NE Monsoon Research Articles

Variability of surface roughness and turbulence intensities at a coastal site in India

Surface-layer features with different prevailing wind directions for two distinct seasons (Southwest Monsoon and Northeast Monsoon) on the west coast of India are studied using data obtained from tower-based sensors at a site located about 500 m from the coast. Only daytime runs have been used for the present analysis. The surface boundary-layer fluxes have been estimated using the eddy correlation method. The surface roughnessz0 obtained using the stability-corrected wind profiles (Paulson, 1970) has been found to be low for the Southwest monsson season. For the other season,z0 is relatively high. The drag coefficientCD varies with height in the NE monsoon season but not in the season with lowz0. This aspect is reflected in the wind profiles for the two seasons and is discussed in detail. The scaling behaviour of friction velocityu* and the turbulence intensity of longitudinal, lateral and vertical winds σu, σv and σw, respectively) are further examined to study their dependence on fetch. Our study shows that for the non-dimensional case, σu/u* and σv/u* do not show any surface roughness dependence in either season. On the other hand, for σw/u* for the season with lowz0, the values are seen to agree well with that of Panofskyet al. (1977) for homogeneous terrain whereas for the other season with highz0, the results seem to conform more to the values observed by Smedman and Hogstrom (1983) for coastal terrain. The results are discussed in the light of observations by other investigators.

Coarse fraction fluctuations in pelagic carbonate sediments from the tropical Indian Ocean: A 1500‐kyr record of carbonate dissolution

Appendix Table Al Is available with entire article onmicrofiche. Order from the American Geophysical Union, 2000Florida Avenue, N.W., Washington, D.C. 20009. DocumentP94‐001; $2.50. Payment must accompany order. We examined coarse fraction contents of pelagic carbonates deposited between 2000‐and 3700‐m water depth in the tropical Indian Ocean using Ocean Drilling Program (ODP) sites 722 (Owen Ridge, Arabian Sea) and 758 (Ninetyeast Ridge, eastern equatorial Indian Ocean), and four giant piston cores collected by the French R/V Marion Dufresne during the SEYMAMA expedition. Over the last 1500 kyr, coarse fraction records display high‐amplitude oscillations with an irregular wavelength on the order of ∼500 kyr. These oscillations can be correlated throughout the entire equatorial Indian Ocean, from the Seychelles area eastward to the Ninetyeast Ridge, and into the Arabian Sea. Changes in grain size mainly result from changes in carbonate dissolution as evidenced by the positive relationship between coarse fraction content and a foraminiferal preservation index based on test fragmentation. The well‐known “mid‐Bruhes dissolution cycle”represents the last part of this irregular long‐term dissolution oscillation. The origin of this long‐term oscillation is still poorly understood. Our observations suggest that it is not a true cycle (it has an irregular wavelength) and we propose that it may result from long‐term changes in Ca++flux to the ocean. Sites 722 and 758 δ18O records provide a high‐resolution stratigraphy that allows a detailed intersite comparison of the two coarse fraction records over the last 1500 kyr. Site 722 (2030 m) lies above the present and late Pleistocene lysocline. The lysocline shoaled to the position of site 758 (2925 m) only during the interglacial intervals that occurred between about 300 and 500 ka (Peterson and Prell, 1985a). Despite these supralysoclinal positions of the two sites, short‐term changes in coarse fraction contents are correctable from one site to another and probably result from regional (or global) dissolution pulses. By stacking the normalized coarse fraction records from sites 722 and 758, we constructed a Composite Coarse Fraction Index (CCFI) curve in which most of the local signals cancelled out. The last 800 kyr of this curve appear to compare extremely well with the Composite Dissolution Index curve from core V34‐53 (Ninetyeast Ridge), which unambiguously records past variations of carbonate dissolution in the equatorial Indian Ocean (Peterson and Prell, 1985a). In the late Pleistocene the CCFI variations are mainly associated with glacial‐interglacial changes. They show strong 100 and 41 kyr periodicities but no clear precession‐related periodicities. As proposed earlier by Peterson and Prell (1985a), the lack of precession frequencies may suggest that the regional carbonate dissolution signal is driven by changes in deepwater circulation. We cannot totally reject the possibility, however, that low temporal resolution and/or bioturbation degrade somehow the precessional signal at ODP sites 722 and 758. In contrast, spectral density of dissolution cycles in the giant (53 m long) piston core MD900963 (Maldives area) displays clear maxima centered on the precession frequencies (23 and 19 kyr−1) as well as on the kyr−1 frequency but shows little power at the 100‐ kyr−1 frequency. These high‐frequency changes most probably result from changes in surface productivity associated with monsoon variability. Dissolution at this site may be ultimately controlled by the oxidation of organic matter which appears to be incorporated into the sediments in greater quantity during periods of weak SW monsoon and/or increased dry NE monsoon.

