institutions. During July 2002, the boundary layer moisture convergence was inhibited as a result of reduced convective heating in the middle and upper troposphere and the resulting lack of compensating upward motion. The upper air profiles simulated using the 1D model as a validation of the high resolution upper air data, obtained for the first time at Goa, compared very well.

Vertical temperature profiles and sea surface water samples were collected along Kochi- Lakshdweep route using ships of opportunity. Spatio-temporal evolution of temperature inversions in the Lakshdweep sea region indicate temperature inversions, migrated westwards with time. The presence of temperature inversions during early December in the Lakshdweep sea region coincides with the arrival of low salinity waters from the Bay of Bengal. These inversions and low salinity water propagated westwards. Model results also confirmed the occurrence of inversions that contribute to heating the low salinity layer above, thus playing an important role in the heat budget of the warm pool.

Airborne measurements of size distribution aerosols and atmospheric electrical conductivity show higher concentrations in all size ranges of aerosols over land than over sea. Further, smaller aerosols can extend over sea to longer distances from the coast line while larger particles settle down under gravity comparatively closer to the coast line. Electrical conductivity values are generally lower during the pre-monsoon period than during the monsoon period. This increase in conductivity may be caused by the highly charged large ions produced at the sea surface by wave braking and bubble burst due to high winds during the monsoon period. Chemical composition of aerosols indicated that sea salt is the major contributor to the total ionic composition of aerosols during the monsoon season and the anthropogenic ions i.e.SO4 and NO3 are the major contributors during the pre-monsoon season.