Meteorological impacts on evapotranspiration in different climatic zones of Pakistan

Arid regions are highly vulnerable and sensitive to drought. The crops cultivated in arid zones are at high risk due to the high evapotranspiration and water demands. This study analyzed the changes in seasonal and annual evapotranspiration（ET） during 1951–2016 at 50 meteorological stations located in the extremely arid, arid, and semi-arid zones of Pakistan using the Penman Monteith（PM） method. The results show that ET is highly sensitive and positively correlated to temperature, solar radiation, and wind speed whereas vapor pressure is negatively correlated to ET. The study also identifies the relationship of ET with the meteorological parameters in different climatic zones of Pakistan. The significant trend analysis of precipitation and temperature（maximum and minimum） are conducted at 95% confidence level to determine the behaviors of these parameters in the extremely arid, arid, and semi-arid zones. The mean annual precipitation and annual mean maximum temperature significantly increased by 0.828 mm/a and 0.014℃/a in the arid and extremely arid zones, respectively. The annual mean minimum temperature increased by 0.017℃/a in the extremely arid zone and 0.019℃/a in the arid zone, whereas a significant decrease of 0.007℃/a was observed in the semi-arid zone. This study provides probabilistic future scenarios that would be helpful for policy-makers, agriculturists to plan effective irrigation measures towards the sustainable development in Pakistan.

The 12th Workshop on Antarctic Meteorology and Climate

1.Overview The 12th Workshop on Antarctic Meteorology and Climate（WAMC）,formerly known as the Antarctic Meteorological Observation,Modeling,and Forecasting（AMOMF）Workshop（AMOMFW）,was held at the National Center for Atmospheric Research（NCAR）in Boulder,Colorado,USA on 26–28 June 2017.The annual workshop dates from 2006,and recent meetings have been the 10th AMOMF Workshop held in 2015 in Cambridge,

Two Ultraviolet Radiation Datasets that Cover China

Ultraviolet（UV） radiation has significant effects on ecosystems, environments, and human health, as well as atmospheric processes and climate change. Two ultraviolet radiation datasets are described in this paper. One contains hourly observations of UV radiation measured at 40 Chinese Ecosystem Research Network stations from 2005 to 2015. CUV3 broadband radiometers were used to observe the UV radiation, with an accuracy of 5%, which meets the World Meteorology Organization＇s measurement standards. The extremum method was used to control the quality of the measured datasets. The other dataset contains daily cumulative UV radiation estimates that were calculated using an all-sky estimation model combined with a hybrid model. The reconstructed daily UV radiation data span from 1961 to 2014. The mean absolute bias error and root-mean-square error are smaller than 30% at most stations, and most of the mean bias error values are negative, which indicates underestimation of the UV radiation intensity. These datasets can improve our basic knowledge of the spatial and temporal variations in UV radiation. Additionally, these datasets can be used in studies of potential ozone formation and atmospheric oxidation, as well as simulations of ecological processes.

The research of sea-land breeze (SLB) on the west coast of Bohai Bay based on field observation

Four automatic meteorological stations were set up in a line from beach to inland perpendicular to the west coast of Bohai Bay. Wind direction and velocity at altitudes of 2 m, 4 m and 12 m were surveyed with 10 minute intervals. On ＂Sea-Land Breeze＂ （SLB） days, the transition from sea breeze to land breeze was very evident in the study area. Direction of sea breeze was basically perpendicular to the coast and mainly from the ENE and E. Duration of sea breeze varied by the stations＇ distance to the coastline, and the near-coast wind velocity was larger than that of the inland and decreases as it reaches inland. There was increased development of SLB on sunny days than on overcast days. The term ＂Climatic Coastal Zone＂ can be defined for the area influenced by SLB, which reaches more than 74 km inland on a typical SLB day but less than 10 km on a non-typical SLB day.

An Assessment of CAMS-CSM in Simulating Land–Atmosphere Heat and Water Exchanges

The Chinese Academy of Meteorological Sciences(CAMS)has been devoted to developing a climate system model(CSM)to meet demand for climate simulation and prediction for the East Asian region.In this study,we evaluated the performance of CAMS-CSM in regard to sensible heat flux(H),latent heat flux(LE),surface temperature,soil moisture,and snow depth,focusing on the Atmospheric Model Intercomparison Project experiment,with the aim of participating in the Coupled Model Intercomparison Project phase 6.We systematically assessed the simulation results achieved by CAMS-CSM for these variables against various reference products and ground observations,including the FLUXNET model tree ensembles H and LE data,Climate Prediction Center soil moisture data,snow depth climatology data,and Chinese ground observations of snow depth and winter surface temperature.We compared these results with data from the ECMWF Interim reanalysis(ERA-Interim)and Global Land Data Assimilation System(GLDAS).Our results indicated that CAMS-CSM simulations were better than or comparable to ERA-Interim reanalysis for snow depth and winter surface temperature at regional scales,but slightly worse when simulating total column soil moisture.The root-mean-square differences of H in CAMS-CSM were all greater than those from the ERA-Interim reanalysis,but less than or comparable to those from GLDAS.The spatial correlations for H in CAMS-CSM were the lowest in nearly all regions,except for North America.CAMS-CSM LE produced the lowest bias in Siberia,North America,and South America,but with the lowest spatial correlation coefficients.Therefore,there are still scopes for improving H and LE simulations in CAMS-CSM,particularly for LE.