Fluxes of material in the Arabian Sea and Bay of Bengal — Sediment trap studies

In order to investigate how monsoons influence biogeochemical fluxes in the ocean, twelve time-series sediment traps were deployed at six locations in the northern Indian Ocean. In this paper we present particle flux data collected during May 1986 to November 1991 and November 1987 to November 1992 in the Arabian Sea and Bay of Bengal respectively. Particle fluxes were high during both the SW and NE monsoons in the Arabian Sea as well as in the Bay of Bengal. The mechanisms of particle production and transport, however, differ in both the regions. In the Arabian Sea, average annual fluxes are over 50gm-2y-1 in the western Arabian Sea and less than 27gm-2 y-1 in the central part. Biogenic matter is dominant at sites located near upwelling centers, and is less degraded during peak flux periods. High particle fluxes in the offshore areas of the Arabian Sea are caused by injection of nutrients into the euphotic zone due to wind-induced mixed layer deepening. In the Bay of Bengal, average annual fluxes are highest in the central Bay of Bengal (over 50gm-2y-1) and are least in the southern part of the Bay (37gm-2y-1). Particle flux patterns coincide with freshwater discharge patterns of the Ganges-Brahmaputra river system. Opal/carbonate and organic carbon/carbonate carbon ratios increase during the SW monsoon due to variations in salinity and productivity patterns in the surface waters as a result of increased freshwater and nutrient input from rivers. Comparison of S years data show that fluxes of biogenic and lithogenic particulate matter are higher in the Bay of Bengal even though the Arabian Sea is considered to be more productive. Our results indicate that in the northern Indian Ocean interannual variability in organic carbon flux is directly related to the strength and intensity of the SW monsoon while its transfer from the upper layers to the deep sea is partly controlled by input of lithogenic matter from adjacent continents.

Tropical stratospheric circulation and monsoon rainfall

Interannual variability of both SW monsoon (June–September) and NE monsoon (October–December) rainfall over subdivisions of Coastal Andhra Pradesh, Rayalaseema and Tamil Nadu have been examined in relation to monthly zonal wind anomaly for 10 hPa, 30 hPa and 50 hPa at Balboa (9°N, 80°W) for the 29 year period (1958–1986). Correlations of zonal wind anomalies to SW monsoon rainfall (r=0.57, significant at 1% level) is highest with the longer lead time (August of the previous year) at 10 hPa level suggesting some predictive value for Coastal Andhra Pradesh. The probabilities estimated from the contingency table reveal non-occurrence of flood during easterly wind anomalies and near non-occurrence of drought during westerly anomalies for August of the previous year at 10 hPa which provides information for forecasting of performance of SW monsoon over Coastal Andhra Pradesh. However, NE monsoon has a weak relationship with zonal wind anomalies of 10 hPa, 30 hPa and 50 hPa for Coastal Andhra Pradesh, Rayalaseema and Tamil Nadu. Tracks of the SW monsoon storms and depressions in association with the stratospheric wind were also examined to couple with the fluctuations in SW monsoon rainfall. It is noted that easterly / westerly wind at 10 hPa, in some manner, suppresses / enhances monsoon storms and depressions activity affecting their tracks.

Seasonality and interannual variability of particle fluxes to the deep Arabian sea

Long-term sediment trap studies have been carried out since 1986 at three locations in the western, central and eastern Arabian Sea. Here we present total and bulk component fluxes measured for 3 years at the central station and for 4 years at the western and eastern stations. Particulate fluxes to the deep sea are controlled by the monsoons with generally higher fluxes during the SW and NE monsoons and lower fluxes during the intermonsoon periods. The increase of particle fluxes occurs simultaneously with a drop in surface water temperature, induced by wind-or convective-mixing and an associated entrainment of nutrients into the euphotic zone. More than 50% of the annual particle fluxes to the deep sea occurs during the SW monsoon at the western location due to the prolonged influence of the monsoonal upwelling as indicated by increased biogenic carbonate and opal fluxes. However, the opal fluxes peak a month later than the carbonate fluxes. The delayed onset of opal flux peak appears to be controlled by the observed premonsoon silica distribution in the Arabian Sea, where the subsurface waters are silica depleted down to the thermocline at 150 m. At the central location particle fluxes are of similar magnitude during the SW and NE monsoons. The interannual variability of particle fluxes at the eastern location is determined by the NE monsoon. At the western and central locations, on the other hand, maximum interannual variability of fluxes occurs during the SW monsoon and particle fluxes were higher during years of stronger SW monsoon. The results further suggest that, apart from monsoon strength, geographic shifts of the area of maximum wind-stress may produce significant variabilities in particle fluxes to the deep ocean at the western Arabian Sea site.

Organic carbon removal in the sea: the continental connection

Abstract Time series sediment traps have been deployed since May 1986 in the Arabian Sea and since October 1987 in the Bay of Bengal. The results of one and a half years from the western, central, and eastern Arabian Sea and of one year from the northern Bay of Bengal show that particle flux patterns are related to the strong monsoon winds and heavy rains. Particle flux maxima in the Arabian Sea are mainly related to wind-induced deeper mixing and nutrient enrichment of surface waters during the SW and NE monsoons. Extremely high particle fluxes with high biogenic opal contents during the SW monsoon at the western location show that it is reached by nutrient-rich water from the near-shore upwelling centres. In the northern Bay of Bengal, particle flux maxima coincide with the period of maximum discharge of the Ganges and Brahmaputra rivers during which river plumes enriched in nutrients are advected into offshore areas. Additionally, the winds and river plumes supply enormous amounts of mineral matter during the periods of high productivity and high particle fluxes. The interaction between marine-biogenic material with eolian and fluviatile mineral particles plays a key role in sedimentation. The incorporation of mineral matter into biologically formed aggregates ensures their rapid sedimentation and thus enhances the removal of biologically fixed atmospheric carbon dioxide to the deep sea.

Last 20,000 years of climatic change

Recent evidence, especially from continental Asia, shows that there are marked latitudinal differences in global climatic changes. From India, we now have new evidence from Kashmir, Rajasthan and the Arabian Sea which shows that in the north (35°- 40° N latitude) warming had started c. 20,000 yrs BP in Kashmir, Ladakh and Nepal when in higher latitudes it was still the Last Glacial Maximum (LGM). At c. 18 Kyr, Butapathri (Kashmir) bogs show emergence of thermophilous plants like Alnus, Juglans, Carpinus at the cost of conifers. A palaeosol on the loess profile of Kashmir is datable to c. 18 Kyr which again shows climatic amelioration. Organic matter from this palaeosol gives δ 13C values of about -24‰ indicating that it was derived from C3 type of vegetation. Presence of an Upper Palaeolithic culture at this time, in Kashmir, again confirms a period of climatic amelioration.
 From Ladakh, Bhattacharya has inferred climatic amelioration from the higher percentage of Juniper during 20- 20 Kyr period. Similarly in Nepal, a climatic amelioration is indicated. In Rajasthan, c. 18 Kyr is a period of aridity. Maximum sand building activity is TL dated by Singhvi to c. 14 Kyr and just preceeds the strengthening of the monsoon in c. 13 Kyr. Upwelling at c. 13 Kyr in the Arabian Sea has been reported by Anderson et at. (1990) and the French group has shown a similar evidence of monsoon strengthening at c. 13 Kyr based on pollen evidence fom African lakes. Unfortunately, we have only one 14C date from Butapathri which shows that at c. 10 Kyr the cooler oscillation was on its way out and warming had gradually started. We need more closely spaced 14C dates for such profiles. In the Arabian Sea cores the spike at c. 18 Kyr of freshwater (low salinity, low δ 18O, high δ 13C) has been interpreted variously as due to the strengthening of NE monsoon or due to Tibetan ice melt. The role of Tibet in climate forcing is being emphasized by multiple new data. It will be relevant to know what was happening in peninsular India during this period.

Glacial to interglacial contrasts in the calcium carbonate content and influence of Indus discharge in two eastern Arabian Sea cores

Two cores collected in the eastern Arabian Sea were studied for coarse fraction, calcium carbonate content and Globorotalia menardii complex abundance. Based on the fluctuations of calcium carbonate and G. menardii complex abundance, the Holocene/Pleistocene boundary is placed at 50 cm level from the top of the core and the Last Glacial Maximum (LGM) at 80 cm depth for the northern Arabian Sea core. While for the southern Arabian Sea core the boundaries of Holocene/Pleistocene and LGM are placed at 40 cm and 65 cm respectively. The carbonate content and G. menardii complex abundance variations in these cores reveal that carbonate maxima with less abundance of G. menardii complex reflects glacials (cold periods). While carbonate minima with high abundance of G. menardii complex reflects interglacials (warm periods). High percentage of coarse fraction and CaCO 3 during glacials attributed to high productivity, low percentage of coarse fraction and CaCO 3 is due to less productivity during interglacials. Productivity variations during glacial and interglacial periods in the Arabian Sea is discussed in relation to SW and NE monsoon intensities. Northern Arabian Sea core shows less CaCO 3 during Holocene period and high during periods suggesting that the dilution by terrigenous flux derived from the Indus river is significantly lower during glacial periods than in the Holocene period.

Influence of monsoonally-forced Ekman dynamics upon surface layer depth and plankton biomass distribution in the Arabian Sea

Oceanic surface layer properties in the central Arabian Sea at the height of the northeast 1986, 1987 and southwest 1987 monsoons are described. Data from two research cruises on the R.R.S. Charles Darwin are combined with Comprehensive Ocean—Atmosphere Data Set (COADS) winds and a simple model to consider the influence of the monsoons on the surface layers of the Arabian Sea. In December 1986 (NE monsoon) the top of the thermocline was fairly uniform with a mean depth of approximately 60 m. In contrast, this depth varied with latitude in the SW monsoon, with the shallowest depths occurring under the region of maximum winds and the maximum depths to the south of the monsoon jet. This situation is tied to the Ekman flow which leads to open ocean upwelling to the north of the wind maximum, thus suppressing the development of the mixed layer. The thermocline to the south is deepened by a combination of Ekman pumping and advection of dense fluid from the north. A simple two-dimensional model incorporating a non-penetrative mixed layer and a slab Ekman layer flow is used to examine the factors involved in the evolution of the surface layers during the monsoons. The combination of upwelling and surface layer deepening leads to latitudinal gradients in phytoplankton biomass. The major effect in the SW monsoon is the upwelling induced by Ekman dynamics and a consequent shoaling of the nitracline in the northern Arabian Sea. Vertical mixing and the associated deepening of the surface layer dominate phytoplankton distributions in the NE monsoons.

Cloud patterns in the NE monsoon season

The rainfall over Tamil Nadu during the NE monsoon occur mostly in association with low pressure areas and depressions. With the advent of satellites. It has been possible to study the weather systems in greater detail. In this study, the daily NOAA-data for the NE monsoon season (October and November) for the period 1979-1985 has been utiliied to classify the synoptic systems Into several cloud patterns. It has been found that the most frequently occurring cloud patterns are the amorphous and the banding type. The occurrence of the cloud patterns vis-à-vis synoptic situations has been analysed and meaningful results obtained.

Withdrawal of southwest monsoon 1985 -Diagnostic study of cyclonic storms and onset of northeast monsoon

In this paper a study has been made of the four cyclonic disturbances that formed in the first fortnight of October 1985 in the Indian seas. The longitude, where these disturbances recurved, progressively advanced from 75° E to 90° E. This is due to the displacement of a quasi-stationary westerly trough in the upper atmosphere from 70° E to 90° E, which further led to the withdrawal of SW monsoon and onset of NE monsoon. The entire development process and steering of these disturbances took place because of their interaction with the westerly troughs of middle latitude.
 

Seasonality in East Africa's coastal waters

A review of existing literature and data on seasonal patterns in East Africa's coastal waters indicates distinct seasonality in physical, chemical and biological oceanographic parameters. Seasonal patterns are dictated by the behavior of the Inter-Tropical Convergence Zone (ITCZ) which creates 2 distinct seasons the northeast and southeast monsoons. SE monsoon (March to October) meteorological parameters are characterized by high cloud cover, rainfall, river discharge, terrestrial runoff and wind energy while solar insolation and temperatures are low; SE monsoon oceanographic parameters are characterized by cool water, a deep thermocline, high water-column mixing and wave energy, fast currents, low s a h ~ t y and high phosphorus. These parameters are reversed during the NE monsoon. Nitrogen availability and planktonic primary productivity are high along the Somali coast and estuarine and river discharge areas during the southeast monsoons due to nutrient upwelling and terrestrial runoff. In near-shore waters off Tanzania, nitrogen fixation is the major source of nitrogen and is highest during NE monsoons when the water column is stable. Coral reef benthic algal biomass and diversity is greatest during the SE monsoons. Fish catch and reproduction are highest during NE monsoons in Kenya and Tanzania. Transition periods between monsoons may also be important times in determining productivity and reproduction.

On the Kuroshio branch in the Taiwan strait during wintertime

Past investigations reported that warm and saline waters originating from the Kuroshio region occupied the northern South China Sea (NSCS) during wintertime. These waters were called a branch of the Kuroshio, and an offshoot of them was long believed to flow persistently along the west coast of Taiwan, contrary to the winter NE monsson. However, these descriptions are not completely consistent with recent evidence. Field measurements in the eastern Taiwan Strait now available display a quasi-stationary oceanic front, whose alignment is roughly normal to the transverse of the strait, which separates the warmer, more saline water to the south, from the colder, fresher China coastal water in the north during most of the winter. This feature implies the further northward movement of southeasterly Kuroshio water having been stagnated by cold waters to the north of the front. Therefore, the intruded Kuroshio water driven by the NE monsoon tends to accumulate in the NSCS, and eventually establishes an anti-cyclonic warm core eddy there. The first event of the intrusion of warm waters from the eddy into, or even through, the Taiwan Strait usually appears when the NE wind weakens from a strong cold-air outbreak in winter or early spring. We believe the inception of the Kuroshio branch in the strait starts from such an intrusion event.

The seasonality of monsoonal primary productivity in Sri Lanka

The relationship between phytoplankton primary production and seasonality of physico-chemical parameters were examined for five man-made lakes in the dry-zone of Sri Lanka. Sri Lanka experiences two monsoons dividing the year into four meteorological seasons: — the North East (October–December) and South West (April–June) monsoons and the two inter-monsoons. A significant log linear relationship was found between Secchi disc depth and the depth of the euphotic zone which was lowest during the NE monsoon. Maximum mean photosynthetic rate ranged from 0.935 ± 0.067 SE to 0.479 mg O2l−1 h−1 ± 0.115. Gross primary productivity which ranged from 0.378 g O2 m−2 h−1 in the NE monsoon to 0.980 g O2 m−2 h−1 in the SW monsoon showed significant season variation. This is shown to be determined either directly or indirectly by the light regime.

Variations of the monsoon regime during the upper quaternary: Evidence from carbon isotopic record of organic matter in North Indian Ocean sediment cores

The 13C/ 12C ratios and contents of organic carbon in deep sea sediment cores of the North Indian Ocean have been compared for the different climatic stages as determined by oxygen isotope stratigraphy. Using the differences in the δ 13C values between marine and terrestrial organic matter, the terrestrial contribution to the eastern Gulf of Bengal and the Andaman Sea has been determined for modern and glacial times. The geographical distribution of the terrestrial organic carbon linked to sea surface circulation shows that during the last glacial period, the NE monsoon circulation was the dominant feature. The organic carbon abundance within the sediment, which is related to local productivity, was greater during glacial times in the areas where production depends on the NE monsoon strength (coast of North India in the Arabian sea and Andaman sea) suggesting its reinforcement.

Plankton of the Red Sea and the Arabian Gulf

Though presenting some similarities, the Red Sea and the Arabian Gulf differ much in their configuration, hydrography and plankton populations. Both the recruitment of pelagic organisms into the Red Sea from the Gulf of Aden and their subsequent northward diffusion within the Red Sea basin, and the fluctuations in biomass and primary productivity are governed by the circulation pattern, which is itself dependent on the periodical Monsoon wind systems. The species diversity of Red Sea plankton is reduced relative to the Indian Ocean, but much higher than that of the Arabian Gulf. An indigenous assemblage of dinoflagellates, tintinnids, copepods and chaetognath species, however, appears to be well adapted to the conditions of this sea. Their wide distributions do not depend on the seasonal inflow. As a rule both the primary productivity and the zooplankton biomass are higher during the NE monsoon. The southern Red Sea is more productive than the northern with the two zones being separated by a low-productivity discontinuity zone at about 20° to 25°N, which is the zone of wind convergence in summer. More than 95% of the zooplankton biomass occurs in the upper 1000m and several endemic species have been reported. The Arabian Gulf is a vast, relatively shallow lagoon connected to the Gulf of Oman through the narrow strait of Hormuz. Circulation is anti-clockwise. Along the Iranian coast salinity rises from 36.6% near the strait to 40.6% in the NE Gulf and even higher along the Arabian coast. The Indian Ocean bathypelagic species as well as the dinoflagellate “Schattenarten” are completely missing from the Gulf. The species diversity is much poorer than that of either the Gulf of Oman or the Red Sea. An indigenous community, however, has developed which at first sight appears to be uniformly distributed especially along the Iranian coast, which is dominated by copepods and myodocopid ostracods. Some horizontal zonation is observable. Both nutrient and biomass concentrations are higher in mid-basin than in coastal waters. The Shatt-el-Arab to Kuwait area where estuarine components are not uncommon, and cladocerans replace ostracods in importance, is more productive and more diversified than the Trucial coast.

RELATIONSHIP BETWEEN ALONGSHORE WAVE ENERGY AND LITTORAL DRIFT IN THE MID-WEST COAST AT TAIWAN

Based on the wave pattern, the geographical location and the disposition of rivers, the littoral drift moves predominantly from NE to SW direction in section II as shown in Fig. 1. Seven rivers of rapid stream bring tremendous amount of sediments from the high mountain to the nearshore of this section in typhoon season (i.e. from June to September). But for the winter monsoon season, i.e. from October to the next April, the waves induced by NE monsoons migrate littoral drift from North toward South. Applying the energy approach for unidirectional steady flow derived by Bagnold(1963), the theoretical relationship between the littoral immersed weight transport rate and the alongshore breaking wave energy is found out. It reveals that the relationship is not strictly linear, i.e. the larger part of the alongshore breaking wave energy is supplied for transporting the sediment as the former increases. But for a coast having a steady oceanographical condition, the relationship could be considered as linear relation since the alongshore breaking wave energy is not varying very much. In this paper, the study of littoral drift vs wave energy at the Taichung Coast from the Ta-Chia River to the Ta-Tu River will be carried out. Using the wave records gained by the ultrasonic wave gauge at 19m depth and the littoral drift quantity obtained from long-term observation, the relationship between alongshore breaking wave energy and littoral immersed weight transport rate is found out. First, the waves which have the same direction are summed up. Then from "THE WAVE CHARACTER COMPUTING PROGRAM", the incident directions of these wave groups at 19m depth are determined. Then the alongshore breaking wave energy per unit time per unit length of beach could be calculated by the same PROGRAM.

Periodicity in rainfall at Madras

Monthly rainfall data from Madras for the period 1813–1976 are spectrally analysed for detection of significant oscillations using the new data adaptive technique of maximum entropy developed by Burg. Spectra for annual, NE monsoon and SW monsoon rainfall are separately presented and compared with the spectra derived from Fourier transform using FFT. The long series of data are divided into several subsets and analysed to determine the stability of the periodicities. The effect of changing the length of PEF on the resultant spectra is also discussed. The analysis reveals that longer period variations (>20 years) in the rainfall is either absent or non-stationary. Solar-cycle periodicity of 11 years is also missing in the rainfall. A quasibiennial oscillation in the annual and monsoon rainfall is observed in all the subsets and in the full series. Stacked spectrum derived from the spectra of monthly rainfall series for 30-year spans is dominated by the annual line and its harmonics. The biennial pulse is absent in the monthly rainfall series.

The planetary boundary layer over the Arabian Sea during the NE monsoon- A numerical study

This paper describes the results of numerical simulation of atmospheric boundary layer over Arabian Sea during NE-Monsoon season. A one-dimensional air-sea interaction model was used to simulate the vertical profiles of momentum, heat and moisture fluxes as well as the interface and near-surface meteorological elements which are important in determining the surface layer energy transports. The in simulation experiments were based on initial data obtained from observations made during February-March 1964 over the eastern part of the Arabian Sea.
 The results demonstrate that the model simulated vertical profiles of temperature and wind are in general agreement with observed structure of the atmospheric boundary layer over Arabian Sea. Comparison with observations of sea surface temperature and near-surface wind and humidity shows that the model is capable of realistic simulations. The model results include the vertical profiles of eddy fluxes of sensible heat, moisture and momentum within the atmospheric boundary layer.

Microclimate over a cotton crop in central Thailand, of special relevance to crop spraying

Wind direction, speed and gradient; insolation; temperature and temperature gradient over a cotton crop in central Thailand have been measured using appropriate sensors and recording equipment over a period of five days coinciding with the autumn transition from SW to NE monsoon. Diurnal and shorter period fluctuations have been analysed with regard to their possible influence on the efficient application of chemical insecticides as fine sprays or aerosols.